@article{demaster_taylor_smith_isla_thomas_2021, title={Using Radiocarbon to Assess the Abundance, Distribution, and Nature of Labile Organic Carbon in Marine Sediments}, volume={35}, ISSN={["1944-9224"]}, DOI={10.1029/2020GB006676}, abstractNote={Positive 14C gradients have recently been observed within the surface mixed layer of several continental‐margin sediments. The best explanation for these positive 14C gradients is the occurrence and rapid degradation of labile organic carbon (LOC) in the upper 5–10 cm of the seabed. Based on a two‐component model for sedimentary organic matter (i.e., a planktonic labile component and an older refractory component), bulk 14Corg data were used to determine the abundances of LOC within the surface mixed layers of three cores from the West Antarctic Peninsula (WAP) shelf and one core from San Clemente Basin (California Borderland). LOC contents in surface samples from the four stations varied from 0.5 to 1.1 mg/cm3, comprising 20% (San Clemente Basin) to 80% (WAP, Sta. G) of the total organic carbon. By incorporating a steady state diagenetic model and particle‐mixing bioturbation coefficients, the LOC profiles were used to determine LOC turnover times (LOC τ) and LOC e‐folding depths. The LOC τ values for the West Antarctic Peninsula sediments varied from 0.09 to 0.59 years, whereas the LOC τ value from the San Clemente Basin core was 63 years. The LOC e‐folding depths for the WAP stations varied from 0.8 to 3.4 cm, in contrast to the LOC e‐folding depth in San Clemente Basin, which was 4.0 cm. LOC characteristics from the four cores examined in this study were compared to LOC data in the literature as a means of substantiating the overall 14Corg‐based approach and justifying model assumptions.}, number={6}, journal={GLOBAL BIOGEOCHEMICAL CYCLES}, author={DeMaster, D. J. and Taylor, R. S. and Smith, C. R. and Isla, E. and Thomas, C. J.}, year={2021}, month={Jun} }
 @article{taylor_demaster_smith_thomas_2020, title={Evaluating the effects of regional climate trends along the West Antarctic Peninsula shelf based on the seabed distribution of naturally occurring radioisotopic tracers}, volume={429}, ISSN={["1872-6151"]}, DOI={10.1016/j.margeo.2020.106315}, abstractNote={Measurements of 230Th, 14C, 210Pb and 234Th activities were made on sediment cores collected along a N-S transect exhibiting a gradient in annual sea-ice duration off the West Antarctic Peninsula. The resultant data were used to evaluate the effects of regional warming on particle flux reaching the seabed on timescales from millennial to seasonal. Shelf samples were collected at five stations, over three cruises, between February 2008 and March 2009, as part of the FOODBANCS2 Project. Sea-ice conditions (the number of days ice-free prior to core collection) were evaluated at the five stations to understand the relationship between ice abundance and particle/radionuclide flux. Based on the millennial tracer 14C, rates of sediment accumulation along the peninsula decrease southward, consistent with the observed sea-ice gradient. 230Th data provide additional evidence on millennial timescales that sediment focusing (i.e., lateral transport) occurs to a greater extent in the northern reaches of the study area compared to the southernmost stations. The distribution of steady-state, 210Pb flux to the seabed (representing centurial trends) displays a similar trend to 14C, showing higher radionuclide/particle flux in the northern study area (where sea-ice duration is diminished) and lower flux southward as sea-ice duration increases. Additionally, 210Pb data suggest that lateral transport plays an important role in the sediment distributions of this radiotracer on hundred-year timescales, which is explainable by the relatively short circulation times of peninsular waters relative to 210Pb's half-life. On seasonal and annual time scales, the distribution of steady-state 234Th flux to the seabed shows an increase in radionuclide flux at the southernmost stations. This increase in radionuclide flux on seasonal and annual time scales is consistent with the warming trend along the peninsula and the reduction in sea-ice duration over the past decade. A significant statistical relationship, however, could not be established between annual sea-ice free days and 234Th-derived particle flux to the seabed. The fluxes/distributions of long-lived particle-reactive tracers (14C, 230Th, and 210Pb) on the West Antarctic Peninsula shelf appear to be controlled primarily by the long-term pattern of increasing annual sea-ice duration in the southward direction, whereas the fluxes of the short-lived tracer (234Th) are consistent with the more recent decreases in sea-ice duration (associated with climate change) that have occurred over the past decade, primarily in the southern West Antarctic Peninsula stations.}, journal={MARINE GEOLOGY}, author={Taylor, Richard S. and DeMaster, David J. and Smith, Craig R. and Thomas, Carrie J.}, year={2020}, month={Nov} }
 @article{mcculloch_kamykowski_morrison_thomas_pridgen_2013, title={A physical and biological context for Karenia brevis seed populations on the northwest Florida shelf during July 2009}, volume={63}, ISSN={["1873-6955"]}, DOI={10.1016/j.csr.2013.05.001}, abstractNote={The current effort focuses on characterizing physical and biological conditions across the northwest Florida shelf during summer as they influence Karenia brevis distributions and phytoplankton/microphytobenthos community associations. Phytoplankton and benthic algal communities were examined in the context of cross-shelf hydrography and sediment conditions during July 2009 between the 20 and 65 m isobaths off Panama City, FL. A towed undulating profiler (SeaSciences Acrobat) mapped water column characteristics between near-surface and ∼1 m above the sediment. A CTD/rosette provided hydrographic profiles and collected water samples at 17 cross-shelf locations at selected depths for nutrient concentration, phytoplankton biomass determination, and chemotaxonomic and taxonomic phytoplankton identification. In addition, a