TY - JOUR TI - Functional response and switching behavior of young-of-the-year piscivorous bluefish AU - Buckel, Jeffrey A AU - Stoner, Allan W T2 - Journal of Experimental Marine Biology and Ecology AB - Young-of-the-year (YOY) bluefish, Pomatomus saltatrix (L.) impose significant mortality on recently metamorphosed striped bass, Morone saxatilis (W.) in the Hudson River estuary. Field observations indicate that bluefish selectivity on striped bass increases with increasing striped bass density suggesting a density-dependent feeding response. Functional response and switching experiments were conducted to aid in determining the mechanism for this response. The type of functional response exhibited by bluefish under several prey treatments was examined. These were striped bass alone, Atlantic silversides, Menidia menidia (L.) alone, striped bass with a background density of alternative prey, and striped bass in the presence of eelgrass Zostera marina (L.). The functional response of bluefish to increasing prey density was more similar to a type I or II model than a type III model under all treatments. Switching was examined by providing bluefish both striped bass and silversides at five different ratios with and without a prey refuge, eelgrass. Bluefish did not exhibit a type III functional response or switching behavior suggesting that these mechanisms do not explain the observed density-dependent selectivity pattern in the field. Switching experiments did suggest that the presence of prey refuge can determine selectivity by YOY bluefish in the field. The abundance of submerged aquatic vegetation and other prey refuge may be important in controlling the predatory impact of bluefish on striped bass in the Hudson River. DA - 2000/3// PY - 2000/3// DO - 10.1016/s0022-0981(99)00155-0 VL - 245 IS - 1 SP - 25-41 J2 - Journal of Experimental Marine Biology and Ecology LA - en OP - SN - 0022-0981 UR - http://dx.doi.org/10.1016/s0022-0981(99)00155-0 DB - Crossref ER - TY - CONF TI - Complicated Urinary Tract Infections In 100 Dogs: A Retrospective Study AU - Seguin, A. AU - Vaden, S. AU - Levine, J. AU - Stone, E. T2 - American College of Veterinary Internal Medicine C2 - 2000/5// CY - Seattle, Washington DA - 2000/5// PY - 2000/5// ER - TY - SOUND TI - Adult and Kitten Survival Time of Feral Cats in Managed Colonies in Randolph County AU - Nutter, F.B. AU - Levine, J.F. AU - Stoskopf, M.K. DA - 2000/6// PY - 2000/6// ER - TY - CONF TI - Prevalence of Bacterial Foodborne Pathogens in Shellfish AU - Tlamka, B AU - Pitts, T AU - Levine, Jf AU - French, Je AU - Mare, Cj AU - Joens, La T2 - Conference of Research Workers in Animal Diseases (CRWAD) C2 - 2000/12// CY - Chicago, IL DA - 2000/12// PY - 2000/12// ER - TY - NEWS TI - Earthquakes and Weather: Lessons for Policy and Science T2 - Weatherzone PY - 2000/4// ET - 21 M3 - Guest editorial PB - University Corporation for Atmospheric Research ER - TY - JOUR TI - Business and political dimensions in disaster management AU - Birkland, T.A. AU - Nath, R. T2 - Journal of Public Policy AB - A considerable and growing body of crisis management literature seeks to help business managers address disasters. Notwithstanding, the business literature on crisis management fails fully to understand the policy and political aspects of business disasters, and concentrates on prescriptive, managerial issues that show disregard and sometimes disdain for plural democracy. We illustrate our argument with a review of the existing crisis management literature, and three case studies: the Exxon Valdez oil spill, the Jack in the Box E. Coli outbreak, and the crash of ValuJet flight 592. We find that the primary gap in the crisis management literature is its failure to understand the motivations of countervailing interest groups and the facts that mobilize them to take action. We argue that the lessons derived from these cases are equally applicable to North American, European and Asian business crises. DA - 2000/// PY - 2000/// DO - 10.1017/S0143814X00000854 VL - 20 IS - 3 SP - 275-303 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0034457730&partnerID=MN8TOARS ER - TY - BOOK TI - Pavilion Key: Isle of Buried Treasure AU - Lewbart, G. DA - 2000/// PY - 2000/// PB - Krieger Publishing, Malabar,FL ER - TY - CONF TI - Interfacial properties effects on microcomposites deformation response: An analytical approach AU - Hamouda, H. AU - Qui, Y. AU - Bennett, S. C2 - 2000/// C3 - ICCE/7: seventh annual International Conference on Composites Engineering: July 2-8, 2000, Denver, Colorado DA - 2000/// PB - [S.l.]: International Community for Composities Engineering ER - TY - CONF TI - Elasticity analysis of 3D cellular matrix composites AU - Hamouda, H. AU - Xu, W. AU - Qui, Y. AU - Mohamed, M. C2 - 2000/// C3 - ICCE/7: seventh annual International Conference on Composites Engineering: July 2-8, 2000, Denver, Colorado DA - 2000/// PB - [S.l.]: International Community for Composities Engineering ER - TY - MAP TI - Geologic map of the Carlsborg 7.5-minute Quadrangle, Clallam County, Washington AU - Schasse, H. W. AU - Wegmann, K. W. DA - 2000/// PY - 2000/// PB - Washington Division of Geology and Earth Resources ER - TY - JOUR TI - Surgery in fish AU - Harms, Craig AU - Lewbart, Gregory T2 - Veterinary Clinics of North America. Exotic Animal Practice AB - Surgery in fish is feasible and practical for clinical and research applications. Certain adjustments in standard surgical procedures are necessary to accommodate piscine tissue handling, skin sensitivity, aqueous respiration, anatomic variations, and patient size. General considerations for fish surgery, including anesthesia, presurgical evaluation, equipment, suture selection, and surgical site preparation, have been presented here. Procedures described include celiotomy, enucleation, pseudobranchectomy, swim bladder surgery, gonadectomy, liver and kidney biopsy techniques, telemetry device implantation, and vascular catheterization. DA - 2000/// PY - 2000/// DO - 10.1016/s1094-9194(17)30074-9 VL - 3 IS - 3 SP - 759–774 ER - TY - JOUR TI - Species profile: Southern flounder AU - Daniels, H.V. T2 - SRAC Publication DA - 2000/// PY - 2000/// IS - 726 SP - 1 ER - TY - JOUR TI - Revisiting dose-response models of foodborne pathogens AU - Vicari, A. S. AU - Morales, R. A. AU - Jaykus, L. A. AU - Cowen, P. T2 - Proceedings of the 9th symposium of the International Society for Veterinary Epidemiology and Economics, Breckenridge, Colorado, USA, August 6-11 2000 DA - 2000/// PY - 2000/// SP - 438 ER - TY - CHAP TI - CVT update: Antibiotic treatment of aquarium fish AU - Lewbart, G. A. T2 - Kirk's current veterinary therapy : small animal practice (13th Ed.) PY - 2000/// SP - 1196 PB - Philadelphia, PA : W.B. Saunders SN - 0721655238 ER - TY - CHAP TI - Tidal salt marsh restoration, creation, and mitigation AU - Broome, S. W. AU - Craft, C. B. T2 - Reclamation of drastically disturbed lands AB - Tidal salt marshes occur in protected, low-energy coastal areas such as estuaries, lagoons, bays and river mouths, and grade into brackish and freshwater marshes where there is significant river flow. The historical loss of tidal wetlands and the goal of "no net loss" of wetlands proposed by former President George Bush have resulted in increased interest in restoration and creation of tidal marshes. Marsh restoration and creation are often used for mitigation to compensate for wetland loss. Nitrogen inputs via N fixation are greater and N losses via denitrification are lower in restored marshes. Careful site selection is important for increasing the probability of success of tidal marsh restoration and creation projects. Techniques for restoring or creating tidal marsh habitat have been developed and applied in many locations with varying degrees of success. PY - 2000/// DO - 10.2134/agronmonogr41.c37 SP - 939 PB - Madison, Wis. : American Society of Agronomy SN - 0891181466 ER - TY - PAT TI - Method for conservatively evaluating continuous thermal treatment process for a particulate-containing food product stream AU - Swartzel, K. R. AU - Simunovic, J. C2 - 2000/// DA - 2000/// PY - 2000/// ER - TY - JOUR TI - Enteric viruses as 'emerging agents' of foodborne disease AU - Jaykus, L. T2 - Irish Journal of Agricultural and Food Research DA - 2000/// PY - 2000/// VL - 39 IS - 2 SP - 245-255 ER - TY - JOUR TI - Topographic analysis of dune volume and position, Jockey's Ridge State Park AU - Judge, E. K. AU - Garriga, C. M. AU - Overton, M. F. T2 - Shore & Beach DA - 2000/// PY - 2000/// VL - 68 IS - 4 SP - 19 ER - TY - JOUR TI - Incorporating users' perceptions of site quality in a recreation travel cost model AU - Siderelis, C AU - Moore, R AU - Lee, JH T2 - JOURNAL OF LEISURE RESEARCH AB - The travel cost method is used to analyze the recreation demand for North Carolina trails. Incorporated in the demand model are users' perceptions of trail quality and their stated number of annual trips. Trail demand is specified with panel data that consists of two separate observations per respondent. Users' behaviors are analyzed by combining both data on the observed trip counts and stated trips. Stated trips are the number of trips a user would have taken to the last trail used had the site quality been ideal. Since both users and non users of trails during the past 12 months were asked their stated trips if quality improved, the non-participation effect was incorporated into the estimates of trail demand. Study findings showed users' ratings of trail quality can be successfully incorporated into a demand model to evaluate a hypothetical improvement in trail conditions. The estimated $15 increase in consumer surplus per trip is of practical importance to policy analyses aimed at improving social and environmental conditions averse to trail users. DA - 2000/// PY - 2000/// DO - 10.1080/00222216.2000.11949924 VL - 32 IS - 4 SP - 406-414 SN - 0022-2216 KW - recreation demand KW - trails KW - travel cost method KW - outdoor recreation KW - contingent behavior ER - TY - JOUR TI - Modified method to detect PCR products by 5 ' nuclease activity and an asymmetric fluorogenic probe set AU - Koo, K AU - Jaykus, LA T2 - BIOTECHNIQUES AB - BioTechniquesVol. 29, No. 4 BenchmarksOpen AccessModified Method to Detect PCR Products by 5′Nuclease Activity and an Asymmetric Fluorogenic Probe SetKai Koo & Lee-Ann JaykusKai KooNorth Carolina State University, Raleigh, NC, USASearch for more papers by this author & Lee-Ann Jaykus*Address correspondence to Dr. Lee-Ann Jaykus, Department of Food Science, North Carolina State University, Raleigh, NC 27695-7624, USA. e-mail: E-mail Address: leeann_jaykus@ncsu.eduNorth Carolina State University, Raleigh, NC, USASearch for more papers by this authorPublished Online:29 Aug 2018https://doi.org/10.2144/00294bm03AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInReddit FiguresReferencesRelatedDetailsCited ByDetection of Listeria monocytogenes from a Model Food by Fluorescence Resonance Energy Transfer-Based PCR with an Asymmetric Fluorogenic Probe SetApplied and Environmental Microbiology, Vol. 69, No. 2Detection of single nucleotide polymorphisms within the Listeria genus using an 'asymmetric' fluorogenic probe set and fluorescence resonance energy transfer based-PCRLetters in Applied Microbiology, Vol. 35, No. 6Human Enteric Viruses as Causes of Foodborne DiseaseComprehensive Reviews in Food Science and Food Safety, Vol. 1, No. 2 Vol. 29, No. 4 Follow us on social media for the latest updates Metrics Downloaded 111 times History Published online 29 August 2018 Published in print October 2000 Information© 2018 Author(s)PDF download DA - 2000/10// PY - 2000/10// DO - 10.2144/00294bm03 VL - 29 IS - 4 SP - 690-+ SN - 0736-6205 ER - TY - JOUR TI - Large-scale blue crab recruitment: linking postlarval transport, post-settlement planktonic dispersal, and multiple nursery habitats AU - Etherington, LL AU - Eggleston, DB T2 - MARINE ECOLOGY PROGRESS SERIES AB - MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 204:179-198 (2000) - doi:10.3354/meps204179 Large-scale blue crab recruitment: linking postlarval transport, post-settlement planktonic dispersal, and multiple nursery habitats Lisa L. Etherington*, David B. Eggleston North Carolina State University, Department of Marine, Earth and Atmospheric Sciences, Raleigh, North Carolina 27695, USA *E-mail: lletheri@unity.ncsu.edu ABSTRACT: A large-scale study of early juvenile blue crab Callinectes sapidus recruitment within a shallow, predominantly wind-driven estuarine system demonstrated that distribution and abundance patterns were jointly influenced by location from oceanic sources of postlarvae, time period, habitat type, and post-settlement planktonic dispersal. The Croatan-Albemarle-Pamlico Estuarine System (CAPES) in North Carolina, USA, is a lagoonal body of water that is separated from the Atlantic Ocean by a chain of barrier islands, which are bisected by Oregon, Hatteras, and Ocracoke Inlets. For sampling purposes, the CAPES was divided into 4 regions that differed in distance and orientation from oceanic sources of postlarvae, as well as available complex benthic habitat types. The Eastern region was closest to oceanic waters, contained 3 major inlets, and harbored extensive seagrass beds. The Northern and Western regions were located along the inland boundary of the CAPES, and contained alternative habitat types including the submersed rooted vascular plant Myriophyllum spicatum and shallow detrital habitats. The Southern region was inshore and contained patchy seagrass. During a period that lacked storm events, virtually all juvenile recruitment occurred within seagrass beds at the Eastern region. Conversely, early juvenile blue crabs were distributed widely throughout the CAPES after the passage of tropical cyclones. The Eastern region appears to act as a relatively consistent initial recruitment site, whereas Northern and Western regions of the CAPES may act as episodic recruitment areas after the passage of tropical cyclones. Similar densities of early juveniles were found in different complex benthic habitats (seagrass, shallow detrital habitat, M. spicatum). A comparison of site-specific, settler-recruit densities (which represent distinct cohorts) suggested that post-settlement juveniles dispersed planktonically throughout the CAPES, most likely due to storm-driven transport. Post-settlement, planktonic dispersal altered the settler-recruit relationship, by both masking and potentially enhancing a density-dependent relationship between settlers and recruits. This study illustrates that ecological processes influencing recruitment, such as post-settlement dispersal, may be missed when studied at relatively small spatial scales, and that our interpretation of population regulation can vary depending on the scale of study. Studies conducted over broad spatial scales can provide a more complete understanding of recruitment dynamics and can elucidate the interconnectedness of subpopulations by identifying potential Œsource¹ areas in species with open populations. KEY WORDS: Blue crab · Recruitment · Nursery habitats · Post-settlement dispersal · Post-larval dispersal · Density-dependence · Hurricanes · Seagrass Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 204. Online publication date: October 05, 2000 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2000 Inter-Research. DA - 2000/// PY - 2000/// DO - 10.3354/meps204179 VL - 204 IS - 2000 SP - 179-198 SN - 1616-1599 KW - blue crab KW - recruitment KW - nursery habitats KW - post-settlement dispersal KW - post-larval dispersal KW - density-dependence KW - hurricanes KW - seagrass ER - TY - JOUR TI - Growth of juvenile Centropomus undecimalis in a tropical island AU - Aliaume, C AU - Zerbi, A AU - Joyeux, JC AU - Miller, JM T2 - ENVIRONMENTAL BIOLOGY OF FISHES DA - 2000/11// PY - 2000/11// DO - 10.1023/A:1007662611839 VL - 59 IS - 3 SP - 299-308 SN - 1573-5133 KW - common snook KW - otolith microstructure KW - daily increment validation KW - seasonal growth KW - Puerto Rico ER - TY - JOUR TI - Fertilizer management impacts on stand establishment, disease, and yield of Irish potato AU - Crozier, CR AU - Creamer, NG AU - Cubeta, MA T2 - POTATO RESEARCH DA - 2000/// PY - 2000/// DO - 10.1007/BF02358513 VL - 43 IS - 1 SP - 49-59 SN - 1871-4528 KW - Solanum tuberosum L. KW - soil fertility KW - soluble salts KW - plant spacing KW - Rhizoctonia ER - TY - JOUR TI - Ecological processes underlying ontogenetic habitat shifts in a coral reef fish AU - Dahlgren, C. P. AU - Eggleston, David T2 - Ecology (Brooklyn, New York, N.Y.) DA - 2000/// PY - 2000/// DO - 10.2307/177110 VL - 81 IS - 8 SP - 2227–2240 ER - TY - JOUR TI - Determination of volatile bases in seafood using the ammonia ion selective electrode: Collaborative study AU - Ellis, P. C. AU - Pivarnik, L. F. AU - Thiam, M. AU - Berger, L. AU - Field, S. AU - Green, D. AU - Hewes, D. AU - Lemerise, D. AU - Lyttle, C. AU - Maciel, J. AU - Soper, K. T2 - Journal of AOAC International DA - 2000/// PY - 2000/// VL - 83 IS - 4 SP - 933-943 ER - TY - JOUR TI - Annual cycle of plasma lipids in captive reared striped bass: effects of environmental conditions and reproductive cycle AU - Lund, ED AU - Sullivan, CV AU - Place, AR T2 - FISH PHYSIOLOGY AND BIOCHEMISTRY DA - 2000/4// PY - 2000/4// DO - 10.1023/A:1007818114057 VL - 22 IS - 3 SP - 263-275 SN - 0920-1742 KW - essential fatty acids KW - reproduction KW - vitellogenin KW - wax esters ER - TY - JOUR TI - Amoxicillin pharmacokinetics in harbor seals (Phoca vitulina) and northern elephant seals (Mirounga angustirostris) following single dose intravenous administration: implications for interspecific dose sealing AU - Gulland, FM AU - Stoskopf, MK AU - Johnson, SP AU - Riviere, J AU - Papich, MG T2 - JOURNAL OF VETERINARY PHARMACOLOGY AND THERAPEUTICS AB - The pharmacokinetics of sodium amoxicillin after a single intravenous dose of 20 mg/kg were determined in ten harbor seals (Phoca vitulina) and ten northern elephant seals (Mirounga angustirostris). The seals ranged in age from 1 to 6 months and the mean weights were 11.7 kg (range, 9.5-18.5 kg) for harbor seals and 47.1 kg (range, 39.5-61.4 kg) for elephant seals. The median half-life of amoxicillin (quartiles) in harbor seals, 1.5 (1.0-3.1) h. was not statistically different from that of elephant seals, 2.0 (1.4-3.8) h, nor were the differences between the terminal elimination rate constants between the two species. The only statistically significant differences between species were for area-under-the-curve (AUC), and total systemic clearance. The lack of statistical significance for differences in the volume of distribution at steady-state (Vss) may have been due to minor differences in the time frame of data collection and dose administered between the two groups. A true physiologic difference in drug handling, possibly related to renal perfusion or tubal secretory efficiency could affect amoxicillin kinetics in these species, and longer administration intervals may be appropriate for elephant seals as compared to harbor seals when administering multiple dose amoxicillin therapy at 20 mg/kg. DA - 2000/8// PY - 2000/8// DO - 10.1046/j.1365-2885.2000.00263.x VL - 23 IS - 4 SP - 223-228 SN - 0140-7783 ER - TY - JOUR TI - A comparison of methods for the detection of Escherichia coli O157 : H7 from artificially-contaminated dairy products using PCR AU - McKillip, JL AU - Jaykus, LA AU - Drake, MA T2 - JOURNAL OF APPLIED MICROBIOLOGY AB - Rapid nucleic acid-based methods to detect human pathogens in foods are dependent on the reliability of the DNA or RNA extraction method used. Skim milk, non-fat dry milk, Cheddar and Brie cheese, and reconstituted whey powder were seeded with serially diluted (10(0)-10(7) cfu 10 ml(-1)) Escherichia coli O157:H7 and subjected to DNA extraction (i) directly from the food product using a solvent-based procedure and (ii) using a guanidinium isothiocyanate (GITC) procedure after previous bacterial concentration. Both the efficiency of DNA extraction and the overall PCR detection limits were evaluated. In almost all instances, the total DNA yield using the solvent method was greater than that obtained for the concentration method. However, the purity of the DNA obtained after bacterial concentration was significantly better than that obtained after organic extraction alone. PCR detection limits after each DNA recovery method varied with the specific food, ranging from 10(1) to 10(4) cfu ml(-1) for all products except whey powder. DNA yields and subsequent PCR detection limits for reconstituted whey powder were extremely poor, and neither procedural changes nor the addition of PCR enhancement agents were able to improve recovery and/or detection. It is concluded that the efficiency of DNA extraction is an extremely important and frequently overlooked variable impacting the overall detection limits of PCR-based detection strategies. DA - 2000/7// PY - 2000/7// DO - 10.1046/j.1365-2672.2000.01079.x VL - 89 IS - 1 SP - 49-55 SN - 1364-5072 ER - TY - JOUR TI - Effects of a low-head dam on the distribution and characteristics of spawning habitat used by striped bass and American shad AU - Beasley, CA AU - Hightower, JE T2 - TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY AB - Striped bass Morone saxatilis and American shad Alosa sapidissima in the Neuse River, North Carolina, historically migrated up to 435 km upriver to spawn. However, migration was impeded in 1952 by the construction of Quaker Neck Dam at river kilometer 225 (measured from the point where the Neuse River enters Pamlico Sound). To determine the fraction of tagged fish that migrated upstream of this low-head dam and the characteristics of selected spawning habitat, we implanted sonic transmitters in 25 striped bass and 25 American shad during 1996 and 1997. We determined preferred depth, water velocity, and substrate composition by measuring those characteristics at both randomly selected sites and sites where spawning was observed. Of 13 striped bass and 8 American shad with transmitters that migrated to the base of Quaker Neck Dam, only 3 striped bass passed the structure, indicating that the dam was an impediment to migration. Striped bass spawning was observed only in the area directly below (within 1.5 km of) Quaker Neck Dam. Although none of the telemetered American shad passed Quaker Neck Dam, American shad spawning was observed from the base of the dam to 1.5 km downstream as well as 3 km above the dam. Striped bass spawned at sites with significantly higher water velocity and significantly larger substrate than on average was found at randomly sampled locations. American shad spawned at sites that were significantly shallower and had significantly larger substrate than was found in random samples. The type of spawning habitat selected by both species is more abundant above than below Quaker Neck Dam, indicating that improved access to upstream reaches would benefit both species. DA - 2000/11// PY - 2000/11// DO - 10.1577/1548-8659(2000)129<1316:EOALHD>2.0.CO;2 VL - 129 IS - 6 SP - 1316-1330 SN - 0002-8487 ER - TY - JOUR TI - The kinetics of oxytetracycline degradation in deionized water under varying temperature, pH, light, substrate, and organic matter AU - Doi, AM AU - Stoskopf, MK T2 - JOURNAL OF AQUATIC ANIMAL HEALTH AB - The kinetics of oxytetracycline (OTC) degradation in deionized water was studied under the influence of various environmental factors. The experiment was conducted with a solution of 10 μg aqueous OTC /mL in 600-mL glass beakers under controlled laboratory conditions. The aqueous concentration of OTC was determined by high-performance liquid chromatography. Low temperatures (4°C) favored high drug stability, and high temperatures (43°C) speeded OTC degradation, resulting in a very short half-life of 0.26 ± 0.11 d. Light exposure caused photodecomposition, reflecting degradation rates threefold higher than those under dark conditions. Acidic conditions (pH 3.0) favored drug stability (half-life = 46.36 ± 4.92 d), and alkaline conditions (pH 10.0) increased the degradation rate (half-life = 9.08 ± 4.22 d). The presence of a substrate (bentonite clay) resulted in an approximate 17% decrease in OTC concentration within 5 min of contact. Addition of organic matter (fish feed) along with the substrate resulted in a 41% decrease in OTC concentrations within 5 min of contact. DA - 2000/9// PY - 2000/9// DO - 10.1577/1548-8667(2000)012<0246:TKOODI>2.0.CO;2 VL - 12 IS - 3 SP - 246-253 SN - 0899-7659 ER - TY - JOUR TI - Slope-enhanced fission of salty hetons under sea ice AU - Chao, SY AU - Shaw, PT T2 - JOURNAL OF PHYSICAL OCEANOGRAPHY AB - Ocean responses to a single brine source under ice and over a sloping bottom are investigated in numerical experiments. Brine sources considered herein are often much stronger than that anticipated from a single seawater freezing event in a time span of about 10 days. The authors have no evidence that such strong sources exist in the ocean, but the consequent heton-like eddies manifest interesting features over a bottom slope. The numerical model contains a stratified ocean capped by an ice layer. The convection initially generates a top cyclone and a submerged anticyclone vertically stacked together. Under sea ice, the top cyclone dissipates in time and often breaks up into several distinct cyclonic vortices. Through heton-type couplings, the breakaway shallow cyclones are often able to tear the underlying anticyclone apart to form distinct anticyclones. Top cyclones are eventually annihilated by ice-exerted friction, leaving submerged anticyclones in stable existence. Fission from a pair of vertically stacked baroclinic vortices is a fundamental process associated with a strong brine source under sea ice. A bottom slope generally enhances fission, often increasing the number of subsurface anticyclones or causing the resulting anticyclones to break farther away from the source. The slope enhancement is consistent with the potential vorticity conservation requirement and a changing Rossby radius with water depths. The foregoing conclusions remain the same in cases with a stationary brine source moving rigidly with a uniform current. Under the less likely scenario of a stationary source embedded in a mean flow, brine waters spread downstream and become less effective in producing distinct vortices. Granting the occurrence of strong baroclinic vortices under sea ice, the preferable increase of anticyclones at depths may help explain the overwhelming predominance of submerged anticyclones in the ice-covered Arctic Ocean. DA - 2000/11// PY - 2000/11// DO - 10.1175/1520-0485(2000)030<2866:SEFOSH>2.0.CO;2 VL - 30 IS - 11 SP - 2866-2882 SN - 0022-3670 ER - TY - JOUR TI - Selective amplification of bacterial RNA: use of a DNA primer containing mismatched bases near its 3 ' terminus to reduce false-positive signals AU - Koo, K AU - Jaykus, LA T2 - LETTERS IN APPLIED MICROBIOLOGY AB - A reverse transcription PCR (RT–PCR) method designed to reduce false‐positive results due to the co‐amplification of contaminating genomic DNA is reported. Feasibility of the method was evaluated using 16S rRNA sequences specific to Bacillus cereus. A DNA oligonucleotide primer, consisting of 22‐bases containing three consecutive mismatched bases near its 3′ terminus (primer B16RT), was used for reverse transcription and in subsequent cDNA amplification. Specific rRNA was reverse transcribed at low temperature (40 °C or 45 °C) in the presence of primer B16RT. As subsequent PCR using primer B16RT at high (62 °C) annealing temperatures is not nearly as efficient as amplification using the specific primer, amplification of genomic DNA was hindered relative to the amplification of cDNA. The method was readily adapted to the selective amplification of mRNA of the Listeria monocytogenes listeriolysin O (hly) gene. DA - 2000/9// PY - 2000/9// DO - 10.1046/j.1365-2672.2000.00798.x VL - 31 IS - 3 SP - 187-192 SN - 0266-8254 ER - TY - JOUR TI - North and South Carolina coasts AU - Mallin, MA AU - Burkholder, JM AU - Cahoon, LB AU - Posey, MH T2 - MARINE POLLUTION BULLETIN AB - This coastal region of North and South Carolina is a gently sloping plain, containing large riverine estuaries, sounds, lagoons, and salt marshes. The most striking feature is the large, enclosed sound known as the Albemarle–Pamlico Estuarine System, covering approximately 7530 km2. The coast also has numerous tidal creek estuaries ranging from 1 to 10 km in length. This coast has a rapidly growing population and greatly increasing point and non-point sources of pollution. Agriculture is important to the region, swine rearing notably increasing fourfold during the 1990s. Estuarine phytoplankton communities in North Carolina are well studied; the most important taxonomic groups are diatoms, dinoflagellates, cryptomonads and cyanobacteria. Several major poorly flushed estuaries are eutrophic due to nutrient inputs, and toxic dinoflagellates (Pfiesteria spp) can reach high densities in nutrient-enriched areas. Fully marine waters are relatively oligotrophic. Southern species enter in subsurface intrusions, eddies, and occasional Gulf Stream rings, while cool water species enter with the flow of the Labrador Current to the Cape Hatteras region. The Carolinas have a low number of endemic macroalgae, but species diversity can be high in this transitional area, which represents the southernmost extension for some cold-adapted species and the northernmost extension of warm-adapted species. In North Carolina the dominant seagrass, Zostera marina, lies at its southernmost extension, while a second species, Halodule wrightii is at its northernmost extent. Widgeon-grass Ruppia maritima is common, growing in brackish water or low-salinity pools in salt marshes. Seagrass meadows are now much reduced, probably due to elevated nitrogen and increased sedimentation. In sounds, numerically dominant benthic taxa include bivalves, polychaetes and amphipods, many showing gradients in community type from mesohaline areas of the eastern shore to near marine salinities in western parts. The semi-enclosed sounds have extensive shellfisheries, especially of blue crab, northern quahogs, eastern oysters, and shrimp. Problems include contamination of some sediments with toxic substances, especially