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CONFERENCE SCHEDULE UPDATES & CHANGES: As a result of the prolonged government shutdown, we experienced a number of cancellations and changes to the schedule. Cancellations and changes are listed here (as of January 26, 2019). 

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T16: Fisheries: Invertebrates [clear filter]
Tuesday, January 29

10:20am EST

(FISHERIES: INVERTEBRATES) Characterizing Macroinvertebrate Community Changes of West Fork White River (1979-2015)
AUTHORS: Caleb Artz, Dr. Mark Pyron – Ball State University

ABSTRACT: Long term macroinvertebrate data (1979-2015) was used to describe and analyze community characteristics of West Fork White River in Muncie, IN. Family abundance, functional feeding group, taxon richness, and sensitivity were analyzed to describe patterns in assemblage shifts. Multivariate statistical analyses was used to determine significant temporal and spatial patterns in the data set. Observed shifts in long term macroinvertebrate data are likely due to advancements in water quality due to the Clean Water Act.

Tuesday January 29, 2019 10:20am - 10:40am EST

10:40am EST

(FISHERIES: INVERTEBRATES) Comparisons of Enzymatic Thermal Optima Among Native and Invasive Crayfish Species
AUTHORS: Hisham Abdelrahman, James Stoeckel – School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University; Jacob Westhoff, Missouri Department of Conservation

ABSTRACT: Previous researchers have shown that extraregional invasive crayfish possess certain life-history and ecological traits that facilitate their ability to successfully invade large areas in distant regions, whereas extralimital invaders tend to remain localized and occupy smaller ranges.  Physiological traits may provide additional explanatory power for realized and potential range of crayfish species. In this study, we tested for thermal performance differences related to respiratory physiology among multiple crayfish species with narrow to broad native and invasive ranges. We hypothesized that species with broad ranges would be thermal generalists relative to species confined to limited ranges. To test this hypothesis, we generated thermal performance curves of respiratory enzymes in the electron transport system (ETS) for 12 individuals from each of five species. Optimal thermal range was defined as the temperature range within which ETS enzyme activity was within 10% of the maximum observed value.  Contrary to our original hypothesis, optimal thermal range of respiratory enzymes was not correlated with geographic range, but was lowest in the most widespread species (Procambarus clarkii) which was also the only species with a strong propensity to burrow.  We also found that the two extraregional invaders (Faxonius virilis and P. clarkii) had significantly lower enzymatic activity levels at optimal temperatures than did the extralimital invader (F. neglectus) or the two native species with restricted ranges (F. eupunctus and F. marchandi).  Results thus far suggest that enzymatic thermal breadth may be more closely tied to habitat plasticity whereas enzyme activity level may be a more useful predictor of geographic range. Additional species are currently being analyzed to better assess the robustness of these conclusions.

Tuesday January 29, 2019 10:40am - 11:00am EST

11:00am EST

(FISHERIES: INVERTEBRATES) Abiotic and Biotic Factors Relating to Mermithid Infection Rates in Larval Midge (Chironomidae) Specimens in Northwestern Wisconsin Streams
AUTHORS: Macayla Greider, Jeffrey Dimick – Aquatic Biomonitoring Laboratory, University of Wisconsin-Stevens Point; Dr. Justin VanDeHey, Dr. Shelli Dubay – College of Natural Resources, University of Wisconsin-Stevens Point

ABSTRACT: Mermithid nematodes are generally considered as biological control agents for pest species like Anopheles, but also may influence Trout (Salmonidae) food sources because they cause reproductive failure and mortality in both midge (Chironomidae) larvae and mayfly (Ephemeroptera) nymphs.  However, much remains unknown about the mermithid life cycle and factors affecting their distribution. Our objectives were to determine if the prevalence of mermithid infections differed (1) between hosts with different feeding strategies, (2) in streams with different macroinvertebrate and fish communities, and (3) with stream flow rates. We hypothesized that (1) filter feeding midges would have higher prevalence of midge infection because filter-feeders passively ingest eggs whereas other midges seek out specific prey, (2) Trout streams would have fewer mermithids, and (3) stream flow would not be related to mermithid prevalence. Mermithid prevalence was assessed in samples collected from 48 streams during 2010-2014 from four northwestern Wisconsin counties. Infection was determined by observation of mermithids within midge bodies. Midges were identified to species to determine feeding behavior and distinguish filter feeders from non-filter feeders. Significantly lower proportions of mermithids were present in Trout streams than non-Trout streams, but no significant differences were present between mermithid presence and either HBI score or stream velocities. Chi-square analysis indicated no significant difference in prevalence between filter feeding and non-filter feeding groups; however, shredders had higher mermithid prevalence than other feeding groups. This research will provide insight into some aspects of mermithid life cycles and host selection.

Tuesday January 29, 2019 11:00am - 11:20am EST

11:20am EST

(FISHERIES: INVERTEBRATES) Evaluating Impacts of Rainbow Trout Farming on Macroinvertebrates in Neotropical Streams in Ecuador
AUTHORS: Dana G. Wessels, Biology Department, Grand Valley State University; Dr. Katherine Krynak, Department of Biological and Allied Health Sciences, Ohio Northern University; Dr. Ed Krynak, Department of Geography, Western University; Andrea Encalada, Universidad San Francisco de Quito, Ecuador; Dr. Eric Snyder, Biology Department, Grand Valley State University

ABSTRACT: Rainbow trout (Oncorhynchus mykiss) aquaculture has increased to accommodate growing human populations, but streams throughout the world are being adversely affected in the process. Understanding how stream ecosystems respond to trout farm effluent is necessary to propose well-informed management practices before habitat and biotic loss become unrecoverable. Our research compared macroinvertebrate communities and environmental parameters along two streams in the Pichincha region of Ecuador; one stream with five non-native rainbow trout farms, and the other stream without trout farms. Macroinvertebrates collected in non-trout farm and headwater (control) sites were compared to those collected at the outflow of the five trout farms. An analysis of similarity based on the non-metric multidimensional scaling analyses (NMDS) of the macroinvertebrate families in qualitative kick samples as well as the EPT genera from the Surber samples showed a significant difference between the three sampling groups (Global R = 0.536, p = 0.004 and Global R = 0.639, p = 0.001 respectively). SIMPER analyses determined the families and genera that contributed the greatest proportion of dissimilarity between the trout farm, non-trout farm, and headwater groups. The Andean Biotic Index pollution tolerance values and functional feeding groups of the most influential families were examined. AICc model selection and model averaging was used to evaluate potential environmental influence on macroinvertebrate community similarity. Model averaged parameter estimates of the interaction between specific conductivity (SC) and percent organic matter (OM) was predictive of the macroinvertebrate community differences between sampling sites from the kick samples. Our results indicated reduced water quality due to the effects of rainbow trout farm effluent. However, treatment methods are limited in this mountainous terrain. Therefore, we would suggest feeding efficiency and utilization of trout farm sludge as fertilizer to minimize the impact of these farms on the neotropical streams.

Tuesday January 29, 2019 11:20am - 11:40am EST