SFS Annual Meeting

Pule Mpopetsi (Primary Presenter/Author)
Rhodes University, pulemp@gmail.com;

Abstract: The Great Fish River (GFR) is one of the anthropogenically modified river systems in South Africa and one characterised by multiple non-native fish species. We aimed to assess current state of invasions and mechanisms that facilitated the establishment of multiple non-native fishes within this system. We hypothesised that non-native fishes would reflect life history traits and environmental association attributes that are consistent with adaptability to disturbed and flow-modified habitat conditions. To date, a total of eleven non-native fish species have been recorded within the GFR. The inter-basin water transfer scheme (IBWT) and angling were responsible for majority of invasions, accounting for 36% and 45% respectively. Six introduced fishes have established, with three of these invading through the Orange-Fish IBWT. Four non-native fishes which were previously recorded during historical research, have failed to establish. Attributes such as large size, greater longevity and wide habitat tolerance appear to have facilitated establishments of most non-native species (Clarias gariepinus, Cyprinus carpio, Labeo capensis and Labeobarbus aeneus). In addition, proliferation of other species (Gambusia affinis and Tilapia sparrmanii) seems to be associated with habitat modification resulting from change in flow regime.

Daniel Szydlowski (Primary Presenter/Author)
University of Illinois, dannyszydlowski1@gmail.com;

Ashley Elgin (Co-Presenter/Co-Author)
NOAA Great Lakes Environmental Research Laboratory, ashley.elgin@noaa.gov;

David Lodge (Co-Presenter/Co-Author)
Cornell University, dml356@cornell.edu;

Jeremy Tiemann (Co-Presenter/Co-Author)
Illinois Natural History Survey, jtiemann@illinois.edu;

Eric Larson (Co-Presenter/Co-Author)
University of Illinois, erlarson@illinois.edu;

Abstract: A central focus of invasive species research has been human efforts to eradicate invaders or reduce their abundance to mitigate their impacts. In some cases, however, populations of invasive species decline without human intervention. Such is the case of the invasive rusty crayfish (Faxonius rusticus) in northern Wisconsin, where systematic trapping since 1975 has revealed population declines in approximately half of the lakes surveyed. Population declines of invasive species without human intervention remain understudied, but there is even less research on whether communities recover after these declines. We investigated community recovery of habitat (macrophytes) and prey (snails) affected by F. rusticus following declines of this invader using a rare, long-term dataset (sampled in 1987, 2002, 2011, and 2020) from ten lakes in Vilas County, Wisconsin. We compared community responses in lakes where F. rusticus populations reached a peak and subsequently declined (boom-bust lakes) and lakes where our dataset only captured the decline of F. rusticus (bust lakes) to high- and low-crayfish reference lakes. We will discuss the recovery of macrophytes and snails (measured as species richness and abundance) following F. rusticus invasion, along with future directions for this research.

Michele Larson (Co-Presenter/Co-Author)
University of Wyoming, mlarso22@uwyo.edu;

Brenda Hansen (Co-Presenter/Co-Author)
University of North Carolina, bkhansen@email.unc.edu;

Heather Thon (Co-Presenter/Co-Author)
NA, mrsthon@gmail.com;

Amy Krist (Primary Presenter/Author)
University of Wyoming, krist@uwyo.edu;

Abstract: Non-native species that become invasive can reach exceptionally high densities in their introduced range, threatening both biodiversity and ecosystem function. The non-native species, Potamopyrgus antipodarum, the New Zealand mudsnail, can achieve very high densities, suppress abundance of native species, and alter nutrient cycling in introduced aquatic ecosystems. From five studies, we summarize factors mediating the success of the genotype that occurs in the western U.S. We found support for the enemy release hypothesis in surveys across the western U.S.: snails are largely released from infection by trematode parasites, which often castrate their hosts. Also, by increasing conductivity and concentrations of multiple ions, geothermal activity promotes high densities of Potamopyrgus in the Greater Yellowstone Ecosystem. Results from field surveys are corroborated by lab studies showing survival and growth of Potamopyrgus increases with conductivity. Once high densities are achieved, experiments suggest that Potamopyrgus maintains relatively high growth rates and are more likely to feed relative to low density. These results reveal a mosaic of traits and environmental conditions favoring the invasive snail and reveal characteristics that make aquatic habitats susceptible to future invasion.

