SFS Annual Meeting

5/22/2018  |   09:00 - 09:15   |  420 A

INFLUENCE OF NATIVE FRESHWATER MUSSEL FUNCTIONAL TRAITS AND COMMUNITY STRUCTURE ON NITROGEN TRANSFORMATIONS IN BENTHIC SEDIMENTS Unionid mussels are long-lived, filter-feeding organisms that thrive in dense, speciose aggregations in lotic ecosystems. Mussels are known to significantly influence benthic biogeochemical processes both directly (e.g. excretion) and indirectly due to their unique functional traits. We examined the indirect influence of native unionid mussel functional traits (total movement, burrowing depth, NH4+ excretion, egestion rate, egestion C:N) on nitrogen removal processes (denitrification, annamox) in a lowland river in the southeastern US. We hypothesized that mussels indirectly stimulate nitrogen removal in the benthos through the interaction of their functional traits with the biotic and abiotic characteristics of the surrounding sediment. To test our hypothesis, we employed a combination of ex situ chamber incubation experiments and an in situ density and community composition manipulation experiment. This multi-fold approach allowed us to model the biogeochemical influence of mussel functional traits on the individual- and community-scale, respectively. Our research adds to the growing knowledge of the functional role these important yet globally imperiled organisms play in freshwater ecosystems.

Behzad Mortazavi (Co-Presenter/Co-Author), University of Alabama, bmortazavi@ua.edu ;


Carla L. Atkinson (Co-Presenter/Co-Author), The University of Alabama, carla.l.atkinson@ua.edu;


Zachary L. Nickerson (Primary Presenter/Author), University of Alabama, znickerson8@gmail.com;


Brian van Ee (Co-Presenter/Co-Author), University of Alabama, bcvanee@gmail.com;


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5/22/2018  |   09:15 - 09:30   |  420 A

CROSS-HABITAT LINKAGES BETWEEN AQUATIC INSECT SUBSIDIES AND TERRESTRIAL ARTHROPODS Ecosystems are increasingly considered as highly open systems, connected by multiple cross-habitat flows of organisms, energy and nutrients that are essential for the maintenance of biodiversity, ecosystem functioning and stability at local- to landscape scales. Currently, there is growing awareness of the importance of aquatic resource transfers into terrestrial food webs via aerial movements of adult stages of aquatic insects. In eight boreal streams along a gradient of in-stream productivity (8.6 - 189 µg TP/L) we quantified the abundance of emerging insects as a measure of potential subsidy, the complexity of riparian microhabitats (e.g. soil and vegetation characteristics) and the abundance and species composition of arthropod consumers, to determine subsidy and habitat effects on riparian ground-dwelling consumers. Results showed that the distribution of arthropods was significantly correlated with aquatic subsidy abundance and microhabitat. However, the strength of the relationships varied with taxon, metric (e.g. composition, diversity) and distance from the stream edge. Distributions of carabids were most strongly related to stream subsidies, whilst staphyinids were most strongly related to microhabitat.

Peter Carlson (Co-Presenter/Co-Author), Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden, peter.carlson@slu.se;


Brendan McKie (Co-Presenter/Co-Author), Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden, brendan.mckie@slu.se;


Richard Johnson (Primary Presenter/Author), Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden, richard.johnson@slu.se;


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5/22/2018  |   09:30 - 09:45   |  420 A

ENGINEER DENSITY, NOT ENVIRONMENTAL HARSHNESS MODULATES INVERTEBRATE COMMUNITY FACILITATION ACROSS A MONTANE GRADIENT Understanding how ecosystem engineering facilitates benthic communities by providing novel habitats is important in describing energy flows and for targeting conservation efforts. Our research identifies substantial facilitation of stream macroinvertebrate communities by net-spinning caddisflies (Hydropsychidae) and seeks to untangle how the strength of facilitation varies along an environmental and engineer density gradient. We quantified macroinvertebrates associated with caddisfly engineered retreats versus neighboring rock substrates using surveys of five study sites from headwaters to the mainstream of the Gunnison River, CO. Survey sites spanned an environmental harshness gradient quantified by discharge and caddisfly engineer densities ranged from 5-70 ind m2 along this gradient. Macroinvertebrate density was significantly higher in retreat structures than on surrounding rock substrates by as much as 5X, suggesting caddisfly retreats create hotspots of invertebrate density. Community facilitation varied predictably with caddisfly density gradients, but did not vary predictably along the environmental gradient, revealing that ecosystem engineered facilitation in lotic ecosystems is context dependent. Future analyses will focus on elucidating community characteristics associated with engineered structures and surrounding habitat along this gradient.

