SFS Annual Meeting

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

How Urbanization Alters Predictions Of The River Continuum Concept In Macroinvertebrate Communities— Testing A Classic Hypothesis With Long-term Monitoring Data The River Continuum Concept (RCC) predicts changes in diversity and feeding strategies in stream invertebrates moving downstream. The RCC predicts that I) headwater habitats should contain predominantly allochthonous feeders, with autochthonous feeding increasing downstream in response to food availability, and II) diversity should increase with stream order as species accumulate downstream and make use of large heterogeneous environments. However, the applicability of this classic ecological theory to urban systems has been called into question— with altered hydrology, nutrient dynamics, and riparian environments in urban streams, can the RCC still function as a valuable tool to understand these systems or has urbanization fundamentally altered the spatial structure of stream communities? We used two decades of benthic invertebrate monitoring data from a Lake Ontario tributary, the Credit River, in Ontario, Canada, to address this question. We found that large-scale patterns of increased diversity and autochthonous feeding in higher order streams were still present, as predicted by the RCC. However, patterns of feeding and diversity across stream orders are diminishing through time in the most urbanized areas, suggesting that urbanization is eroding spatial patterns of the RCC. Conversely, we found that differences in functional feeding strategies among stream orders became more distinct through time in less urban sites, likely in response to legislative and restoration efforts. Our findings suggest the RCC is still a valuable tool for understanding diversity and function of urban streams, however, we caution that without effective management, urbanization may erode spatial patterns and fundamentally alter the structure of communities.

Dale Pebesma (Primary Presenter/Author), University of Toronto, dale.pebesma@mail.utoronto.ca;

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

Assessing the effects of urbanization on organic matter decomposition using cotton strip assays in a tropical watershed, Puerto Rico Organic matter decomposition in urban streams is affected by a diversity of factors, with altered flow regimes and warm temperatures, among the most important. Our objective was to assess how urbanization affects organic matter decomposition in a tropical watershed using cotton strips assays, which reduces variability associated with leaf litter quality and vulnerability to flashy streams. We studied the Río Piedras watershed, a highly urbanized system in the San Juan Metropolitan area, Puerto Rico. We deployed cotton strips in six streams, forming an urban gradient (~12-77% impervious cover). Strips were placed in three pools per stream, collected in three dates, and measurements included the loss of tensile strength and microbial respiration rates. Temperature was measured every hour using HOBO sensors. Warmest water temperatures were found in the most urbanized areas (35°C) and lowest in least urbanized (24°C). Cotton strip tension loss ranged from ~0-11% per day. While we did not find any relation between the cotton strips' tensile strength loss and temperature, there was a significant relation with the watershed land cover variables (i.e. quadratic relationship with impervious surface). Microbial respiration rates ranged from 0.25-1.84 mgO2gDM-1hr-1. The cotton strips tensile strength loss did not show any relation to our respiration measurements. Our study shows how urbanization alters organic matter decomposition rates and microbial activity in urban streams. We detected high variability within a single stream (e.g., pool to pool variability), highlighting the importance of assessing urban effects within and among streams.

Vamery González-Hernández (Primary Presenter/Author), Department of Applied Ecology, North Carolina State University, vgonzal5@ncsu.edu;

Alonso Ramirez (Co-Presenter/Co-Author), Department of Applied Ecology, North Carolina State University, alonso.ramirez@ncsu.edu;

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

It all becomes clearer: the filter feeding effect of Corbicula fluminea on turbidity levels Many waterbodies are characterised by high turbidity levels due to the presence of high abundances of algae or suspended fine inorganic sediment in the water column. In many locations, large populations of bivalves act as ecosystem engineers, actively filtering the water they inhabit by extracting fine organic and inorganic particles from the water column. As such when population densities are high, bivalves can have a significant influence on turbidity levels potentially resulting in major changes to the water clarity of the aquatic systems they inhabit. As water temperatures increase due to climate change, filter feeding effects may be enhanced as the rate of metabolic activity increases. This paper examines the filtering activity of small and large Asian Clams, Corbicula fluminea, on turbidity levels at different temperatures (10-25°C) in a series of controlled experiments. The results clearly indicate that as water temperatures increased, turbidity levels were reduced more rapidly than at lower temperatures. There was a strong association between the size of the individual clam and the reduction in turbidity over time. Filter-feeding activity of C. fluminea reduced turbidity levels significantly compared to control treatments (no C. fluminea) with the fine sediments bound together in their pseudo-faeces. The binding of fine sediment may lead to a reduction in the subsequent resuspension of fine sediments. The wider implications of the filter-feeding activity of C. fluminea populations is considered in relation to wider habitat characteristics and how this may change under future warmer conditions.