CTD/rosette time series sample set was collected following a holey sock drogue set at ∼34 m along the ∼50 m isobath, and cores were collected at eight stations approximately along the 30, 40 and 55 m isobaths. Cross-shelf, a pycnocline existed at ∼10 m depth, the 1% light level penetrated to ∼45 m depth, and nitrate–nitrite (NO3−+NO2−) concentrations increased in the lower 10 m of the water column to the 50 m isobath and then below 40-m depth to the 65 m isobath. A chlorophyll a peak occurred near-bottom between the 25 and 35 m isobaths. Gyroxanthin dinoflagellates (GD) representing K. brevis occurred across the shelf in near-surface and near-bottom waters. Near-surface GD co-occurred with cyanophytes at low density in the upper 20 m of the water column where NO3−+NO2− concentrations were low. Above sediments in the euphotic zone, near-bottom GD were most abundant between the 25 and 35 m isobaths where the NO3−+NO2− concentrations were 1–4 µM and where microphytobenthos competed for nutrient sources. Below the euphotic zone, GD were present near-bottom to the 60 m isobath where NO3−+NO2− concentrations approached 6 µM. A pattern consistent with dinoflagellate diel vertical migration was inferred at the 50-m isobath time-series station. The results provide insight into offshore K. brevis seed populations and their associations with other phytoplankton and microphytobenthos. Under summer light and nutrient conditions along the northwest Florida shelf, K. brevis coastal blooms may be seeded by diffuse near-surface populations during occasional downwelling conditions and by more concentrated near-bottom populations during more prevalent upwelling conditions.}, journal={CONTINENTAL SHELF RESEARCH}, author={McCulloch, Anita A. and Kamykowski, Daniel and Morrison, John M. and Thomas, Carrie J. and Pridgen, Katy Grabowski}, year={2013}, month={Jul}, pages={94–111} }
 @article{kamykowski_pridgen_morrison_mcculloch_nyadjro_thomas_sinclair_2013, title={Cold front induced changes on the Florida panhandle shelf during October 2008}, volume={54}, ISSN={["1873-6955"]}, DOI={10.1016/j.csr.2012.12.006}, abstractNote={A significant step transition between seasonally stratified and destratified hydrographic conditions occurred during an October 2008 cruise to the Florida Panhandle Shelf along a cross-shelf transect that was sampled before and after a cold front passed through the area. Meteorological measurements from nearby ocean and land-based stations characterized the event. Cross-shelf continuous Acrobat profiles and discrete CTD stations characterized water column hydrographic patterns, while mid-shelf multicorer and box corer samples characterized sediment texture and nutrients. Water samples collected from selected depths biased toward the sediment interface were analyzed for nutrient content and phytoplankton community composition. Pre-front, the cross-shelf water column exhibited vertical stratification with complex temperature and salinity patterns. A prominent near-bottom chlorophyll a maximum of ∼1.5 μg L−1 between the 25–35 m isobaths occurred with the 1% light level at ∼18 m depth and a near-bottom nitrate+nitrite (NO3−+NO2−) maximum >3 μM between the 30–40 m isobaths. HPLC-determined phytoplankton community composition in the near-bottom chlorophyll a maximum consisted of gyroxanthin-containing dinoflagellates (Karenia brevis) and less abundant diatoms, both verified by FlowCAM analysis, mixed with detectable cryptophytes and chlorophytes. Sediment trends based on limited core replicates suggested the sediments were a potential source of nutrients to near-bottom populations of K. brevis and that shell hash could provide abundant pore space for K. brevis incursions. Between the 40–50 m isobaths, diatoms, cryptophytes and chlorophytes dominated near-bottom, gyroxanthin-containing dinoflagellates and prasinophytes occurred throughout the water column, and cyanophytes dominated near-surface. Post-front, the cross-shelf water column exhibited destratification with temperature and salinity increasing offshore. A chlorophyll a maximum of ∼0.75 μg Chl a L−1 left the sediment between 25–35 m isobaths and extended offshore especially in the lower water column with the 1% light level at ∼15 m depth and NO3−+NO2− concentrations ∼2 μM to the 60 m isobath. HPLC-determined phytoplankton community composition of the offshore plume retained the signature of gyroxanthin-containing dinoflagellates and chlorophytes. Between the 30–50 m isobaths, prasinophytes increased in the lower water column, while cyanophytes increased at all depths across the shelf. The observed step transition from stratification to destratification on the Florida Panhandle Shelf contributed to altered phytoplankton community patterns in response to predominant downwelling favorable winds. Pre-front, K. brevis cells were broadly distributed cross-shelf, but concentrated near-bottom between the 25–35 m isobaths and staged for prolific bloom seeding in response to the upwelling favorable west winds more typical of spring-summer. Post-front, K. brevis cells were mixed throughout the mid-shelf water column and were staged for diffuse bloom seeding in response to either the downwelling or upwelling favorable winds occurring fall-winter. Cyanophytes located predominantly near-surface offshore pre-front, were ubiquitous cross-shelf and more closely associated with K. brevis post-front.}, journal={CONTINENTAL SHELF RESEARCH}, author={Kamykowski, D. and Pridgen, K. Grabowski and Morrison, J. M. and McCulloch, A. A. and Nyadjro, E. S. and Thomas, C. A. and Sinclair, G. A.}, year={2013}, month={Feb}, pages={52–66} }
 @article{spence_thomas_2013, title={Science and Technology Centers Deliver New Oceanographic Concepts to Educators}, volume={28}, url={https://www.marine-ed.org/journal}, journal={Current: Journal of Marine Science Education}, author={Spence, L. and Thomas, C.}, year={2013}, pages={2–4} }
 @inproceedings{thomas_spence_2012, title={Building Bridges: Proceedings from the Invitational Working Conference on Building Diversity in the Ocean Sciences}, url={http://www.cosee-se.org/files/southeast/ProceedingsDocument.pdf}, booktitle={orking Conference on Building Diversity in the Ocean Sciences}, author={Thomas, C. and Spence, L.}, year={2012} }
