SFS Annual Meeting

5/21/2018  |   14:00 - 14:15   |  321

DEATH AND DECOMPOSITION IN AQUATIC ECOSYSTEMS Resource subsidies affect food webs, nutrient cycling, and community interactions, but their effects depend on natural history, magnitude, and recurrence. In aquatic ecosystems, plant detritus is considered a predominant form of subsidies; however, while less abundant in many ecosystems, carrion represents subsidies with relatively rapid turnover and concentrated nutrient and energy release that can have lasting effects on ecosystems. Carrion subsidies come in the form of phenology-based frequency (e.g., salmon spawning and death) or as stochastic and episodic (e.g., fish kills). Some aquatic ecosystems have a natural history of carrion resource subsidies (e.g., natural salmon-bearing streams), while others have recent introductions of phenology-based carrion subsidies (e.g., salmon introductions around the world). Other ecosystems only experience episodic subsidies in the form of unexpected mass mortalities (e.g., eutrophication- or disease-related fish kills). The responses of ecosystems to these different histories and frequencies of carrion subsidies have often been investigated independently, with little effort to compare and bridge research boundaries in the broader context of resource subsidies. We review carrion resource subsidies and compare characteristics such as frequency and turnover to other forms of detritus in aquatic ecosystems.

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


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


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5/21/2018  |   14:15 - 14:30   |  321

AQUATIC MACROINVERTEBRATE SIZE-SPECTRA IN SALMON-BEARING STREAMS Pacific salmon are known to mediate energy transfer across the marine-freshwater boundary. The dual-role of spawning salmon in freshwater ecosystems — nutrient enrichment from carcasses and substrate disturbance from spawning behavior — has been investigated in numerous studies of stream invertebrates. A size-based alternative to the traditional taxonomic approach, using community size spectra, offers a complimentary, visually-intuitive, and ecologically-meaningful way to evaluate how aquatic macroinvertebrate communities respond to spawning salmon. We sampled benthic biota and abiotic parameters from 15 streams along the central coast of British Columbia throughout three consecutive time periods: in the summer prior to, during, and in the spring following peak salmon abundance. In a subset of the 15 streams, aquatic macroinvertebrates were additionally collected upstream of a salmon migration barrier as a within-stream comparison. Individual insect biomass was calculated using published length-weight regressions to produce size-spectra for the communities. Preliminary results show a unimodal distribution across body size classes in community size spectra. This study suggests that a size-based perspective of community dynamics will improve our understanding of the functional roles of spawning salmon in stream ecosystems.

Ryan Walquist (Primary Presenter/Author), Simon Fraser University, rwalquis@sfu.ca;


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5/21/2018  |   14:30 - 14:45   |  321

THE ROLE OF THE MISSING DEAD IN NORTH AMERICAN RIVERS While leaf litter, wood, and other terrestrial plant remnants are known to play a central role in lotic ecosystems, animal remnants (carcasses, bones, shells) have received less attention. Here we estimate the magnitude and effect that three different animal legacies may formerly have played in North American rivers: (1) terrestrial megafauna; (2) snapping turtles; and (3) mussels. North America once supported a diverse assemblage of megafauna, many of which were migratory and could have provided regionally important subsidies of carcasses. Snapping turtles were once common enough to support a major commercial riverine fishery, but populations collapsed in the 1970s and recovery has been slow. Mussels were extensively harvested in the first three decades of the 20th century until populations collapsed, again with limited recovery. We use historical records, measured decay rates and simple extrapolations to estimate the role that animal bones, turtle shells and mussel shells may have played in nutrient cycling and in physically structuring North American rivers. We conclude that in at least some regions these roles were substantial, and we argue that our models of these rivers are incomplete without consideration of these lost legacies.

Seth Wenger (Primary Presenter/Author), University of Georgia, sethwenger@fastmail.fm;


Amanda Subalusky (Co-Presenter/Co-Author), University of Florida, asubalusky@ufl.edu;


Mary Freeman (Co-Presenter/Co-Author), US Geological Survey, mcfreeman@usgs.gov;


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5/21/2018  |   14:45 - 15:00   |  321

DIRECT AND INDIRECT IMPACTS OF MASS MORTALITY EVENTS OF INVASIVE BIVALVES Invasive bivalves such as the Asian clam Corbicula fluminea, the zebra mussel Dreissena polymorpha, and the Chinese pond mussel Sinanodonta woodiana can play dominant roles in aquatic ecosystems due to their ability to reach high densities and biomass. Here, we review the immediate and longer term impacts of mass mortality events of invasive bivalves through a variety of mechanisms, including drought, flooding, and high and low temperatures, and compare these impacts in aquatic and riparian habitats. Mass mortality events can lead to short term impacts, such as large pulses of nitrogen and phosphorus becoming available, but also can have consequences for both aquatic and terrestrial communities (from bacteria to vertebrates). These invasive species can best be described as R-selected species, they may be prone to boom and bust population dynamics due to their ability to be resilient, but not resistant to the extremes conditions that cause these mortality events. As such, these mass mortality events could become a more common occurrence in aquatic ecosystems, particularly in the face of the increased spread of these invasive bivalves and higher predicted variability due to global climate change.

William G. McDowell (Primary Presenter/Author), Merrimack College, wgmcdowell@gmail.com;


Ronaldo Sousa (Co-Presenter/Co-Author), University of Minho, Portugal, rg.eco.sousa@gmail.com;


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5/21/2018  |   15:00 - 15:15   |  321

FORENSIC APPLICATIONS OF STUDYING DEATH AND DECOMPOSITION In aquatic systems, the forensic application is focused on death scene investigations where the question of concern is the post-mortem submersion interval (PMSI) or the moment at which a human body is submerged to the point of discovery. This time interval is different from that applied to death scenes in terrestrial systems where the time of colonization is used. Bridging the relationship between carrion decomposition and terrestrial invertebrates with criminal investigations has been facilitated by our current knowledge on their life histories and basic ecological specialization to feed on carrion. Necrophagous-specific taxa appear to be absent in freshwater systems and the ecological and evolutionary drivers of trophic and other ecological relationships in aquatic systems might explain the absence of necrophagic specialization among aquatic invertebrates. However, the application of benthic ecological/molecular methodologies in the last decade has elucidated how algae/insect/microbe associations with carrion have provided some promise toward their use in the world of criminal justice and forensic science. Evidence of these advances will be presented in the form of actual criminal case studies.

John Wallace (Primary Presenter/Author), Millersville University, john.wallace@millersville.edu;


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