SFS Annual Meeting

6/05/2024  |   13:30 - 13:45   |  Freedom Ballroom E

Trait-mediated species interactions drive co-occurrence of invasive and native species in an aridland riverscape Trait-based community assembly theory can elucidate mechanisms by which invasive species establish populations. Invasive crayfish are globally pervasive, but the mechanisms underlying their impact on native biodiversity remains equivocal. Here, use community assembly theory to understand the abiotic and biotic drivers of co-occurrence between fishes and invasive virile crayfish (Faxonius virilis). We surveyed both taxa from 5,104 quadrats nested within 117 wadeable stream reaches in the lower Colorado River system, southwestern USA in the summers of 2021 and 2022. Next, we used null models to quantify co-occurrence between crayfish and 17 fish species at two spatial scales: among reaches within the region and among quadrats within reaches. Finally, abiotic niche dissimilarity with crayfish, functional traits indicating strength of competition or predation, and provenance (native vs non-native) were tested as mechanisms driving these co-occurrences using generalized linear mixed effects models. Among reaches, native fishes segregated from crayfish but this pattern could not be attributed to niche dissimilarity or biotic interactions, suggesting that unmeasured traits related to ecological naiveté drive negative co-occurrence. Among quadrats, competition and predation drive segregation for both native and non-native fishes. These findings demonstrate that invasive crayfish negatively impact native fishes, that the impact is scale dependent, and can be predicted to some extent by functional traits. While trait-based community assembly theory is widely used to predict invasion success of non-native species, we further demonstrate that this framework can predict invader impact on native biodiversity.

Matthew Troia (Primary Presenter/Author), University of Texas San Antonio, troiamj@gmail.com;

Jennifer A. Smith (Co-Presenter/Co-Author), University of Texas San Antonio, Jennifer.smith@utsa.edu;

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6/05/2024  |   13:45 - 14:00   |  Freedom Ballroom E

EFFECTS OF INVASIVE WATERWEED (ELODEA CANADENSIS) ON WATER CHEMISTRY AND FOOD WEB DYNAMICS OF AN ALASKAN LAKE Biological invasions by non-native species into novel environments can induce ecological changes that negatively impact local communities and ecosystems. Elodea canadensis is a freshwater submerged macrophyte that was introduced to Alaska in 1982. Elodea has been shown to reduce the growth and trophic position of juvenile Coho salmon (Oncorhynchus kisutch) but effects on more pelagic-feeding sockeye salmon (O. nerka) are unknown. In both 2021 and 2022, we investigated potential effects of Elodea on juvenile sockeye salmon by placing full water-column permeable mesocosms in a freshwater lake near Cordova, Alaska, supporting an economically important sockeye salmon population. Across three replicates, one mesocosm was placed over a bed of native vegetation and one over a bed of Elodea. We stocked mesocosms with juvenile sockeye salmon (N=33-40 depending on year) and collected water chemistry samples (water-column nutrients, dissolved organic carbon, chlorophyll-a, and dissolved oxygen) biweekly. After 6 weeks, community members (fish, invertebrates, zooplankton, and macrophytes) were harvested from the mesocosms. We analyzed carbon and nitrogen stable isotopes of the community members to infer resource use pathways between treatments. Elodea did not produce detectable effects on water chemistry likely because of the permeable nature of the mesocosms. However, we observed a shift in the carbon isotope ratios of sockeye salmon towards Elodea isotope signatures. These findings indicate that water chemistry may not be a mechanism by which Elodea induces ecological change in this Alaskan lake, and that Elodea is partially incorporated into sockeye salmon food chains.

Corbin Hite (Primary Presenter/Author), University of Notre Dame, chite@nd.edu;

Amaryllis Adey (Co-Presenter/Co-Author), The University of Notre Dame, aadey@nd.edu;

Sean Meade (Co-Presenter/Co-Author), USDA Forest Service, sean.meade@usda.gov;

Martin Berg (Co-Presenter/Co-Author), Loyola University Chicago, mberg@luc.edu;

Gordon Reeves (Co-Presenter/Co-Author), USDA Forest Service, gordon.reeves@oregonstate.edu;

Ryan Bellmore (Co-Presenter/Co-Author), USDA Forest Service, james.r.bellmore@usda.gov;

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

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6/05/2024  |   14:00 - 14:15   |  Freedom Ballroom E