 @article{smith_demaster_thomas_srsen_grange_evrard_deleo_2012, title={PELAGIC-BENTHIC COUPLING, FOOD BANKS, AND CLIMATE CHANGE ON THE WEST ANTARCTIC PENINSULA SHELF}, volume={25}, ISSN={["1042-8275"]}, DOI={10.5670/oceanog.2012.94}, abstractNote={The West Antarctic Peninsula (WAP) shelf is deep and detritus-based (i.e., it is fueled by organic material sinking from intense seasonal cycles of primary production in the water column), leading to pelagic-benthic coupling. The WAP is warming rapidly, yielding increases in seawater temperatures and reductions in sea ice that may fundamentally alter pelagic-benthic coupling and shelf benthic ecosystems. RVIB Nathaniel B. Palmer and ARSV Laurence M. Gould have provided year-round access to the WAP sea ice zone, facilitating studies of pelagic-benthic coupling and climate change. In the Food for Benthos along the Antarctic Continental Shelf (FOODBANCS) Project, we conducted a 15-month field program to evaluate benthic ecosystem function across the mid-WAP shelf, testing the hypothesis that "phytodetrital material deposited from the summer bloom provides a sustained source of food for benthic detritivores during winter months, when organic-matter flux from the water column is extremely low." We found that the intense seasonality in primary production and food availability in the WAP water column is heavily dampened at the shelf floor by the presence of a "food bank" that sustains benthic ecosystem functions (including sediment-community respiration, deposit feeding, vitellogenesis, spawning, and recruitment of benthos) over the winter; this food bank also influences community structure and life-history strategies of the WAP benthos. The persistence of the food bank may be mediated by low bottom-water temperatures, with the consequence that climate warming might reduce food availability in shelf communities. During the FOODBANCS2 Project, we studied the benthic ecosystem response to the strong latitudinal sea ice gradient along the WAP to explore the ecosystem consequences of sea ice loss from climate change. We found that some aspects of benthic ecosystem structure (e.g., macrofaunal dominance by the polychaete Aurospio foodbancsia) covaried with sea ice duration and are likely to be sensitive to sea ice loss. Other benthic parameters (e.g., the standing crop of macro- and megabenthos) exhibited nonlinear responses, with evidence of resilience along much of the sea ice gradient and abrupt change near one end. Still other benthic parameters (e.g., sediment community respiration) changed very little with sea ice duration. We also found that climate warming is facilitating invasion of the WAP shelf by predacious king crabs, with dramatic reduction in benthic biodiversity and altered ecosystem function. In summary, some important benthic ecosystem parameters along the WAP may be resilient to climate-induced changes in pelagic-benthic coupling, while many others may be highly sensitive, responding nonlinearly to sea ice loss. Incorporation of climate change effects into WAP benthic ecosystem models, including the effects of invasive species, will be challenging until mechanisms, nonlinearities, synergies, and tipping points of climate change effects are better understood. - See more at: http://www.tos.org/oceanography/archive/25-3_smith_c.html#sthash.YDijuDU5.dpuf}, number={3}, journal={OCEANOGRAPHY}, author={Smith, Craig R. and DeMaster, David J. and Thomas, Carrie and Srsen, Pavica and Grange, Laura and Evrard, Victor and DeLeo, Fabio}, year={2012}, month={Sep}, pages={188–201} }
 @article{null_corbett_demaster_burkholder_thomas_reed_2011, title={Porewater advection of ammonium into the Neuse River Estuary, North Carolina, USA}, volume={95}, ISSN={["1096-0015"]}, DOI={10.1016/j.ecss.2011.09.016}, abstractNote={Radon-222 (222Rn) and ammonium (NH4+) were measured in interstitial water of the Neuse River Estuary (NRE), North Carolina, USA to determine the advective flux of NH4+ from sediments to the overlying water column. Porewater samples were collected over an annual cycle from multi-level piezometers installed in nearshore sites. NH4+ concentrations in sandy environments of the NRE were 10-fold higher than concentrations in the overlying water column. Shallow porewaters exhibited seasonal variations in NH4+ concentrations, which resulted in temporal changes in NH4+ flux from the sediment. Submarine groundwater discharge (SGD) was measured indirectly by using 222Rn as a tracer and directly via seepage meters. Discharge rates were variable depending upon the sampling location and season. The mean SGD was 9.1 ± 1.5 cm d−1 with a maximum SGD during spring at a rate of 13.6 cm d−1 based on 222Rn porewater distribution. High porewater NH4+ concentrations in sandy nearshore sediments contributed NH4+ to the overlying water via groundwater discharge as an advective process. The overall mean NH4+ flux was 11.2 ± 2.0 mmol NH4+ m−2 d−1. Seasonal trends in groundwater seepage rates and NH4+ concentration suggest that groundwater is an important mechanism advecting nutrients from porewaters to surface waters, which is comparable to riverine NH4+ discharge. SGD N:P ratios (NH4+ as N) were >16:1, indicating that SGD is an important contributor of inorganic N for phytoplankton growth and may influence the NRE toward a less N-limited system. The data from this study will advance current understanding about the role of NH4+ in the progressive eutrophication of shallow estuarine ecosystems.}, number={2-3}, journal={ESTUARINE COASTAL AND SHELF SCIENCE}, author={Null, Kimberly A. and Corbett, D. Reide and DeMaster, David J. and Burkholder, JoAnn M. and Thomas, Carrie J. and Reed, Robert E.}, year={2011}, month={Dec}, pages={314–325} }
