5/23/2016  |   15:30 - 15:45   |  315

FACEBOOK FOR FISH: NEW INSIGHT INTO FISH ASSEMBLAGE STRUCTURE AND STABILTY THROUGH SOCIAL NETWORK ANALYSIS Social network models are commonly used in studies of discrete, well-defined biotic associations such as plant-pollinator and host-parasite interactions. However, these network applications (which are distinct from dendritic river networks) are relatively unknown in the freshwater literature. Using standardized samples from a large survey of stream fishes throughout the Mississippi River basin, I show how social network analysis (SNA) can reveal novel structure within large, multi-species assemblages. Topological properties of fish networks, such as the clustering coefficient and network diameter, were found to differ among streams with varying levels of physical habitat disturbance. A small number of highly connected ‘hub’ species was consistently detected when examining fish networks at nested spatial scales. And multiple, distinct subsets or ‘modules’ of species with characteristic functional traits were documented. I conclude by showing how SNA may be used to characterize the overall stability of fish assemblages under changing conditions.

Daniel McGarvey (Primary Presenter/Author), Center for Environmental Studies, Virginia Commonwealth University, djmcgarvey@vcu.edu;


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5/23/2016  |   15:45 - 16:00   |  315

INFLUENCES OF FISHES ON MACROINVERTEBRATE AND ALGAL COLONIZATION OF PRAIRIE STREAM POOL MESOCOSMS Physical factors, such as hydrologic variability, are major structuring forces of prairie stream communities. Less is known about the influences of biological factors such as fishes, and potential interactions between hydrology and fishes. We examined macroinvertebrate and algal colonization across varying densities of fishes in prairie stream pool mesocosms at the Konza Prairie Biological Station in northeastern Kansas. Mesocosms were stocked with low (7.1±0.4 g/m2) or high (18.1±0.6 g/m2) densities of a combination of three common prairie fishes: southern redbelly dace (Chrosomus erythrogaster), central stoneroller (Campostoma anomalum), and orangethroat darter (Etheostoma spectabile). Six additional pools contained no fishes. During the six-week experiment, each pool was sampled three times for macroinvertebrates and twice for chlorophyll-a. Fish presence significantly reduced abundance of colonizing insects (p<0.001) and total invertebrate biomass (p=0.001). Insect communities differed with treatment and were characterized by more Chironomidae, Culicidae, and Corduliidae in fishless pools (p<0.001 for all). Chlorophyll-a increased between sampling dates but did not differ among treatments. Results suggest fishes can influence colonization and community structure in prairie stream pools, which serve as important refugia during hydrologic disturbance.

Sophia Bonjour (Primary Presenter/Author), U.S. Geological Survey, Columbia Environmental Research Center, sbonjour@usgs.gov;


Matt Whiles ( Co-Presenter/Co-Author), University of Florida, mwhiles@ufl.edu;


Keith Gido ( Co-Presenter/Co-Author), Kansas State University, kgido@ksu.edu;


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5/23/2016  |   16:00 - 16:15   |  315

WHAT MAKES A FISH RARE? DRIVERS AND INTERRELATIONSHIPS BETWEEN MULTIPLE FORMS OF RARITY Within a taxonomic group, some species are common whereas others are rare. Understanding why some species are rarer than others is not only fundamentally interesting; it also has significant implications for biodiversity conservation. We addressed this challenge by analyzing ~8000 stream fish communities in ~1500 independent watersheds that span a broad environmental gradient across continental U.S.A. Using hierarchical and path models, we identified possible pathways by which species traits, historical biogeography, and phylogeny govern three different forms of rarity—local abundance, habitat breadth, and geographic range—in ~400 native fish species. Species with small-to-moderate body size, larger eggs, and non-benthic habit were found to be more locally abundant. Habitat breadth increased with body size and fecundity but decreased with egg size and maturation age. Species with larger geographic ranges are more likely to be lacustrine, have smaller eggs and higher fecundity, and found in eastern USA. Both habitat breadth and local abundance drove variation in geographic range size, albeit in different directions. Our analysis indicates that trade-off between geographic range size and local abundance are mediated by species life-history strategies.

