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    P1: ASIH Storer Award, Ichthyology Storer II

    2021-07-26   16:00 - 18:00

    To view the posters go to You will be able to chat one-on-one during the Monday poster session, the e-poster platform.

    1.  16:00  Diversity, distribution, and development of the ligastyle, a component of the poeciliine gonopodial suspensory skeleton of uncertain homology. Tiffany D. Inbody*, Texas A&M University; Kevin W. Conway, Texas A&M University

    The gonopodium is an emblematic, sexually dimorphic feature of the Poeciliinae (Poeciliidae), comprising a highly modified anal fin supported by an internal suspensory skeleton, comprising elements of the vertebral column, anal fin pterygiophores, and associated musculature. In some members of the Poeciliinae (livebearers), a small bony element referred to as the ligastyle (or suspensory ossicle) contributes to the internal suspensory skeleton of the gonopodium. The ligastyle is located anterodorsal to the remainder of the suspensory skeleton and encased in a ligamentous sheet that extends from the ventral surface of the vertebral column to the anterior gonactinosts (modified proximal radials). Typically, a thin rod-shaped bone, the ligastyle varies both in size and shape between the different genera of poeciliines in which it is present. Though without bony contact to the vertebral column in the adult, the ligastyle is hypothesized to represent a hemal spine that has become disassociated from the serially associated hemal arch during development. An alternative hypothesis on the homology of the ligastyle is that it represents a de novo ligamentous ossification and is not an element of the vertebral column. In order to further our understanding of the ligastyle, we document variation in: (1) presence/absence; (2) shape; and (3) position of the ligastyle across poeciliine taxa available to us for study. We also document development of the ligastyle using developmental series compiled for three species of poeciliine to clarify the homology of this potentially functionally important yet understudied component of the gonopodial suspensory skeleton.

    2.  16:00  The Colors of the Rainbow: Using TagSeq to Investigate Nuptial Coloration Gene Expression in Rainbow Darters (Etheostoma caeruluem). Andrew Sherman*, Southeastern Louisiana University; Kyle Piller, Southeastern Louisiana University

    Sexually dimorphic traits are common throughout the tree of life and manifest themselves in a variety of forms from body size differences to the development of secondary sexual characteristics. One such secondary sexual characteristic that is found to be sexually dimorphic in many fishes is coloration. Historically, studies have focused on the proliferation of sexually dimorphic coloration during maturation, but little has been done to examine the genetic architecture of seasonal changes in coloration, or nuptial coloration. Darters (Percidae), specifically those in the genus Etheostoma, are strong candidates to examine nuptial coloration proliferation because the males of many of these species develop vibrant nuptial coloration. The goal of this study was to use TagSeq (3’mRNA sequencing), to compare gene expression within male and female Rainbow Darters (Etheostoma caeruleum) from Louisiana, across seasons in order to investigate the genetic mechanisms that result in male nuptial coloration proliferation. TagSeq was utilized as it is a low-cost, low-noise alternative to traditional RNASeq that focuses on gene expression. Our results showed that there is an appreciable difference in gene expression in males between seasons, but little difference in females between seasons.

    3.  16:00  Searching for Topeka Shiners (Notropis topeka) in Missouri using Environmental DNA (eDNA). Austin Mueller*, University of Central Missouri; Aaron Geheber, University of Central Missouri

    The Topeka Shiner (Notropis topeka) is a federally endangered stream fish native to the Midwest United States. In the state of Missouri, the Topeka Shiner has undergone a drastic reduction in distributional range over the last half century, leaving few remaining populations. Although conservation and reintroduction efforts have aided in maintaining a small number of these isolated populations, efficient monitoring is critical for future recovery and stability. Furthermore, effective management decisions require a thorough understanding of the current Topeka Shiner distribution in Missouri. Due to the reduction and rarity of Topeka Shiners within their historic distributional range, traditional monitoring efforts (e.g., seining or electroshocking) may be unreliable (i.e., because of high potential for false negatives). Therefore, the overall aim of this project is to effectively determine the current distribution of Topeka Shiner in select Missouri watersheds using environmental DNA (eDNA) methods, which may allow detection without physical capture. In addition to examining detection ability of eDNA methods in the field, we also aim to experimentally test detection ability using controlled artificial stream units. Specifically, these experiments test detection ability across different Topeka Shiner biomass treatments, and across differing downstream sampling distances. Overall, this project will provide greater understanding of Topeka Shiner occurrence in Missouri, and in turn, will help focus monitoring efforts, aid in future management, and refine species recovery strategies. Current project progress and results will be presented and discussed.