James Hogan (Primary Presenter/Author)
Texas A&M University – Corpus Christi, james.hogan@tamucc.edu;

David O'Connor (Co-Presenter/Co-Author)
Texas A&M University – Corpus Christi, david.oconnor@mail.mcgill.ca;

Kristine Moody (Co-Presenter/Co-Author)
Oak Ridge National Lab, moodykn@ornl.gov;

Heidi Heim-Ballew (Co-Presenter/Co-Author)
Texas A&M University – Corpus Christi, heidi.ballew@tamucc.edu;

Peter McIntyre (Co-Presenter/Co-Author)
Cornell University, pbm3@cornell.edu;

Michael Blum (Co-Presenter/Co-Author)
Univ. Tennessee - Knoxville, mblum@utk.edu;

Abstract: Understanding ecological outcomes of stream restoration can promote evidence-based decision-making. We assessed demographic responses of a native Hawaiian fish to aquatic invasive species (AIS) removal from treatment reaches in 12 watersheds on O‘ahu. Live-bearing fishes (Poeciliidae) and armored catfishes (Loricariidae) accounted for 66% of AIS removed. Population size, recruitment, growth rate, body condition, and in-stream movement of native fish were monitored in treatment and control reaches before and after removals. Population sizes did not change compared to pre-removal numbers. We observed no change in movement of individuals. The proportion of recruits increased significantly 3–6 months post-removals. Growth rates and body condition increased in the first 3 months following removal. The pulse in recruitment was short-lived; however elevated growth and body condition persisted for the duration of the study. Recruitment response magnitude correlated positively with effect size of poeciliid removals whereas growth and body condition response correlated positively with loricariid removals and negatively with stream discharge. AIS removal from Hawaiian streams can elicit demographic recovery of native fish. Populations should increase if elevated levels of recruitment and growth can be sustained long-term through more aggressive AIS removal or periodic control.

Reuben Keller (Co-Presenter/Co-Author)
Loyola University Chicago, rkeller1@luc.edu;

Carter Cranberg (Primary Presenter/Author)
Loyola University Chicago, ccranberg@luc.edu;

Abstract: Aquatic ecosystems in the Chicagoland area connect the Mississippi River and Great Lakes Basins, creating concerns for the spread of aquatic invasive species. Small lentic waterbodies in the area have rarely been sampled for native and non-native species and little is known about the role these waterbodies play for the conservation of native species and the spread of invaders. To address this, we sampled crayfish and macrophytes in 66 small waterbodies during summer 2020. The most widespread crayfish found was rusty crayfish (Faxonius rusticus), and it was most likely to be found at waterbodies where angling is promoted (p=0.0069). Red swamp crayfish (Procambarus clarkii) – another invader – was found at one site. Many small waterbodies contained populations of native crayfish species. The most common invasive macrophytes sampled were Eurasian watermilfoil (Myriophyllum spicatum) and curly pondweed (Potamogeton crispus). These species were most likely to be found in the presence of each other. Our results indicate that small lentic waterbodies serve as both sites for invasion and important habitat for native species. Management efforts that work to limit spread of invasive species would help to prevent the loss of native species.

Emily Lorkovic (Co-Presenter/Co-Author)
Texas State University, e_l328@txstate.edu;

Weston Nowlin (Co-Presenter/Co-Author)
Texas State University, wnowlin@txstate.edu;

Astrid Schwalb (Co-Presenter/Co-Author)
Texas State University, schwalb@txstate.edu;

David Swearingen (Primary Presenter/Author)
Texas State University, d_s279@txstate.edu;

Abstract: Large mortality events can cause nutrient pulses that affect nutrient cycling withing a system and ecosystem functioning. Invasive zebra mussels (Dreissena polymorpha) in Canyon Lake, Texas occur at the southern edge of their North American distribution and hot temperatures during summer can lead to high mortality. The goal of this study was to examine nutrient release of decaying mussel tissue in the laboratory and to combine this with field observations of zebra mussel density and mortality to estimate the amount of nutrients released during summer mortality events. Zebra mussels were decayed at 30°C to determine mass loss and nutrient release rates. Dive surveys along several transects were used to estimate population size of zebra mussels at different depths throughout the lake. Cages with smaller and larger zebra mussels were placed at three marinas and monitored bimonthly to determine mortality rates. Preliminary findings showed that about 60% of the mussel tissue was decayed within the first 2 days and decay constants did not differ between smaller (10-15mm) and larger (15-25mm) mussels.