Benjamin Tumolo (Primary Presenter/Author), University of Wyoming, bbtumolo@gmail.com;


Lindsey Albertson (Co-Presenter/Co-Author), Montana State University, lalbertson@stroudcenter.org;


Melinda Daniels (Co-Presenter/Co-Author), Stroud Water Research Center, mdaniels@stroudcenter.org;


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5/22/2018  |   09:45 - 10:00   |  420 A

SYMBIONT DENSITY DETERMINES INTERACTION OUTCOMES IN A FISH REPRODUCTIVE MUTUALISM We examined context dependency in interaction outcomes in a reproductive symbiosis between lotic minnows. In this interaction, ‘associate’ fishes deposit eggs in nests built by host species. The interaction is always advantageous for associates, while host benefits depend on a dilution effect: adding associate eggs increases host reproductive success by reducing the probability of egg predation. This relationship is usually mutualistic, but low associate density may reduce brood dilution to the point that hosts no longer benefit, resulting in a commensalistic or even parasitic interaction. We conducted a randomized complete block experiment in which we manipulated density of Yellowfin Shiner, a common associate, at constant densities of the host Bluehead Chub and two egg predator fishes. We measured reproductive success as the number of eggs on nests after three days. Chub reproduction was highest at high associate densities (p = 0.03). Surprisingly, chub reproductive success in the absence of associates was higher than at low associate densities (p = 0.048). These results suggest costs (e.g. predation) of interspecific reproduction outweigh benefits at low symbiont densities. Changes in biotic context can shift nest association from a mutualistic to a parasitic interaction.

Yoichiro Kanno (Co-Presenter/Co-Author), Colorado State University; Department of Fish, Wildlife, and Conservation Biology, Yoichiro.Kanno@colostate.edu;


Brandon K. Peoples (Co-Presenter/Co-Author), Clemson University, peoples@clemson.edu;


Sam Silknetter (Primary Presenter/Author), Virginia Tech, silknets@vt.edu;


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5/22/2018  |   10:00 - 10:15   |  420 A

HABITAT AND LANDSCAPE EFFECTS ON THE RECOVERY OF LARVAL DRAGONFLY COMMUNITIES FOLLOWING POND DRYING Landscape context can affect the recovery of freshwater communities following disturbances such as drying. Community recovery after drying may depend on how well dispersers recolonize habitats, in part driven by their responses to the heterogeneous terrestrial landscape surrounding aquatic habitats. To assess the impacts of landscape type on community reassembly following pond drying, we surveyed larval dragonfly communities over 15 years, in ponds situated among fields and forests. We predicted that forest cover in between ponds and canopy cover at ponds would slow the reassembly of larval communities following drying, by limiting adult dispersal and colonization. Pond canopy cover reduced the diversity of larval dragonflies across years (p < 0.001), independent of drying regime. Pond canopy cover was positively associated with relative richness after a drying event (p = 0.03), however neither canopy or landscape forest cover affected Shannon diversity (p > 0.1 in both cases). Presence/absence-based community composition changed marginally over time in relation to canopy cover (p = 0.07) and least cost distance (p = 0.08), however abundance-based composition did not change. Canopy cover may therefore affect how semi-aquatic species detect and colonize aquatic habitats following a disturbance.

Michael Benard (Co-Presenter/Co-Author), Case Western Reserve University, mfb38@case.edu;


Jason Hoverman (Co-Presenter/Co-Author), Purdue University, jhoverm@purdue.edu;


Rick Relyea (Co-Presenter/Co-Author), Rensselaer Polytechnic Institute, relyer@rpi.edu;


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


Earl Werner (Co-Presenter/Co-Author), University of Michigan, eewerner@umich.edu;


Kerry Yurewicz (Co-Presenter/Co-Author), Plymouth State University, klyurewicz@plymouth.edu;


Shannon McCauley (Co-Presenter/Co-Author), University of Toronto Mississauga, shannon.mccauley@utoronto.ca;


Sarah French (Primary Presenter/Author), University of Toronto Mississauga, sarah.french@mail.utoronto.ca;


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5/22/2018  |   10:15 - 10:30   |  420 A

COMMUNITY RESPONSE OF BENTHIC AND EMERGING INSECTS TO FISH DENSITY IN PRAIRIE STREAM PERMANENT WATER REFUGIA Hydrologic disturbances are major structuring forces in prairie streams, with permanent reaches serving as refugia during disturbance and source areas of colonists during recovery. Hydrologic disturbances likely influence biotic interactions as competition and predation might intensify in constricted reaches during low flow periods, possibly affecting invertebrate recovery patterns. We examined community structure of fishes, benthic invertebrates, and emerging adult aquatic insects from permanent pools in stream networks at the Konza Prairie Biological Station in northeastern KS. We also examined how varying densities of fishes influenced insect colonization of pool mesocosms. Fish densities were negatively associated with benthic invertebrate abundance but not total biomass. Fishes reduced emerging Chironomidae biomass (r2 = 0.43, p = 0.047) and body size (r2 = 0.61, p = 0.014), and overall emergence was delayed where predatory fish biomass was higher (fish, date interaction p = 0.036). The mesocosm experiment showed clear patterns of reduced colonizing insect abundance (p < 0.001) and invertebrate biomass (p = 0.001), as well as shift in functional feeding group composition, with increasing fish biomass. Results suggest that fishes influence colonization and community structure in critical refugia habitats in intermittent stream networks.

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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