    4.  16:00  Trophic analysis of invasive lionfish (Pterois volitans) from deep reefs in the Caribbean. Megan Ewing*, University of Washington; Rachel Welicky, School of Aquatic and Fishery Sciences, University of Washington; Carole Baldwin, Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution; Ross Robertson, Smithsonian Tropical Research Institute; Luke Tornabene, University of Washington

    In the decades since their introduction, invasive lionfish (Pterois volitans) have spread throughout reef ecosystems in the entire tropical western Atlantic Ocean. Lionfish are free from predation in their introduced range, have consumed and depleted native fish populations, and competed with native mesopredators. Recent explorations of deep-reef habitats in the Caribbean via submersible have found that lionfish are common on mesophotic and rariphotic reefs, down to 304 m, bringing into question the extent of the ecosystem impact invasive lionfish have on deep reefs compared to shallow habitats. Previous studies have found evidence suggesting lionfish from mesophotic reefs are older, bigger, more reproductively mature, and more densely populated compared to those from shallow reefs, indicating a clear difference between shallow reef and deep populations. However, the difference in trophic position between these two populations is not well understood. This study used bulk stable carbon and nitrogen isotope analysis of lionfish from Curaçao, collected at depths ranging from 5–174 m, to determine trophic differences between shallow and mesophotic populations. The findings of this study are important in understanding the impact invasive lionfish have on Carribean reef ecosystems, and have broader implications for the effectiveness of invasive species management of mesophotic reefs.

    5.  16:00  Examining Alterations in Darter Functional Morphology along Stream Gradients. Christopher Hockaday*, University of Central Missouri; Aaron Geheber, University of Central Missouri; Jaime Smith*, Western Carolina University

    Darters are a group of small benthic freshwater fishes endemic to North America that often occur in fast moving riffle habitats. Previous research has indicated that stream flow may impact darter morphology, possibly through plastic response and or natural selection processes. The goal of this study was to quantify the effects of differing levels of flow on functional morphological traits of Etheostomaspectabile (Orangethroat Darter) within the Osage Drainage in Central Missouri, USA. We gathered abiotic stream elements including elevation, flow velocity, stream depth, and substrate type to identify factors influential on darter morphology. We examined darter geometric morphometric data based on 14 homologous lateral landmarks, and five homologous dorsal landmarks. Additionally, pectoral fin surface areas, scaled to body length, were quantified for individuals. Morphometric data were visualized using principal component analysis to assess body shape differences among individuals. Lateral data suggested that individuals at higher elevations (i.e., upper reaches of streams) had more compact bodies with fins closer together compared to individuals at lower elevations. Dorsal landmarks showed that individuals at higher elevations had shorter and narrower heads compared to the longer and wider heads of individuals at lower elevations. Additionally, we found that pectoral fins were of greater size at higher elevations. The perceived functional benefits of such morphological alterations in relation to abiotic stream gradient features will be discussed.

    6.  16:00  Verification of Giant Sea Bass (Stereolepis gigas) Spawning: Through Auditory and Visual Observations. Elizabeth Burns*, California State University, Northridge; Larry Allen, California State University, Northridge; Michael Franklin, California State University, Northridge

    Giant Sea Bass (GSB), Stereolepis gigas, is the largest marine bony fish off the coast of California, an apex predator, and is currently classified as critically endangered by IUCN Red List. Despite recent studies on GSB, there is no documentation of their spawning and related reproductive behaviors in their natural environment due to their depressed population size. Through preliminary data and past research, we have discovered that GSB can produce a variety of sounds (many sounding like a “boom”). Some of these sounds have been observed to be linked with antagonistic behaviors towards GSB males by other GSB males. Past studies have observed that the closer in proximity you are to a GSB spawning aggregation the louder and more numerous GSB sounds are heard. Along with “booms”, GSB have also been observed to display courtship behaviors that have only been seen in spawning aggregations. We hypothesize that GSB vocalization occurs frequently during spawning and is used in combination with courtship behaviors to signal reproduction readiness. This poster explores the in-progress investigation into the hypothesized acoustical and courtship behaviors exhibited by GSB during spawning. Presented is a portion of preliminary data gathered in the summer of 2014, 2015, and 2019. During which, we recorded a novel sound produced by captive GSBs that successfully spawned. I argue that by identifying these behaviors, we will be able to verify GSB spawning when these auditory and visual behaviors are observed.

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