Abagael Pruitt (Co-Presenter/Co-Author)
University of Notre Dame, apruitt2@nd.edu;

Elise Snyder (Primary Presenter/Author)
The University of Notre Dame, esnyder4@nd.edu;

Jennifer Tank (Co-Presenter/Co-Author)
University of Notre Dame, jtank@nd.edu;

Kyle Bibby (Co-Presenter/Co-Author)
University of Notre Dame, kbibby@nd.edu;

Aaron Bivins (Co-Presenter/Co-Author)
The University of Notre Dame, abivins@nd.edu;

Pedro Brandao Dias F Pinto (Co-Presenter/Co-Author)
Rice University, pb21@rice.edu;

Anna Vincent (Co-Presenter/Co-Author)
University of Notre Dame, avincen5@nd.edu;

Shannon Speir (Co-Presenter/Co-Author)
University of Arkansas, slspeir@uark.edu;

Gary Lamberti (Co-Presenter/Co-Author)
University of Notre Dame, glambert@nd.edu;

Abstract: The use of environmental DNA (eDNA) analysis offers insight into the distribution of invasive and endangered aquatic species without intensive traditional sampling. However, our understanding of eDNA fate and transport in flowing waters is limited, which constrains predictions about the location and density of target organisms. We used sequential filtration to investigate the size distribution of eDNA from Common Carp and found that the majority were in the 1.0 micrometer size category, although both larger and smaller particles were present. We also used short-term additions of carp eDNA to experimental streams to quantify the effect of biofilm colonization on eDNA removal from the water column. We hypothesized that there would be shorter transport lengths (Sw) in streams with the highest biofilm colonization. After refinement of molecular extraction techniques, our preliminary analysis of the field releases showed that under low biofilm (i.e., shaded) conditions, Sw was measurable (17 m), and additional analyses are ongoing. Improved understanding of eDNA particle size distribution in relation to biofilm conditions will enhance our ability to predict eDNA transport in streams and rivers and advance the use of eDNA as a tool for monitoring and management.

Emily Bovee (Co-Presenter/Co-Author)
Dept. of Biological Sciences, Oakland University, enbovee@oakland.edu;

Abigail Gonzales (Co-Presenter/Co-Author)
Dept. of Biological Sciences, Oakland University, abigailgonzales@oakland.edu;

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

Kennedy Bommarito (Primary Presenter/Author)
Dept. of Biological Sciences, Oakland University, kpphillips@oakland.edu;

Abstract: Invasive species are an ever-increasing problem in freshwaters, particularly in the Laurentian Great Lakes region. The New Zealand mud snail (NZMS) is a widespread invasive gastropod first introduced to the Great Lakes in 1991; recently, it has been found in rivers in the region, where little is known about fundamental aspects of its ecology. We combined mesocosm experiments with field studies to assess the diets of NZMS and impacts on leaf-litter decomposition. In laboratory mesocosms individual NZMS growth rates depended on the species of leaves they consumed; litter-decomposition rates were increased by NZMS and depended on leaf species. Growth and decomposition rates were explained by the nitrogen content of the litter. Stable isotopes and a 2-source mixing model revealed that 65% of carbon in NZMS from the Au Sable River (Michigan, USA) originates from terrestrial leaves, with 35% originating from periphyton. Despite this finding, NZMS enclosed in fine-mesh bags in the field had a non-detectible influence on decomposition. Our results indicate that NZMS are generalist feeders potentially impacting multiple compartments in food webs, although their impacts might not be evident early in the invasion process when population densities are low.

