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SFS Annual Meeting

Tuesday, May 22, 2018
09:00 - 10:30

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09:00 - 09:15: / 321 A RIVER OF BONES: WILDEBEEST SKELETONS LEAVE A LEGACY OF MASS MORTALITY IN THE MARA RIVER

5/22/2018  |   09:00 - 09:15   |  321

A RIVER OF BONES: WILDEBEEST SKELETONS LEAVE A LEGACY OF MASS MORTALITY IN THE MARA RIVER Large ungulate migrations were once features of many landscapes, although they have largely declined or been extirpated. The Serengeti wildebeest migration is the largest remaining overland migration of 1.3 million animals, and it has wide-ranging effects on both terrestrial and aquatic ecosystems. Mass drownings occur nearly annually during crossings of the Mara River, resulting in an average of 6,250 carcasses and 1,100 tons of biomass entering the river every year. Approximately half the carcass is soft tissue, which is high in carbon and nitrogen, and it decomposes in 2-10 weeks. The other half of the carcass is bone, which contains 95% of the phosphorus. Bones decompose in 7.4 years, forming a legacy of mass mortality events and influencing the river’s nutrient cycling and food web at decadal time scales. Biofilms that grow on bones differ in productivity and composition from those that grow on rocks. Stable isotope analysis shows that bone biofilm can provide 7-24% of the assimilated diet of fish months after carcasses have otherwise decomposed. The loss of ungulate migrations and associated mass drownings may be reflected in the absence of bones in rivers with unknown ecological consequences.

Christopher Dutton (Co-Presenter/Co-Author), Yale University, cldutton@gmail.com;


Emma Rosi (Co-Presenter/Co-Author), Cary Institute of Ecosystem Studies, rosie@caryinstitute.org;


Linda Puth (Co-Presenter/Co-Author), Yale University, linda.puth@yale.edu;


David Post (Co-Presenter/Co-Author), Yale University, david.post@yale.edu;


Amanda Subalusky (Primary Presenter/Author), Cary Institute of Ecosystem Studies, asubalusky@gmail.com;


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09:15 - 09:30: / 321 CONSEQUENCES OF SALMON SPAWNING TO RESIDENT FISH IN GREAT LAKES TRIBUTARIES

5/22/2018  |   09:15 - 09:30   |  321

CONSEQUENCES OF SALMON SPAWNING TO RESIDENT FISH IN GREAT LAKES TRIBUTARIES In Great Lakes tributaries, introduced Pacific salmon deposit energy and contaminants as carcass and gametic tissue during spawning migrations. Such ecosystem linkages increase both growth and bioaccumulation in resident fish but mechanisms are unclear. Using observational surveys, experimental manipulations, and modeling we assessed the salmon role in resident fish growth and bioaccumulation. In stream reaches with salmon, resident fish had 25-fold higher PCB but marginally lower Hg levels than fish from upstream reaches without salmon. A mesocosm experiment suggested that fish growth did not improve with carcass consumption while isotope and Hg data suggested incorporation of salmon. In a salmon addition to a naïve stream, resident fish increased PCBs by 50-fold whereas Hg did not change. Coincident with increased PCB levels was a shift to salmon egg consumption. Analysis of salmon tissue indicate that eggs have elevated PCBs, lower Hg, and higher energy density than carcasses. A bioenergetic model synthesized our empirical results suggesting that salmon egg consumption controls growth and PCB bioaccumulation of resident fish, and indirectly mediates reduced Hg through growth dilution. Our study identifies mechanisms controlling the transfer of salmon-derived energy and contaminants to resident fish.

Brandon Gerig (Primary Presenter/Author), Northern Michigan University, bgerig@nmu.edu;


Dominic Chaloner (Co-Presenter/Co-Author), University of Notre Dame, dchalone@nd.edu;


Richard Rediske (Co-Presenter/Co-Author), Grand Valley State University - Annis Water Resources Institute, redisker@gvsu.edu;


Ashley Moerke (Co-Presenter/Co-Author), Aquatic Research Laboratory, Lake Superior State University, amoerke@lssu.edu;


David Janetski (Co-Presenter/Co-Author), Indiana University of Pennsylvania, janetski@iup.edu;


Gary Lamberti (Co-Presenter/Co-Author), University of Notre Dame, glambert@nd.edu;


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09:30 - 09:45: / 321 SHORT AND LONG-TERM IMPACTS OF SALMON CARCASS DECOMPOSITION ON STREAM MICROBIAL COMMUNITY STRUCTRE: ALLOCHTHONOUS MICROBIAL SUBSIDIES TO DOWNSTREAM FOOD WEBS.

5/22/2018  |   09:30 - 09:45   |  321

SHORT AND LONG-TERM IMPACTS OF SALMON CARCASS DECOMPOSITION ON STREAM MICROBIAL COMMUNITY STRUCTRE: ALLOCHTHONOUS MICROBIAL SUBSIDIES TO DOWNSTREAM FOOD WEBS. Salmon decomposition is traditionally viewed through the lens of energy and nutrient subsidies, but not from the perspective of also acting as “microbial subsidies.” Salmon have microbial communities residing on and within them that are directly introduced into streams, by microbes sloughing off and integrating into biofilms, or indirectly, by invertebrates facilitating dispersal. The objective of this study was to track the effects of salmon decomposition on stream microbial communities over time. Microbial communities (epilithic biofilms and macroinvertebrate internal) were sampled at both treatment (downstream reach) and reference sites (upstream reach) before (September), during (October), and after (November to August) salmon carrion introduction. The study was repeated to assess inter-annual variation (September 2014-August 2016). A significant influence of treatment and time on biofilm communities (PERMANOVA, p<0.01) was detected. These results were predominately influenced by Cyanobacteria dynamics, which had a significant reduction (relative abundance) in the treatment reach two weeks after carcass introduction. The internal microbiomes of Baetis brunneicolor (collector-gatherer) and Stegopterna mutata (collector-filterer) were not significantly different between reaches over time (PERMANOVA, p>0.05). These foundational data highlight the importance of carrion’s role in the microbial ecology of lotic systems.