of metals and PCBs at sufficiently high levels to depress growth of some benthic macroinvertebrates. Numerous fish kills have been caused by toxic Pfiesteria outbreaks, and fish kills and habitat loss have been caused by episodic hypoxia and anoxia in rivers and estuaries. Oyster beds currently are in decline because of overharvesting, high siltation and suspended particulate loads, disease, hypoxia, and coastal development. Fisheries monitoring which began in the late 1970s shows greatest recorded landings in 1978–1982; since then, harvests have declined by about a half. Some management plans have been developed toward improving water quality and fisheries sustainability. Major challenges include; high coliform levels leading to closures of shellfish beds, a problem that has increased with urban development and increasing cover of watershed by impervious surfaces; high by-catch and heavy trawling activity; overfishing which has led to serious declines in many wild fish stocks; and eutrophication. Comprehensive plans limiting nutrient inputs are needed for all coastal rivers and estuaries, not only those that already exhibit problems. There is a critical need to improve management of non-point nutrient runoff through increased use of streamside vegetated buffers, preservation of remaining natural wetlands and construction of artificial wetlands. Improved treatment processes, based on strong incentive programmes, should also be mandated for present and future industrial-scale animal operations. DA - 2000/// PY - 2000/// DO - 10.1016/S0025-326X(00)00102-8 VL - 41 IS - 1-6 SP - 56-75 SN - 1879-3363 ER - TY - JOUR TI - Effects of insulin-like growth factor-I on in vitro final oocyte maturation and ovarian steroidogenesis in striped bass, Morone saxatilis AU - Weber, GM AU - Sullivan, CV T2 - BIOLOGY OF REPRODUCTION AB - Recombinant human (rh) insulin-like growth factor-I (IGF-I) was more potent than rhIGF-II at inducing in vitro germinal vesicle breakdown (GVBD), a marker for resumption of meiosis, in oocytes of striped bass. Treatment of ovarian fragments containing oocytes in intact follicles with rhIGF-I increased concentrations of estradiol-17beta and maturation-inducing steroid (MIS) 17,20beta, 21-trihydoxy-4-pregnen-3-one (20beta-S) in the culture medium and decreased testosterone levels. The follicles were too immature for oocytes to complete GVBD in response to 20beta-S (MIS incompetent) or hCG. Addition of 20beta-S to cultures did not increase the percentage of oocytes completing GVBD in response to rhIGF-I or rhIGF-II. Bovine insulin was without effect on GVBD or steroid production. Incubation of MIS-competent follicles with actinomycin D, cyanoketone, trilostane, 1-heptanol, or 1-octanol had no effect on rhIGF-I-induced GVBD, but attenuated hCG-induced GVBD and 20beta-S production. Cycloheximide inhibited rhIGF-I-induced GVBD. Collectively, these observations indicate that IGF-I can induce GVBD via MIS- and transcription-independent pathways without coupled gap junctions between oocytes and granulosa cells or among granulosa cells, but requires protein synthesis to do so. An rhIGF-I analogue that does not bind IGF-binding proteins, des(1,3)IGF-I, was more potent than rhIGF-I in inducing GVBD, suggesting ovarian IGF-binding proteins may inhibit IGF-I action. DA - 2000/10// PY - 2000/10// DO - 10.1095/biolreprod63.4.1049 VL - 63 IS - 4 SP - 1049-1057 SN - 1529-7268 KW - follicle KW - growth factors KW - hCG KW - meiosis KW - oocyte development KW - ovary ER - TY - JOUR TI - Detection methods for human enteric viruses in representative foods AU - Leggitt, PR AU - Jaykus, LA T2 - JOURNAL OF FOOD PROTECTION AB - Although viral foodborne disease is a significant problem, foods are rarely tested for viral contamination, and when done, testing is limited to shellfish commodities. In this work, we report a method to extract and detect human enteric viruses from alternative food commodities using an elution-concentration approach followed by detection using reverse transcription-polymerase chain reaction (RT-PCR). Fifty-gram lettuce or hamburger samples were artificially inoculated with poliovirus type 1 (PV1), hepatitis A virus (HAV), or the Norwalk virus and processed by the sequential steps of homogenization, filtration, Freon extraction (hamburger), and polyethylene glycol (PEG) precipitation. To reduce volumes further and remove RT-PCR inhibitors, a secondary PEG precipitation was necessary, resulting in an overall 10- to 20-fold sample size reduction from 50 g to 3 to 5 ml. Virus recoveries in secondary PEG concentrates ranged from 10 to 70% for PV1 and 2 to 4% for HAV as evaluated by mammalian cell culture infectivity assay. Total RNA from PEG concentrates was extracted to a small volume (30 to 40 μl) and subjected to RT-PCR amplification of viral RNA sequences. Detection limit studies indicated that viral RNA was consistently detected by RT-PCR at initial inoculum levels ≥102 PFU/50-g food sample for PV1 and ≥103 PFU/50-g food sample for HAV. In similar studies with the Norwalk virus, detection at inoculum levels ≥1.5 × 103 PCR-amplifiable units/50-g sample for both food products was possible. All RT-PCR amplicons were confirmed by subsequent Southern hybridization. The procedure reported represents progress toward the development of methods to detect human enteric viral contamination in foods other than shellfish. DA - 2000/12// PY - 2000/12// DO - 10.4315/0362-028X-63.12.1738 VL - 63 IS - 12 SP - 1738-1744 SN - 0362-028X ER - TY - JOUR TI - A review of the Si cycle in the modem ocean: recent progress and missing gaps in the application of biogenic opal as a paleoproductivity proxy AU - Ragueneau, O AU - Treguer, P AU - Leynaert, A AU - Anderson, RF AU - Brzezinski, MA AU - DeMaster, DJ AU - Dugdale, RC AU - Dymond, J AU - Fischer, G AU - Francois, R AU - Heinze, C AU - Maier-Reimer, E AU - Martin-Jezequel, V AU - Nelson, DM AU - Queguiner, B T2 - GLOBAL AND PLANETARY CHANGE AB - Due to the major role played by diatoms in the biological pump of CO2, and to the presence of silica-rich sediments in areas that play a major role in air–sea CO2 exchange (e.g. the Southern Ocean and the Equatorial Pacific), opal has a strong potential as a proxy for paleoproductivity reconstructions. However, because of spatial variations in the biogenic silica preservation, and in the degree of coupling between the marine Si and C biogeochemical cycles, paleoreconstructions are not straitghtforward. A better calibration of this proxy in the modern ocean is required, which needs a good understanding of the mechanisms that control the Si cycle, in close relation to the carbon cycle. This review of the Si cycle in the modern ocean starts with the mechanisms that control the uptake of silicic acid (Si(OH)4) by diatoms and the subsequent silicification processes, the regulatory mechanisms of which are uncoupled. This has strong implications for the direct measurement in the field of the kinetics of Si(OH)4 uptake and diatom growth. It also strongly influences the Si:C ratio within diatoms, clearly linked to environmental conditions. Diatoms tend to dominate new production at marine ergoclines. At depth, they also succeed to form mats, which sedimentation is at the origin of laminated sediments and marine sapropels. The concentration of Si(OH)4 with respect to other macronutrients exerts a major influence on diatom dominance and on the rain ratio between siliceous and calcareous material, which severely impacts surface waters pCO2. A compilation of biogenic fluxes collected at about 40 sites by means of sediment traps also shows a remarkable pattern of increasing BSi:Corg ratio along the path of the “conveyor belt”, accompanying the relative enrichment of waters in Si compared to N and P. This observation suggests an extension of the Si pump model described by Dugdale and Wilkerson (Dugdale, R.C., Wilkerson, F.P., 1998. Understanding the eastern equatorial Pacific as a continuous new production system regulating on silicate. Nature 391, 270–273.), giving to Si(OH)4 a major role in the control of the rain ratio, which is of major importance in the global carbon cycle. The fate of the BSi produced in surface waters is then described, in relation to Corg, in terms of both dissolution and preservation mechanisms. Difficulties in quantifying the dissolution of biogenic silica in the water column as well as the sinking rates and forms of BSi to the deep, provide evidence for a major gap in our understanding of the mechanisms controlling the competition between retention in and export from surface waters. The relative influences of environmental conditions, seasonality, food web structure or aggregation are however explored. Quantitatively, assuming steady state, the measurements of the opal rain rate by means of sediment traps matches reasonably well those obtained by adding the recycling and burial fluxes in the underlying abyssal sediments, for most of the sites where such a comparison is possible. The major exception is the Southern Ocean where sediment focusing precludes the closing of mass balances. Focusing in fact is also an important aspect of the downward revision of the importance of Southern Ocean sediments in the global biogenic silica accumulation. Qualitatively, little is known about the duration of the transfer through the deep and the quality of the material that reaches the seabed, which is suggested to represent a major gap in our understanding of the processes governing the early diagenesis of BSi in sediments. The sediment composition (special emphasis on Al availability), the sedimentation rate or bioturbation are shown to exert an important control on the competition between dissolution and preservation of BSi in sediments. It is suggested that a primary control on the kinetic and thermodynamic properties of BSi dissolution, both in coastal and abyssal sediments, is exerted by water column processes, either occuring in surface waters during the formation of the frustules, or linked to the transfer of the particles through the water column, which duration may influence the quality of the biogenic rain. This highlights the importance of studying the factors controlling the degree of coupling between pelagic and benthic processes in various regions of the world ocean, and its consequences, not only in terms of benthic biology but also for the constitution of the sediment archive. The last section, first calls for the end of the “NPZD” models, and for the introduction of processes linked to the Si cycle, into models describing the phytoplankton cycles in surface waters and the early diagenesis of BSi in sediments. It also calls for the creation of an integrated 1-D diagnostic model of the Si:C coupling, for a better understanding of the interactions between surface waters, deep waters and the upper sedimentary column. The importance of Si(OH)4 in the control of the rain ratio and the improved parametrization of the Si cycle in the 1-D diagnostic models should lead to a reasonable incorporation of the Si cycle into 3-D regional circulation models and OGCMs, with important implications for climate change studies and paleoreconstructions at regional and global scale. DA - 2000/12/15/ PY - 2000/12/15/ DO - 10.1016/S0921-8181(00)00052-7 VL - 26 IS - 4 SP - 317-365 SN - 1872-6364 KW - Si cycle KW - biogenic opal KW - paleoproductivity ER - TY - JOUR TI - A dinoflagellate adaptive behavior model: response to internal biochemical cues AU - Yamazaki, AK AU - Kamykowski, D T2 - ECOLOGICAL MODELLING AB - In this study we built two models to simulate vertical movements of an individual dinoflagellate. In the models, we laid out the flows of the chemical substances inside the cell and their changes in response to such environmental changes as nitrate concentration and light intensity. One of the models is called the Clock-Driven Model, in which the cell moves only according to the clock time and exhibits a regular vertical diel movement. The other model, which we call the Decision-Making Model, contains a network to make decisions for the next move, based on the interactions among biochemicals inside the phytoplankter and its environment. In this model, the decision emerges from the results of a cell's internal biochemical fluxes controlled by the threshold setting. The simulation results of both models with different nutrient conditions were compared in terms of the cell's behavioral patterns and the amount of protein produced by the cell. The results indicated that balances among the biochemicals and their fluxes can play a significant role in the directional decisions made by dinoflagellates under some environmental nitrate conditions, and that irregularity in a cell's movements may be affected by nitrate availability. Also, the simulation results suggest that irregular migration produced to meet the predefined criteria for biochemical fluxes inside the cell can benefit the cell in terms of protein accumulation. We propose that the essence of a cell's adaptivity to the environment resides in the internal cellular condition represented here by threshold values associated with biochemical fluxes and their balances, and that it is important to consider an organism's internal condition when constructing an adaptive behavior model. DA - 2000/9/30/ PY - 2000/9/30/ DO - 10.1016/S0304-3800(00)00336-7 VL - 134 IS - 1 SP - 59-72 SN - 0304-3800 KW - behavior model KW - dinoflagellates KW - diel vertical movement KW - adaptivity KW - biochemicals ER - TY - JOUR TI - Use of a two-step Percoll (R) gradient for separation of loggerhead sea turtle peripheral blood mononuclear cells AU - Harms, CA AU - Keller, JM AU - Kennedy-Stoskopf, S T2 - JOURNAL OF WILDLIFE DISEASES AB - In order to determine a suitable procedure for isolating peripheral blood mononuclear cells (PBMCs) from loggerhead sea turtles (Caretta caretta), blood was collected using three different anticoagulants (sodium heparin, sodium citrate or potassium EDTA) and separated using a single step commercially-prepared arabinogalactan gradient of 1.077 g/ml density or multiple step Percoll gradients between 1.053 and 1.076 g/ml density (40-60% stock isotonic Percoll suspension). Heparinized blood centrifuged over a two-step 45/55% (1.059/1.070 g/ml) Percoll gradient yielded 99 to 100% mononuclear cells at the 45/55% interface. Mononuclear cell viability ranged from 85 to 97% with cell yields up to 9.2 x 10(6) cells/mL. An unexpected finding was a population of low density granulocytes migrating to 40% (1.053 g/ml) and 45% Percoll layers in the multiple step gradients. These granulocytes could be eliminated from the PBMC preparation by use of the two-step 45/55% Percoll gradient. Isolated PBMCs can be used for cellular immunology and toxicology studies on these threatened marine organisms for which other tissues can usually be obtained only sporadically from post-mortem specimens. DA - 2000/7// PY - 2000/7// DO - 10.7589/0090-3558-36.3.535 VL - 36 IS - 3 SP - 535-540 SN - 1943-3700 KW - Caretta caretta KW - density gradient centrifugation KW - loggerhead turtle KW - peripheral blood mononuclear cells ER - TY - JOUR TI - Quantitative polymerase chain reaction for