Mariah Millington (Primary Presenter/Author)
Australian Rivers Institute- Griffith University, mariahmillington24@gmail.com;

Abstract: With significant volumes of non–native freshwater fish transported globally for ornamental trade, effective biosecurity management and compliance measures are critical. Active management, as opposed to traditional passive management currently routine in Australia, is vital for protecting sensitive aquatic ecosystems. However, this is unachievable without a sound understanding of species already present and traded within borders. Direct surveys of species traded in traditional storefronts and online are needed to create an accurate list of the ornamental community. In particular, the wealth of data present in online aquarium stores remains relatively untouched, as few publications in Australia have taken advantage of the potential abundance of information present here, instead turning to private collections proffered. As part of my PhD research, we monitored aquarium stores and ornamental hobbyist groups trading freshwater fish in Queensland, Australia online over several months. A considerable ornamental community emerged, involving thousands of participants from all around Queensland advertising and transporting hundreds of species online including highly invasive and restricted fish. In my presentation I will shine a light on the dark web and the real biosecurity threat this prosperous and prolific community poses to our freshwater ecosystems.

Jamie Bojko (Co-Presenter/Co-Author)
Teesside University, J.Bojko@tees.ac.uk;

Donald Behringer (Co-Presenter/Co-Author)
University of Florida, behringer@ufl.edu;

Lindsey Reisinger (Co-Presenter/Co-Author)
University of Florida, lreisinger1@ufl.edu;

Cheyenne Stratton (Primary Presenter/Author)
University of Florida, c.stratton@ufl.edu;

Abstract: Invasive crayfishes are among the most widespread freshwater invaders, causing ecological harm through competition and habitat alternation. Invasive rusty crayfish, for example, impact macrophyte, invertebrate, and fish communities at the whole-lake scale. Crayfish can harbor a diverse suite of pathogens, but the potential for these pathogens to mitigate invasive crayfish impacts is not well understood. In 2019, our research team discovered a Nosema sp. microsporidian (spore-forming parasite) outbreak in rusty crayfish in Trout Lake, WI. We evaluated the effects of this parasite on crayfish density, condition (righting response), behavior (activity and foraging), growth, and survival using lake-wide trapping surveys, behavioral assays, and a laboratory transmission experiment. Rusty crayfish in Trout Lake were infected at a high rate by the Nosema sp. microsporidian (48% prevalence) and their density has declined by 79% since 2016. Individuals infected with the microsporidian were in poor condition, were less active, and had altered foraging behavior. Preliminary results suggest crayfish fed microsporidian infected tissue consume less food and are less likely to molt, leading to a slower growth rate. Thus, infection with Nosema sp. may decrease the ecological impacts from rusty crayfish invasions.

Angela De Palma-Dow (Primary Presenter/Author)
Lake County Water Resources Department, Adepalmadow@gmail.com;

Abstract: Clear Lake (Lake County, CA) is the largest natural freshwater lake located entirely within California and is extremely susceptible to an invasive Quagga & Zebra (Q/Z) mussel invasion. Clear Lake is open and accessible year-around at any of its 400+ public and private ramps and the water temperature, calcium, pH, and salinity are well within the preferred ranges of Q/Z mussels. The shallow, calm, and productive waters along the littoral zone attracts water users and fishermen from all over the country. In 2020, Clear Lake was voted the #1 USA Bass fishing lake and now holds the state record for both the largest White and Black Crappie. The current Q/Z prevention program is supported by federal, state, city and tribal partners and has widespread buy-in from local businesses and the public. Based on substrate and tow monitoring data, we have so far been successful in preventing QZ introductions. This talk will present how this program is executed and sustained, how it has been impacted by the COVID-19 pandemic, and how managers plan to enhance the program using digital technology and improved education and outreach so that Clear Lake maintains mussel-free.

