Session 29: ASIH Stoye Ecology and Ethology III (first 8)/ Contributed Ichthyology Physiology & Development (last 2)Room: Room 206C2022-07-29 13:30 - 16:00 |
| Moderator: Terry Donaldson |
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1. 13:30 The Impact of Social Structure and Female Population Density on Mating Behaviour and Sexual Pattern, Protogynous Pseudanthias rubrizonatus. Emma Moritoshi*, Kagoshima university; Midori Matsuoka, Kagoshima university; Tomoki Sunobe, Tokyo University of Marine Science and Technology; Shinichi Dewa, Diving service Umiannai; Gen Kume, Kagoshima university emmahinako@gmail.com
Pseudanthias rubrizonatus is known as polygyny and monandric protogyny. However, in Kagoshima Bay, Japan, this species has been found as well in large groups of over 10,000 individuals and sexuality is diandric protogyny. Still unclear are the conditions in which primary males emerge. This research focuses on how the female population density affects intraspecies variations in mating behaviour and sexual patterns. Field observations were made by SCUBA-diving between October 2018 and March 2022, between 5 a.m. to 7 p.m. before, during, and after the May-October breeding season. Observations of male courtship behaviour (n=107) and the mating system, population and sex ratio of each group were recorded. Results showed variation in social structures based on group size. In groups with 50-100 individuals, a dominant male established a harem with about four females. In contrast, large groups (over 10,000 individuals) had more complex social structure. Dominant males (n≒1,200) established territories around high density aggregation of females (n≒8,700) near food sources, while subordinate males (n≒800) scattered below the females. The females mainly visited and spawned with the dominant males. Males engaged in precourtship even during dormancy before and after breeding season, which may have function of preventing sex change by the female. In areas with such high female density, three small males (1 year old) were collected. These individuals may not have received precourtship, and differentiate to primary males. Thus, in large groups with a high density of females, sexuality of this species can be diandric protogyny. |
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2. 13:45 Impacts of Asynchronous Emergence of Batrachochytrium dendrobatidis and Ranavirus in Florida Amphibian Assemblages. Arik Hartmann*, University of Florida; María Torres-Sánchez, University of Florida; Ana Longo, University of Florida arikhartmann@ufl.edu
As emerging pathogens expand and overlap in geographic ranges, novel interactions can potentially exacerbate declines in already fragile host populations. Alternatively, heightened immune responses of infected hosts may suppress additional infections. Here we focus on characterizing the interactions between two emerging pathogens impacting North American amphibians: the chytrid fungus Batrachochytrium dendrobatidis (Bd) and Frog-Virus 3-related Ranavirus. We investigated the co-occurrence of these pathogens in amphibian assemblages in Florida over two years, identified factors associated with their emergence using linear models, and quantified the impacts of subsequent disease outbreaks. The emergence of Bd and Ranavirus was asynchronous but overlapping, and patterns of infection and disease varied among sites and species. Ranavirus infections were more prevalent and caused lethal episodes of ranavirosis in susceptible life stages, resulting in severe population declines of striped newts (Notophthalmus perstriatus). In contrast, Bd often emerged after Ranavirus, and infections were milder and limited to fewer host species. Co-infections of Bd and Ranavirus were common at a single site where Bd was the dominant pathogen and Ranavirus showed consistently lower prevalence and infection intensity. Interestingly, striped newt populations persisted at this site and did not experience severe ranavirosis. Our findings provide strong evidence that Ranavirus has driven declines of threatened species in Florida, permanently changing host community composition of sites post-outbreaks. Overall, our results highlight that immune-mediated competition between Bd and Ranavirus may be associated with dampened ranavirosis and population stability. Quantifying pathogen interactions can help us design management strategies to change the course in natural outbreaks. |
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3. 14:00 Habitat fragmentation influences amphibian skin microbiome composition, helminth parasitism, and disease status in the Brazilian Atlantic Forest. Wesley Neely*, The University of Alabama; Gui Becker, Pennsylvania State University wesleyjneely@gmail.com
Habitat destruction is one of the greatest modern threats to wildlife, particularly in biodiversity hotspots like the Brazilian Atlantic Forest. In heterogeneous landscape, habitat fragments are frequently left in areas that are less desirable for farming, allowing for persistence of certain wildlife populations. However, these populations are now faced with the stressors of reduced genetic diversity due to reduced population sizes, increases in disease due to increased population densities, and an overall reduction in complex community interactions due to community simplification. For this study, we collected samples from Blacksmith Tree Frogs (Boana faber) across 3 sites in continuous forest and 3 forest fragments to see the effects of habitat fragmentation on microbiome composition, helminth parasite diversity, and disease status. We aim to discover how helminth infection may be priming the immune system against further pathogen infection or alternatively overloading the immune system allowing for high pathogen loads. We also aim to find out what role the skin and gut microbiome play in this complex dynamic. |
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4. 14:15 Photoperiod Effects in an Aquatic Community: Amphibian Larvae Develop Faster and Zooplankton Abundance Increases Under an Early-Season Photoperiod. Troy Neptune*, Case Western Reserve University; Michael Benard, Case Western Reserve University tcn27@case.edu