transforming growth factor-beta applied to a field study of fish health in Chesapeake Bay tributaries AU - Harms, CA AU - Ottinger, CA AU - Blazer, VS AU - Densmore, CL AU - Pieper, LH AU - Kennedy-Stoskopf, S T2 - ENVIRONMENTAL HEALTH PERSPECTIVES DA - 2000/5// PY - 2000/5// DO - 10.2307/3454386 VL - 108 IS - 5 SP - 447-452 SN - 1552-9924 KW - Chesapeake Bay KW - field study KW - macrophage bactericidal activity KW - Morone americana KW - quantitative PCR KW - transforming growth factor-beta KW - white perch ER - TY - JOUR TI - Immobilization with metal hydroxides as a means to concentrate food-borne bacteria for detection by cultural and molecular methods AU - Lucore, LA AU - Cullison, MA AU - Jaykus, LA T2 - APPLIED AND ENVIRONMENTAL MICROBIOLOGY AB - ABSTRACT The application of nucleic acid amplification methods to the detection of food-borne pathogens could be facilitated by concentrating the organisms from the food matrix before detection. This study evaluated the utility of metal hydroxide immobilization for the concentration of bacterial cells from dairy foods prior to detection by cultural and molecular methods. Using reconstituted nonfat dry milk (NFDM) as a model, two food-borne pathogens ( Listeria monocytogenes and Salmonella enterica serovar Enteritidis) were concentrated from 25-ml samples by the sequential steps of clarification and high-speed centrifugation (designated primary concentration) and immobilization with zirconium hydroxide and low-speed centrifugation (designated secondary concentration). Sample volume reduction after immobilization with zirconium hydroxide was 50-fold, with total bacterial recoveries ranging from 78 to 96% of input for serovar Enteritidis and 65 to 96% of input for L. monocytogenes . Immobilized bacteria remained viable and could be enumerated by standard cultural procedures. When followed by RNA extraction and subsequent detection by reverse transcription (RT)-PCR, detection limits of 10 1 to 10 2 CFU/25 ml of reconstituted NFDM were achieved for both organisms. The bacterial-immobilization step was relatively nonspecific, resulting in recovery of >50% of the input cells when evaluated on a panel of representative bacterial strains of significance to foods. The method could be adapted to more complex dairy products, such as whole milk and ice cream, for which bacterial recoveries after immobilization ranged from 64 to >100%, with subsequent RT-PCR detection limits of ≥10 2 CFU/ml for whole milk and ≥10 1 CFU for ice cream for both serovar Enteritidis and L. monocytogenes . The bacterial-immobilization method is easy, rapid, and inexpensive and may have applications for the concentration of a wide variety of food-borne bacteria prior to detection by both conventional and alternative methods. DA - 2000/5// PY - 2000/5// DO - 10.1128/AEM.66.5.1769-1776.2000 VL - 66 IS - 5 SP - 1769-1776 SN - 0099-2240 ER - TY - JOUR TI - Heteroduplex mobility assay-guided sequence discovery: Elucidation of the small subunit (18S) rDNA sequences of Pfiesteria piscicida and related dinoflagellates from complex algal culture and environmental sample DNA pools AU - Oldach, DW AU - Delwiche, CF AU - Jakobsen, KS AU - Tengs, T AU - Brown, EG AU - Kempton, JW AU - Schaefer, EF AU - Bowers, HA AU - Glasgow, HB AU - Burkholder, JM AU - Steidinger, KA AU - Rublee, PA T2 - PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA AB - The newly described heterotrophic estuarine dinoflagellate Pfiesteria piscicida has been linked with fish kills in field and laboratory settings, and with a novel clinical syndrome of impaired cognition and memory disturbance among humans after presumptive toxin exposure. As a result, there is a pressing need to better characterize the organism and these associations. Advances in Pfiesteria research have been hampered, however, by the absence of genomic sequence data. We employed a sequencing strategy directed by heteroduplex mobility assay to detect Pfiesteria piscicida 18S rDNA "signature" sequences in complex pools of DNA and used those data as the basis for determination of the complete P. piscicida 18S rDNA sequence. Specific PCR assays for P. piscicida and other estuarine heterotrophic dinoflagellates were developed, permitting their detection in algal cultures and in estuarine water samples collected during fish kill and fish lesion events. These tools should enhance efforts to characterize these organisms and their ecological relationships. Heteroduplex mobility assay-directed sequence discovery is broadly applicable, and may be adapted for the detection of genomic sequence data of other novel or nonculturable organisms in complex assemblages. DA - 2000/4/11/ PY - 2000/4/11/ DO - 10.1073/pnas.97.8.4303 VL - 97 IS - 8 SP - 4303-4308 SN - 0027-8424 KW - harmful algal blooms KW - Pfiesteria shumwayae ER - TY - JOUR TI - Foraging behavior of an estuarine predator, the blue crab Callinectes sapidus in a patchy environment AU - Clark, ME AU - Wolcott, TG AU - Wolcott, DL AU - Hines, AH T2 - ECOGRAPHY DA - 2000/2// PY - 2000/2// DO - 10.1034/j.1600-0587.2000.230103.x VL - 23 IS - 1 SP - 21-31 SN - 1600-0587 ER - TY - JOUR TI - Effects of controlled drainage on storm event hydrology in a loblolly pine plantation AU - Amatya, DM AU - Gregory, JD AU - Skaggs, RW T2 - JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION AB - ABSTRACT: A paired watershed approach was utilized to study the effects of three water management regimes on storm event hydrology in three experimental watersheds in a drained loblolly pine ( Pinus taeda L. ) plantation in eastern North Carolina. The regimes were: (1) conventional drainage, (2) controlled drainage (CD) to reduce outflows during spring fish recruitment, and (3) controlled drainage to reduce outflows and conserve water during the growing season. Data from two pit‐treatment years and three years of CD treatment with raised weirs at the watershed outlet are presented. CD treatment resulted in rises in water table elevations during the summer. But the rises were small and short‐lived due to increased evapotranspiration (ET) rates as compared to the spring treatment with lower ET demands. CD treatment had no effect on water tables deeper than 1.3 m. CD treatments, however, significantly (α= 0.05) reduced the stoning outflows for all events, and peak outflow rates for most of the events depending upon the outlet weir level. In some events, flows did not occur at all in watersheds with CD. When event outflows occurred, duration of the event was sharply reduced because of reduced effective ditch depth. Water table depth at the start of an event influenced the effect of CD treatment on storm event hydrology. DA - 2000/2// PY - 2000/2// DO - 10.1111/j.1752-1688.2000.tb04258.x VL - 36 IS - 1 SP - 175-190 SN - 1093-474X KW - controlled drainage KW - loblolly pine KW - water table KW - drainage outflow KW - event hydrograph ER - TY - JOUR TI - Cloning and sequencing hybrid striped bass (Morone saxatilis x M. chrysops) transforming growth factor-β (TGF-β), and development of a reverse transcription quantitative competitive polymerase chain reaction (RT-qcPCR) assay to measure TGF-β mRNA of teleost fish AU - Harms, C.A AU - Kennedy-Stoskopf, S AU - Horne, W.A AU - Fuller, F.J AU - Tompkins, W.A.F T2 - Fish & Shellfish Immunology AB - A transforming growth factor (TGF)-beta was isolated and cloned from hybrid striped bass (Morone saxatilis x M. chrysops) anterior kidney mononuclear cells. This isolate (Genbank accession number AF140363) contains an open reading frame of 1146 bases coding for a 382 amino acid protein most similar to rainbow trout TGF-beta (57.3 and 78.6% identity with precursor and active protein, respectively) and rat TGF-beta 1 (41.1 and 68.8% identity with precursor and active protein, respectively). Consensus primers were demonstrated to amplify specifically by polymerase chain reaction (PCR), a TGF-beta segment from 14 species of teleost fish comprising 10 taxonomic families in 7 orders. A reverse transcription quantitative competitive polymerase chain reaction (RT-qcPCR) assay was devised to measure TGF-beta mRNA expression in teleost fish. Higher levels of TGF-beta mRNA expression were detected in mononuclear cells of peripheral blood than from spleen or anterior kidney. DA - 2000/1// PY - 2000/1// DO - 10.1006/fsim.1999.0230 VL - 10 IS - 1 SP - 61-85 J2 - Fish & Shellfish Immunology LA - en OP - SN - 1050-4648 UR - http://dx.doi.org/10.1006/fsim.1999.0230 DB - Crossref KW - transforming growth factor-beta KW - TGF-beta KW - sequence KW - hybrid striped bass KW - Morone saxatilis X M-chrysops KW - quantitative PCR ER - TY - JOUR TI - Review of nitrogen and phosphorus metabolism in seagrasses AU - Touchette, BW AU - Burkholder, JM T2 - JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY AB - Within the past few decades, major losses of seagrass habitats in coastal waters impacted by cultural eutrophication have been documented worldwide. In confronting a pressing need to improve the management and protection of seagrass meadows, surprisingly little is known about the basic nutritional physiology of these critical habitat species, or the physiological mechanisms that control their responses to N and P gradients. The limited available evidence to date already has revealed, for some seagrass species such as the north temperate dominant Zostera marina, unusual responses to nutrient enrichment in comparison to other vascular plants. Seagrasses derive N and P from sediment pore water (especially ammonium) and the water column (most nitrate). The importance of leaves versus roots in nutrient acquisition depends, in part, on the enrichment conditions. For example, a shift from reliance on sediment pore water to increased reliance on the overlying water for N and P supplies has been observed under progressive water-column nutrient enrichment. Seagrasses may be N-limited in nutrient-poor waters with sandy or (less so) organic sediments, and P-limited in carbonate sediments. On the basis of data from few species, seagrasses appear to have active uptake systems for NO3− and PO4−3, but NH4+ uptake may involve both low- and high-affinity systems. Pi uptake affinities reported thus far are much lower than values for active ammonium uptake, but comparable to values for nitrate uptake by leaf tissues. Beyond such basic information, seagrass species have shown considerable variation in nutritional response. Dominance of acropetal versus basipetal nutrient translocation appears to vary among species as an innate trait. While some species follow classic Michaelis–Menten kinetics for Ni uptake, others have exhibited sustained linear uptake with limited or negligible product feedback inhibition, perhaps in adaptation to oligotrophic environments. Zostera marina also is able to maintain nitrate reductase (NR) activity during dark periods if adequate carbohydrate reserves and substrate are available. Thus, this species can respond to nitrate pulses throughout a diel cycle, rather than being limited as most plants to nitrate uptake during the light period. Further adaptations may have occurred for seagrasses in extremely nitrate-depauperate conditions. For example, Halophila decipiens and H. stipulacea lack inducible NR and apparently have lost the ability to reduce nitrate; and a biphasic rather than hyperbolic Pi uptake curve, with ‘surge’ uptake, has been described for Zostera noltii. Many seagrasses respond favorably to low or moderate N and/or P enrichment. However, excessive Ni loading to the water column can inhibit seagrass growth and survival, not only as an indirect effect by stimulating algal overgrowth and associated light reduction, but—for some species—as a direct physiological effect. The latter direct impact has been most pronounced for plants growing in sandy (nutrient-poor) sediments, and is exacerbated by elevated temperatures and/or light reduction. Ammonia toxicity, known for many vascular plants, has been reported in seagrasses Ruppia drepanensis and Z. marina (125 μM water-column NH4+, 5 weeks). Z. marina has shown to be inhibited, as well, by pulsed water-column nitrate enrichment (as low as 3.5–7 μM NO3−, 3–5 weeks), which is actively taken up without apparent product feedback inhibition. Inhibition by elevated nitrate has also been reported, with description of the underlying physiological mechanisms, in certain macroalgae and microalgae. In Z. marina, this effect has been related to the high, sustained energy demands of nitrate uptake, and to inducement of internal carbon limitation by the concomitant ‘carbon drain’ into amino acid assimilation. In contrast, nitrate enrichment can stimulate growth of Z. marina when the sediment, rather than the water column, is the source. Because seagrass species have shown considerable variation in nutritional response, inferences about one well-studied species, from one geographic location, should not be applied a priori to that species in other regions or to seagrasses in general. Most of the available information has been obtained from study of a few species, and the basic nutritional physiology of many seagrasses remains to be examined and compared across geographic regions. Nonetheless, the relatively recent gains in general understanding about the physiological responses of some seagrass species to nutrient gradients already have proven valuable in both basic and applied research. For example, physiological variables such as tissue C:N:P content have begun to be developed as integrative indicators of nutrient conditions and anthropogenic nutrient enrichment. To strengthen insights for management strategies to optimize seagrass survival in coastal waters adjacent to exponential human population growth and associated nutrient inputs, additional emphasis is critically needed to assess the role of variable interactions—among inorganic as well as organic N, P and C, environmental factors such as temperature, light, and other community components—in controlling the physiology, growth and survival of these ecologically important marine angiosperms. DA - 2000/7/30/ PY - 2000/7/30/ DO - 10.1016/S0022-0981(00)00195-7 VL - 250 IS - 1-2 SP - 133-167 SN - 1879-1697 KW - carbon KW - light KW - nitrogen KW - phosphorus KW - seagrasses KW - temperature ER - TY - JOUR TI - Overview of the physiological ecology of carbon metabolism in seagrasses AU - Touchette, B. W. AU - Burkholder, J. M. T2 - Journal of Experimental Marine Biology and Ecology AB - The small but diverse group of angiosperms known as seagrasses form submersed meadow communities that are among the most productive on earth. Seagrasses are frequently light-limited and, despite access to carbon-rich seawaters, they may also sustain periodic internal carbon limitation. They have been regarded as C3 plants, but many species appear to be C3-C4 intermediates and/or have various carbon-concentrating mechanisms to aid the Rubisco enzyme in carbon acquisition. Photorespiration can occur as a C loss process that may protect photosynthetic electron transport during periods of low CO(2) availability and high light intensity. Seagrasses can also become photoinhibited in high light (generally>1000 µE m(-2) s(-1)) as a