William G. McDowell (Primary Presenter/Author)
Merrimack College, wgmcdowell@gmail.com;

David Giuffre (Co-Presenter/Co-Author)
Merrimack College, dgiuffre4@gmail.com;

Sydney Savard (Co-Presenter/Co-Author)
Merrimack College, savards@merrimack.edu;

Alexys Cuthbert-Holmes (Co-Presenter/Co-Author)
Merrimack College, cuthberthola@merrimack.edu;

Abstract: The Chinese pond mussel Sinanodonta woodiana is native to eastern Asia, but is now a widespread invasive species throughout Europe. S. woodiana is a large bivalve, with shell lengths as large as 200 mm. S. woodiana can impact ecosystems through high densities (100 ind m^-2 ), wet biomasses (up to 33 kg m^-2 ), or through mass mortality events,. We used Maximum Entropy modeling to predict the potential distribution of S. woodiana in Europe using bioclimatic variables, and known locations from its invasive range from both the Global Biodiversity Information Facility and published literature. Mean annual temperature was the strongest predictor of habitat suitability. Our model predicts that the climate is suitable for S. woodiana throughout Europe, including areas where it is not yet widespread, such as the Iberian Peninsula, or not yet established, such as the British Isles. Ongoing work is modeling the potential distribution of S. woodiana for Europe, North America, and South America using points from both its native range and invasive range in order to assess whether the invasive lineage has different abiotic tolerances or has adapted to cooler temperatures.

Erin Crone (Co-Presenter/Co-Author)
University of Arkansas, Erin.Crone@colostate.edu;

Daniel Preston (Co-Presenter/Co-Author)
Colorado State University, Dan.Preston@colostate.edu;

Erin Crone (Primary Presenter/Author)
Colorado State University, Erin.Crone@colostate.edu;

Abstract: Invasive species can affect native communities through multiple mechanisms including competition, predation, and habitat alteration. Untangling these effects in a dynamic ecosystem presents a challenge, especially when multiple invaders are present. Co-occurrence of multiple invaders may lead to invasional meltdown, in which invaders facilitate one another and amplify effects on native communities. Urban habitats such as stormwater ponds are particularly prone to species invasions due to habitat alteration and increased likelihood of anthropogenic introductions. We conducted a mesocosm experiment to study how urban pond communities are impacted by two freshwater invasive species that co-occur in Dane County, Wisconsin: goldfish (Carassius auratus) and Chinese mystery snails (Cipangopaludina chinensis). We found that Chinese mystery snails exerted competitive effects on native amphibians. Goldfish altered primary production and reduced zooplankton, amphibian, and juvenile native snail survival through predation. Chinese mystery snails had higher reproductive success when goldfish were present, likely due to competitive release from native grazers. Our results indicate that facilitation may be occurring between these two nonnative species, suggesting potential for invasional meltdown in urban ponds.

Natalia Szklaruk (Co-Presenter/Co-Author)
Loyola University Chicago, nszklaruk@luc.edu;

Reuben Keller (Co-Presenter/Co-Author)
Loyola University Chicago, rkeller1@luc.edu;

Colette Copic (Primary Presenter/Author)
Loyola University Chicago, ccopic@luc.edu;

Abstract: The US EPA recently registered dissolved carbon dioxide (CO2) as a management tool for preventing aquatic invasive species spread. This allows managers to infuse strategic areas with 100-150 mg/L of dissolved CO2 to induce avoidance behavior in organisms. A primary motivation of this is to prevent the spread of Asian carp into the Great Lakes. Invertebrates regularly become serious invaders but the impact of dissolved CO2 on invertebrates is largely unknown. We tested three crayfish species, three mollusk species, two amphipod species and zooplankton to determine the efficacy of this tool. First, we tested the short-term (30 and 60 minutes) behavioral and lethal effects of dissolved CO2 by exposing invertebrates to a range of concentrations (70-500 mg/L). Next, we tested whether invertebrates actively avoid areas with high CO2. Although behavioral responses varied by species most had low mortality below 500 mg/L CO2. Adult crayfish avoided CO2 concentrations ranging from 100-250 mg/L but juvenile crayfish and other species did not. Our results show that permissible levels of dissolved CO2 may be effective at preventing spread of fish and adult crayfish but will not likely affect spread of other invertebrate invaders.

