Midwest Fish & Wildlife Conference 2019

AUTHORS. Jeffrey C. Jolley, Duane C. Chapman, Curt G. Byrd, Patrick M. Kocovský –U.S. Geological Survey

ABSTRACT. Grass carp Ctenopharyngodon idella reproduction has occurred in the Lake Erie basin; understanding spawning cues could be useful in designing control methods and determine which Great Lakes tributaries are potential spawning locations.  Grass carp broadcast spawn and require flowing water to keep their semi-buoyant eggs suspended; spawning cues are unknown. At least 633 cumulative degree days = 15 ºC (ADD15) has been reported necessary for the maturation of gonads.  To validate this estimate, we evaluated oocyte maturation of 67 and 50 females in experimental ponds in 2017 and 2018, respectively.  In 2017, the first female with ripe oocytes occurred >800 ADD15, occurring 7 days after 633 ADD15.  In 2018, the first female with ripe oocytes occurred >1,000 ADD15, over 2 weeks after 633 ADD15.  Estimated threshold for 50% of females to have ripe oocytes was 906 ADD15 in 2017 and 1,265 ADD15 in 2018.   April 2018 had record low temperatures followed by record high May temperatures, suggesting that the sequencing of accumulation of thermal units may also be important.  A pond mesocosm was used to simulate river conditions and variable spawning cues (i.e., flow, turbidity, temperature).  Spawning occurred during the first trial, when fish were injected with hormones (HCG, carp pituitary), was confirmed by spawning behavior recordings (chasing, rubbing) in high velocity areas, and collection of fertilized eggs.  Spawning also occurred when the mesocosm was held in a stagnant condition (fish were hormone injected).  Fish spawned at the deep outlet kettle where the water input was also located.  Grass carp did not spawn in additional trials, but water temperatures may have increased beyond the suitable range.  Future trials will focus on replicating the results of trial one, precise temperature control, and further variation of environmental cues.

AUTHORS. Alyssa J. Ulrich, Caleb T. Austin, Amber A. Burgett – Wittenberg University

ABSTRACT. Agricultural runoff into aquatic habitats such as streams, wetlands, and ponds can impact the survival and behavior of aquatic organisms. Additionally, climate change and warming temperatures in some areas can increase the stress, change behavior, and also increase mortality for some aquatic species. Using the species, Orconectes rusticus, we examined the impact of a sublethal dose of roundup and warmer temperatures to examine how this impacted their behavior towards conspecifics. Roundup and a warmer temperature reduced the overall activity of crayfish. There was no impact of Roundup on overall aggression towards conspecifics, however temperature did reduce aggression levels. Alterations in crayfish activity level as a result of roundup and warming temperatures could impact their role in the stream food web, as they potentially become less territorial, less adept at foraging, or shift their diet towards less active foraging methods. Crayfish behavioral changes could ultimately impact the structure and function of aquatic ecosystems.

AUTHORS. Hannah TerMarsch, Jessica Ward – Ball State University

ABSTRACT. The lateral line system of aquatic vertebrates is made up of mechanoreceptors called neuromasts that are arranged in a series of rows along the head and body, and serve to detect movement, vibration, and pressure gradients in the water. Although the structure and use of the lateral line system varies among species, the ability of receivers to exploit mechanosensory information has been shown to affect the outcome of interspecific interactions (e.g., predator evasion, or prey capture). However, comparatively less is known about how mechanosensory information might influence organismal decision-making during intraspecific interactions, such as reproduction. In this study, we investigated the role of the lateral line during male-male territorial interactions in the fathead minnow (Pimephales promelas). Male fathead minnows compete for territories and display several aggressive displays, including charging, tail flicking, and broadside (lateral) threats—all of which displace water. Receivers who exploit such information could more accurately assess the condition or level of aggressive motivation of their opponent. We pharmacologically manipulated the lateral line of breeding male minnows using aminoglycoside antibiotics and conducted a behavioral experiment that paired males with and without access to mechanosensory information in territorial contests. Our results indicate that mechanosensory signals are likely an important component of male-male aggressive communication and provide insight into the evolution of complex signals in fishes. These data also suggest that antibiotics in streams and rivers have potential to alter intraspecific interactions in natural populations, with significant ecological and evolutionary effects.

