SFS Annual Meeting

6/06/2024  |   10:30 - 10:45   |  Independence Ballroom B

Quantifying spatiotemporal metacommunity variability using benthic and drift sampling of stream macroinvertebrates Metacommunity theory has received considerable attention in freshwater macroinvertebrate ecological research due to its utility in informing the mechanisms underlying community assembly. However, spatiotemporal variation in macroinvertebrate metacommunity dynamics is still relatively poorly understood, despite seasonal variation in macroinvertebrate dispersal being well-documented. Here, we present research aimed at quantifying spatiotemporal metacommunity variability through the combination of benthic and drift surveys in a single river network. We hypothesized that headwater and mainstem sites would exhibit distinct communities, with headwater sites exhibiting stronger temporal variation in community dissimilarity in line with a species sorting perspective (as opposed to mass effects in mainstems). We also hypothesized that concurrent drift surveys would be more similar to benthic surveys in headwaters compared to mainstems, also in line with current understanding of metacommunity dynamics in stream networks. For our survey design, 8 sites were sampled monthly along Little Stony Creek, a 3rd order stream network in Giles County, VA. Sites were established along a drainage area gradient (1st - 3rd order), allowing for a distinction between headwaters and mainstem sites. Environmental parameters and channel dimensions were collected concurrently with biological data as covariates. While sample identification is ongoing, we predict ordination of the community data using Nonmetric multi-dimensional scaling (NMDS) will show distinct spatially structured communities that vary temporally in accordance with the degree of dissimilarity of drift samples. Considering the many anthropogenic factors altering freshwater metacommunities, incorporation of temporal, instead of simply spatial, variability can better inform management of these impressively complex systems.

Brian Bush (Primary Presenter/Author), Virginia Tech, brianbush@vt.edu;

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6/06/2024  |   10:45 - 11:00   |  Independence Ballroom B

Artificial Light At Night Impacts Cross-System Subsidies And Insect-Community Composition Human impacts on freshwaters are increasing in extent and intensity across the globe, including those stemming from artificial light at night (ALAN). Emergent aquatic insects, a crucial link between aquatic and terrestrial ecosystems, may be especially susceptible to ALAN due to their unique physiological and behavioral traits. As anthropogenic lighting becomes dominated by LEDs the effects of this technology on aquatic insects are little studied. To investigate the impact of narrow-band, spectra-specific LED lighting on insect community metrics at the aquatic-terrestrial interface we experimentally added LED fixtures of variable spectral composition in the littoral and adjacent riparian area of a pond. We installed replicated treatments of narrow-band LEDs (410, 530 and 630 nm), broad-spectrum white (4000k) and a dark control, and sampled insect communities in both habitats. Wavelength impacted insect abundance, with insects being 188% more abundant in violet treatments than dark controls. Community composition also differed among treatments (p<0.001), as did total insect biomass (p < 0.001), with total biomass being, on average, 184% greater in violet traps than all other colors. Aquatic insects were also differently impacted by light compared to those of terrestrial origin (p < 0.01), suggesting an asymmetrical effect of LEDs on aquatic-terrestrial resource exchange. Overall, our findings suggest taxa-specific responses to ALAN resulting in altered community makeup under narrow bands of LED emissions. This has consequences for how insects move between ecosystems and how these vital resources are managed.

Elizabeth Parkinson (Primary Presenter/Author), Dept. Biological Sciences, Oakland University, emparkinson@oakland.edu;

Scott Tiegs (Co-Presenter/Co-Author), Oakland University, tiegs@oakland.edu;

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6/06/2024  |   11:00 - 11:15   |  Independence Ballroom B

BEAVER DAM ANALOGS INFLUENCE MACROINVERTEBRATE COMMUNITIES AND SUBSIDY FLUXES BETWEEN AQUATIC AND TERRESTRIAL ECOSYSTEMS IN HEADWATER STREAMS OF WESTERN MONTANA In response to stream degradation resulting from the near eradication of American Beavers (Castor canadensis), managers of freshwater systems have turned to using beaver dam analogs (BDAs) as one means of restoring waterways from incision and declining water tables. Though BDAs have been shown to restore physical traits of riparian areas, their influence on macroinvertebrates and linked aquatic-terrestrial systems is not well understood. To examine how BDAs influence macroinvertebrate communities and riparian insectivores, we compared unrestored reference stream reaches to BDA-restored reaches, with 7-14 BDAs, in three Montana headwater streams. We collected physical stream measurements and quantitative samples of benthic macroinvertebrates using a Surber sampler, emerging adult insects using emergence traps, and macroinvertebrate in-fall using pan traps. We also conducted spider and bird surveys to assess if BDAs influence riparian insectivores. We found that overall, BDA-restored reaches had wider wetted widths, deeper thalweg depths, smaller sediment sizes, and a lower percentage of riffle habitat. Most BDA-restored reaches had higher benthic densities (p = 0.003), with high proportions of midges. At two reference reaches, benthic densities had higher proportions of sensitive taxa (Ephemeroptera, Plecoptera, and Trichoptera). Overall, emergence flux and terrestrial in-fall were similar for reference and BDA-restored reaches. However, midges comprised a greater percentage of the flux out of BDA-restored reaches. Bird diversity was not impacted by BDA-treatment, while spider abundance, specifically Tetragnathidae, was higher in BDA-restored reaches (p = 0.048). By modifying aquatic habitats, BDAs alter benthic community structure and therefore fluxes of subsidies across the aquatic-terrestrial interface. ¬¬