protective mechanism that allows excessive light energy to be dissipated as heat. Many photosynthesis-irradiance curves have been developed to assess light levels needed for seagrass growth. However, most available data (e.g. compensation irradiance I(c)) do not account for belowground tissue respiration and, thus, are of limited use in assessing the whole-plant carbon balance across light gradients. Caution is recommended in use of I(k) (saturating irradiance for photosynthesis), since seagrass photosynthesis commonly increases under higher light intensities than I(k); and in estimating seagrass productivity from H(sat) (duration of daily light period when light equals or exceeds I(k)) which varies considerably among species and sites, and which fails to account for light-limited photosynthesis at light levels less than I(k). The dominant storage carbohydrate in seagrasses is sucrose (primarily stored in rhizomes), which generally forms more than 90% of the total soluble carbohydrate pool. Seagrasses with high I(c) levels (suggesting lower efficiency in C acquisition) have relatively low levels of leaf carbohydrates. Sucrose-P synthase (SPS, involved in sucrose synthesis) activity increases with leaf age, consistent with leaf maturation from carbon sink to source. Unlike terrestrial plants, SPS apparently is not light-activated, and is positively influenced by increasing temperature and salinity. This response may indicate an osmotic adjustment in marine angiosperms, analogous to increased SPS activity as a cryoprotectant response in terrestrial non-halophytic plants. Sucrose synthase (SS, involved in sucrose metabolism and degradation in sink tissues) of both above- and belowground tissues decreases with tissue age. In belowground tissues, SS activity increases under low oxygen availability and with increasing temperatures, likely indicating increased metabolic carbohydrate demand. Respiration in seagrasses is primarily influenced by temperature and, in belowground tissues, by oxygen availability. Aboveground tissues (involved in C assimilation and other energy-costly processes) generally have higher respiration rates than belowground (mostly storage) tissues. Respiration rates increase with increasing temperature (in excess of 40 degrees C) and increasing water-column nitrate enrichment (Z. marina), which may help to supply the energy and carbon needed to assimilate and reduce nitrate. Seagrasses translocate oxygen from photosynthesizing leaves to belowground tissues for aerobic respiration. During darkness or extended periods of low light, belowground tissues can sustain extended anerobiosis. Documented alternate fermentation pathways have yielded high alanine, a metabolic 'strategy' that would depress production of the more toxic product ethanol, while conserving carbon skeletons and assimilated nitrogen. In comparison to the wealth of information available for terrestrial plants, little is known about the physiological ecology of seagrasses in carbon acquisition and metabolism. Many aspects of their carbon metabolism - controls by interactive environmental factors; and the role of carbon metabolism in salt tolerance, growth under resource-limited conditions, and survival through periods of dormancy - remain to be resolved as directions in future research. Such research will strengthen the understanding needed to improve management and protection of these environmentally important marine angiosperms. DA - 2000/// PY - 2000/// DO - 10.1016/S0022-0981(00)00196-9 VL - 250 IS - 1-2 SP - 169-205 ER - TY - JOUR TI - Influence of soil calcium, potassium, and pH on development of leaf tipburn of cabbage in eastern North Carolina AU - Cubeta, MA AU - Cody, BR AU - Sugg, RE AU - Crozier, CR T2 - COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS AB - Abstract Three hypotheses that involved manipulation of soil calcium (Ca), potassium (K), and pH in relation to the occurrence of leaf tipburn of cabbage in eastern North Carolina (NC) were formulated and tested: 1) adding K to soil will increase (induce) leaf tipburn; 2) adding Ca and K together to soil will block K‐related tipburn induction, and 3) raising soil pH to levels of 6.0 to 6.5 will decrease leaf tipburn. Six experiments were conducted in commercial cabbage production fields in eastern NC in 1996 and 1997 to test these hypotheses. Hypothesis 1 was accepted since higher rates of K significantly (p<0.05) increased leaf K concentration, soil K content and leaf tipburn incidence compared with the control. Total cabbage yield increased as K rates increased, however, significant differences were only observed between the control and the highest rate (365 kg K ha‐1) in 1996. Hypothesis 2 was accepted since adding increased amounts of Ca and K. did not significantly increase leaf tipburn incidence. Hypothesis 3 was rejected since a range of soil pH from 5.3 to 6.6 did not increase or decrease leaf tipburn incidence, nutrient uptake or total yield. These data suggest that leaf tipburn of cabbage can be increased (induced) with excessive K fertilization and that this practice may be associated with the disorder observed in NC. Also, the addition of Ca with K may potentially reduce the risk associated with K‐related leaf tipburn of cabbage. DA - 2000/// PY - 2000/// DO - 10.1080/00103620009370435 VL - 31 IS - 3-4 SP - 259-275 SN - 1532-2416 ER - TY - JOUR TI - Hepatic sinusoidal dilatation in a Pearsei cichlid (Cichlasoma pearsei) AU - Barlow, NJ AU - Lewbart, GA AU - Whitney, KM T2 - VETERINARY RECORD AB - Veterinary RecordVolume 146, Issue 1 p. 23-25 Short Communication Hepatic sinusoidal dilatation in a Pearsei cichlid (Cichlasoma pearsei) N. J. Barlow DVM, DACVP, N. J. Barlow DVM, DACVP Chemical Industry Institute of Toxicology, Endocrine, Reproductive, and Developmental Toxicology Program, 6 Davis Drive, PO Box 12137, Research Triangle Park, North Carolina, 27709 USASearch for more papers by this authorG. A. Lewbart VMD, MS, G. A. Lewbart VMD, MS Department of Clinical Sciences, Pathology and Parasitology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, 27606 USASearch for more papers by this authorK. M. Whitney DVM, PhD, DACVP, K. M. Whitney DVM, PhD, DACVP Department of Microbiology, Pathology and Parasitology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, 27606 USASearch for more papers by this author N. J. Barlow DVM, DACVP, N. J. Barlow DVM, DACVP Chemical Industry Institute of Toxicology, Endocrine, Reproductive, and Developmental Toxicology Program, 6 Davis Drive, PO Box 12137, Research Triangle Park, North Carolina, 27709 USASearch for more papers by this authorG. A. Lewbart VMD, MS, G. A. Lewbart VMD, MS Department of Clinical Sciences, Pathology and Parasitology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, 27606 USASearch for more papers by this authorK. M. Whitney DVM, PhD, DACVP, K. M. Whitney DVM, PhD, DACVP Department of Microbiology, Pathology and Parasitology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, 27606 USASearch for more papers by this author First published: 01 January 2000 https://doi.org/10.1136/vr.146.1.23Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References BRUNO, D. W. & ELLIS, A. E. (1986) Multiple hepatic cysts in farmed Atlantic salmon, Salmo salar L. Journal of Fish Diseases 9, 79–81 BUNTON, T. E. (1993) The immunocytochemistry of cytokeratin in fish tissues. Veterinary Pathology 30, 418–425 CONKEL, D. (1993) Systematic write-ups of the subgenera ‘Cichlasoma’. In Cichlids of North and Central America. Neptune City, THF Publications. p 112 EUSTIS, S. L., BOORMAN, G. A., HARADA, T. & POPP, J. A. (1990) Liver. In Pathology of the Fischer Rat. Eds G. A. Boorman, C. A. Montogomery, W. F. Mackenzie. San Diego, Academic Press. pp 76–77 FERGUSON, H. W. (1989) Liver. In Systemic Pathology of Fish: a Text and Atlas of Comparative Tissue Responses in Diseases of Teleosts. Ames, Iowa Sate University Press. pp 146–157 KELLY, W. J. (1993) Vascular factors in liver injury. In Pathology of Domestic Animals. Eds K. V. F. Jubb, P. C. Kennedy, N. Palmer. San Diego, Academic Press. pp 358–359 MAXIE, M. G. (1993) The urinary system. In Pathology of Domestic Animals. Eds K. V. F. Jubb, P. C. Kennedy, N. Palmer. San Diego, Academic Press. pp 323, 464 NOGA, E. J. (1996) Fish Diseases: Diagnosis and Treatment. St. Louis, Mosby-Year Book Citing Literature Volume146, Issue1January 2000Pages 23-25 ReferencesRelatedInformation DA - 2000/1/1/ PY - 2000/1/1/ DO - 10.1136/vr.146.1.23 VL - 146 IS - 1 SP - 23-25 SN - 0042-4900 ER - TY - JOUR TI - Hemiovariosalpingectomy in a loggerhead sea turtle (Caretta caretta) AU - Nutter, FB AU - Lee, DD AU - Stamper, MA AU - Lewbart, GA AU - Stoskopf, MK T2 - VETERINARY RECORD AB - Veterinary RecordVolume 146, Issue 3 p. 78-80 Short Communication Hemiovanosalpingecomy in a loggerhead sea turtle (Caretta caretta) F. B. Nutter DVM, F. B. Nutter DVM Environmental Medicine Consortium, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this authorD. D. Lee DVM, D. D. Lee DVM Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this authorM. A. Stamper DVM, DipACZM, M. A. Stamper DVM, DipACZM Environmental Medicine Consortium, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this authorG. A. Lewbart MS, VMD, G. A. Lewbart MS, VMD Environmental Medicine Consortium, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this authorM. K. Stoskopf DVM, PhD, DipACZM, M. K. Stoskopf DVM, PhD, DipACZM Environmental Medicine Consortium, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this author F. B. Nutter DVM, F. B. Nutter DVM Environmental Medicine Consortium, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this authorD. D. Lee DVM, D. D. Lee DVM Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this authorM. A. Stamper DVM, DipACZM, M. A. Stamper DVM, DipACZM Environmental Medicine Consortium, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this authorG. A. Lewbart MS, VMD, G. A. Lewbart MS, VMD Environmental Medicine Consortium, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this authorM. K. Stoskopf DVM, PhD, DipACZM, M. K. Stoskopf DVM, PhD, DipACZM Environmental Medicine Consortium, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina, 27606 USASearch for more papers by this author First published: 15 January 2000 https://doi.org/10.1136/vr.146.3.78Citations: 25Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. References FRAZER, N. B. (1995) Loggerhead sea turtle, Caretta caretta. In National Marine Fisheries Service and US Fish and Wildlife Service Status Reviews for Sea Turtles Listed Under the Endangered Species Act of 1973. Ed P. T. Plotkin. Maryland, Silver Spring, National Marine Fisheries Service. pp 1– 13 LEGLER, J. M. (1958) Extra-uterine migration of ova in turtles. Herpetologica 14, 49– 52 LUTZ, P. L. & DUNBAR-COOPER, A. (1987) Variations in the blood chemistry of the loggerhead sea turtle, Caretta caretta. Fishery Bulletin 85, 37– 43 MAHMOUD, I. Y. & KLICKA, J. (1975) Extra-uterine egg migration in snapping turtle, Chelydra serpentina serpentina. Journal of Herpetology 9, 242– 243 MILLER, J. D. (1997) Reproductive in sea turtles. In The Biology of Sea Turtles. Eds P. L. Lutz, J. A. Musick. CRC Press, New York. pp 51– 81 RAITI, P. (1995) Reproductive problems of reptiles. Proceedings of the Association of Reptilian and Amphibian Veterinarians. pp 101– 105 TINKLE, D. W. (1959) Additional remarks on extra-uterine egg migration in turtles. Herpetologica 15, 161– 162 United States Department Of Commerce (1997) Endangered Species Act biennial report to Congress on the status of recovery programs, July 1994 – September 1996. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Office of Protected Resources, Silver Spring, Maryland, USA. p 45 Citing Literature Volume146, Issue3January 2000Pages 78-80 ReferencesRelatedInformation DA - 2000/1/15/ PY - 2000/1/15/ DO - 10.1136/vr.146.3.78 VL - 146 IS - 3 SP - 78-80 SN - 0042-4900 ER - TY - JOUR TI - Development of real-time PCR assays for rapid detection of Pfiesteria piscicida and related dinoflagellates AU - Bowers, HA AU - Tengs, T AU - Glasgow, HB AU - Burkholder, JM AU - Rublee, PA AU - Oldach, DW T2 - APPLIED AND ENVIRONMENTAL MICROBIOLOGY AB - ABSTRACT Pfiesteria complex species are heterotrophic and mixotrophic dinoflagellates that have been recognized as harmful algal bloom species associated with adverse fish and human health effects along the East Coast of North America, particularly in its largest (Chesapeake Bay in Maryland) and second largest (Albermarle-Pamlico Sound in North Carolina) estuaries. In response to impacts on human health and the economy, monitoring programs to detect the organism have been implemented in affected areas. However, until recently, specific identification of the two toxic species known thus far, Pfiesteria piscicida and P. shumwayae (sp. nov.), required scanning electron microscopy (SEM). SEM is a labor-intensive process in which a small number of cells can be analyzed, posing limitations when the method is applied to environmental estuarine water samples. To overcome these problems, we developed a real-time PCR-based assay that permits rapid and specific identification of these organisms in culture and heterogeneous environmental water samples. Various factors likely to be encountered when assessing environmental samples were addressed, and assay specificity was validated through screening of a comprehensive panel of cultures, including the two recognized Pfiesteria species, morphologically similar species, and a wide range of other estuarine dinoflagellates. Assay sensitivity and sample stability were established for both unpreserved and fixative (acidic Lugol's solution)-preserved samples. The effects of background DNA on organism detection and enumeration were also explored, and based on these results, we conclude that the assay may be utilized to derive quantitative data. This real-time PCR-based method will be useful for many other applications, including adaptation for field-based technology. DA - 2000/11// PY - 2000/11// DO - 10.1128/AEM.66.11.4641-4648.2000 VL - 66 IS - 11 SP - 4641-4648 SN - 0099-2240 ER - TY - JOUR TI - Water quality trends and management implications from a five- year study of a eutrophic estuary AU - Glasgow, H. B. AU - Burkholder, J. M. T2 - Ecological Applications AB - The Neuse River and Estuary, a major tributary of the second largest estuary on the United States mainland, historically has sustained excessive blooms of algae and toxic dinoflagellates, hypoxia, and fish kills. Previous attempts have been made to use short-term databases of 2–3 years, or data sets from infrequent (monthly) sampling, to assess whether nutrient inputs to the Neuse are increasing and supporting higher algal production. These previous efforts also have relied on single-point-determined flow velocity data, at upstream sites remote from the estuary, to estimate the volume of flow in quantifying nutrient loading to the estuary. We completed a five-year study of the Neuse, including a comparative inventory of nutrients to the watershed from point sources and from concentrated animal operations (CAOs) as recent nonpoint sources, as well as an