Stephen M. Bollens (Co-Presenter/Co-Author)
Washington State University, sbollens@wsu.edu ;

Gretchen Rollwagen-Bollens (Co-Presenter/Co-Author)
Washington State University, rollboll@wsu.edu;

Salvador Robb-Chavez (Primary Presenter/Author)
Washington State University, sbchavez@wsu.edu;

Abstract: The Asian clam, Corbicula fluminea, is an invasive freshwater bivalve that has established populations throughout the globe, including the Pacific Northwest, USA, and is known to have deleterious effects on natural and human systems. During 2017-2020 we collected adult and juvenile C. fluminea from 15 mid-channel and 29 shore-based sampling locations spanning 537 rkm of the Columbia River (CR) to elucidate the association of C. fluminea abundance and condition with habitat characteristics including dissolved O2, pH, temperature, salinity, specific conductivity, depth, geographic location, chlorophyll a concentration, bank slope, and sediment composition (granulometry, TOC). C. fluminea abundance was greatest at the confluence of the Sandy River with the CR near Gresham, OR (avg. 342 ind. m-2), with the majority of sample sites with abundances >100 ind. m-2 located downstream of Bonneville Dam and the majority of sample sites with abundances <100 ind. m-2 located upstream. Our results provide a better understanding of the basic biology and ecology of this global invader, as well as provide natural resource managers with information on where, when, and why this bivalve invades temperate ecosystems.

Brielle Kwarta (Primary Presenter/Author)
University of Washington, bkwarta@uw.edu;

Abstract: Estimates of population spread and growth rates are fundamental to identification of optimal allocation of invasive species removal effort. Novel insights into invasive population dynamics can be gained from spatially-structured removal and monitoring data collected during a removal effort. In this study, we evaluated the degree to which different monitoring data streams influence management outcomes based on their ability to inform the decision-making process through estimates of the rate of growth and spread of rusty crayfish in the John Day River, a major tributary of the Columbia River. We built an integrated population model to simulate rusty crayfish population dynamics within the context of an adaptive management framework and evaluated the efficacy of potential monitoring and analysis strategies in promoting informed decision making and favorable management outcomes. We assumed a fixed budget for monitoring and management and simulations were run over a fixed time frame. At the end of each simulation, the number of individuals remaining on the landscape and total river length occupied was assessed. We found that integrating all available monitoring data streams produced the best management outcome and most accurate abundance measure.

James Vonesh (Co-Presenter/Co-Author)
Virginia Commonwealth University, jrvonesh@vcu.edu;

Lesley Bulluck (Co-Presenter/Co-Author)
Virginia Commonwealth University, lpbulluck@vcu.edu;

Ryland Stunkle (Co-Presenter/Co-Author)
Virginia Commonwealth University, crstunkle@vcu.edu;

Andrew Davidson (Co-Presenter/Co-Author)
Virginia Commonwealth University, davidsonat@mymail.vcu.edu;

Joshua Armstrong (Primary Presenter/Author)
Virginia Commonwealth University, j.armstrong9280@gmail.com;

Abstract: Invasive species pose a threat to ecosystems by outcompeting native species and/or modifying habitats. Understanding what drives invasion has been a central question for invasion biology for decades. Hydrilla verticillata is an invasive macrophyte throughout the United States, dominating lakes and streams, negatively impacting local economies. We studied drivers of Hydrilla invasion and persistence in riverine rock pools. Leveraging a four-year data set collected from hundreds (N=745) of independent rock pools, we dynamically modeled occupancy, colonization, and extinction probabilities of Hydrilla using the “unmarked” package in R. Occupancy was greater in more voluminous pools with higher flood levels. Colonization was greater in pools with higher flood levels and increased across years; while lower in pools further away from Hydrilla pools. Extinction was greater further away from Hydrilla pools and decreased across years; while lower in more voluminous pools that were further away from the river channel and flooded at higher levels. Pool morphology, temporal, and spatial factors heavily influenced Hydrilla in the rock pool system. It is important to understand the drivers of invasion to predict the spread of invasive species in lakes and streams to better inform management strategies.

