SFS Annual Meeting

6/04/2024  |   10:30 - 10:45   |  Independence Ballroom B

Ecology and taxonomy of Chironomidae (Diptera): A memorial session to honor Leonard C. Ferrington The late Leonard C. Ferrington, Jr. (1948-2021) was a dedicated and long-standing member of SFS and NABS who attended 46 consecutive meetings, hosted a meeting (1986), and served as NABS president (1989-1990). He also encouraged his students to engage in SFS/NABS, and many are still active members. Len was selected as an SFS Fellow in 2021, and he considered this to be one of his greatest honors. Len’s research encompassed many areas of freshwater biology including biological monitoring and assessment, biodiversity and biotic surveys, fish diet analyses, gut fungi/chironomid interactions, phenology and life history studies, stream ecology and aquatic resource sustainability, systematics and taxonomy, and diversity and cold hardiness of winter-emerging Chironomidae. Given the diversity of Len's interests and expertise, this session could be open to nearly any topic. However, one common thread that ran through most of his research was the fly family, Chironomidae (Diptera). This family is found in nearly every aquatic habitat and is often one of the most speciose and abundant macroinvertebrate taxa encountered in aquatic studies. As a result, Len always championed research on Chironomidae. To honor Len, this session will focus on a major area of his extensive professional career - aquatic science research focused on chironomid ecology and taxonomy and related topics. This session will serve to honor and carry on an important part of Len's legacy and further inspire current and future Chironomidae researchers.

Will Bouchard (Primary Presenter/Author), Minnesota Pollution Control Agency and University of Minnesota, bouc0048@umn.edu;

Alyssa Anderson (Co-Presenter/Co-Author), Southwest Minnesota State University, alyssa.anderson@smsu.edu;

Corrie Nyquist (Co-Presenter/Co-Author), Lund University, corrie.nyquist@biol.lu.se;

Barbara Hayford (Co-Presenter/Co-Author), University of Montana, barbara.hayford@umt.edu;

Alexander Egan (Co-Presenter/Co-Author), National Park Service - Great Lakes I&M Network, Alex_Egan@nps.gov;

Petra Kranzfelder (Co-Presenter/Co-Author), University of California, Santa Barbara, pkranzfelder@ucsb.edu;

Jessica Miller (Co-Presenter/Co-Author), Dragons Wynd, jessica@dragonswynd.com;

Tessa Durnin (Co-Presenter/Co-Author), Normandeau Associates, Inc., tdurnin@normandeau.com;

Hannah Bodmer (Co-Presenter/Co-Author), University of Toronto Mississauga, hannah.bodmer@mail.utoronto.ca;

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6/04/2024  |   10:45 - 11:00   |  Independence Ballroom B

Tritrophic interactions drive cyclic population fluctuations of threespine sticklebacks (Gasterosteus aculeatus) in Lake Mývatn, Iceland Identifying drivers of population fluctuations is a long-standing goal of ecology. Much attention has been paid to cyclic fluctuations arising from consumer-resource interactions, with many examples from pairwise interactions (i.e., a single consumer and single resource species). However, consumer-resource interactions span multiple trophic levels, each of which can comprise multiple species, and this has the potential to alter the dynamics of species at intermediate trophic levels. Here, we use 30 years of time series data spanning three trophic levels and comprising >10 species to investigate the population fluctuations threespine sticklebacks in Lake Mývatn. The sticklebacks are secondary consumers, preying on aquatic invertebrates (e.g., chironomid midges) and predated upon by fish (e.g., Arctic charr) and birds (e.g., mergansers). Using autoregressive state-species models, we inferred interactions between sticklebacks, their prey, and their predators. A model including midge larvae, threespine sticklebacks, and two avian predators provided the best account of the stickleback population fluctuations, thus establishing the tritrophic nature of the dynamics. The high-amplitude fluctuations of the midge larvae (themselves influenced by interactions with their own food) coupled with the sticklebacks appear to have the largest effect on the overall dynamics, with the contributions from avian predators being more modest. Our results illustrate the potential for cyclic population fluctuations to arise from tritrophic interactions in wild populations.

