SFS Annual Meeting

5/21/2018  |   14:00 - 14:15   |  310 B

EXPLORING THE RELATIONSHIP BETWEEN FLOW AND METACOMMUNITIES IN CATCHMENTS The effects of flow disturbance on freshwater benthic invertebrates have been studied in the context of floods, droughts and variability. More recently, we have taken advantage of large deployments of flow gauges and flow modeling to mechanistically understand how hydrographs are interacting with species sorting and movement in catchments. By utilizing readily available flow gauge data within the Sierra Nevada Mountains in California, we sought to relate ecologically important parts of the hydrograph to large spatial patterns in the benthic invertebrate community. We did this by calculating various flow metrics, and observing which ones described most variation in the benthic community. Then, we analyzed the extent to which various metrics and space were structuring the benthic community along a catchment. The benthic community was structured according to flow at sites with a lesser prevalence of dams, while there was more spatial structuring evident in catchments with a strong presence of flow regulation. Ongoing methods comparisons will help further our understanding of the relationship between flow and metacommunity dynamics.

Parsa Saffarinia (Primary Presenter/Author), University of California, Riverside, psaff001@ucr.edu;


Kurt Anderson (Co-Presenter/Co-Author), University of California, Riverside, kurt.anderson@ucr.edu;


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5/21/2018  |   14:15 - 14:30   |  310 B

CONNECTING LONG-TERM DATA WITH FINE-SCALE VARIATION: USING REMOTE SENSING TO EVALUATE SPATIOTEMPORAL DYNAMICS OF DRYLAND PONDS In the American Southwest, lentic habitats are threatened by unsustainable water use and projections of more frequent, extreme drought. Small, manmade lentic habitats such as cattle ponds may provide critical habitat for aquatic organisms when natural habitats are lost. However, spatiotemporal dynamics of lentic habitat availability in this region are poorly understood, including spatial distribution and hydroperiod dynamics of manmade ponds. To address this knowledge gap, we asked: (1) How are manmade ponds spatially distributed in this region? (2) Which ponds are permanent, and which are intermittent? (3) What are the hydroperiod dynamics of these ponds, and do they change over time? To answer these questions, we used graph theory and spectral mixture analysis to analyze 33 consecutive years (1984-2017) of satellite imagery in Coronado National Forest, Arizona. Understanding and quantifying the spatiotemporal dynamics of these ponds can help link fine-scale environmental variability to aquatic community dynamics – an important step in managing aquatic habitats, biotic communities, and water demands in an area with increasing water demands and decreasing water supply.

Mary Farruggia (Primary Presenter/Author), Virginia Tech, mfarrugg@vt.edu;


Meghan Halabisky (Co-Presenter/Co-Author), University of Washington, halabisk@u.washington.edu;


Meryl C. Mims (Co-Presenter/Co-Author), Virginia Tech, mims@vt.edu;


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5/21/2018  |   14:30 - 14:45   |  310 B

SEASONAL VARIATION IN COMMUNITY SIZE STRUCTURE: POTENTIAL EFFECTS OF TEMPERATURE AND HYDROLOGY ON THE SIZE-SPECTRUM Consistent seasonal variation in the slopes and intercepts of size-spectra models has previously been demonstrated but not explained in lotic ecosystems. In this study, we append size-spectra results for fish and benthic invertebrates in three southern West Virginia streams with coincident time-series data on water temperature and discharge, testing for predictable associations between seasonal size-spectra parameters, temperature, and hydrology. We find that variable size-spectra slopes may be driven by differential responses of invertebrates and fishes to the annual accumulation of degree days; earlier onset of spring invertebrate growth may increase invertebrate density relative to fish density, thereby elevating the left-side of size-spectra plots in pre-summer months and steeping the overall slopes. Differences among the size-spectra intercepts may be explained by hydrology. An anomalous mid-summer flood reduced abundances of both invertebrates and fishes in late-summer and fall, thereby lowering the intercepts of the size spectra model. We predict that similar dynamics can explain variation in size-spectra models from other lotic systems.