Michelle Fillion (Primary Presenter/Author), University of Montana, michelle.fillion@umconnect.umt.edu;

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6/06/2024  |   11:15 - 11:30   |  Independence Ballroom B

A STOCHASTIC MODEL OF DISTURBANCE EFFECTS ON BENTHIC COMMUNITY SUCCESSION AND PATCH DYNAMICS IN STREAMS: SOME ANALYTICAL RESULTS We previously published simulation results for a model of disturbance effects on stream benthic communities, where disturbance is created by high-flow events. We now present new analytical results for this model. The model addresses three spatial scales: a stream reach, which comprises multiple habitats, each divided into multiple patches (e.g., stones on the stream bed). Consistent with the conceptual patch-dynamics framework developed by A. S. Watt in the 1940s, the incremental process of temporal change within each patch consists of a forward process (succession) and a backward process (retrogression) that, during sufficiently long periods between high-flow events, produce a quasi-climax community structure. Disturbance due to high-flow events resets patches to earlier successional stages. Classical models of disturbance effects on succession assume disturbance acts at the patch scale, independently on each patch. The ultimate result is a temporally constant overall community structure as changes in different patches balance. By contrast, our model assumes that disturbance by high-flow events acts at the habitat or reach scale, simultaneously affecting all patches within a given habitat. Patches no longer behave independently, and the simple ways of characterizing overall community structure based on the stochastic dynamics of a single patch are no longer valid. Instead, the joint distribution of patch states must be explicitly modeled. The model is potentially useful in interpreting assessments of anthropogenic impacts on streams based on the taxonomic composition of benthic communities, which is transiently altered by high-flow events.

James McNair (Primary Presenter/Author), Robert B. Annis Water Resources Institute, mcnairja@gvsu.edu;

Jiyeon Suh (Co-Presenter/Co-Author), Grand Valley State University, suhj@gvsu.edu;

Dean DeNicola (Co-Presenter/Co-Author), Slippery Rock University, dean.denicola@sru.edu;

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6/06/2024  |   11:30 - 11:45   |  Independence Ballroom B

LONG-TERM AQUATIC MACROINVERTEBRATE AND FISH COMMUNITY ASSESSMENT IN THE OGEECHEE RIVER Long-term data assessments can help in understanding temporal community shifts, and the resistance and resilience of freshwater communities in response to anthropogenic impacts. The Ogeechee River is an unimpeded blackwater river that drains a large portion of southeastern Georgia. The relative stability of the climate makes this basin rich in diversity. There are large, historical datasets for this area from decades of previous research in the Ogeechee River. The purpose of this study is to assess community composition changes in aquatic macroinvertebrates and fish across a decade-long time span. Aquatic macroinvertebrate and fish were collected using historical methods denoted by the Georgia Department of Natural Resources. Aquatic macroinvertebrates are assessed over time using length measurements as well as taxonomic identifications to family level or lower that will a) allow us to assess length-mass relationships over time and b) assess potential shifts in community composition and abundance. Fish are assessed for community diversity and composition changes through time. Macroinvertebrates and fish are also evaluated using functional characteristics that can further aid in the understanding of community composition. Results from this study will further the understanding of how communities change over extended time frames. Long-term assessments can help build our understanding of how communities are adapting to an ever-changing environment facing threats of climate change and land development.

Molly McKeon (Primary Presenter/Author), Georgia Southern University, molly.mckeon94@gmail.com;

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6/06/2024  |   11:45 - 12:00   |  Independence Ballroom B

EFFECTS OF IBUPROFEN AND IMIDACLOPRID ON STREAM INVERTEBRATE COMMUNITIES: AN OUTDOOR MULTIPLE-STRESSOR MESOCOSM EXPERIMENT Pharmaceuticals have been detected in freshwater systems. Their risks remain poorly understood as most current evidence is based on short-term, laboratory experiments often using unrealistically high exposure concentrations. Our study aimed to better characterise their hazards under field conditions. Using a full-factorial design, we conducted a 30-day multiple-stressor experiment of the drug ibuprofen (IBF, 0 vs. 32 µg/L) and the neonicotinoid imidacloprid (IMIDA, 0 vs. 0.7 µg/L) under slow vs. fast flow velocity using 64 circular outdoor stream mesocosms at the Kauru River, New Zealand. We studied changes in benthic invertebrate communities, invertebrate drift, and insect emergence. IBF caused increased benthic EPT taxa in both flows, while IMIDA caused a decline. Among the common taxa, Chironomidae, Ephemeroptera, Nematoda and Ostracoda were negatively affected by IMIDA but not by IBF. IBF caused fewer drifting EPT in slow flow but greater in fast flow, while IMIDA caused increased drifting in both flows. IBF and IMIDA decreased EPT emergence in both flows, but these effects did not sustain over time due to the declining abundance of EPT in the mesocosms. Abundance of emerged Chironomidae remained high and IBF caused increased emergence in both flows, while IMIDA caused a decline. The effects of IBF on emergence weakened with time, while it enhanced for IMIDA. Overall, IBF had weak effects on the invertebrate communities, while IMIDA showed consistently negative effects. Our study contributes towards gaining a better understanding of the hazards of pharmaceuticals to freshwater systems through a field-realistic experiment with environmentally relevant stressor concentrations.

Nina Batucan (Primary Presenter/Author), University of Otago, batni629@student.otago.ac.nz;

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