6/05/2017  |   09:00 - 09:15   |  306B

CASCADING EFFECTS OF ANURAN PRODUCTION IN GEOGRAPHICALLY ISOLATED WETLANDS The role of consumer-driven nutrient dynamics and organismal movement has developed considerable interest due to the connection to cross ecosystem nutrient and energy transport. Production of consumers with biphasic lifecycles affects nutrient dynamics in ecosystems due to changes in organismal requirements. Larval anurans in isolated wetlands are of interest due to significant change in homeostatic demands across larval ontogenetic stages. We measured anuran tissue stoichiometry and excretion rate at 5 wetlands with high densities (~37 indiv./m2) across the hydroperiod. We found that breeding phenology drives patterns in abundance and anurans are found at a range of stages in development across a hydroperiod. Ontogenetic stage predicted tissue C:P and N:P, and excreted N:P, due to anuran demand for phosphorus during osteogenesis. The ontogenetic demand during metamorphosis suggests their contribution to nutrient cycling is best predicted by development stage. Relative abundance and life history of individual taxa contribute to the large temporal variability in areal excretion and storage ratios within and across wetlands. Variation in consumer-driven nutrient dynamics due to species-specific traits may have bottom-up impacts on wetland characteristics such as nutrient limitation and resource quality.

Scott Mcleay (Primary Presenter/Author), University of Alabama, smcleay27@gmail.com;


Carla L. Atkinson ( Co-Presenter/Co-Author), University of Alabama, carlalatkinson@gmail.com;


Lora L. Smith ( Co-Presenter/Co-Author), Joseph W. Jones Ecological Research Center at Ichauway, lsmith@jonesctr.org;


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6/05/2017  |   09:15 - 09:30   |  306B

Host Diet Stoichiometry Influences Transmission Dynamics in Whirling Disease For many parasites their host is both their habitat and their source of nutrients. Further, because hosts have finite lifespans, and some parasites require multiple hosts to complete their lifecycle, the ability to migrate from one host to the next is critical for parasite lineages to persist. Whirling disease in salmonids is caused by the Myxozoan parasite Myxobolus cerebralis. M. cerebralis requires both the oligochaete worm Tubifex tubifex and a salmonid fish in order to complete its life cycle. I infected T. tubifex worms and reared them on 5 diets ranging in C:P from 1464 to 35 and recorded the number of infectious spores of M. cerebralis produced by individual worms over the course of 112 days. Preliminary results suggest that spore production was negatively correlated with diet C:P, duration of spore release was negatively correlated with diet C:P, and mortality was positively correlated with diet C:P. Together these results suggest that worms feeding on nutrient rich diets are themselves higher quality diet resources for the parasite, and that eutrophication may result in greater transmission pressure in wildlife diseases of interest.

Andrew Sanders (Primary Presenter/Author), North Carolina State University Dept. of Applied Ecology; Rocky Mountain Biological Laboratory, ajsande5@ncsu.edu;


Brad Taylor ( Co-Presenter/Co-Author), North Carolina State University Dept. of Applied Ecology; Rocky Mountain Biological Laboratory, bwtaylo3@ncsu.edu ;


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6/05/2017  |   09:30 - 09:45   |  306B

NITROGEN AND PHOSPHORUS LIMITATION OF BENTHIC INVERTEBRATES IN GREEN VERSUS BROWN FOOD WEBS - A META-ANALYSIS Resource nitrogen:carbon (N:C) and phosphorus:carbon (P:C) ratios are often considered limiting to consumer growth across ecosystems. However, because tests of this generalization are mostly from individual species, the breadth and strength of limitation across diverse taxa remains unclear. We conducted a meta-analysis of feeding studies to assess resource N:C and P:C effects on growth, consumption, and excretion rates across benthic invertebrates. From n=15-54 datasets we calculated Pearson’s r and used weighted mixed effects models to compare effect sizes between herbivorous and detritivorous taxa. Detritivores exhibited a positive growth response to resource N:C (P<0.001) and P:C (P<0.01), whereas herbivores exhibited positive responses that did not differ from zero. In their consumption response to N:C and P:C, detritivores consistently responded positively whereas herbivores responded negatively (P<0.05). Nitrogen excretion rates did not respond to N:C among either trophic group, but herbivore P excretion rates responded positively to P:C, a greater response than detritivores’ (P<0.05). Our results support broad N- and P-limited consumer growth in benthic systems, yet different mechanistic responses between trophic groups, possibly due to contrasting quality of detrital versus autotrophic C.