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


Andrew Kirk (Co-Presenter/Co-Author), Virginia Commonwealth University, andrew.kirk@deq.virginia.gov;


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5/21/2018  |   14:45 - 15:00   |  310 B

SPATIAL AND TEMPORAL DRIVERS OF VARIATION IN FEEDING RATES OF A STREAM PREDATOR Species interaction strengths are recognized as being dynamic in time and space, yet few studies have quantified this variation or its drivers. We used an observational approach to estimate the prey-specific feeding rates of reticulate sculpin (Cottus perplexus) at nine stream sites over three seasons in western Oregon. Feeding rates varied across prey taxa by three orders of magnitude, varying less across seasons and sites for a given taxon than between prey taxa within a season or site. Of the 25 most common prey recovered from sculpin stomachs, feeding rates on seven taxa were best predicted by a model including site identity and season. The top model for seven other prey included only site, and for eleven taxa it included only season. Variation within prey taxa in feeding rates was driven by variation in both prey density and prey body sizes, with 19 of 25 taxa showing a positive power law (log-log) relationship between feeding rate and prey density. Our results highlight how spatial and temporal variation in prey demographics drive variation in the feeding rates of generalist predators.

Dan Preston (Primary Presenter/Author), Oregon State University, daniel.preston@oregonstate.edu;


Landon Falke (Co-Presenter/Co-Author), Oregon State University, falkel@oregonstate.edu;


Jeremy Henderson (Co-Presenter/Co-Author), Oregon State University, hendejer@onid.orst.edu;


Mark Novak (Co-Presenter/Co-Author), Oregon State University, Mark.novak@oregonstate.edu;


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5/21/2018  |   15:00 - 15:15   |  310 B

THE INFLUENCE OF NUTRIENT ENRICHMENT OF RIVERINE FOOD WEB RESILIENCE Eutrophication is one of the most ubiquitous anthropogenic stresses altering the structure and function of communities and ecosystems. Excess nutrients clearly alter community composition and productivity, but how do these changes alter the distribution of energy flow within stream food webs and thus the ability of those communities to recover from disturbance? We used ecological network analysis (ENA) to examine the emergent properties of 12 quantitative food webs across a nutrient enrichment gradient in the Manawatu, New Zealand. Nutrient enrichment resulted in communities composed of energy inefficient species with high community (excluding microbes) respiration. Community respiration was several times greater in enriched communities and this may drive hypoxic conditions even without concomitant changes in microbial respiration. Enriched communities also had weaker trophic cascades, which may yield greater robustness to energy flow loss. Interestingly, enriched communities were also more structurally and functionally affected by species sensitive to flow disturbance making these communities more vulnerable to floods.

Russell Death (Primary Presenter/Author), Massey University, r.death@massey.ac.nz;


Adam Canning (Co-Presenter/Co-Author), Massey University, acanning@fishandgame.org.nz;


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5/21/2018  |   15:15 - 15:30   |  310 B

AN INVESTIGATION OF DEMOGRAPHIC RESPONSE VARIATION AMONG STREAM FISHES AS A MECHANISM TO MAINTAIN COMMUNITY DIVERSITY. The southeastern United States retains some of the highest freshwater fish diversity in North America, however it's unclear how this diversity is maintained over evolutionary timescales. Sympatric species in communities are exposed to biotic interactions and the same abiotic environment. These environments can vary over time, some of this variation is regular (e.g. seasonal variation) and some of it is stochastic. There is also documented temporal variation in the persistence and stability of stream fishes, and this has been shown by studies examining how stream fish communities change over time. Key questions that remain is whether or not the species in these communities show similar responses to variation. We investigated potential coexistence mechanisms for fish communities in two piedmont streams in South Carolina using a mark-recapture study to examine variation of a demographical parameter such as survival. Study species included Bluehead chub (Nocomis leptocephalus), Mottled sculpin (Cottus bairdii), Creek chub (Semotilus atromaculatus), and Striped jumprock (Moxostoma rupiscartes). Bi-monthly apparent survival was estimated using a Cormack-Jolly Seber model from the months of September 2015 – March 2018. Interspecies variation in population dynamics can buffer species against environmental change and maintain diversity.

Kasey Pregler (Primary Presenter/Author), Colorado State University; Department of Fish, Wildlife, and Conservation Biology, kasey.pregler@colostate.edu;


Seoghyun Kim (Co-Presenter/Co-Author), University of North Carolina at Greensboro, seoghyun.kim@colostate.edu;


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


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