@article{moslemi_snider_macneill_gilliam_flecker_2012, title={Impacts of an Invasive Snail (Tarebia granifera) on Nutrient Cycling in Tropical Streams: The Role of Riparian Deforestation in Trinidad, West Indies}, volume={7}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0038806}, abstractNote={Non-native species and habitat degradation are two major catalysts of environmental change and often occur simultaneously. In freshwater systems, degradation of adjacent terrestrial vegetation may facilitate introduced species by altering resource availability. Here we examine how the presence of intact riparian cover influences the impact of an invasive herbivorous snail, Tarebia granifera, on nitrogen (N) cycling in aquatic systems on the island of Trinidad. We quantified snail biomass, growth, and N excretion in locations where riparian vegetation was present or removed to determine how snail demographics and excretion were related to the condition of the riparian zone. In three Neotropical streams, we measured snail biomass and N excretion in open and closed canopy habitats to generate estimates of mass- and area-specific N excretion rates. Snail biomass was 2 to 8 times greater and areal N excretion rates ranged from 3 to 9 times greater in open canopy habitats. Snails foraging in open canopy habitat also had access to more abundant food resources and exhibited greater growth and mass-specific N excretion rates. Estimates of ecosystem N demand indicated that snail N excretion in fully closed, partially closed, and open canopy habitats supplied 2%, 11%, and 16% of integrated ecosystem N demand, respectively. We conclude that human-mediated riparian canopy loss can generate hotspots of snail biomass, growth, and N excretion along tropical stream networks, altering the impacts of an invasive snail on the biogeochemical cycling of N.}, number={6}, journal={PLOS ONE}, author={Moslemi, Jennifer M. and Snider, Sunny B. and MacNeill, Keeley and Gilliam, James F. and Flecker, Alexander S.}, year={2012}, month={Jun} }
 @article{snider_gilliam_2008, title={Movement ecology: Size-specific behavioral response of an invasive snail to food availability}, volume={89}, ISSN={["1939-9170"]}, DOI={10.1890/07-0715.1}, abstractNote={Immigration, emigration, migration, and redistribution describe processes that involve movement of individuals. These movements are an essential part of contemporary ecological models, and understanding how movement is affected by biotic and abiotic factors is important for effectively modeling ecological processes that depend on movement. We asked how phenotypic heterogeneity (body size) and environmental heterogeneity (food resource level) affect the movement behavior of an aquatic snail (Tarebia granifera), and whether including these phenotypic and environmental effects improves advection-diffusion models of movement. We postulated various elaborations of the basic advection diffusion model as a priori working hypotheses. To test our hypotheses we measured individual snail movements in experimental streams at high- and low-food resource treatments. Using these experimental movement data, we examined the dependency of model selection on resource level and body size using Akaike's Information Criterion (AIC). At low resources, large individuals moved faster than small individuals, producing a platykurtic movement distribution; including size dependency in the model improved model performance. In stark contrast, at high resources, individuals moved upstream together as a wave, and body size differences largely disappeared. The model selection exercise indicated that population heterogeneity is best described by the advection component of movement for this species, because the top-ranked model included size dependency in advection, but not diffusion. Also, all probable models included resource dependency. Thus population and environmental heterogeneities both influence individual movement behaviors and the population-level distribution kernels, and their interaction may drive variation in movement behaviors in terms of both advection rates and diffusion rates. A behaviorally informed modeling framework will integrate the sentient response of individuals in terms of movement and enhance our ability to accurately model ecological processes that depend on animal movement.}, number={7}, journal={ECOLOGY}, author={Snider, Sunny B. and Gilliam, James F.}, year={2008}, month={Jul}, pages={1961–1971} }
 @article{hess_bartel_leidner_rosenfeld_rubino_snider_ricketts_2006, title={Effectiveness of biodiversity indicators varies with extent, grain, and region}, volume={132}, ISSN={["1873-2917"]}, DOI={10.1016/j.biocon.2006.04.037}, abstractNote={Abstract The use of indicator taxa for conservation planning is common, despite inconsistent evidence regarding their effectiveness. These inconsistencies may be the result of differences among species and taxonomic groups studied, geographic location, or scale of analysis. The scale of analysis can be defined by grain and extent, which are often confounded. Grain is the size of each observational unit and extent is the size of the entire study area. Using species occurrence records compiled by NatureServe from survey data, range maps, and expert opinion, we examined correlations in species richness between each of seven taxa (amphibians, birds, butterflies, freshwater fish, mammals, freshwater mussels, and reptiles) and total richness of the remaining six taxa at varying grains and extents in two regions of the US (Mid-Atlantic and Pacific Northwest). We examined four different spatial units of interest: hexagon (∼649 km 2 ), subecoregion (3800–34,000 km 2 ), ecoregion (8300–79,000 km 2 ), and geographic region (315,000–426,000 km 2 ). We analyzed the correlations with varying extent of analysis (grain held constant at the hexagon) and varying grain (extent held constant at the region). The strength of correlation among taxa was context dependent, varying widely with grain, extent, region, and taxon. This suggests that (1) taxon, grain, extent, and study location explain, in part, inconsistent results of previous studies; (2) planning based on indicator relationships developed at other grains or extents should be undertaken cautiously; and (3) planning based on indicator relationships developed in other geographic locations is risky, even if planning occurs at an equivalent grain and extent.}, number={4}, journal={BIOLOGICAL CONSERVATION}, publisher={Elsevier BV}, author={Hess, George R. and Bartel, Rebecca A. and Leidner, Allison K. and Rosenfeld, Kristen M. and Rubino, Matthew J. and Snider, Sunny B. and Ricketts, Taylor H.}, year={2006}, month={Oct}, pages={448–457} }
 @article{fraser_gilliam_albanese_snider_2006, title={Effects of temporal patterning of predation threat on movement of a stream fish: evaluating an intermediate threat hypothesis}, volume={76}, ISSN={["0378-1909"]}, DOI={10.1007/s10641-006-9004-9}, number={1}, journal={ENVIRONMENTAL BIOLOGY OF FISHES}, author={Fraser, Douglas F. and Gilliam, James F. and Albanese, Brett W. and Snider, Sunny B.}, year={2006}, month={May}, pages={25–35} }
 @article{fraser_gilliam_akkara_albanese_snider_2004, title={Night feeding by guppies under predator release: Effects on growth and daytime courtship}, volume={85}, ISSN={["0012-9658"]}, DOI={10.1890/03-3023}, abstractNote={The nonlethal effects of predation threat can be pervasive but are also easily overlooked. We investigated effects of predation threat on feeding by guppies (Poecilia reticulata), and how threat-induced temporal shifts in feeding activity affect reproductive behavior and growth. Contrary to the view of the guppy as a “diurnal” species, our observations revealed that guppies free from severe predation threat expand their foraging into the nocturnal period. We found such nocturnal foraging to be as profitable as diurnal foraging, and guppies under threat incurred a substantial growth penalty when predators inhibited night feeding. Denial of night feeding also decreased daytime courtship by males, facultatively duplicating a classical observation comparing courtship intensity in contrasting predator regimes, but providing a novel mechanism for the effect. Our findings support the view that evaluations of predator effects on life histories should consider potential predator-caused alterations in size-specific...}, number={2}, journal={ECOLOGY}, author={Fraser, DF and Gilliam, JF and Akkara, JT and Albanese, BW and Snider, SB}, year={2004}, month={Feb}, pages={312–319} }