Halvor Halvorson (Primary Presenter/Author), University of Central Arkansas, hhalvorson@uca.edu;


Michelle Evans-White ( Co-Presenter/Co-Author), University of Arkansas, mevanswh@uark.edu;


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6/05/2017  |   09:45 - 10:00   |  306B

RECIPROCAL TRANSPLANTS DISPLAY CONTRASTING RESPONSES OF MAYFLY GROWTH AND BODY PHOSPHORUS IN TEMPERATE AND TROPICAL STREAMS Increases in temperature associated with climate change may impact aquatic biota differentially depending on the temperature variability they currently experience. We conducted reciprocal transplants using mayflies in the family Baetidae across a ~1200m elevational gradient in the Colorado Rockies (CO) and Ecuadorian Andes (EC). We hypothesized that insects from temperate streams, which experience greater seasonal and diel temperature fluctuations, would be less vulnerable to elevated stream temperatures than phylogenetically-related organisms from tropical regions, where temperatures are annually stable. Responses followed expectations: when high elevation CO mayflies were moved to lower, warmer streams, their growth rate and body % Phosphorus (P) increased. In contrast EC mayflies experienced lower growth rates and body %P when moved from higher elevation streams to lower elevation streams. Furthermore, both CO and EC populations had lower growth rates when moved from lower warm streams to higher cool streams with little to no change in body %P. Populations in EC may be locally adapted and closer to their thermal limits and therefore more sensitive to temperature change than CO where populations show plasticity in their thermal tolerance. 

Amanda Rugenski (Primary Presenter/Author), University of Georgia, atrugenski@gmail.com;


Andrea Landeira-Dabarca ( Co-Presenter/Co-Author), Universidad San Francisco de Quito, andrealandab@gmail.com;


Carla L. Atkinson ( Co-Presenter/Co-Author), University of Alabama, carlalatkinson@gmail.com;


Andrea C. Encalada ( Co-Presenter/Co-Author), Instituto BIOSFERA, Universidad San Francisco de Quito, Cumbayá, Ecuador Biológicas y Ambientales, Universidad San Francisco de Quito, Cumbaya, Ecuador, aencalada@usfq.edu.ec;


Steven Thomas ( Co-Presenter/Co-Author), University of Alabama, sathomas16@ua.edu;


LeRoy Poff ( Co-Presenter/Co-Author), Colorado State University, n.poff@rams.colostate.edu;


Alexander Flecker ( Co-Presenter/Co-Author), Cornell University, Ithaca, NY, USA, asf3@cornell.edu;


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6/05/2017  |   10:00 - 10:15   |  306B

From farms to fish pee: Agricultural growth alters the stoichiometry of nutrient recycling by a desert fish Consumer-driven nutrient recycling can have substantial effects on primary production and nutrient limitation in aquatic ecosystems by altering the relative supplies of the nutrients nitrogen and phosphorus. We examined intraspecific variation in nutrient recycling by the fish Gambusia marshi over a gradient in spring discharge in the Cuatro Ciénegas basin in Coahuila, Mexico. Groundwater-fed habitats are warmer and host higher piscivore biomass than runoff-dominated sites. Female fish in groundwater-fed sites had lower body %C and higher body %P. These fish excreted N at a lower rate and P at a higher rate, leading to a lower N:P ratio. Experimentally, developmental temperature did not explain variation in excretion N:P when fish were fed ad libitum. However, experimentally restricting diet ration led to reduced rates of P excretion and a higher excretion N:P ratio. Reduced consumption under reduced predation pressure had stronger consequences for P retention and excretion among populations than did variation in body stoichiometry. As growth of irrigated agriculture in the region causes spring flows to decline, these changes will alter nutrient storage and recycling by these fish.

Eric Moody (Primary Presenter/Author), Middlebury College, erickmoody@gmail.com;


Jessica Corman ( Co-Presenter/Co-Author), University of Nebraska-Lincoln, jcorman3@unl.edu;


Hector Espinosa-Perez ( Co-Presenter/Co-Author), Universidad Autonoma de Mexico, hector@unam.mx;


Jorge Ramos ( Co-Presenter/Co-Author), Arizona State University, jramos10@asu.edu;


John Sabo ( Co-Presenter/Co-Author), Arizona State University, John.L.Sabo@asu.edu;


James Elser ( Co-Presenter/Co-Author), Arizona State University, j.elser@asu.edu;


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6/05/2017  |   10:15 - 10:30   |  306B

FEAR AND FOOD: THE INTERACTIVE EFFECTS OF STOICHIOMETRIC FOOD QUALITY AND PREDATOR-DERIVED CHEMICAL CUES ON LIFE HISTORY AND PHYSIOLOGY OF DAPHNIA Both nutrient availability and predator-derived chemical cues can have profound effects on zooplankton populations and alter how they function in ecosystems. We conducted a 30-day life table experiment to evaluate how food phosphorus (P) content affects life history responses of Daphnia pulicaria to predator-derived chemical cues. We compared the responses of control animals to animals exposed to cues derived from fish predators (juvenile Lepomis machrochirus) fed food across a P-content gradient (food C:P ratios of 100, 300, 600). We found significant effects of both predator cues and food C:P ratios on nearly all variables measured. Exposure to predator cue generally reduced mass-specific growth rate, age/size at first reproduction, population growth rate, and survival; these same variables were affected additively by elevated food C:P ratios. When dietary P was high, Daphnia exposed to predator cues significantly increased respiration rates compared to control daphnids; however, this trend was reversed as P-availability decreased, suggesting P-limitation of this response to predation risk. These results demonstrate that stoichiometric food quality can modulate responses of Daphnia to predator cues, which can translate into broader effects on population dynamics and ecosystem function.

Alex Bell (Primary Presenter/Author), Trent University, albell@trentu.ca;


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