6/08/2017  |   09:00 - 09:15   |  302C

DESCRIBING COMMUNITY CONTROLS ON NUTRIENT SEQUESTRATION AND FLUXES WITH SPATIAL MODELS Animal aggregations can lead to localized hotspots of nutrient and material flux in streams. Yet, the abiotic characteristics and the spatial structure of these hotspots due to species-specific preferences remain a mystery. Historically, unionid mussels dominated benthic biomass in many riverine ecosystems, but have undergone extensive declines. We examined reach-scale physical attributes of sites encompassing a gradient of mussel densities, evaluated quadrat-scale abiotic variables, and the role various species play in nutrient sequestration and regeneration (C, N, P). We sampled mussels and abiotic variables at 1,218 quadrats, measured tissue composition and excretion and biodeposition rates of 11 species across 12 reaches in the Sipsey River, Alabama. Using geostatistical analyses, species distributions and their ecological functions were mapped and models were developed to examine species distributions and species’ roles in recycling and storing nutrients. These models were used to examine species-specific roles in reach- and quadrat-scale nutrient recycling and storage. Our results demonstrate that mussels are important to nutrient dynamics through nutrient regeneration and the creation of storage hotspots, but their significance varies with distribution, species composition, and abiotic context.

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


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


Presentation:
This presentation has not yet been uploaded.

6/08/2017  |   09:15 - 09:30   |  302C

Retrospective Analysis of Fish Communities After Watershed Alteration in the Ouachita River System, Arkansas Changes in fish communities can be gradual or abrupt after watershed alteration with no return towards earlier structure. The Saline River is one of the longest unregulated rivers in Arkansas (325 km), but anthropogenic activities (e.g., development, logging, and gravel mining) continue to influence fish communities. We quantified temporal changes in fish communities at six local stream reaches over multiple decades (period I [1969-1971], period II [1980-1982], and period III [2016]). At the broadest spatial scale, fish community composition significantly shifted (PERMANOVA: P < 0.01) through time, and similarity percentage analysis (SIMPER) identified a suite of species driving community divergence. Average community dissimilarity was greatest between period I and period III (SIMPER: average dissimilarity = 74%), and three species (Hybognathus nuchalis, Percina vigil-uranidea, and Notropis boops) each contributed to >8% total dissimilarity. Communities most downstream deviated the furthest from period I with no return towards earlier structure and communities upstream moved less through multivariate space. Similar species patterns were observed in the Little Missouri River. Our findings suggest fish communities have transitioned permanently to alternative community states after watershed alteration and communities downstream appear the most affected.

Reid Adams (Primary Presenter/Author), University of Central Arkansas, radams@uca.edu;


Ginny Adams ( Co-Presenter/Co-Author), University of Central Arkansas, gadams@uca.edu;


Aaron Burgad ( Co-Presenter/Co-Author), University of Central Arkansas, aburgad1@cub.uca.edu;


Michelle Furr ( Co-Presenter/Co-Author), University of Central Arkansas, mfleming4@cub.uca.edu;


Presentation:
This presentation has not yet been uploaded.

6/08/2017  |   09:30 - 09:45   |  302C

Allometric body mass – abundance scaling relationships vary in response to a gradient of mining impacts Body mass – abundance scaling relationships have been shown to be a remarkably consistent organizing principle, particularly in aquatic communities. This relationship has been shown to change in response to anthropogenic impacts, and has been proposed as a potential metric for community health. To test the utility of this approach, we constructed body mass – abundance relationships at 26 sites across an acid mine drainage impact gradient on the West Coast South Island, New Zealand. Body mass – abundance relationships varied significantly in response to acid mine drainage. When moving across the gradient from circumneutral and naturally acidic reference streams to more heavily impacted sites, slopes increased (approaching 0), while community abundance and the range of body sizes both decreased. The largest body size classes were more heavily impacted than smaller body sizes. These results indicate that acid mine drainage can have serious impacts to the distribution of biomass within aquatic communities. This has implications in food web structure and function in impacted sites, since many aquatic food webs are strongly size-structured.

Justin Pomeranz (Primary Presenter/Author), Colorado Mesa University, jfpomeranz@gmail.com;
o Justin is an assistant professor of environmental science at Colorado Mesa University. He is a community ecologist with a special affinity for streams and benthic macroinvertebrates. Justin’s research is focused on understanding the variation in community biomass distributions from both natural and anthropogenic causes. He enjoys working with large datasets across scales and playing the banjo. Justin received a BS and MS from Colorado State University and a PhD from the University of Canterbury in New Zealand.

Helen Warburton ( Co-Presenter/Co-Author), University of Canterbury, helen.warburton@canterbury.ac.nz;


Jon Harding ( Co-Presenter/Co-Author), University Canterbury, jon.harding@canterbry.ac.nz;


Presentation:
This presentation has not yet been uploaded.

6/08/2017  |   10:00 - 10:15   |  302C

AQUATIC MACROINVERTEBRATE RESPONSES TO PREDATION AND TEMPERATURE: VARIATION IN CONTEXT DEPENDENT TROPHIC INTERACTIONS Trophic cascades, the indirect effects of carnivores on primary producers mediated by herbivores, remains a central theme of ecological theory. How climate change will alter the mechanisms controlling such interactions remains largely unexplored, certainly in stream ecosystems. In montane streams, stonefly predators have been documented to indirectly affect algal biomass by influencing the distribution, abundance, behavior, and life histories of invertebrate grazers. Density mediated interactions (DMI) occur when community composition is primarily influenced by changes in herbivore abundance due to consumption by predators. Trait-mediated interactions (TMI) alter available basal resources through non-consumptive interactions such as anti-predatory behaviors. In this research, we conducted mesocosm experiments on stonefly predators and mayfly prey to determine the relative importance of grazers on regulating algal production under 3 temperature treatments intended to simulate climate warming. Furthermore, we examined the influence of both TMI and DMI on algal production through consumptive and non-consumptive predatory treatments. We found algal production to decrease as temperature increased but no differences among grazer-alone treatments versus DMI or TMI on algal production.

Scott Morton (Primary Presenter/Author), Colorado State Univeristy, smorton9292@gmail.com;


Presentation:
This presentation has not yet been uploaded.

6/08/2017  |   10:15 - 10:30   |  302C

CO-OCCURRENCE AND SPECIES INTERACTION PATTERNS OF MUSSEL SPECIES WITHIN BEDS To aid in the conservation of freshwater mussels (Bivalvia, Unionidae), a better understanding of mussel species composition and co-occurrence patterns is needed. We examined patterns among mussel occurrence, abundance, and biomass in the Little River, a 6th order tributary of the Red River in southeastern Oklahoma with high mussel species richness (35 species). We semi-quantitatively sampled 42 mussel beds along a 111 km stretch of the river by conducting timed searches. In addition, we quantitatively sampled 12 large mussel beds by excavating 0.25m2 quadrats. We are analyzing these data to look for patterns of co-occurrence and association that might indicate underlying species interactions. To date we have found strong, positive relationships between the biomass of three dominant species (Actinonaias ligamentina, Amblema plicata, and Quadrula pustulosa) and the abundance of most rare species.

Kathryn Murphy (Primary Presenter/Author), University of Oklahoma, Kathrynmurphy@ou.edu;


Caryn C. Vaughn ( Co-Presenter/Co-Author), University of Oklahoma, carynvaughn@gmail;


Lara Souza ( Co-Presenter/Co-Author), University of Oklahoma , lara.souza@ou.edu;


Presentation:
This presentation has not yet been uploaded.