 @article{hartnett_boehme_thomas_demaster_smith_2008, title={Benthic oxygen fluxes and denitrification rates from high-resolution porewater profiles from the Western Antarctic Peninsula continental shelf}, volume={55}, ISSN={["1879-0100"]}, DOI={10.1016/j.dsr2.2008.06.002}, abstractNote={Benthic fluxes of dissolved oxygen and nitrate were calculated from high-resolution porewater profiles collected on the continental margin of the Western Antarctic Peninsula. Profiles were collected in four seasons between March 2000 and February 2001 as part of the FOODBANCS program. Oxygen consumption rates ranged from 0.92 to 3.11 mmol O2 m−2 d−1 over the course of the year with an average annual oxygen consumption rate of 1.74 mmol O2 m−2 d−1. The oxygen fluxes follow a trend similar to the particulate carbon export flux with smaller fluxes during the winter and larger fluxes during the spring bloom period. However, the range in oxygen fluxes is substantially smaller than the range in the particulate carbon export. Denitrification rates ranged from 0.66 to 1.46 mmol N m−2 d−1, and the average annual denitrification rate was 1.29 mmol N m−2 d−1. The O2 consumption and denitrification rates are of similar magnitude to rates measured on other deep (∼500 m) continental margins. Denitrification rates are strongly coupled to nitrification rates, with coupled nitrification–denitrification accounting for more than 80% of the total denitrification rate in these sediments. The Antarctic continental-margin sediment denitrification rates correspond to ∼3–5 Tg N yr−1, and thus these continental-margin sediments account for roughly 1–2% of the global sediment denitrification signal.}, number={22-23}, journal={DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY}, author={Hartnett, Hilairy and Boehme, Susan and Thomas, Carrie and DeMaster, David and Smith, Craig}, year={2008}, month={Nov}, pages={2415–2424} }
 @article{purinton_demaster_thomas_smith_2008, title={C-14 as a tracer of labile organic matter in Antarctic benthic food webs}, volume={55}, ISSN={["1879-0100"]}, DOI={10.1016/j.dsr2.2008.06.004}, abstractNote={14C measurements were made on surface plankton, particle-trap material, surface sediment, benthic invertebrate gut contents, and body tissue samples to assess the effectiveness of this radioisotope as a tracer of labile organic carbon in Antarctic benthic food webs. Samples were collected on five cruises to the West Antarctic Peninsula (WAP) shelf between November 1999 and March 2001 as part of the Food for Benthos on the ANtarctic Continental-Shelf (FOODBANCS) Project. The 14C contents of the body tissues from a variety of deposit feeders (−126±13 per mil) were substantially enriched relative to the surface sediment (−234±13 per mil) and statistically similar to the organic matter collected in plankton tows (−135±10 per mil), indicating that recently produced marine plankton are the primary source of nutrition for these deposit feeders on the West Antarctic shelf. Selective ingestion was the primary feeding strategy used by echiuran worms and certain holothurians (i.e. Peniagone vignoni) for incorporating labile organic carbon into their tissues as demonstrated by the large differences (105±13 per mil) between surface sediment and gut content 14C activities. In contrast, digestive and/or assimilatory selection was the predominant strategy used by an irregular urchin (Amphipneustes lorioli) and several other holothurians (Protelpidia murrayi, Bathyplotes fuscivinculum and the head-down conveyor belt feeder, Molpadia musculus), as demonstrated by large differences (42±7 per mil) between the 14C activities of their foregut or whole-gut organic contents and their body tissues. Despite large fluctuations in carbon export from the euphotic zone, benthic feeding strategies remained essentially constant over the 15-month sampling period. No seasonal variation was evident in either the 14C abundance of the deposit-feeder body tissues, or in the 14C abundance of their gut contents. The mean 14C abundance in the body tissues of the two sub-surface deposit feeders (A. lorioli and M. musculus; mean=−136.2±8.5 per mil) was distinct (p=0.0008) from the mean 14C abundance in the body tissues of the four surface deposit feeders (echiuran worm, P. vignoni, P. murrayi, and B. fusciviculum; −122.6±12.3 per mil). The mean 14C abundance of the gut contents from the sub-surface deposit feeders (−178.0±18.6 per mil) also was significantly depleted (p=0.0009) relative to that of the surface deposit feeders (−149.5±26.6 per mil). The 14C measurements proved to be a much more sensitive tracer for tracking labile organic carbon during ingestive and assimilatory processes than the stable isotopes of carbon or nitrogen.}, number={22-23}, journal={DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY}, author={Purinton, Brett L. and DeMaster, David J. and Thomas, Carrie J. and Smith, Craig R.}, year={2008}, month={Nov}, pages={2438–2450} }
 @article{gallinari_ragueneau_demaster_hartnett_rickert_thomas_2008, title={Influence of seasonal phytodetritus deposition on biogenic silica dissolution in marine sediments-Potential effects on preservation}, volume={55}, ISSN={["1879-0100"]}, DOI={10.1016/j.dsr2.2008.06.005}, abstractNote={The deposition of fresh phytoplankton detritus (phytodetritus) following phytoplankton blooms may influence biogenic silica (BSi) dissolution in marine sediments. We studied BSi dissolution properties before, during, and after periods of phytodetritus deposition during time-series field programs in the abyssal North Atlantic (the BENGAL project), and on the West Antarctic Peninsula Shelf (the FOODBANCS project). Dissolution experiments, performed by means of flow-through reactors, showed temporal variations in the dissolution properties of BSi in the sediment column after phytodetritus deposition. This non-steady-state character of benthic silica dynamics is an important aspect of pelagic–benthic coupling. The last FOODBANCS cruise occurred after a phytodetritus deposition event, and yielded high pore-water dissolved silica (DSi) concentrations and DSi effluxes in the upper centimetres of the sediment column, suggesting a rapid turnover of recently deposited siliceous material. Higher dissolution rates were measured in the