Xingli Giam (Primary Presenter/Author), University of Tennessee, xgiam@utk.edu;


Julian Olden ( Co-Presenter/Co-Author), University of Washington, olden@uw.edu;


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5/23/2016  |   16:15 - 16:30   |  315

DISTURBANCE MODIFIES THE IMPORTANCE OF DETERMINISTIC AND STOCHASTIC ASSEMBLY MECHANISMS IN STREAM MACROINVERTEBRATE COMMUNITIES Expanding global biodiversity declines require a heightened understanding of community assembly in natural and managed ecosystems. Neutral theory and species sorting represent ends of a stochastic-deterministic community assembly gradient, with empirical work showing contrasting assembly related to physical disturbance. We conducted a field experiment in a sandy, piedmont stream in the SE US to quantify the relationship between community assembly and nearbed disturbance. Colonization of benthic macroinvertebrate assemblage structure (as taxa and trait composition) was subjected to 5 disturbance regimes simulating a full range of disturbance intensity (i.e., 0, low, low/moderate, moderate/high, high disturbance), and also compared with an unmanipulated streambed control. We found that the streambed control and the moderate/high disturbance treatment showed lower beta–diversity, higher nestedness, and similar mean trait values when compared to other disturbance treatments. These results suggest that disturbance intensity modifies the relative importance of deterministic vs. stochastic processes in assembling sand-bed stream communities, being deterministic at intermediate-high levels and more stochastic at relatively lower and higher levels of disturbance.

Stephen A. Sefick (Primary Presenter/Author), Auburn University, sas0025@auburn.edu;


Nina N. Noreika ( Co-Presenter/Co-Author), Auburn University, nen0002@tigermail.auburn.edu ;


Jack W. Feminella ( Co-Presenter/Co-Author), Auburn University, feminjw@auburn.edu;


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5/23/2016  |   16:30 - 16:45   |  315

COMMUNITY TRAITS DEVIATE IN RESPONSE TO A DISTURBANCE AT DIFFERENT LOCATIONS WITHIN A STREAM NETWORK. The “currency” of community ecology has traditionally been the species concept. Biological communities are often incredibly speciously diverse which has undoubtedly complicated the search for general principles in community ecology. For this reason, species functional traits have been proposed as a new currency which would be more suited to making community ecology a predictive science. The relative importance of the local environment and dispersal in influencing stream communities is theorized to differ depending on location with a dendritic stream network (e.g., headwaters are isolated and mainstems are well connected). We evaluated the potential for macroinvertebrate functional trait assemblages to respond differently to manipulations of local habitat at varying locations within stream networks. Specifically, we were interested in differences between isolated headwater and well-connected mainstem streams. We determined that functional trait assemblages differ between substrate types in headwater streams but not in mainstem streams. Additionally, substrate type affected functional trait redundancy in headwater streams. One possible reason for this is that high dispersal rates in mainstem streams overwhelm the effects of local habitat as a functional trait filter.

Bryan Brown (Primary Presenter/Author), Virginia Tech, stonefly@vt.edu;


Brett Tornwall ( Co-Presenter/Co-Author), Virginia Tech, bretttornwall@gmail.com;


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5/23/2016  |   16:45 - 17:00   |  315

BIODIVERSITY AND ECOSYSTEM FUNCTIONS – CAN TADPOLES TELL US ANYTHING ABOUT THEIR RELATIONSHIP? Globally over 30% of amphibian species are recognized as endangered, and another quarter may be at risk. Their larvae are important components of freshwater ecosystems, with distinct roles before and after metamorphosis. Reductions in amphibian species richness or changes in their composition are likely to alter important ecosystem processes, including primary production, nutrient dynamics and decomposition. However, the relationship between their biodiversity and ecosystem functioning remains unclear. This study attempts to understand how tadpole assemblages affect ecosystem processes in stream and wetland ecosystems. Two series of mesocosm experiments are being undertaken: two stream-dwelling amphibians, one filter feeder and one grazer, have been combined in stream mesocosms, and four wetland species, two filter feeders and two grazers, have been combined in wetland mesocosms. Each experiment comprises single and multispecies mixtures of tadpoles, comparing their effects on ecosystem functioning such as algal accrual, nitrogen and phosphorus dynamics and leaf-litter breakdown, and relating this to survival and growth rates of the tadpoles. Preliminary results show that species composition has an effect on algae biomass and decomposition rates in mesocosms.

Nicole T.K. Kit (Primary Presenter/Author), School of Biological Sciences, the University of Hong Kong, Hong Kong, nicokit@hku.hk;


David Dudgeon ( Co-Presenter/Co-Author), School of Biological Sciences, the University of Hong Kong, Hong Kong, ddudgeon@hku.hk;


Nancy E. Karraker ( Co-Presenter/Co-Author), Department of Natural Resources Science, University of Rhode Island, Kingston, USA, nkarraker@uri.edu;


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