intensive assessment of water quality over time in the mesohaline estuary. Estimates of nutrient loads were based on volume of flow data from shore-to-shore transect cross sections, taken with a boat-mounted acoustic Doppler current profiler at the westernmost edge of the estuary. A total of 441 point dischargers contributed at least 3.34 × 108 L effluent/d to the Neuse system, much of which came from municipal wastewater treatment plants (2.03 × 108 L effluent/d, excluding periods of plant malfunctions; total annual loadings of at least 9 × 105 kg P and 2.1 × 106 kg N, with a 17% increase in human population over the past decade). The Neuse basin also included 554 CAOs, with 76% in swine production (1.7 × 106 animals, from a 285% increase in the past decade) and 23% in poultry (5.5 × 105 animals). An estimated 5.9 × 109 kg manure produced by swine and poultry during 1998 contributed ∼4.1 × 107 kg N and 1.4 × 107 kg P to the Neuse watershed. About 20% of the area in the watershed now has enough manure from CAOs to exceed the P requirements of all nonlegume crops and forages. About two-thirds of the N- and P-rich feeds for these animals are imported (with 4.0 × 107 kg N and 1.6 × 107 kg P in 1998); thus, the watershed increasingly has become a nutrient sink. Over the five-year study in the Neuse Estuary study area, P loading significantly declined (by an estimated 14%), whereas TN (total nitrogen) loading significantly increased (by an average of 16%) and TNi (total inorganic nitrogen) increased by ∼38%. The increased inorganic N (Ni), partly related to severe storms with high precipitation in years 4–5, coincided with a decrease in phytoplankton biomass (as chlorophyll a) that likely reflected displacement/washout of algal populations and cysts. Thus, while both N and P supplies have increased in the watershed, there is evidence for a significant increase in Ni loading but, as yet, no apparent signal for increased P in the lower estuary. Weather patterns ultimately control when/whether the elevated Ni supply will support increased algal production, so that estuarine algal blooms, hypoxia, and fish kills will remain difficult, at best, to predict in modeling efforts. We recommend that decadal data sets, with sufficient sampling frequency to capture nutrient loadings from major storm events, be used to assess fluctuations in algal production of lower rivers and estuaries, and relationships with changing nutrient inputs. Given increased N and P supplies in the Neuse watershed from ongoing growth of both human and swine populations, a current management goal of 30% N reduction should be altered to include increased focus on Ni and strengthened comanagement of P. As for estuaries in other regions, nutrient reduction goals should be interpreted as “moving targets” that likely will have to be substantially adjusted upward, over time, to accomplish noticeable reductions in algal blooms, hypoxia, and fish kills in the lower Neuse River and Estuary. DA - 2000/// PY - 2000/// DO - 10.2307/2641015 VL - 10 IS - 4 SP - 1024-1046 ER - TY - JOUR TI - Validation and analysis of modeled predictions of growth of Bacillus cereus spores in boiled rice AU - McElroy, DM AU - Jaykus, LA AU - Foegeding, PM T2 - JOURNAL OF FOOD PROTECTION AB - The growth of psychrotrophic Bacillus cereus 404 from spores in boiled rice was examined experimentally at 15, 20, and 30 degrees C. Using the Gompertz function, observed growth was modeled, and these kinetic values were compared with kinetic values for the growth of mesophilic vegetative cells as predicted by the U.S. Department of Agriculture's Pathogen Modeling Program, version 5.1. An analysis of variance indicated no statistically significant difference between observed and predicted values. A graphical comparison of kinetic values demonstrated that modeled predictions were "fail safe" for generation time and exponential growth rate at all temperatures. The model also was fail safe for lag-phase duration at 20 and 30 degrees C but not at 15 degrees C. Bias factors of 0.55, 0.82, and 1.82 for generation time, lag-phase duration, and exponential growth rate, respectively, indicated that the model generally was fail safe and hence provided a margin of safety in its growth predictions. Accuracy factors of 1.82, 1.60, and 1.82 for generation time, lag-phase duration, and exponential growth rate, respectively, quantitatively demonstrated the degree of difference between predicted and observed values. Although the Pathogen Modeling Program produced reasonably accurate predictions of the growth of psychrotrophic B. cereus from spores in boiled rice, the margin of safety provided by the model may be more conservative than desired for some applications. It is recommended that if microbial growth modeling is to be applied to any food safety or processing situation, it is best to validate the model before use. Once experimental data are gathered, graphical and quantitative methods of analysis can be useful tools for evaluating specific trends in model prediction and identifying important deviations between predicted and observed data. DA - 2000/2// PY - 2000/2// DO - 10.4315/0362-028X-63.2.268 VL - 63 IS - 2 SP - 268-272 SN - 0362-028X ER - TY - JOUR TI - Rapid neurobehavioral analysis of Pfiesteria piscicida effects in juvenile and adult rats AU - Levin, ED AU - Rezvani, AH AU - Christopher, NC AU - Glasgow, HB AU - Deamer-Melia, NJ AU - Burkholder, JM AU - Moser, VC AU - Jensen, K T2 - NEUROTOXICOLOGY AND TERATOLOGY AB - The estuarine dinoflagellate Pfiesteria piscicida is known to kill fish and has been associated with neurocognitive deficits in humans. We have developed a rat model to demonstrate that exposure to Pfiesteria causes significant learning impairments. This has been repeatedly seen as a choice accuracy impairment during radial-arm maze learning. Pfiesteria-induced effects were also seen in a locomotor activity test in the figure-8 apparatus. The current studies used the short-term radial-arm maze acquisition, the figure-8 activity test, and the functional observational battery (FOB) to assess Pfiesteria-induced neurobehavioral effects in adult and juvenile rats. In study 1, the neurobehavioral potency of three different Pfiesteria cultures (Pf 113, Pf 728, and Pf Vandermere) was assessed. Ninety-six (12 per group) adult female Sprague-Dawley rats were injected subcutaneously with a single dose of Pfiesteria taken from aquarium-cultured Pfiesteria (35,600 or 106,800 Pfiesteria cells per kilogram of rat body weight). One control group (N = 12) was injected with saline and one (N = 12) with aquarium water not containing Pfiesteria. All three of the Pfiesteria samples (p < 0.05) impaired choice accuracy over the first six sessions of training. At the time of the radial-arm maze choice accuracy impairment, no overt Pfiesteria-related effects were seen using an FOB, indicating that the Pfiesteria-induced choice accuracy deficit was not due to generalized debilitation. In the figure-8 apparatus, Pfiesteria treatment caused a significant decrease in mean locomotor activity. In study 2, the neurobehavioral effects of the Pf 728 sample type were assessed in juvenile rats. Twenty-four day-old male and female rats were injected with 35,600 or 106,800 Pf-728 Pfiesteria cells per kilogram of rat body weight. As with adult females, the juvenile rats showed a significant impairment in radial-arm maze choice accuracy. No changes in locomotor activity or the FOB were detected in the juvenile rats. Furthermore, there were no differences between male and female rats in the Pfiesteria-induced choice accuracy impairment. Pfiesteria effects on choice accuracy in the radial-arm maze in rats constitute a critical component of the model of Pfiesteria toxicity, because the hallmark of Pfiesteria toxicity in humans is cognitive dysfunction. Our finding that analysis of the first six sessions of radial-arm maze testing is sufficient for determining the effect means that this test will be useful as a rapid screen for identifying the critical neurotoxin(s) of Pfiesteria in future studies. DA - 2000/// PY - 2000/// DO - 10.1016/S0892-0362(00)00080-5 VL - 22 IS - 4 SP - 533-540 SN - 0892-0362 KW - Pfiesteria piscicida KW - radial-arm maze KW - activity KW - functional observational battery KW - FOB ER - TY - JOUR TI - Comparative behaviour and survival of hatchery-reared versus wild summer flounder (Paralichthys dentatus) AU - Kellison, GT AU - Eggleston, DB AU - Burke, JS T2 - CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES AB - We describe the use of laboratory trials to compare substrate-specific behaviour and susceptibility to predation of hatchery-reared (HR) versus wild summer flounder (Paralichthys dentatus) juveniles. HR fish spent significantly more time swimming in the water column than wild fish and took significantly longer to become cryptic on the benthos than wild fish, regardless of substrate type. In predation trials with a blue crab (Callinectes sapidus) predator, naïve HR fish were significantly more susceptible to predation than wild fish. Antipredator-conditioned HR fish were significantly less susceptible to predation than naïve HR fish but significantly more susceptible than wild fish, irrespective of substrate. The modified behavioural patterns and increased susceptibility to predation of HR individuals observed in this study indicate that flounder reared in psychosensory-deprived hatchery environments may be poorly equipped to survive in natural habitats; they also indicate that it may be possible to mitigate detrimental behavioural patterns by exposing naïve HR fish to natural stimuli before release into natural environments. These results have important implications for stock enhancement, suggesting that stocked organisms are more likely to achieve postrelease survival if they are conditioned with natural stimuli prior to release into the wild. DA - 2000/9// PY - 2000/9// DO - 10.1139/cjfas-57-9-1870 VL - 57 IS - 9 SP - 1870-1877 SN - 1205-7533 ER - TY - JOUR TI - Cardiorespiratory effects of four alpha(2)-adrenoceptor agonist-ketamine combinations in captive red wolves AU - Sladky, KK AU - Kelly, BT AU - Loomis, MR AU - Stoskopf, MK AU - Horne, WA T2 - JOURNAL OF THE AMERICAN VETERINARY MEDICAL ASSOCIATION AB - Abstract Objective —To evaluate the cardiopulmonary effects of immobilizing doses of xylazine-ketamine (XK), medetomidine-ketamine (MK), medetomidine-ketamine- acepromazine (MKA), and medetomidine-butorphanol- ketamine (MBK) in captive red wolves. Design —Prospective study. Animals —32 adult captive red wolves. Procedure —Wolves were randomly assigned to 1 of 4 treatment groups: XK, MK, MKA, or MBK. Physiologic variables measured included heart rate, blood pressure, respiratory rate, tidal volume, oxygen-hemoglobin saturation (SpO 2 ), end-tidal CO 2 , arterial blood gases, and rectal temperature. Induction time, muscle relaxation, and quality of recovery were assessed. Results —Heart rates were lower in wolves in the MBK group than for the other groups. All 4 drug combinations induced considerable hypertension, with diastolic pressures exceeding 116 mm Hg. Blood pressure was lowest in wolves receiving the MBK combination. Respiratory rate was significantly higher in wolves receiving XK, MK, and MKA. Tidal volumes were similar for all groups. Wolves receiving XK, MK, and MKA were well-oxygenated throughout the procedure (SpO 2 > 93%), whereas those receiving MBK were moderately hypoxemic (87% < SpO2 < 93%) during the first 20 minutes of the procedure. Hyperthermia was detected initially following induction in all groups. Conclusions and Clinical Relevance —The α 2 - adrenoceptor agonist-ketamine combinations provide rapid reversible anesthesia for red wolves but cause severe sustained hypertension. Such an adverse effect puts animals at risk for development of cerebral encephalopathy, retinal hemorrhage, pulmonary edema, and myocardial failure. Although the MBK combination offers some advantages over the others, it is advised that further protocol refinements be made to minimize risks associated with acute hypertension. ( J Am Vet Med Assoc 2000;217:1366–1371) DA - 2000/11/1/ PY - 2000/11/1/ DO - 10.2460/javma.2000.217.1366 VL - 217 IS - 9 SP - 1366-1371 SN - 0003-1488 ER - TY - JOUR TI - The use of poultry mortalities as an alternative bait for the harvesting of blue crabs Callinectes sapidus (Rathbun, 1885) AU - Middleton, T. F. AU - Ferket, P. R. AU - Daniels, H. V. AU - Boyd, L. C. AU - Stikeleather, L. F. AU - Hines, R. J. T2 - Journal of Shellfish Research DA - 2000/// PY - 2000/// VL - 19 IS - 2 SP - 723-729 ER - TY - JOUR TI - Sex steroids relative to alternative mating behaviors in the simultaneous hermaphrodite Serranus subligarius (Perciformes : Serranidae) AU - Cheek, AO AU - Thomas, P AU - Sullivan, CV T2 - HORMONES AND BEHAVIOR AB - This study is the first investigation of reproductive endocrinology in a simultaneously hermaphroditic teleost, the belted sandfish (Serranus subligarius). We address two questions: (1) Do steroid hormone levels vary during the spawning season or during the daily spawning cycle of sandfish? (2) Do hormone levels vary relative to an individual's phenotype—size, frequency of spawning and aggressive behaviors, and proportion of testis in the gonad? We analyzed circulating estradiol-17β (E2), testosterone (T), 11-ketotestosterone (11KT), 17α,20β,21-trihydroxy-4-pregnen-3-one (20βS), and 17α,20β-dihydroxy-4-pregnen-3-one (DHP) concentrations in a field population. Only E2 levels were significantly higher at the new and full moon, suggesting peak periods of vitellogenesis at these times. Naturally spawning sandfish were sampled every 2 h during the photophase of a 25-h period (12 pm to 1 pm the following day) and gonadosomatic index, degree of oocyte hydration and ovulation, and plasma levels of E2, T, DHP, and 20βS were analyzed. E2 and T levels did not vary during photophase, suggesting continuous recruitment of oocytes into vitellogenesis. The 20βS levels peaked around the time of final oocyte maturation. Since frequency of spawning behaviors changes with body size, we captured individuals of various sizes throughout the spawning season and analyzed circulating levels of hormones. 11KT and 20βS levels increased significantly with body size. In 1992, we quantified frequency of spawning and aggressive behaviors, circulating T and 11KT levels and testicular mass relative to ovotestis mass in focal animals. 