phytodetritus-rich sediments relative to surface sediments collected during previous seasons on earlier FOODBANCS cruises. During the BENGAL project, high dissolution rates were measured at depth in the sediment column only after a summer phytodetritus deposition event. In the highly detrital sediment matrix of the abyssal North Atlantic Ocean, resolution of increased dissolution rates and experimental artefacts of the flow-through reactors can be difficult because of the low abundance of BSi. Depending on the sediment matrix, bioturbation can play a crucial role in transporting fresh BSi particles to depth, where DSi concentrations are close to experimentally determined BSi solubilities. The potential impacts of such processes on BSi preservation are discussed. We suggest that future models of BSi early diagenesis should include the rapid mixing of freshly deposited particles if we want to describe further the preservation of BSi in marine sediments.}, number={22-23}, journal={DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY}, author={Gallinari, M. and Ragueneau, O. and DeMaster, D. J. and Hartnett, H. and Rickert, D. and Thomas, C.}, year={2008}, month={Nov}, pages={2451–2464} }
 @article{mcclintic_demaster_thomas_smith_2008, title={Testing the FOODBANCS hypothesis: Seasonal variations in near-bottom particle flux, bioturbation intensity, and deposit feeding based on Th-234 measurements}, volume={55}, ISSN={["1879-0100"]}, DOI={10.1016/j.dsr2.2008.06.003}, abstractNote={Naturally occurring 234Th (24-d half-life) was used on the West Antarctic continental shelf to evaluate temporal variations in the flux of particulate material reaching the seabed, bioturbation intensity, the seasonal continuity of feeding by benthic fauna, and trends in particle selection during ingestion for six common detritivores (four surface deposit feeders and two subsurface deposit feeders). These measurements were made at three stations during the five FOODBANCS cruises (December 1999, March, June, and October 2000, and March 2001) to assess the nature of pelagic–benthic coupling on the shelf and to evaluate the seabed as a potential food bank for deposit feeders when surface primary production is minimal. Two summer regimes were sampled (March 2000 and March 2001) with the latter exhibiting a distinct 1–2-cm-thick phytodetritus layer in nearly all sediment core samples. At site B, the 234Th fluxes into the near-bottom (150/170 mab) sediment traps were indistinguishable for the December–March 2000, March–June 2000, and June–October 2000 sampling intervals (fluxes ranging from 170 to 280 dpm m−2 d−1). However, the sediment-trap 234Th flux measured for the October 2000–March 2001 interval (1000 dpm m−2 d−1) was ∼5-fold greater than during the other three sampling periods, consistent with the deposition of a phytodetritus layer. The steady-state 234Th fluxes derived from seabed inventories at site B were 2.4–2.7 times greater than the sediment-trap 234Th fluxes, indicating substantial scavenging of this particle-reactive radiotracer in the bottom 150 m of the water column and/or lateral transport near the seabed. The seabed 234Th inventories at the three stations showed no variation during the first four cruises, but were significantly greater during cruise FB-V (March 2001), when the phytodetritus layer occurred. Based on 234Th distributions in the seabed, bioturbation intensities (quantified using the diffusive mixing coefficient, Db) varied from 0.5 to 97 cm2 yr−1. Mixing coefficients were significantly lower during FB-II than during FB-III, but no other time comparisons were statistically significant (p>0.05). 234Th Dbs showed no distinct seasonality, and no correlation with either organic carbon flux into the sediment traps or 234Th inventory in the seabed. The four surface deposit feeders examined, an echiuran worm and three holothurians (Protelpidia murrayi, Bathyplotes fuscivinculum, and Peniagone vignoni), exhibited greater particle selection for recently deposited sediment during ingestion than the two subsurface deposit feeders studied (a head-down deposit feeding holothurian, Molpadia musculus, and an irregular urchin, Amphipneustes lorioli). All six deposit feeders contained excess 234Th activity in gut sediments during all five cruises, indicating sediment ingestion year round, even during the austral winter. The lack of seasonal variation in bioturbation intensity and the demonstration of year-round feeding in deposit feeders are consistent with the hypothesis that the seafloor sediments accumulate labile organic matter produced during periods of high primary production and that deposit feeders utilize this food source as a food bank on a year-round basis.}, number={22-23}, journal={DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY}, author={McClintic, Mark A. and DeMaster, David J. and Thomas, Carrie J. and Smith, Craig R.}, year={2008}, month={Nov}, pages={2425–2437} }
 @inproceedings{titus-becker_rajala_bottomley_raubenheimer_cohen_bullett_grant_cobb payton_kirkman_kirby_et al._2007, place={Honolulu, Hawaii}, title={An Integrated Living and Learning Community for First and Second Year Undergraduate Women in Science & Engineering}, url={https://peer.asee.org/an-integrated-living-and-learning-community-for-first-and-second-year-undergraduate-women-in-science-and-engineering}, booktitle={American Society for Engineering Education 2007 Annual Conference and Exposition}, author={Titus-Becker, K. and Rajala, S. and Bottomley, L. and Raubenheimer, D. and Cohen, J. and Bullett, K. and Grant, S. and Cobb Payton, F. and Kirkman, A. and Kirby, B. and et al.}, year={2007} }