Tradeoffs in Acoustic Detection Error for Invasive and Native Anurans in the Southwestern US Consistent and accurate detection of invasive and threatened species is a critical part of protecting biodiversity in threatened environments, including aquatic ecosystems. Optimizing detection methods for both species presents challenges and potential tradeoffs. For example, false negative detections present different problems and management outcomes for invasive vs threatened species. Bioacoustic monitoring is an effective method for monitoring distributions of vocalizing species, yet potential tradeoffs in detection precision have largely been unexplored, especially at fine spatiotemporal scales. We used bioacoustic monitoring to detect the presence of the invasive American bullfrog (Lithobates catesbeianus) and native Arizona treefrog (Hyla wrightorum) across multiple locations, at daily intervals, in the southwestern United States during the summer of 2021. We deployed an array of acoustic recorders at 50 ponds throughout a 50 square kilometer region of southern Arizona. First, we built a high-precision “test-pond” dataset for which we manually identified calls across a subset of sites. Second, we used a simple classifier to identify likely bullfrog and treefrog calls based on reference recordings. This allowed us to calculate a precise detection error rate for both species. We were able to detect treefrogs more accurately than bullfrogs (8% vs 23% error rate of detection, respectively) and found significant tradeoffs in the overall error rate of detection when minimizing Type I vs Type II error. Overall, we found that efforts to minimize one type of error could increase the other, highlighting the need to carefully consider management goals in acoustic monitoring study design.

Grace O'Malley (Primary Presenter/Author), Virginia Tech, graceomalley@vt.edu;

Charlotte Tury (Co-Presenter/Co-Author), Virginia Tech, chartury@aol.com;

Joseph Drake (Co-Presenter/Co-Author), Virginia Tech, drakej@vt.edu;

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

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6/05/2024  |   14:15 - 14:30   |  Freedom Ballroom E

Climatic effects or duration of establishment? What invertebrate responses to Asian clam invasions can tell us about climate change. In the northern hemisphere, invasive Asian clams (Corbicula fluminea) decrease with increasing latitude, establishing in areas below 40° north. However, climate change may be facilitating a northward range expansion. In North America, C. fluminea was first detected in the Pacific Northwest in the 1930s, the Southeast in the 60s, and the upper Midwest in the 1980s. Invasive clams can disrupt native communities, but it is unknown if their northern impacts are like those observed in the south. The objective of this research was to determine how benthic communities are impacted by C. fluminea populations along a latitudinal gradient. We quantified Asian clam densities in river substrates with a ½m2 quadrat at each site and compared macroinvertebrate communities in invaded streams of four different latitudes (Michigan, 43°N; Ohio, 39°N; Georgia, 31°N; and Puerto Rico, 18°N). Macroinvertebrates were collected, targeting riffle zones following the Environmental Protection Agency’s rapid bioassessment protocol, and a suite of diversity and tolerance metrics were conducted. In northern climates, we found that C. fluminea impacts were less harmful than in the south, with results showing a positive relationship between population density and increasing macroinvertebrate diversity and evenness. In contrast, diversity and evenness decreased with increasing population densities in the south. Biodiversity losses in C. fluminea-invaded streams in southern climates may be attributed to the temporal scale of the invasion. With southern invasions established longer than those in northern climates, similar family diversity and evenness declines may be inevitable with continued pressures from invasive clams in a changing climate.

Darrin Hunt (Primary Presenter/Author), University of the Ozarks, dhunt@ozarks.edu;

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

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6/05/2024  |   14:30 - 14:45   |  Freedom Ballroom E

A new aquatic invasive in Minnesota: The diatom Didymosphenia along Lake Superior’s North Shore In 2018, the nuisance diatom, Didymosphenia geminata (aka didymo, rocksnot), appeared in the Poplar River along Lake Superior’s North Shore. Although there are Didymo populations native to nearshore Lake Superior, invasive and nuisance didymo has appeared in coolwater streams throughout North America and globally to threaten stream ecology, recreational opportunities, and regional economies dependent on healthy streams and fisheries. In streams, didymo forms thick mucilaginous growths that coat all hard substrates in centimeters-thick goo. Since 2021 we have been monitoring streams and nearby lake sites along Minnesota’s North Shore to understand the distribution of didymo, its seasonality, environmental drivers, and its effect on stream and lake ecology. Ongoing molecular studies are investigating the potential source of didymo on the North Shore as well as how didymo mats affect bacterial and algal diversity and functioning in nutrient dynamics. To date, didymo has been recorded in eight North Shore streams incuding multiple streams each year with severe didymo infestations. Didymo become more abundant in streams during late summer/early fall and seems to thrive under long-term baseflow conditions, low nutrients, and in open canopy stream segments. Efforts are underway to expand our sampling to broader longitudinal surveys, evaluate didymo effects on stream benthos and fishes, and to promote efforts to control the spread of this new aquatic invasive species in Minnesota.