Joseph Phillips (Primary Presenter/Author), Creighton University , JosephPhillips@creighton.edu;

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6/04/2024  |   11:00 - 11:15   |  Independence Ballroom B

EXPLORING THE DISTRIBUTION PATTERNS OF CHIRONOMID TRAITS AND ECOLOGICAL PREFERENCES IN RESPONSE TO POLLUTION IN THE BUFFALO RIVER, EASTERN CAPE, SOUTH AFRICA Urbanisation negatively impacts riverine ecosystem structure and function and alters the delivery of ecosystem services by aquatic biota. The Buffalo River is an important freshwater ecosystem in South Africa that is impacted by anthropogenic factors, including effluent from industrial and domestic activities, and pollutants from agricultural land use. Although the diversity and composition of macroinvertebrate families have been explored, research on the effects of urban pollution on chironomid trait assemblage structure in South African river systems is sparse. The spatial and temporal distribution of chironomid traits in the Buffalo River was investigated in this study. Sampling sites were selected based on the predominant land use in the catchment of the site. Chironomids and physicochemical variables were sampled four times from the selected sites (once per season) between November 2021 and June 2022. The results showed that chironomid traits and ecological preferences such as a predatory lifestyle, shredding, crawling, swimming, medium body size (>10–20 mm) and a food preference for macrophytes, macroinvertebrates, and wood, were positively associated with the least impacted sites. Traits such as the possession of large body size (>20-40mm), ventral gills, rigid tubes, laying of more than 1000 eggs per egg mass, and a preference for detritus were positively associated with highly impacted sites and were considered urban pollution tolerant traits. The results showed that chironomid species traits and ecological preferences can be used to develop trait-based tools for long-term monitoring of pollution in South African urban freshwater ecosystems.

Miracle Osoh (Primary Presenter/Author), Institute for Water Research, miracleosoh@gmail.com;

Chika Nnadozie (Co-Presenter/Co-Author), Institute for Water Reaseach, Rhodes University, Grahamstown, Eastern Cape, South Africa , c_nwaneri@yahoo.com;

Nelson Odume (Co-Presenter/Co-Author), Institute for Water Research, Rhodes University, Grahamstown, n.odume@ru.ac.za;

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6/04/2024  |   11:15 - 11:30   |  Independence Ballroom B

USING CHIRONOMIDAE GENERA TO DISTINGUISH MACROINVERTEBRATE ESTABLISHMENT RESPONSES TO DIFFERING HABITAT REGIMES IN RESTORED SAV IN AUSTIN, TX RESERVOIRS Lady Bird Lake and Lake Austin are adjacent reservoirs in Austin, Texas with the primary functions of electrical power generation, flood control, and recreation. In 1999, the invasive submerged aquatic vegetation (SAV), Hydrilla verticillata was observed in Lake Austin and management strategies to eradicate Hydrilla included the stocking of sterile Asian grass carp, Ctenopharyngodon idella. This practice nearly eliminated Hydrilla and resulted in the decline of native aquatic vegetation and increased shoreline erosion. Conservation efforts to reestablish the native vegetation are underway. SAV, in addition to facilitating nutrient uptake and retention, enhancing water clarity, stabilizing substrate, and attenuating wave energy, provides food and refugia for aquatic fauna. My research aims to understand the biological implications of the restoration of various SAV assemblages by analyzing the macroinvertebrate communities present within bare, mixed, and monocultured habitat regimes. This data suggests that mixed-cultured SAV, site disturbance, substrate composition, and macroinvertebrate taxonomic resolution are the primary determinants of macroinvertebrate richness, abundance, and diversity. With Chironomidae accounting for nearly half of all macroinvertebrates collected, this study emphasizes the need for Chironomidae identifications to be taken to the genus level to comprehend how macroinvertebrates establish in differing habitat regimes within a restorative context.