 @article{koontz_steelman_carmin_korfmacher_moseley_thomas_2007, title={Collaborative environmental management: What roles for government?}, volume={62}, ISSN={["0921-8009"]}, DOI={10.1016/j.ecolecon.2006.05.024}, abstractNote={Faculty development (FD) is important for continued professional development, but expense and distance remain challenging. These challenges could be minimized by the free and asynchronous nature of social media (SM). We sought to determine the utility and effectiveness of conducting a national online FD activity on Facebook by assessing participants' perceptions and use and facilitators' challenges.An educational activity of a national FD program was managed on a closed Facebook group. Activities included postings of educational technology goals, abstracting an article, and commenting on peers' postings. Sources of quantitative data included the Facebook postings and the survey responses. Surveys before, after, and 6 months after the activity assessed knowledge, attitudes and self-reported behaviors. Sources of qualitative data were the open-ended survey questions and the content of the Facebook postings.All participants completed the FD activity and evaluations, yielding 38 postings and 115 comments. Before the activity, 88% had a personal Facebook account, 64% were somewhat/very confident using Facebook, 77% thought SM would be useful for professional networking, and 12% had used it professionally. Six months after the activity, professional usage had increased to 35%. Continued use of Facebook for future presentations of this FD activity was recommended by 76%. Qualitative analysis yielded 12 types of Facebook postings and 7 themes related to using SM for FD.Conducting a national FD activity on Facebook yielded excellent participation rates and positive participant impressions, and it affected professional usage. Facebook may become an additional tool in the educator's toolbox for FD as a result of its acceptability and accessibility.}, number={2}, journal={ECOLOGICAL ECONOMICS}, publisher={Washington, DC: Resources for the Future}, author={Koontz, T. and Steelman, T. A. and Carmin, J. and Korfmacher, K. Smith and Moseley, C. and Thomas, Carrie}, year={2007}, month={Apr}, pages={373–374} }
 @article{spence_schaeffer_thomas_hathaway_olsen_2005, title={Coastal ocean observing technology transfer to educators}, volume={39}, ISSN={["0025-3324"]}, DOI={10.4031/002533205787465931}, abstractNote={Coastal ocean observing systems provide an opportunity to connect scientific concepts, technology and careers to education. These systems also provide outreach opportunities for researchers to connect beyond their peers to the public. Use of real/near real-time coastal ocean observational
 data has local relevance and can generate excitement for teachers and students about the changes and patterns in the ocean environment. New collaborations, strategies and models must be forged between scientists and educators to meet challenges and provide benefits. Challenges include the
 identification of connections between coastal ocean observing science and precollege science standards and curricula, the design of effective professional development workshops to transfer technology to teachers, the development of Web-based observation data that is accessible to teachers
 and their students, and the construction and testing of model inquiry lessons, which include use of real/near real-time observations data and GIS maps. Benefits include outreach opportunities for researchers, inquiry-driven applications for precollege students and the introduction of coastal
 ocean observing to students with the outcome of a highly trained and diverse work force in ocean sciences for the future. Effective strategies for transfer require new opportunities for engagement between scientists and educators, sharing of credit, evaluations, and solid technical reviews
 of all products to ensure scientific and educational accuracy.}, number={4}, journal={MARINE TECHNOLOGY SOCIETY JOURNAL}, author={Spence, L and Schaeffer, BA and Thomas, C and Hathaway, TK and Olsen, M}, year={2005}, pages={78–82} }
 @inproceedings{rajala_bottomley_parry_cohen_grant_thomas_doxey_perez_collins_spurlin_2004, place={Salt Lake City, Utah}, title={The North Carolina State University Women in Science and Engineering Program:  A Community for Living and Learning}, url={https://peer.asee.org/13892}, booktitle={American Society for Engineering Education 2004 Annual Conference and Exposition}, author={Rajala, Sarah A. and Bottomley, Laura J. and Parry, E.A. and Cohen, J.D. and Grant, Susan C. and Thomas, C.J. and Doxey, T.M. and Perez, G. and Collins, R.E. and Spurlin, J.E.}, year={2004} }
 @article{demaster_thomas_blair_fornes_plaia_levin_2002, title={Deposition of bomb (14)C in continental slope sediments of the Mid-Atlantic Bight: assessing organic matter sources and burial rates}, volume={49}, ISSN={["0967-0645"]}, DOI={10.1016/S0967-0645(02)00134-0}, abstractNote={As part of the Ocean Margins Program (OMP), organic carbon 14C measurements have been made on benthic fauna and kasten core sediments from the North Carolina continental slope. These analyses are used to evaluate the nature and burial flux of organic matter in the OMP study area off Cape Hatteras. Despite the fact that surface sediment 14C contents ranged from −41 to −215 per mil, the benthic fauna (primarily polychaetes) all contained significant amounts of bomb-14C (body tissue 14C contents ranging from +20 to +82 per mil). Bomb-14C clearly is reaching the seabed on the North Carolina slope, and the labile planktonic material carrying this signal is a primary source of nutrition to the benthic ecosystem. The enrichment of 14C in benthic faunal tissue relative to the 14C content of bulk surface-sediment organic matter (a difference of ∼150 per mil) is attributed to a combination of particle selection and selective digestive processes. Organic carbon burial rates from 12 stations on the North Carolina slope varied from 0.02 to 1.7 mol of C m−2 yr−1, with a mean value of 0.7 mol of C m−2 yr−1. The accumulation of organic matter on the upper slope accounts for <1% of the primary production in the entire continental margin system. The North Carolina margin was deliberately selected because of its potential for offshore transport and high sediment deposition rates, and even in this environment, burial of organic carbon accounts for a very small fraction of the primary production occurring in surface waters.}, number={20}, journal={DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY}, author={DeMaster, DJ and Thomas, CJ and Blair, NE and Fornes, WL and Plaia, G and Levin, LA}, year={2002}, pages={4667–4685} }