As the Earth warms, many organisms that shift their phenologies with temperature will experience novel photic environments, as photoperiod (daylength) changes seasonally. While some studies investigate the direct effects of photoperiod within single species, few studies examine how photoperiod simultaneously affects multiple taxa in ecological communities. We conducted an outdoor mesocosm experiment exposing gray treefrog (Hyla versicolor) and green frog (Rana clamitans) larvae to two photoperiods: an early-season photoperiod (simulating development in April) and a late-season photoperiod (simulating development in July). We manipulated photoperiod by covering and uncovering tanks with clear or light-blocking lids to mimic realistic day length changes. Since gray treefrogs metamorphose within a season, we predicted gray treefrogs in the late-season photoperiod to develop faster to metamorphose before the season’s end. Conversely, green frogs can metamorphose within the same season if eggs are laid early; otherwise, they overwinter as larvae. We, therefore, expected green frogs to develop faster under the early-season photoperiod to metamorphose within the same season. In contrast to our prediction, gray treefrogs reduced development during metamorphosis under the late-season photoperiod. Gray treefrog total length was also significantly longer under the late-season photoperiod. Additionally, we found a marginally significant acceleration of development in green frog larvae exposed to the early-season photoperiod. Although photoperiod did not affect algal abundance, zooplankton nauplii were in greater abundance under the early-season photoperiod. Despite a three-month shift, photoperiod did not drastically affect the aquatic community, instead acting through minor yet significant changes in amphibian development and zooplankton abundance. |
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5. 14:30 The Effects of Pyrophytic Pine Forest Restoration on Herpetofaunal Community Assemblages in Bankhead National Forest
. Rachel Brubaker*, Tennessee State University; Allison Cochran, U.S. Forest Service; William Sutton, Tennessee State University rbrubake@my.tnstate.edu
The forest ecosystems of the southeastern United States are valuable both economically for forest products and ecologically for use as habitat by many endemic and imperiled species. Amphibian and reptile biodiversity is especially high within southeastern forests and these habitats are important for herpetofaunal conservation in the United States. The Southeast historically contained between 57 and 92 million acres of Pinus palustris habitats but less than five percent of these habitats remain today. The US Forest Service is working toward P. palustris restoration in the William B. Bankhead National Forest located within the northern terminus of the P. palustris historic distribution. Relatively little sampling of the herpetofaunal communities has occurred in the southern portion of the forest within P. palustris restoration stands. These restoration practices create distinct stages characterized by forest structures that likely generate distinct microhabitats and may influence the herpetofaunal assemblages that utilize these stands. This study employs the use of passive herpetofauna trapping to evaluate community assemblages among the stages of P. palustris restoration. My research will help answer questions regarding the effects of P. palustris restoration management on southeastern biodiversity. Additionally, it will investigate the relationship between forest structure, microhabitats, and disturbance on species richness within the northern terminus of P. palustris forests. This study will assist managers in future forest management decisions, expand species records of Alabama herpetofauna, and help clarify the effects of P. palustris restoration on herpetofaunal communities in the southeastern United States. |
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6. 14:45 Effects of simulated soundscapes on calling in Cope’s Gray Treefrog. James Erdmann*, Oklahoma State University; Michael Reichert, Oklahoma State University muddynaturalist@gmail.com
Soundscapes, or the acoustic makeup of an environment, can play an important role in driving and constraining acoustic signaling across species. Animals can alter their signaling behavior to maintain effective communication in the presence of different acoustic backgrounds, but little is known about how these responses vary across the wide range of soundscapes present in nature. We explore this question in a population of Cope’s Gray Treefrogs (Hyla chrysoscelis) (Cope, 1880) by performing a field playback experiment of simulated background noise derived from a variety of habitats the species could potentially be exposed to. These stimuli consist of spectrally averaged noises from a combination of natural, urban, forested, and grassland habitats. Preliminary results suggest that there are stimulus-specific responses, with frogs having lower calling efforts when exposed to stimuli incorporating more anthropogenic noise sources. Frogs show individual variation in the type of behavioral response, with some increasing calling effort while others cease calling, two distinct strategies to handle signal masking. These findings shed light on the level to which behavioral plasticity may play a role in explaining the geographical variation of mating signals, and highlight challenges of studying the acoustic adaptation hypothesis. |
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7. 15:00 Abiotic and biotic predictors of the Coastal Giant Salamander (Dicamptodon tenebrosus) in headwater streams. Nathaniel Neal*, Oregon State University; Ashley Coble, NCASI; Ashley Sanders, Oregon State University; Brian Sidlauskas, Oregon State University; Dana Warren, Oregon State University nateneal1110@gmail.com