Mark Edlund (Primary Presenter/Author), Science Museum of MN, medlund@smm.org;

David Burge (Co-Presenter/Co-Author), Science Museum of MN, dburge@smm.org;

Kui Hu (Co-Presenter/Co-Author), Science Museum of MN, khu@smm.org;

Heidi Rantala (Co-Presenter/Co-Author), Minnesota Department of Natural Resources, heidi.rantala@state.mn.us;

Robert Pillsbury (Co-Presenter/Co-Author), University of Wisconsin Oshkosh, pillsbur@uwosh.edu;

Sarah Clauss (Co-Presenter/Co-Author), University of Minnesota Duluth, claus503@d.umn.edu;

Cody Sheik (Co-Presenter/Co-Author), University of Michigan, csheik@umich.edu;

Nick Peterson (Co-Presenter/Co-Author), MN Dept of Natural Resources, nick.peterson@state.mn.us;

Cory Goldsworthy (Co-Presenter/Co-Author), MN Dept of Natural Resources, cory.goldsworthy@state.mn.us;

Adam Heathcote (Co-Presenter/Co-Author), Science Museum of MN, aheathcote@smm.org;

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6/05/2024  |   14:45 - 15:00   |  Freedom Ballroom E

Population genetic structure and demographic history reconstruction of introduced flathead catfish (Pylodictis olivaris) in two US mid-Atlantic rivers Population genetic analysis of invasive populations can provide valuable insights into the source of introductions, pathways for expansion, and their demographic histories. Flathead catfish are a prolific invasive species with high fecundity, long-distance dispersal, and piscivorous feeding habits that can lead to declines of native fish populations. In this study, we analyze the genetics of invasive flathead catfish (Pylodictus olivaris) in the mid-Atlantic region to assess their connectivity and attempt to reconstruct the history of introduced populations. Based on an assessment across 13 microsatellite loci, flathead catfish from the Susquehanna River system (N=537), Schuylkill River (N=33), and Delaware River (N=1) have low genetic diversity, although we detected no evidence of substantial inbreeding. Flathead catfish from these different river systems were genetically distinct, suggesting separate introductions. However, population structure was much weaker within each river system and exhibited a pattern of high connectivity with some evidence of isolation by distance. Catfish from the Susquehanna and Schuylkill Rivers showed evidence for recent genetic bottlenecks, and demographic models were consistent with historical records which suggest that populations were established by recent founder events consisting of a small number of individuals. Our results show the risk posed by small introductions of flathead catfish, which can spread widely once a population is established, and highlight the importance of prevention and sensitive early detection methods to prevent the spread of flathead catfish in the future.

Justin Waraniak (Primary Presenter/Author), Pennsylvania State University, jxw6349@psu.edu;

Michael Eackles (Co-Presenter/Co-Author), US Geological Survey, meackles@usgs.gov;

Jason Keagy (Co-Presenter/Co-Author), Pennsylvania State University, keagy@psu.edu;

Geoffrey Smith (Co-Presenter/Co-Author), Pennsylvania Fish and Boat Commission, geofsmith@pa.gov;

Megan Schall (Co-Presenter/Co-Author), Pennsylvania State University, mvk10@psu.edu;

Sydney Stark (Co-Presenter/Co-Author), Pennsylvania State University, sps6558@psu.edu;

Shannon White (Co-Presenter/Co-Author), Pennsylvania State University, slw361@psu.edu;

David Kazyak (Co-Presenter/Co-Author), US Geological Survey, dkazyak@usgs.gov;

Tyler Wagner (Co-Presenter/Co-Author), U.S. Geological Survey, Pennsylvania Cooperative Fish and Wildlife Research Unit, Pennsylvania State University, txw19@psu.edu;

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