 @article{thomas_blair_alperin_demaster_jahnke_martens_mayer_2002, title={Organic carbon deposition on the North Carolina continental slope off Cape Hatteras (USA)}, volume={49}, ISSN={["1879-0100"]}, DOI={10.1016/s0967-0645(02)00135-2}, abstractNote={The continental slope off Cape Hatteras, NC is a region of high sediment accumulation and organic matter deposition. Sediment accumulation rates range from 3 to 151 cm kyr−1. Organic carbon deposition rates are 5–13 moles C m−2 yr−1, the highest reported for the slope off the eastern US. Burial efficiencies are 3–40%. The organic matter deposited is marine in origin and a mix of old and young particles. High organic carbon deposition rates support remineralization throughout the upper 2–3 m of sediment. Deep bioirrigation to depths of 60–100 cm within the seabed affects the biogeochemistry of the sediments by extending the zone of sulfate reduction and by steepening DIC porewater gradients through the non-local exchange of porewater. Stable and radiocarbon isotope mixing curves for porewater dissolved inorganic carbon (DIC) indicate that the dominant source of DIC accumulating in the upper 2–3 m of the seabed is of nearly uniform δ13C (−21.10‰) and Δ14C (−546‰).}, number={20}, journal={DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY}, publisher={Elsevier BV}, author={Thomas, CJ and Blair, NE and Alperin, MJ and DeMaster, DJ and Jahnke, RA and Martens, CS and Mayer, L}, year={2002}, pages={4687–4709} }
 @article{thomas_blair_2002, title={Transport and digestive alteration of uniformly C-13-labeled diatoms in mudflat sediments}, volume={60}, ISSN={["1543-9542"]}, DOI={10.1357/002224002762231205}, abstractNote={Uniformly 13 C-labeled diatoms were used to elucidate the effect deposit feeders have on the distribution and composition of phytodetritus within the seabed. Mudflat infauna contained in microcosms reacted quickly to the emplacement of labeled diatoms onto the sediment-water interface by moving the phytodetritus nonlocally during feeding and hoeing activities. Although redistribution of tracer was rapid, not all infauna exposed to the tracer ingested it. Using four species of deposit-feeding annelids that had ingested the 13 C-labeled phytodetritus during the microcosm experiment, molecular-level, digestive alterations of 13 C-labeled diatoms were documented. Fecal material produced by the deposit feeders had 13 C amino acid signatures distinctly different from that of the diatom. Alterations in the amino acid composition of the diatom were correlated to the gut morphology and digestive physiology of the polychaete taxa.}, number={3}, journal={JOURNAL OF MARINE RESEARCH}, publisher={Journal of Marine Research/Yale}, author={Thomas, CJ and Blair, NE}, year={2002}, month={May}, pages={517–535} }
 @article{levin_blair_martin_demaster_plaia_thomas_1999, title={Macrofaunal processing of phytodetritus at two sites on the Carolina margin: in situ experiments using C-13-labeled diatoms}, volume={182}, ISSN={["0171-8630"]}, DOI={10.3354/meps182037}, abstractNote={Tracer experiments using 13 C-labeled diatoms Thalassiosira pseudonana were carried out at two 850 m sites (I off Cape Fear and III off Cape Hatteras) on the North Carolina, USA, slope to examine patterns of macrofaunal consumption of fresh phytodetritus. Experiments examined the influence of taxon, feeding mode, body size and vertical position within the sediment column on access to surficial organic matter. δ 13 C measurements were made on macrofaunal metazoans and agglutinating protozoans from background sediments and from sediment plots in which 13 C-labeled diatoms were deposited and then sampled 0.3 h, 1 to 1.5 d, 3 mo and 14 mo later. Significant between-site differences were observed in background δ 13 C signatures of sediments, metazoans, and large, agglutinating protozoans, with values 2 to 3‰ lower at Site III than at Site I. Background δ 13 C signatures also varied as a function of taxon and of vertical position in the sediment column at Site III. The background δ 13 C value of carnivores was higher than that of surface-deposit feeders among Site I annelids, but no annelid feeding-group differences were observed at Site III. δ 13 C data from short-term (1 to 1.5 d) experiments revealed rapid diatom ingestion, primarily by agglutinated protozoans and annelids at Site I and mainly by annelids at Site III. Selective feeding on diatoms was exhibited by paraonid polychaetes, especially Aricidea spp. Exceptionally high uptake and retention of diatom C also was observed in the maldanid Praxillella sp., the nereid Ceratocephale sp. and several other surface-deposit feeding polychaetes. After 14 mo, little of the diatom 13 C remained at Site III, but high concentrations of the tracer were present in annelids and agglutinating protozoans at Site I. At both sites, non-annelid metazoans and subsurface-deposit feeding annelids exhibited the least uptake and retention of diatom C Our hypotheses that large-bodied taxa and shallow-dwelling infauna should have greatest access to freshly deposited organic matter were not borne out. Some small, deep-dwelling taxa acquired label more readily than large or near-surface forms. Differences in tracer fates between sites reflected greater vertical mixing at Site III. These results indicate heterogeneity in benthic processes along the Carolina margin, but suggest that labile organic matter is consumed quickly at both sites. Because most of the taxa found to consume freshly deposited diatoms in these experiments are typical of bathyal settings, we infer that phytodetritus reaching the seabed in margin environments is rapidly processed by protozoan and metazoan components of the benthic fauna.}, journal={MARINE ECOLOGY PROGRESS SERIES}, publisher={Inter-Research Science Center}, author={Levin, LA and Blair, NE and Martin, CM and DeMaster, DJ and Plaia, G and Thomas, CJ}, year={1999}, pages={37–54} }