Kasey Fralick (Co-Presenter/Co-Author)
Florida Fish and Wildlife Conservation Commission , Kasey.Fralick@MyFWC.com;

Katherine Lawlor (Co-Presenter/Co-Author)
Florida Fish and Wildlife Conservation Commission , Katherine.Lawlor@MyFWC.com;

Gary Warren (Co-Presenter/Co-Author)
Florida Fish and Wildlife Conservation Commission , gary.warren@myfwc.com;

Lindsey Reisinger (Co-Presenter/Co-Author)
University of Florida, lreisinger1@ufl.edu;

Nicole Tripp (Primary Presenter/Author)
University of Florida, tripp17@ufl.edu;

Hannah VanBuren (Co-Presenter/Co-Author)
Florida Fish and Wildlife Conservation Commission , hannah.vanburen@myfwc.com;

Abstract: Freshwater crayfish are one of the most imperiled taxonomic groups in North America, and nonnative crayfish pose a major threat to native crayfishes. Many crayfish have limited distributions, so merely moving crayfish between adjacent drainages can cause species replacements that threaten native species. Here, we investigate the mechanism behind one of these replacements to inform the conservation of an imperiled crayfish. Specifically, we examine competitive interactions between the imperiled Black Creek crayfish (BCC; Procambarus pictus), which is endemic to the lower St. Johns River drainage, Florida, and the white tubercled crayfish (WTC; P. spiculifer), an introduced species from a neighboring drainage. Changes in the distribution of these species over the past decade suggest that WTC is replacing BCC throughout much of its range. We are conducting laboratory experiments to examine aggressive interactions between these species and their relative competitive ability for shelter and food resources. Preliminary results suggest that BCC outcompete WTC when size matched, but WTC are larger in the stream system. We are currently conducting competition experiments with sizes that reflect those in the field and hypothesize that WTC will be the superior competitor in these experiments.

Courtney Larson (Primary Presenter/Author)
U.S. Environmental Protection Agency, larson.courtney@epa.gov;

M. Eric Benbow (Co-Presenter/Co-Author)
Michigan State University, benbow@msu.edu;

Abstract: An array of deleterious terrestrial impacts following emerald ash borer (EAB) invasion are documented, but research on the effects of widespread ash mortality on aquatic ecosystems is scarce. Mortality of ash trees along headwater streams can result in canopy gaps, altering riparian plant community structure and potentially subsequent organic matter processing in streams. Our aim was to determine how leaf litter taxa (ash vs. other overstory) and canopy gaps alter aquatic leaf litter decomposition rates and colonization by macroinvertebrate and bacterial communities. We hypothesized a functional community shift in response to increased light in canopy gaps. Leaf packs of four types (ash, oak, buckthorn and cotton control) were introduced upstream, downstream, and at the center of one EAB-related canopy gap and collected monthly to quantify decomposition and assess colonizing macroinvertebrate and microbial communities, via morphological and genomic sequencing methods respectively. Gap location and leaf type significantly influenced macroinvertebrate community structure and diversity (p<0.03). The aquatic leaf litter bacterial diversity was lowest in oak leaves, compared to ash and buckthorn (p<0.01). This represents the first evidence that EAB invasion alters aquatic communities via the allochthonous resource of leaf litter.

Christina Wyss Castelo Branco (Co-Presenter/Co-Author)
Universidade Federal do Estado do Rio de Janeiro (UNIRIO), cbranco.unirio@gmail.com;

Samira da Guia Mello Portugal (Co-Presenter/Co-Author)
Universidade Federal do Estado do Rio de Janeiro (UNIRIO), samiraportugal@unirio.br;

Timothy Peter Moulton (Co-Presenter/Co-Author)
Universidade do Estado do Rio de Janeiro (UERJ), moulton@uerj.br;

Kauan Fonseca (Primary Presenter/Author)
State University of Rio de Janeiro , n.kauan@gmail.com;