Courtney Larson (Primary Presenter/Author), Michigan State University, larso126@msu.edu;


Courtney Weatherbee (Co-Presenter/Co-Author), Michigan State University, weath108@msu.edu;


Jennifer L. Pechal (Co-Presenter/Co-Author), Michigan State University, pechalje@msu.edu;


Brandon Gerig (Co-Presenter/Co-Author), Northern Michigan University, bgerig@nmu.edu;


Dominic Chaloner (Co-Presenter/Co-Author), University of Notre Dame, dchaloner@nd.edu;


Gary Lamberti (Co-Presenter/Co-Author), University of Notre Dame, glambert@nd.edu;


M. Eric Benbow (Co-Presenter/Co-Author), Michigan State University, benbow@msu.edu;


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09:45 - 10:00: / 321 WHEN ARE FISH SOURCES VS. SINKS OF NUTRIENTS IN LAKE ECOSYSTEMS? THE ROLE OF CARCASS DECOMPOSITION

5/22/2018  |   09:45 - 10:00   |  321

WHEN ARE FISH SOURCES VS. SINKS OF NUTRIENTS IN LAKE ECOSYSTEMS? THE ROLE OF CARCASS DECOMPOSITION Fish can be sources or sinks of nutrients in ecosystems, and their role in this context may depend on the fate of nutrients in carcasses. We measured nutrient release rates from decomposing fish (gizzard shad) carcasses in field and lab experiments, and quantified ecosystem-level fluxes of nutrients through a population over a 19 year period. Our goal was to assess when fish are nutrients sources or sinks to the pelagic habitat. Rates of nutrient release from carcasses increased with temperature (Q10 range: 1.07-2.77 for N and 1.07-3.57 for P) and were higher especially for young-of-year (YOY). Nutrient release rates were also faster when macroinvertebrates had access to carcasses, compared to when only microbes had access. Carcasses lost N more rapidly than P. At the ecosystem level, the gizzard shad population is usually a source of dissolved nutrients to the pelagic zone, because of high rates of excretion of benthic-derived nutrients. However, during periods of rapid YOY growth and high mortality, the population can be a sink for pelagic nutrients. However, whether the population is a source or sink at these times depends on nutrient release rates from decomposing carcasses.

Luciana S. Carneiro (Co-Presenter/Co-Author), Universidade Federal do Rio Grande do Norte, lscarnei@gmail.com;


Sarah E. Panek (Co-Presenter/Co-Author), Florida Department of Environmental Protection, sarah.panek@dep.state.fl.us;


Regina Nobre (Primary Presenter/Author), Miami University - Oxford Ohio, reginanobre.eco@gmail.com;


Michael Vanni (Co-Presenter/Co-Author), Miami University, vannimj@miamioh.edu;


Maria Gonzalez (Co-Presenter/Co-Author), Miami University - Oxford Ohio, gonzalmj@miamioh.edu ;


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10:00 - 10:15: / 321 ANIMAL MASS MORTALITIES IN AQUATIC ECOSYSTEMS: HOW COMMON AND INFLUENTIAL?

5/22/2018  |   10:00 - 10:15   |  321

ANIMAL MASS MORTALITIES IN AQUATIC ECOSYSTEMS: HOW COMMON AND INFLUENTIAL? The prototypical animal mass mortality in aquatic ecosystems is the annual spawning migration of Pacific salmon (Oncoryhnchus spp.) that can transport thousands of kilograms of labile resources to rivers and lakes. However, many other mass dieoffs of vertebrates and invertebrates can strongly influence the structure and function of aquatic ecosystems. Here we discuss the spatial and temporal occurrence of mass dieoffs in aquatic and riparian systems, and their influence on ecological processes. Salmonidae, Clupeidae, and Petromyzontidae are fish families which undertake annual mass migrations that often result in their death in the ecosystem where they spawn, and therefore their macronutrients (C, N, P) subsidize recipient ecosystems. Terrestrial vertebrates such as wildebeest and saiga antelope, and marine mammals such as sei whales, can also subsidize aquatic and coastal ecosystems during mortality episodes. We develop a paradigm of ‘programmed versus catastrophic’ death whereby recipient ecosystems vary in their history and capacity to process these subsidies based on the predictability and timing of the resource pulse. Such mortality events may be increasing in frequency and severity with global change, and therefore a more robust understanding of their ecological effects is needed.

Gary Lamberti (Primary Presenter/Author), University of Notre Dame, glambert@nd.edu;


M. Eric Benbow (Co-Presenter/Co-Author), Michigan State University, benbow@msu.edu;


Dominic Chaloner (Co-Presenter/Co-Author), University of Notre Dame, dchalone@nd.edu;


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