 @article{levin_blair_demaster_plaia_fornes_martin_thomas_1997, title={Rapid subduction of organic matter by maldanid polychaetes on the North Carolina slope}, volume={55}, ISSN={["0022-2402"]}, DOI={10.1357/0022240973224337}, abstractNote={In situ tracer experiments conducted on the North Carolina continental slope reveal that tube-building worms (Polychaeta: Maldanidae) can, without ingestion, rapidly subduct freshly deposited, algal carbon ( 13 C-labeled diatoms) and inorganic materials (slope sediment and glass beads) to depths of 10 cm or more in the sediment column. Transport over 1.5 days appears to be nonselective but spatially patchy, creating localized, deep hotspots. As a result of this transport, relatively fresh organic matter becomes available soon after deposition to deep-dwelling microbes and other infauna, and both aerobic and anaerobic processes may be enhanced. Comparison of tracer subduction with estimates from a diffusive mixing model using 234 Th-based coefficients, suggests that maldanid subduction activities, within 1.5 d of particle deposition, could account for 25-100% of the mixing below 5 cm that occurs on 100-day time scales. Comparisons of community data from the North Carolina slope for different places and times indicate a correlation between the abundance of deep-dwelling maldanids and the abundance and the dwelling depth in the sediment column of other infauna. Pulsed inputs of organic matter occur frequently in margin environments and maldanid polychaetes are a common component of continental slope macrobenthos. Thus, the activities we observe are likely to be widespread and significant for chemical cycling (natural and anthropogenic materials) on the slope. We propose that species like maldanids, that rapidly redistribute labile organic matter within the seabed, probably function as keystone resource modifiers. They may exert a disproportionately strong influence (relative to their abundance) on the structure of infaunal communities and on the timing, location and nature of organic matter diagenesis and burial in continental margin sediments.}, number={3}, journal={JOURNAL OF MARINE RESEARCH}, publisher={Journal of Marine Research/Yale}, author={Levin, L and Blair, N and DeMaster, D and Plaia, G and Fornes, W and Martin, C and Thomas, C}, year={1997}, month={May}, pages={595–611} }
 @article{cahoon_laws_thomas_1994, title={Viable diatoms and chlorophylla in continental slope sediments off Cape Hatteras, North Carolina}, volume={41}, DOI={10.1016/0967-0645(94)90047-7}, abstractNote={Continental slope sediments off Cape Hatteras, North Carolina, were sampled by ☐ coring in late summer, 1992. The chlorophylla concentrations measured in sediments from 16 sites at depths ranging from 530 to 2003 m averaged 19.9 mg chla m−2, a concentration much higher than observed elsewhere on the eastern U.S. continental slope, indicating high depositional rates for microalgal material. The variability in the chlorophylla values suggests strong environmental heterogeneity at both small and large spatial scales in this slope habitat, probably a consequence of both topography and bioturbation. Viable diatoms were found in sediment samples across the range of depths sampled, and up to 14 cm deep in sediments, indicating high rates of deposition and bioturbation. Bulk sediment samples contained planktonic, tychopelagic and benthic diatoms, indicating that both phytoplankton and benthic microalgae from the continental shelf may be sources of organic matter for these slope sediments.}, number={4-6}, journal={Deep Sea Research Part II: Topical Studies in Oceanography}, publisher={Elsevier BV}, author={Cahoon, Lawrence B. and Laws, Richard A. and Thomas, Carrie J.}, year={1994}, month={Jan}, pages={767–782} }
 @article{cahoon_beretich_thomas_mcdonald_1993, title={Benthic microalgal production at Stellwagen Bank, Massachusetts Bay, USA}, volume={102}, DOI={10.3354/meps102179}, abstractNote={Benthic microalgal chlorophyll a and production were measured at 3 sites at Stellwagen Bank, a cold temperate continental shelf habitat in Massachusetts Bay, USA, during August 1991. Benthic microalgal chlorophyll a averaged 39.8 mg m-2, vs average integrated phytoplankton chlorophyll a of 25.9 mg m-2. Gross benthic microalgal production, measured by oxygen exchange in clear and opaque benthic chambers, averaged 20.9 mg C m-2 h-' This production was supported by average daily light fluxes to the bottom that never exceeded 1 % of surface incident radiation and were as low as 4.7 pE m-2 S-'. These results indicate that benthic microalgal production can be spatially extensive and quantitatively important in continental shelf ecosystems.}, journal={Marine Ecology Progress Series}, publisher={Inter-Research Science Center}, author={Cahoon, LB and Beretich, GR and Thomas, CJ and McDonald, AM}, year={1993}, pages={179–185} }
 @article{thomas_cahoon_1993, title={Stable isotope analyses differentiate between different trophic pathways supporting rocky-reef fishes}, volume={95}, DOI={10.3354/meps095019}, abstractNote={Stable isotope analyses of 5 reef-associated fishes, Decapterus punctatus. Diplodus holbrooki, Rhornboplites aurorubens. Pagrus pagrus, and Haernulon aurolineatum, were conducted to determine the ability of stable isotope analysis to distinguish among the species and the trophic pathways that support them. Analyses of F13C, 6 1 5 ~ , and 6 3 4 ~ from white swimming muscle yielded significant differences between species. Multiple stable isotope signatures of these 5 species indicated that at least 2 trophic pathways, one planktonic and one benthic, supported these reef-associated species. Variability of isotopic signatures within species was largely a result of collection site differences. 8l3C and 615N values inchcated that all fishes were feeding at similar trophic levels. P 4 S values proved to be useful supplements to carbon and nitrogen isotope values in separating species by signature.}, journal={Marine Ecology Progress Series}, publisher={Inter-Research Science Center}, author={Thomas, CJ and Cahoon, LB}, year={1993}, pages={19–24} }