11KT levels tended to be positively correlated with frequency of courting male behavior, but were unrelated to the frequency of aggressive behavior or testis mass. Because hormone levels increased with size and frequency of each spawning behavior changes with size, we propose that sex steroids influence growth-related changes in spawning tactics of individuals. DA - 2000/5// PY - 2000/5// DO - 10.1006/hbeh.2000.1570 VL - 37 IS - 3 SP - 198-211 SN - 0018-506X KW - spawning cycle KW - conditional mating strategy KW - reproduction ER - TY - JOUR TI - Quantitative polymerase chain reaction for transforming growth factor-beta applied to a field study of fish health in Chesapeake Bay tributaries AU - Harms, Craig AU - Ottinger, C. A. AU - Blazer, V. S. AU - Densmore, C. L. AU - Pieper, L. H. AU - Kennedy-Stoskopf, S. T2 - Environmental Health Perspectives AB - Fish morbidity and mortality events in Chesapeake Bay tributaries have aroused concern over the health of this important aquatic ecosystem. We applied a recently described method for quantifying mRNA of an immunosuppressive cytokine, transforming growth factor-beta (TGF-beta), by reverse transcription quantitative-competitive polymerase chain reaction to a field study of fish health in the Chesapeake Basin, and compared the results to those of a traditional cellular immunoassay macrophage bactericidal activity. We selected the white perch (Morone americana) as the sentinel fish species because of its abundance at all of the collection sites. White perch were sampled from Chesapeake Bay tributaries in June, August, and October 1998. Splenic mononuclear cell TGF-beta mRNA levels increased and anterior kidney macrophage bactericidal activity decreased, particularly in eastern shore tributaries, from June to August and October. The results of the two assays correlated inversely (Kendall's [Tau] b = -0.600; p = 0.0102). The results indicated both temporal and spatial modulation of white perch immune systems in the Chesapeake Basin, and demonstrated the utility of quantitative PCR for TGF-beta as a molecular biomarker for field assessment of teleost fish immune status. DA - 2000/// PY - 2000/// DO - 10.1289/ehp.00108447 VL - 108 IS - 5 SP - 447–452 ER - TY - JOUR TI - Periodicity of increment formation in otoliths of overwintering postlarval and prejuvenile Atlantic menhaden, Brevoortia tyrannus AU - Ahrenholz, D. W. AU - Squires, D. D. AU - Rice, J. A. AU - Nixon, S. W. AU - Fitzhugh, G. R. T2 - Fishery Bulletin (Washington, D.C.) DA - 2000/// PY - 2000/// VL - 98 IS - 2 SP - 421-426 ER - TY - JOUR TI - Identification of gender and reproductive maturity in the absence of gonads: muscle tissue levels of sex steroids and vitellogenin in gag (Mycteroperca microlepis) AU - Heppell, S. A. AU - Sullivan, C. V. T2 - Canadian Journal of Fisheries and Aquatic Sciences AB - Gag (Mycteroperca microlepis) are often landed eviscerated, so their gonads are not available for histological verification of gender and stage of maturity. Information on gender is particularly important for the management of hermaphroditic grouper, where increased mortality through fishing can directly affect sex ratio and therefore the reproductive capacity of the population. Alternative techniques for evaluating fish gender and maturity therefore need to be developed for gag and other grouper. We utilized sensitive immunoassays to measure levels of the sex steroids estradiol-17beta (E 2 ), testosterone (T), and 11-ketotestosterone (11KT) and the egg-yolk precursor vitellogenin (VTG) in gag on a quarterly basis. Plasma and muscle levels of E 2 , T, and VTG in females were lowest during summer, rising in winter to reach peak values in spring. During winter and spring, plasma and muscle levels of 11KT were significantly higher in males than in adult females or immature fish. Combined measurement of VTG and 11KT in gag muscle proved useful for differentiating between males, adult females, and immature fish between December and April, the period of active gonadal recrudescence. This technique should prove useful in cases where fishery data are primarily collected through port sampling and gonads are not available for analysis. DA - 2000/// PY - 2000/// DO - 10.1139/f99-188 VL - 57 IS - 1 SP - 148-159 ER - TY - JOUR TI - Correlation of transforming growth factor-beta messenger RNA (TGF-beta mRNA) expression with cellular immunoassays in triamcinolone-treated captive hybrid striped bass AU - Harms, CA AU - Ottinger, CA AU - Kennedy-Stoskopf, S T2 - JOURNAL OF AQUATIC ANIMAL HEALTH AB - Assessing fish immune status with molecular markers has been hampered by a lack of specific reagents. A quantitative polymerase chain reaction (PCR) method (reverse transcription quantitative-competitive PCR, RT-qcPCR) for measuring transforming growth factor-β (TGF-β) transcription from a broad range of teleost fish has recently been developed. The quantitative PCR now permits monitoring production of this important immunosuppressive cytokine in response to immunomodulating agents and conditions. We examined anterior kidney and spleen mononuclear cells from hybrid striped bass (female striped bass Morone saxatilis × male white bass M. chrysops) for production of TGF-β messenger RNA (mRNA) in response to administration of the synthetic glucocorticoid triamcinolone. We also compared TGF-β transcription with anterior kidney macrophage bactericidal activity and splenic lymphocyte blastogenesis. Anterior kidney mononuclear cell TGF-β mRNA levels decreased, whereas bactericidal activity increased. Spleen TGF-β mRNA levels did not change significantly, and splenic lymphocyte pokeweed mitogen stimulation index increased in triamcinolone-treated fish. Since triamcinolone is used therapeutically as a suppressive immunomodulator, the enhanced immune functions indicated by the cellular immunoassays were unexpected; however, the inverse response of TGF-β production and macrophage bactericidal activity was consistent with the known relationship between TGF-β and macrophage activation in mammals. Induced immunomodulation in hybrid striped bass was detectable by both traditional cellular immunoassays and the new RT-qcPCR for TGF-β. DA - 2000/3// PY - 2000/3// DO - 10.1577/1548-8667(2000)012<0009:COTGFM>2.0.CO;2 VL - 12 IS - 1 SP - 9-17 SN - 0899-7659 ER - TY - JOUR TI - Cardiovascular evidence for an intermediate or higher metabolic rate in an ornithischian dinosaur AU - Fisher, PE AU - Russell, DA AU - Stoskopf, MK AU - Barrick, RE AU - Hammer, M AU - Kuzmitz, AA T2 - SCIENCE AB - Computerized tomography scans of a ferruginous concretion within the chest region of an ornithischian dinosaur reveal structures that are suggestive of a four-chambered heart and a single systemic aorta. The apparently derived condition of the cardiovascular system in turn suggests the existence of intermediate-to-high metabolic rates among dinosaurs. DA - 2000/4/21/ PY - 2000/4/21/ DO - 10.1126/science.288.5465.503 VL - 288 IS - 5465 SP - 503-505 SN - 0036-8075 ER - TY - JOUR TI - Purification, characterization, and bioassay of prolactin and growth hormone from temperate basses, genus Morone AU - Jackson, LF AU - Swanson, P AU - Duan, CM AU - Fruchtman, S AU - Sullivan, CV T2 - GENERAL AND COMPARATIVE ENDOCRINOLOGY AB - Prolactin (PRL) and two variants of growth hormone (GH), purified from pituitaries of striped bass (Morone saxatilis) and its hybrid with white bass (M. saxatilis x M. chrysops) by gel filtration chromatography under alkaline conditions followed by reversed-phase high pressure liquid chromatography, appear similar between species. Both the minor (GH I) and the major (GH II) forms of purified GH appeared as single bands (M(r) approximately 23,000) after sodium dodecyl sulfate-polyacrylamide gel electrophoresis, as did the purified PRL (M(r) approximately 24,000). The molecular weights of GH II and PRL determined by MALDI TOF mass spectroscopy were 21.2 and 21.3 kDa, respectively. In Western blotting experiments, an antiserum against tilapia (Oreochromis mossambicus) 24K PRL specifically recognized Morone PRL, while an antiserum against tilapia GH specifically recognized Morone GH I and II. Chemical identities of the putative PRL and GH I were further confirmed by N-terminal peptide sequencing, while internal sequence analysis was performed on GH II because it was blocked at its N-terminus. Over a stretch of 29 amino acids, Morone PRL was found to be 76% identical to tilapia 24K PRL, 72% identical to tilapia 20K PRL, 72% identical to chum salmon (Oncorhynchus keta) PRL I, and 69% identical to eel (Anguilla japonica) PRL I. Alignment of the hybrid striped bass GH sequences with those of several other advanced marine teleosts indicated 75-85% sequence identity for GH I (40 amino acids) and 95-98% identity for GH II (45 amino acids). Biological activity of striped bass GH II was confirmed using a heterologous in vitro assay of insulin-like growth factor I mRNA production by coho salmon (On. kisutch) hepatocytes. An in vivo bioassay, involving hypophysectomy of hybrid striped bass and treatment of the fish maintained in fresh water with homologous PRL, confirmed that the purified striped bass PRL was also bioactive. DA - 2000/1// PY - 2000/1// DO - 10.1006/gcen.1999.7399 VL - 117 IS - 1 SP - 138-150 SN - 1095-6840 KW - prolactin KW - growth hormone KW - temperate basses ER - TY - JOUR TI - Effects of hypoxia on movements and behavior of selected estuarine organisms from the southeastern United States AU - Wannamaker, CM AU - Rice, JA T2 - JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY AB - Hypoxia, or low dissolved oxygen, remains a common occurrence in estuarine waters as human activity in coastal areas expands. Fish kills, probably the most recognized indicator of these and other water quality problems, have significantly increased in recent years in many Southeastern United States estuaries. While entire aquatic communities are impacted by changes in available oxygen, estuarine organisms serve as appropriate indicators of these changes as they exhibit complex physiological and behavioral responses to hypoxia. The consequences of hypoxia for these species depend on their ability to detect and avoid areas of low dissolved oxygen. We conducted a series of two-way, replicated choice experiments with juvenile spot (Leiostomus xanthurus), pinfish (Lagodon rhomboides), croaker (Micropogonias undulatus), menhaden (Brevoortia tyrannus), white mullet (Mugil curema), mummichog (Fundulus heteroclitus), and brown shrimp (Penaeus aztecus) to determine their ability to detect and avoid specific levels of hypoxia. Additional data on organisms' movement patterns, aquatic surface respiration, and ventilation rates were collected. All species tested could detect and avoid 1 mgl(-1) dissolved oxygen. The hypoxia avoidance response differed among species, as some species exhibited an avoidance threshold while others exhibited a graded avoidance response. These data supply baseline information necessary to assess how some mobile estuarine organisms respond behaviorally to oxygen concentrations, and to understand how hypoxia more broadly impacts fish populations and estuarine community health. DA - 2000/6/28/ PY - 2000/6/28/ DO - 10.1016/S0022-0981(00)00160-X VL - 249 IS - 2 SP - 145-163 SN - 0022-0981 KW - avoidance KW - dissolved oxygen KW - fish behavior KW - hypoxia KW - sublethal effects ER - TY - JOUR TI - Effects of hypoxia on an estuarine predator-prey interaction: foraging behavior and mutual interference in the blue crab Callinectes sapidus and the infaunal clam prey Mya arenaria AU - Taylor, DL AU - Eggleston, DB T2 - MARINE ECOLOGY PROGRESS SERIES AB - MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 196:221-237 (2000) - doi:10.3354/meps196221 Effects of hypoxia on an estuarine predator-prey interaction: foraging behavior and mutual interference in the blue crab Callinectes sapidus and the infaunal clam prey Mya arenaria David L. Taylor*, David B. Eggleston North Carolina State University, Department of Marine, Earth, and Atmospheric Sciences Box 8208, Raleigh, North Carolina 27695-8208, USA *Present address: Graduate School of Oceanography, Univer-sity of Rhode Island, Narragansett, Rhode Island 02882, USA. E-mail: dtaylor@gso.uri.edu ABSTRACT: The effects of hypoxia on trophic interactions could vary dramatically depending on whether the benthos is experiencing the onset of a hypoxic event (decreasing dissolved oxygen concentrations from normoxia), or its dissipation (increasing dissolved oxygen concentrations from hypoxia). Predator-prey dynamics between the blue crab Callinectes sapidus and an infaunal clam prey Mya arenaria were examined to assess the impact of hypoxia upon predator foraging rates and prey mortality. Laboratory experiments quantified the behavioral response of M. arenaria to varying dissolved oxygen levels through the analyses of (1) sediment burial depth, and (2) siphon extension above the sediment surface. Moreover, the functional response (relationship between predator consumption rates and prey density) of single and 2 adult blue crabs to 2 densities of M. arenaria (6 and 24 clams tank-1) was examined across 3 dissolved oxygen treatments: (1) normoxia (≥6.0 DO l-1); (2) moderate hypoxia (3.0 to 4.0 mg DO l-1), subsequent to clam acclimation at high oxygen conditions (≥6.0 mg DO l-1); and (3) moderate hypoxia (3.0 to 4.0 mg DO l-1), subsequent to clam acclimation low oxygen conditions (≤1.5 mg DO l-1). M. arenaria sediment burial depth decreased and siphon extension increased during exposure to severe hypoxia. Initiation of moderate hypoxia following normoxia altered blue crab foraging behavi from a destabilizing, type II functional response, to a partially stabilizing, type I functional response. Conversely, blue crabs exhibited a type II functional response under moderate hypoxia subsequent to clam exposure to severe hypoxia. Therefore, low dissolved oxygen concentrations appear to affect the predator-prey interaction between C. sapidus and M. arenaria by either hindering blue crab foraging, or alternatively, increasing clam vulnerability by altering their siphon extension and depth distribution within the sediment column. Moreover, the inclusion of a second blue crab in experimental trials further modified functional responses through both mutual interference and agonistic behavior or cooperative foraging between predators. The collective results indicate that fluctuations in dissolved oxygen concentrations, as well as both predator and prey density, must be examined jointly to understand their impact upon predator-prey dynamics in marine systems. KEY WORDS: Hypoxia · Trophic dynamics · Callinectes sapidus · Blue crab · Mya arenaria · Predator-prey interaction · Functional response · Mutual interference Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 196. Publication date: April 18, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research. DA - 2000/// PY - 2000/// DO - 10.3354/meps196221 VL - 196 IS - 2000 SP - 221-237 SN - 1616-1599 KW - hypoxia KW - trophic dynamics KW - Callinectes sapidus KW - blue crab KW - Mya arenaria KW - predator-prey interaction KW - functional response KW - mutual interference ER - TY - JOUR TI - Serum oxytetracycline concentrations in African elephant (Loxodonta africana) calves after long-acting formulation injection AU - Bush, M. AU - Stoskopf, M. K. AU - Raath, J. P. AU - Papich, M. G. T2 - Journal of Zoo and Wildlife Medicine DA - 2000/// PY - 2000/// VL - 31 IS - 1 SP - 41-46 ER - TY - JOUR TI - Recruitment in flatfish, with special emphasis on North Atlantic species: Progress made by the Flatfish Symposia AU - Veer, HW AU - Berghahn, R AU - Miller, JM AU - Rijnsdorp, AD T2 - ICES JOURNAL OF MARINE SCIENCE AB - In summarizing the main results on recruitment that emerged from the series of Flatfish Symposia, two aspects were distinguished: mean level and interannual