Abstract: The widespread filter-feeding Corbicula fluminea is generally abundant in freshwater environments however, in neotropical ecosystems its effects are poorly measured. We aimed to estimate the possible impact of filtration and nutrient remineralization (NH4-N, PO4-3-P) in the tropical shallow lake of Paracambi small hydropower plant (SHP), Rio de Janeiro-Brazil. We sampled individuals during the winter of 2019 and summer of 2020 to access size as well field density and areal biomass. Then we combine our empirical data with published specific-size filtration and excretion models. We did not observe interannual difference in abundance or population filtration. There was no interannual difference in NH4-N areal excretion. The population potentially excretes significantly more PO4-3-P in summer. At the highest density sites (4760 ind m-2) C. fluminea can filter the entire water column (~13 L) within 19 minutes, excrete 2502 umol NH4-N m-2 h-1 and 643 umol PO4-3-P m-2 h-1. Our results suggest a potential and important ecological role of C. fluminea in the studied ecosystem. Once reached high densities, C. fluminea may modulate ecosystem function (e.g., dynamics of organic matter and nutrient cycling) through filtration and nutrient remineralization.

Katrina Lewandowski (Primary Presenter/Author)
Wayne State University, lewandowskikatrina@gmail.com;

Kishore Gopalakrishnan (Co-Presenter/Co-Author)
Wayne State University, kishore.gopalakrishnan@wayne.edu;

Jeffrey Ram (Co-Presenter/Co-Author)
Department of Physiology, Wayne State University, jeffram@wayne.edu;

Donna Kashian (Co-Presenter/Co-Author)
Wayne State University, dkashian@wayne.edu;

Abstract: Quagga mussels (Dreissena bugensis) first invaded the Great Lakes region of North America in the 1980’s and more recently the western United States. This project investigates how separate populations of mussels respond to environmental stressors and if they are genetically distinct. Mussels were collected from the Detroit River, MI and Lake Mohave, NV. Experiments compared mussel spawning between the two populations when exposed to cyanobacteria: (Aphanizomenon flos-aquae, Planktothrix suspensa, Anabaena flos-aquae, Microcystis wesenbergii). Cyanobacteria was diluted into three concentrations: 550, 340, 130, 0 µg/L chlorophyll-a. The two populations of mussels responded with a similar reduction in spawning when exposed to 550 µg/L A. flos-aquae (p<0.001). Oxidative stress analysis was performed with concentrated microcystin-LR (MCLR) over 72 hours at 400, 100, and 0 µg/L. Peak oxidative stress occurred at the highest concentration of MCLR at 42 hours. For the genetic comparison, DNA was extracted with DNAzol Direct from 5 Mojave Lake and 5 Detroit River quagga mussels. COI sequencing indicated both mussel populations had the same quagga haplotypes. Understanding differential responses among quagga mussel populations to stressors such as cyanobacterial blooms is critical for management efforts.

Emma Arneson (Primary Presenter/Author)
University of Alabama, emarneson@crimson.ua.edu;

Jonathan P. Benstead (Co-Presenter/Co-Author)
The University of Alabama, jbenstead@ua.edu;

Nate Jones (Co-Presenter/Co-Author)
University of Alabama, cnjones7@ua.edu;

Christopher A. Taylor (Co-Presenter/Co-Author)
Illinois Natural History Survey, cataylor@illinois.edu;

Abstract: Freshwater biodiversity is threatened globally by introductions of invasive species. Invasive crayfish pose a particular threat to native communities as they often change taxonomic composition through habitat modification and displacement of native species. Alabama’s crayfish community is threatened most severely by the invasive crayfish Faxonius virilis, which is now found across 9 sub-watersheds of the Mobile River basin. To examine how environmental variables relate to the probability of F. virilis occurrence, we used a spatial stream network (SSN) model and species locality records dating back from 1929 through 2018 to model occurrence as a function of nearest distance to a dam, stream slope, and predominant land use at local, regional, and catchment levels. This geostatistical approach accounts for spatial autocorrelation along dendritic river networks, allowing us to determine if movement over time of F. virilis can be characterized as Euclidean (i.e. related to land distances), flow-connected along the river network, or flow-unconnected. Examining the relationship between species distributions and potential drivers of distribution for this highly invasive species is critical both to understanding the consequences of invasion and maintaining the unique crayfish diversity found in Alabama.