Katie Vasquez (Primary Presenter/Author), University of North Texas, katievasquez@my.unt.edu;

James Kennedy (Co-Presenter/Co-Author), University of North Texas, james.kennedy@unt.edu;

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6/04/2024  |   11:30 - 11:45   |  Independence Ballroom B

WHO EATS WHAT: THE DIET OF CHIRONOMIDS LIVING IN HEADWATERS RECONSTRUCTED FROM CARBON AND NITROGEN ISOTOPES, GUT CONTENT AND DNA METABARCODING ANALYSES We used gut content analysis (GCA) and stable isotope analysis (SIA) to characterise the diet and the food web structure of invertebrate communities in streams and ponds differently fed by glaciers in the Rhaetian Alps (Italy). The relative importance of allochthonous and autochthonous food resources was quantified using stable isotopes of carbon (13C) and nitrogen (15N). GCA was performed on a selection of species, including 13 Diptera Chironomidae (non-biting midges) that represent the most frequent and abundant taxon in these habitats: Diamesa bertrami, Diamesa latitarsis, Diamesa steinboecki, Diamesa zernyi, Pseudokiefferella parva, Eukiefferella minor, Metriocnemus eurynotus gr., Parametriocnemus stylatus, Thienemaniella clavicornis, Tvetenia calvescens, Macropelopia sp., Zavrelimyia sp., Micropsectra atrofasciata gr. In addition, the gut microbial structure of Chironomid larvae from the most food-poor glacial habitats was evaluated and compared with microbes from abiotic matrices (via metabarcoding 16S rRNA). New insights were provided as to which bacteria ingested from the environment can be configured as 'food' and which, among those present in the gut, can be considered the stable, resident metabolic 'chefs' of the host animal. Overall, the diet and trophic category (functional feeding groups) of the different species were reviewed. A certain trophic flexibility and omnivory was found, which may facilitate the adaptation of Chironomids and other invertebrates to changes in the quality and quantity of available resources due to glacier retreat. This knowledge will therefore improve our ability to predict future trends in alpine biodiversity in the context of ongoing climate change.

Valeria Lencioni (Primary Presenter/Author), MUSE-Museo delle Scienze of Trento (Italy), valeria.lencioni@muse.it;

Federica Camin (Co-Presenter/Co-Author), University of Trento & Edmund Mach Foundation (Italy), federica.camin@unitn.it;

Francesca Paoli (Co-Presenter/Co-Author), MUSE-Museo delle Scienze of Trento (Italy), francesca.paoli@muse.it;

Maria Grazia Zanoni (Co-Presenter/Co-Author), ETH Zürich (Switzerland), mariagrazia.zanoni@usys.ethz.ch;

Andrea Squartini (Co-Presenter/Co-Author), University of Padova (Italy), squart@unipd.it;

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6/04/2024  |   11:45 - 12:00   |  Independence Ballroom B

NEAR SHORE AND PROFUNDAL CHIRONOMIDS SHED LIGHT ON ORGANIC MATTER DYNAMICS IN PRAIRIE POTHOLE LAKES In Cottonwood and Page Lakes, two prairie pothole lakes in west-central Minnesota, chironomids comprise 46% and 54% of macroinvertebrate diversity and 55% and 36% of abundance respectively. Recognizing the diverse feeding strategies of the Chironomidae from these lakes provided an opportunity to evaluate roles of chironomids in food webs of prairie pothole lakes. Shredders in Cottonwood Lake, 35.7% of which were Glyptotendipes, Polypedilum and Cricotopus, were significantly more abundant close to shore but still comprised 17.3% of macroinvertebrates from profundal samples. Profundal chironomids made up 80% of collector-gatherers (Chironomus) and 76.3% of the predators (Procladius). This suggests that chironomids utilize CPOM close to shore but it is also available to macroinvertebrates throughout the lake. Processing of the CPOM may provide food for profundal collector-gatherers. In Page Lake, shredder abundance close to shore (mostly Polypedilum) was significantly lower than in Cottonwood Lake. Profundal samples contained no shredders and had significantly lower abundance than profundal samples from Cottonwood Lake. No shredders occurred in the profundal zone. There were significantly fewer collector-gatherers compared to Cottonwood Lake and the profundal community was dominated by the dipteran predators, Ceratopogonidae and Procladius. Differences in trophic structure between lakes suggest that when lakes have fewer sources of CPOM both near shore and profundal macroinvertebrate communities may be influenced. Examination of the macroinvertebrate community associated with leaves, macrophytes and algae, which are sources of CPOM will help clarify the organic matter dynamics in prairie pothole lakes.

Tracey Anderson (Primary Presenter/Author), University of Minnesota Morris, anderstm@morris.umn.edu;

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