Paul Wood (Primary Presenter/Author), Loughborough University, UK, p.j.wood@lboro.ac.uk;

Sarah Evans (Co-Presenter/Co-Author), Loughborough University, sarah.evans1991@hotmail.co.uk;

Jonathan Millett (Co-Presenter/Co-Author), Loughborough University, J.Millett@lboro.ac.uk;

Kate Mathers (Co-Presenter/Co-Author), Loughborough University, k.mathers@lboro.ac.uk;

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

LEAF-PACKS AND ARTISTS, REDUX: CAN WE FIGURE OUT WHAT’S HAPPENED TO OUR LEAF-PACK SITES SINCE BEFORE COVID? Since 2014 my Urban Ecology: How Wildlife Interacts with an Urbanizing Landscape course at RISD has been conducting modified leaf-pack experiments every (feasible) spring (n = 7). The entire process of collecting and processing the data at two sites along one of RI’s major rivers—one urban, one semi-rural—is done by the whole class. Small groups (or individuals) conduct their own spatial analysis of 600m of surrounding land-use—depending upon each group’s consensus on how to categorize land-use and how to quantify it—with or without any technological tools. They consider the biological and spatial data together to form a hypothesis and ultimately a conclusion about the impacts of land-use on adjacent aquatic communities. Before COVID, the BIV was higher and %EPT was a lot lower at the more urban site. In the two years we’ve conducted this experiment post-COVID, both sites have equally high BIV and the %EPT at the semi-rural site has plummeted to the same level as the urban site. This spring we will take on the additional component of analyzing watershed land-use beyond the 600m square to determine what factors, if any, might be at play in this recent change.

Maria Aliberti-Lubertazzi (Primary Presenter/Author), RHODE ISLAND SCHOOL OF DESIGN, MALIBERT@RISD.EDU;

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

City Scales and Guppy Tales: Stoichiometric Insights into Urban Nutrient Enrichment in Trinidadian Streams Although urbanization degrades freshwater biodiversity and ecosystems globally, invasive fish species often manage to navigate these challenges. Mechanisms such as human commensalism, high disturbance tolerance, and enhanced competitive ability have been identified as key drivers facilitating invasive species establishment beyond native ranges. However, we still do not know how inputs of carbon, nitrogen, and phosphorus via sewage systems into streams affect the functional traits of invasive species. It has been proposed that invasive species would thrive in high-nutrient environments - such as urban systems - if they can take advantage of the increased nutrients and allocate them to growth and reproduction. To test this hypothesis, we use the Trinidadian guppy (Poecilia reticulata). This species is a well-studied generalist invader worldwide and is found across a wide range of sites in its native range. We sampled females in Trinidad from sites with high and low levels of urbanization and analyzed their stoichiometries, along with quantifying the abundance of their local resources and other native species occupying the same trophic level. Our preliminary results on guppy stoichiometry indicate significant differences in the average values of C: element ratios between high- and low-urbanization sites. Specifically, fish from low urbanization areas exhibited higher C: N, C: P, and N: P ratios than their highly urbanized counterparts. In other words, guppies are becoming more nutrient-rich in urban environments. Understanding the mechanisms behind invasive species' adaptation to urban environments and how they disrupt food webs can help mitigate their impact on freshwater ecosystems.

Jeferson Ribeiro Amaral (Primary Presenter/Author), Cornell University, jefersonr.amaral@gmail.com;

Amina Mohamed (Co-Presenter/Co-Author), Cornell University, am2565@cornell.edu;

Peter Searle (Co-Presenter/Co-Author), Cornell University, pcs222@cornell.edu;

Stephanie Tran (Co-Presenter/Co-Author), Cornell University, stephxtran@gmail.com;

Jillon Lewis (Co-Presenter/Co-Author), The University of the West Indies St. Augustine, jillonlewis@gmail.com;

Caleb Axelrod (Co-Presenter/Co-Author), Cornell University, ca537@cornell.edu;

Amy Deacon (Co-Presenter/Co-Author), The University of the West Indies St. Augustine, amy.deacon@sta.uwi.edu;

Swanne P Gordon (Co-Presenter/Co-Author), Cornell University, swannegordon@cornell.edu;

Andrés López-Sepulcre (Co-Presenter/Co-Author), Cornell University, al2365@cornell.edu;

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

ABIOTIC AND BIOTIC FACTORS ASSOCIATED WITH FISH BIODIVERSITY IN STORMWATER PONDS Urbanization is associated with the ecological degradation of urban freshwater streams due to the high inflow of stormwater runoff from impervious surfaces such as roads, roofs, and pavement. Stormwater ponds (SWPs) are artificial ponds designed to mitigate these detrimental effects on urban freshwater by retaining stormwater before slowly releasing it into streams. In highly urbanized areas where aquatic habitat is otherwise scarce, SWPs can be biodiversity hotspots for many aquatic taxa. However, many SWPs can suffer from salinization, pollution, eutrophication, and hypoxia which can negatively affect aquatic organisms. While groups such as benthic invertebrates have been well studied in SWPs, there is little existing research on fishes despite reports of fish being found in these ponds. We sampled fish community composition for 50 SWPs in Brampton, Ontario, Canada in 2022. We used generalized linear mixed models and multivariate ordinations to examine water quality, pond design, and landscape variables predicting fish species richness and community composition. Despite no simple, natural pathways for colonization, fish were found in 76% of the ponds sampled. Road cover and total suspended solids were significantly positively associated with fish species richness, while nitrate showed a significant negative association with richness. Fish community composition was best explained by road cover and nitrate. The findings of this study may help inform SWP management decisions to improve their function and ecological condition, as well as identify the potential effects of SWPs on downstream freshwater ecosystems.

Gloria Wang (Primary Presenter/Author), University of Toronto, gloriahuamei.wang@mail.utoronto.ca;

Donald Jackson (Co-Presenter/Co-Author), University of Toronto, don.jackson@utoronto.ca;

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