variability. Recruitment to a stock appears to be related to the quantity of juvenile nursery habitats, suggesting that either larval supply or the carrying capacity of the nurseries is the limiting factor. However, available information on growth of 0-group flatfish suggests that the carrying capacity of nursery areas is never reached. Variability in year-class strength is generated during the pelagic egg and larval stage, probably by variations in the hydrodynamic circulation and in the mortality rates of eggs and larvae. Density-dependent processes seem to occur only during the juvenile stages, particularly in respect of growth. However, no impact on recruitment variability has been found. Density-dependent mortality during the phase shortly after settlement dampens the interannual recruitment variability. There is no evidence of density-dependent effects in the adult phase at present, but these may have been important at lower levels of exploitation. The importance of the factors determining recruitment vary not only among species, but also over the species' range. It is suggested that damping processes can only occur in the demersal stage, implying that variability in year-class strength can only decrease in fish species with a demersal stage. If true, ultimate variability in recruitment in fish species will be related to the relative duration of the pelagic and demersal stages. DA - 2000/4// PY - 2000/4// DO - 10.1006/jmsc.1999.0523 VL - 57 IS - 2 SP - 202-215 SN - 1054-3139 KW - control KW - flatfish KW - recruitment KW - regulation KW - year-class strength ER - TY - JOUR TI - Morpho-physiological predictors of ovulatory success in captive striped bass (Morone saxatilis) AU - Weber, GM AU - King, W AU - Clark, RW AU - Hodson, RG AU - Sullivan, CV T2 - AQUACULTURE AB - This study evaluates morpho-physiological characters as predictors of ovulatory success in cultured striped bass, Morone saxatilis, that could be used by farmers to select females for induced spawning. Diameter, size homogeneity and growth of ovarian follicles; blood plasma levels of testosterone (T), oestradiol-17β (E2) and vitellogenin (VTG); and in vitro maturation of oocytes, in response to a combination of insulin-like growth factor-I (IGF-I, 100 nM) and 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S, 290 nM) were examined for females prior to spawning induction and compared with their subsequent ovulatory response. Fish spawning within 8 days of implantation with pelleted analogue of mammalian gonadotropin-releasing hormone analogue (GnRHa; [d-Ala6-des-Gly10-NEt]-LHRH) were considered to have given a satisfactory maturational response. The in vitro assay was the most reliable predictor for ovulatory success. All fish whose oocytes completed final oocyte maturation (FOM) in vitro in response to the combination of IGF-I and 20β-S spawned, whereas, 12 out of 13 fish, whose oocytes did not complete FOM in vitro, failed to spawn within 8 days of GnRHa treatment. The in vitro assay was field-tested on commercial farms, and correctly identified all four females that spawned out of the eight females that were given hormone treatment. Among the other measurements, follicle diameter best differentiated between fish that later spawned and those that did not spawn. Plasma T concentrations were greater on average in fish that spawned, but the technical complexity of the assay and overlap in T concentrations between fish that spawned and those that did not limits the value of this measurement to farmers. There was no significant difference in follicle size homogeneity, follicle growth over the 2-week period prior to hormone treatment, or plasma levels of E2 and VTG between fish that spawned and those that did not. DA - 2000/8/1/ PY - 2000/8/1/ DO - 10.1016/S0044-8486(00)00328-8 VL - 188 IS - 1-2 SP - 133-146 SN - 1873-5622 KW - Morone KW - IGF-I KW - oocyte maturation KW - spawning KW - broodstock ER - TY - JOUR TI - Temporal shift in the presence of a chemical cue contributes to a diel shift in sociality AU - Ratchford, SG AU - Eggleston, DB T2 - ANIMAL BEHAVIOUR AB - Spatial and temporal variation in animal aggregations may be due to variation in the presence of cues for aggregation (or disaggregation) or to variation in the receptivity of the animal to a particular cue or suite of cues. Spiny lobsters, Panulirus argus, forage solitarily but are often found aggregated in their diurnal shelters. An important proximate cause of aggregation among spiny lobsters is a scent they produce that influences shelter choice by conspecifics. We examined how variability in the presence of, or response to, such a chemical cue may contribute to diel shifts in sociality among spiny lobsters. We conducted a series of Y-maze shelter choice experiments using lobsters that were either maintained under altered dark:light schedules in the experimental arena or under natural lighting in the head tanks. Lobsters that were maintained on a light schedule 8 h later than normal chose shelters at their dawn (corresponding to the middle of the night for lobsters in the head tanks); however, their choices of shelter were not influenced by scents of conspecifics. Lobsters that were maintained on a schedule 8 h earlier than normal chose shelters in the middle of their night (corresponding to dawn for the lobsters in the head tanks). Their choices of shelter were significantly influenced by conspecific scents. These results suggest that the chemical cues for aggregation, released by spiny lobsters, are present discontinuously, that spiny lobsters are influenced by conspecific odours continuously, and that aggregation is controlled by temporal variation in the presence of a chemical cue. Copyright 2000 The Association for the Study of Animal Behaviour. DA - 2000/4// PY - 2000/4// DO - 10.1006/anbe.1999.1383 VL - 59 IS - 2000 Apr. SP - 793-799 SN - 0003-3472 ER - TY - JOUR TI - Characterization of Lyme disease spirochetes isolated from ticks and vertebrates in North Carolina AU - Ryan, , JR AU - Apperson, CS AU - Orndorff, PE AU - Levine, JF T2 - JOURNAL OF WILDLIFE DISEASES AB - Borrelia burgdorferi isolates obtained from numerous locations and from different hosts in North Carolina, were compared to previously characterized strains of the Lyme disease spirochete and other Borrelia spp. The spirochete isolates were confirmed to be B. burgdorferi sensu stricto based on immunofluorescence (IFA) using a monoclonal antibody to outer surface protein A (Osp A [H5332]) and polymerase chain reaction (PCR) using a species-specific nested primer for a conserved region of the gene that encodes for flagellin. In addition, the isolates tested positive in Western blots with species-specific monoclonal antibodies for outer surface protein A and OspB (84c), and the genus-specific, monoclonal antibody to flagellin (H9724). Infectivity studies with several of these isolates were conducted using Mus musculus and Oryzomys palustris and the isolates exhibited markedly different levels of infectivity. This study demonstrates that B. burgdorferi sensu stricto is present and naturally transmitted on the Outer Banks and in the Coastal Plain and Piedmont regions of North Carolina. DA - 2000/1// PY - 2000/1// DO - 10.7589/0090-3558-36.1.48 VL - 36 IS - 1 SP - 48-55 SN - 1943-3700 KW - Borrelia burgdorferi KW - isolate characterization KW - Lyme disease KW - ticks KW - vertebrates ER - TY - JOUR TI - Gulf sturgeon spawning migration and habitat in the Choctawhatchee River system, Alabama-Florida AU - Fox, DA AU - Hightower, JE AU - Paruka, FM T2 - TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY AB - Information about spawning migration and spawning habitat is essential to maintain and ultimately restore populations of endangered and threatened species of anadromous fish. We used ultrasonic and radiotelemetry to monitor the movements of 35 adult Gulf sturgeon Acipenser oxyrinchus desotoi (a subspecies of the Atlantic sturgeon A. oxyrinchus) as they moved between Choctawhatchee Bay and the Choctawhatchee River system during the spring of 1996 and 1997. Histological analysis of gonadal biopsies was used to determine the sex and reproductive status of individuals. Telemetry results and egg sampling were used to identify Gulf sturgeon spawning sites and to examine the roles that sex and reproductive status play in migratory behavior. Fertilized Gulf sturgeon eggs were collected in six locations in both the upper Choctawhatchee and Pea rivers. Hard bottom substrate, steep banks, and relatively high flows characterized collection sites. Ripe Gulf sturgeon occupied these spawning areas from late March through early May, which included the interval when Gulf sturgeon eggs were collected. For both sexes, ripe fish entered the Choctawhatchee River significantly earlier and at a lower water temperature and migrated further upstream than did nonripe fish. Males entered the Choctawhatchee River at a lower water temperature than females. Results from histology and telemetry support the hypothesis that male Gulf sturgeon may spawn annually, whereas females require more than 1 year between spawning events. Upper river hard bottom areas appear important for the successful spawning of Gulf sturgeon, and care should be taken to protect against habitat loss or degradation of known spawning habitat. DA - 2000/5// PY - 2000/5// DO - 10.1577/1548-8659(2000)129<0811:GSSMAH>2.3.CO;2 VL - 129 IS - 3 SP - 811-826 SN - 0002-8487 ER - TY - GEN TI - Scary monsters super creeps AU - Burkholder, J. AU - Pain, S. T2 - New Scientist DA - 2000/// PY - 2000/// SP - 42-45 ER - TY - JOUR TI - M6P/IGF2R imprinting evolution in mammals AU - Killian, JK AU - Byrd, JC AU - Jirtle, JV AU - Munday, BL AU - Stoskopf, MK AU - MacDonald, RG T2 - MOLECULAR CELL AB - Imprinted gene identification in animals has been limited to eutherian mammals, suggesting a significant role for intrauterine fetal development in the evolution of imprinting. We report herein that M6P/IGF2R is not imprinted in monotremes and does not encode for a receptor that binds IGF2. In contrast, M6P/IGF2R is imprinted in a didelphid marsupial, the opossum, but it strikingly lacks the differentially methylated CpG island in intron 2 postulated to be involved in imprint control. Thus, invasive placentation and gestational fetal growth are not required for imprinted genes to evolve. Unless there was convergent evolution of M6P/ IGF2R imprinting and receptor IGF2 binding in marsupials and eutherians, our results also demonstrate that these two functions evolved in a mammalian clade exclusive of monotremes. DA - 2000/4// PY - 2000/4// DO - 10.1016/S1097-2765(00)80249-X VL - 5 IS - 4 SP - 707-716 SN - 1097-2765 ER - TY - JOUR TI - Influence of on-site choices on recreation demand AU - Siderelis, C AU - Gustke, L T2 - LEISURE SCIENCES AB - Abstract The role of on-site trips in recreation demand modeling is examined by means of the travel cost method. An understanding of on-site choices of site attractions and costs incurred by visitors is important if analysts are to estimate the popularity of the various attractions and, ultimately, to derive site benefits. We investigate two primary questions. First, can on-site trips to attractions be adequately modeled? Next, how important is onsite travel in valuing site benefits? Visitor survey data for the North Carolina Zoological Park were used to determine that economic site benefits are underestimated by 24% if expected on-site travel costs from recreation demand analysis are excluded. Keywords: Nested Choice Models On-SITE Travel Behavior Recreation Demand Travel Cost Method Zoological Parks DA - 2000/// PY - 2000/// DO - 10.1080/014904000272894 VL - 22 IS - 2 SP - 123-132 SN - 0149-0400 KW - nested-choice models KW - on-site travel behavior KW - recreation demand KW - travel cost method KW - zoological parks ER - TY - JOUR TI - Feeding selectivity and rapid particle processing by deep-sea megafaunal deposit feeders: A Th-234 tracer approach AU - Miller, RJ AU - Smith, CR AU - DeMaster, DJ AU - Fornes, WL T2 - JOURNAL OF MARINE RESEARCH AB - Deposit-feeding megafauna occur in virtually all deep-sea environments, yet their feeding selectivity and particle processing rates are poorly known. Excess 234 Th activity is commonly used as a geochemical tracer for recently settled (<100-d old) particles in the quiescent deep sea, but it has rarely been applied to the study of deposit feeders. To explore the selectivity and rates of megafaunal deposit feeding, we compared excess 234 Th activities in the gut contents of deposit feeders from Santa Catalina Basin (SCB) (∼1200 m depth) and the Hawaiian slope (∼1680 m) to the activity of surface sediments and, in SCB, to material from sediment traps moored ∼150 m above the seafloor. We also measured concentrations of chlorophyll a and phaeopigments in animal guts and surface sediments to evaluate feeding selectivity. In the SCB, excess 234 Th ( 234 Th xs ) activities in the guts of four species of surface-deposit feeders were 14-17 fold greater than those of the top 5 mm of sediment. Pannychia moseleyi and Scotoplanes globosa, two highly mobile, surface-deposit-feeding elasipodid holothurians, were the most enriched in gut 234 Th xs activity, suggesting that these species fed very selectively on particles settled to the seafloor within the previous ∼20 d. Pannychia moseleyi guts also exhibited 500-fold enrichment of chlorophyll a relative to surface sediments indicating highly selective ingestion of phytodetritus. Chiridota sp., a burrowing, surface-deposit-feeding, chiridotid holothurian, and Bathybembix bairdii, a surface-deposit-feeding trochid gastropod, were less enriched in gut 234 Th xs activity, reflecting lower mobility and/or less selectivity at time of particle pickup. A subsurface-deposit-feeding, molpadiid holothurian was not enriched in gut 234 Th xs activity compared to surface sediments, but was greatly enriched compared to average activities at its presumed feeding depth of 6-7 cm. On the Hawaiian slope, gut contents of two surface-deposit feeders, the synallactid holothurians Mesothuria carnosa and Paleopatides retifer, were not enriched in 234 Th xs activity; however, M. carnosa and Phryssocystis sp. (a surface-deposit-feeding echinoid) were enriched in chlorophyll a, suggesting that the Hawaiian slope species are also selective feeders. Presumably, frequent sediment resuspension makes 234 Th xs activity a poor tracer for recently settled, food-rich particles on the Hawaiian slope. Based on a newly developed 234 Th-flux model, we calculate that the three dominant megafaunal, surface-deposit feeders in SCB consumed on average 39-52% (s.e. 13-27%) of the daily flux of 234 Th xs activity to the SCB floor. By chemically altering (e.g., digesting) and redistributing recently settled particulate organic matter, these megafauna are likely to substantially influence carbon diagenesis and food-web structure in this bathyal habitat. DA - 2000/7// PY - 2000/7// DO - 10.1357/002224000321511061 VL - 58 IS - 4 SP - 653-673 SN - 1543-9542 ER - TY - JOUR TI - Engineering the future AU - Swartzel, K. R. T2 - Food Technology DA - 2000/// PY - 2000/// VL - 54 IS - 5 SP - 246 ER -