AUTHORS. Gina Lamka, Hannah Mullinax, Autum Auxier, Jessica Ward – Ball State University

ABSTRACT. Cyanotoxins produced by harmful algal blooms (HABs) are commonly detected in freshwater systems in the United States and abroad. Emerging evidence suggests that chronic exposure of fish and other aquatic organisms to cyanotoxins may induce sub-lethal effects on behavior, negatively influencing individual fitness. Along with reducing recruitment of young into the population, exposure may increase the rate of transfer up the food chain, posing significant health risks for humans. For example, exposure to neurodegenerative cyanotoxins through the consumption of contaminated foods has been linked to sporadic increases in diseases such as amyotrophic lateral sclerosis (ALS), and Parkinson’s and Alzheimer’s disease. Despite the potential for similar cognitive and motor impairment in aquatic organisms, the effects of neurodegenerative cyanotoxins on the performance of fish in real-world contexts is largely unknown. In this study, we examined the sub-lethal effects of a common algal neurotoxin, 2,4-diaminobutyric acid dihydrochloride (DABA), on the innate predator-evasion performance of larval fathead minnows, Pimephales promelas. Eggs and larvae were exposed to a range of environmentally relevant concentrations of DABA (0, 1, 5, 25, 125 and 625 µg/L) for 21 days. On day 22, behavioral assays were conducted by administering a non-point source vibrational stimulus to an arena containing a focal larva. Responses were filmed using a high-speed camera at 1000 fps, and perceptual and motor components of the response were analyzed separately. Compared with nonexposed fish, exposure to DABA significantly modulated the response of larvae to a simulated predator. This research is among the first to attempt to understand how neurodegenerative cyanotoxins affect the behavior of aquatic organisms in real-world contexts and could be used by managers to predict the fate of aquatic communities in areas afflicted by HABs.

AUTHORS. Ryan Seymour, Jessica Ward, Autum Auxier, Hannah Mullinax – Ball State University

ABSTRACT. Cyanobacteria are prevalent blue-green algae that impact Midwestern freshwater systems, important environmental and economic resources. Emerging evidence suggests that exposure to neurotoxic compounds can induce sub-lethal behavioral and central nervous system (CNS) changes that have potential to affect individual fitness. The long-term goal of this research is to evaluate the significance of emerging algal neurotoxins for fish populations and aquatic communities. A first step toward this goal, this project used a low-dose, lab-controlled exposure regime to quantify the effects of 2,4-diaminobutyric acid (DABA) on the sensorimotor performance of embryos, and 21-day-old larvae . Despite reports of impaired motor function in humans linked to the consumption of contaminated fish, the effects of these compounds on fish themselves is largely unknown. Embryo motor activity and prey capture efficiency decreased with increased exposures to the cyanotoxins. The results will fill critical gaps in knowledge regarding the short- and long-term effects of sub-lethal exposure to algal neurotoxins on fish and provide direct insight into the factors affecting routes of human exposure and health risks

AUTHORS. Katherine Rexroad, Western Illinois University; Shelli Dubay, University of Wisconsin-Stevens Point; Christopher Jacques, Western Illinois University

ABSTRACT. Southern flying squirrels (Glaucomys volans; SFS) are forest-dependent, nocturnal, non-hibernating, arboreal mammals that den in tree cavities.  Previous studies suggest that several structural attributes of overstory hardwood trees are essential to SFS life-history needs, especially locomotion, den site selection, and food sources.  Nevertheless, little information is available on the influence of vegetation structure on microhabitat use across fragmented Midwestern landscapes.  To date, no studies have evaluated whether proximate factors (e.g., structural differences in overstory vegetation) influence microhabitat partitioning between activity areas of male and female SFS across Midwestern landscapes.  The goal of this research is continue the long-term SFS research program to better understand the additive or antagonistic effects of intrinsic factors (sex, age, nutritional condition), microhabitat features, habitat fragmentation, and parasite loads on home range dynamics and nest-switching behavior of SFS.  Specific project objectives include 1) quantifying nest occupancy patterns, and rates of nest switching/reuse by SFS between sexes and across activity areas, 2) investigating associations between microhabitat (tree diameter-at-breast height, snag density, tree height, availability of mast trees), habitat fragmentation (patch size, distance to nearest habitat edge) and home range (size, shape) metrics of SFS, and 3) estimating prevalence and intensity of infection with parasites in local populations of SFS.  Increasing basic knowledge of interactions and interrelationships between intrinsic and habitat effects on SFS nesting patterns, particularly in regions characterized by low habitat quality and animal densities will provide greater insight into future conservation strategies for SFS along the western boundary of their geographic range.