Across the Oregon Coast Range, Dicamptodon tenebrosus is of significant importance as one of the dominant aquatic vertebrates in headwater streams. With females guarding eggs for 9 months, larvae then reside in the streams until maturity and even through adulthood if neotenic. Though widespread, health and abundance levels differ greatly between locations, provoking the question as to what factors may influence this variation and whether habitat features or biotic competition play a larger role. The collected data included 4 biotic and 8 abiotic factors for 25 different study streams in second-growth forests. We explored each variable in relation to the condition, abundance, and biomass density of Dicamptodon tenebrosus. With global models, individual models, and a null model included, we designed a set of 40 models that tested alternative hypotheses predicting Dicamptodon tenebrosus. We performed AICc analysis on each model to determine AICc weights and ran linear regression analyses on the top 10 models for each response variable. With the initial expectation that biotic and abiotic factors would be equivalently useful in prediction of Dicamptodon tenebrosus, AICc and model usefulness instead indicated that abiotic data points were far more helpful. Pool area, substrate size, and depth in particular held the most influence across the alternative hypotheses proposed. The importance of abiotic features shed light on the dominance of Dicamptodon tenebrosus, where habitat selection was more heavily weighted by stream morphology than competition or biotic productivity. |
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7. 15:15 Assessing Spatial Ecology of a Long-Lived Lizard. Jocelyn Stalker*, Center of Excellence for Field Biology, Austin Peay State University; Jason L. Jones, Wildlife Diversity Division, Nevada Department of Wildlife; C. M. Gienger, Center of Excellence for Field Biology, Austin Peay State University jocelynstalker@gmail.com
For individuals exhibiting range residency, the home range is a useful framework to quantify critical space use. Some reptiles, such as the Gila monster (Heloderma suspectum), can live decades in the wild and experience extreme environmental variation common to desert habitats. Individuals may modify their spatial use over time, making single-year estimates biologically uninformative. VHF telemetry data were collected for Gila monsters at three Mojave Desert sites in Clark County, Nevada and home range utilization distributions were calculated using an autocorrelated kernel density estimator. We assessed the stability of home range size across years using a repeatability analysis and found that home range size is repeatable across years but not across individuals. To measure stability of home range overall (year to year reuse), we calculated Bhattacharyya’s affinity (BA) for each combination of years an individual was tracked and averaged this for individuals and populations. Average BA score was 0.70 on a scale from 0-1 (0= no overlap and 1= total overlap) and did not vary significantly by population. We modeled home range accumulation to estimate minimum sample size needed for asymptotic stability and found home range accumulation to be dynamic within and across years and individuals. Heterogeneity of spatial use among populations and individuals suggests that individual and local environmental variation drive home range size of H. suspectum in southern Nevada. |
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8. 15:30 Preliminary Measures of Physiological Stress from Bottom Trawl and Hook-and-Line Captured Pacific Cod in the Eastern Bering Sea. Bianca Prohaska*, AFSC; Anita Kroska, APU; Nathan Wolf, APU bianca.prohaska@gmail.com
Pacific cod (Gadus macrocephalus) is one of the most valuable commercial species fished in the Bering Sea; however, little is known about the physiological effects of capture on this species. With greater insight into a fish’s physiological response to stress, a multitude of questions can be addressed, ranging from estimates of bycatch mortality, to a proxy for ecosystem health. Preliminary data must be gathered to assess if these data can be collected at sea, and if these targeted physiological parameters are reliable indicators of stress. Thus far, two discrete sampling methods have occured, the first of which was a paired blood and mucus collection in which a Pacific cod was sampled immediately after a 30-minute bottom trawl, and again after 30 minutes in a live tank on board. The second sampling method was collecting blood from hook-and-line captured Pacific cod as soon as the fish was landed. Collected blood was immediately analyzed for pH, glucose, lactate and hematocrit, and remaining plasma was stored for future analysis of the stress hormone cortisol. The mucus collected was also immediately stored frozen for future analysis of cortisol. These collections will allow us to compare stress between two capture methods, bottom trawl and hook-and-line, analyze how on-board fish holding may affect stress, and also allow us to determine if mucus collected at-sea can be used to analyze the stress response in Pacific cod. |
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9. 15:45 Does rearing temperature impact lateral line development in brook trout, Salvelinus fontinalis? Aubree Jones*, University of Rhode Island; Matthew O'Donnell, USGS-Eastern Ecological Science Center at the S. O. Conte Research Laboratory; Amy Regish, USGS-Eastern Ecological Science Center at the S. O. Conte Research Laboratory; Jacqueline Webb, University of Rhode Island aubree_jones@uri.edu
The length of the larval period in salmonids decreases at higher temperatures. This is likely to have implications for the ontogeny of sensory system morphology and function. The neuromast receptor organs of the mechanosensory lateral line system (LL) detect local water flows that mediate critical behaviors (e.g., predator avoidance, prey detection). In larval fishes, neuromasts on the skin increase in number over time and then either enclose in bony canals (canal neuromasts) or remain on the skin (superficial neuromasts). In this study, we compared temperature effects on the ontogenetic trends in neuromast number, size, and the timing of canal formation in brook trout raised at three temperatures: the temperature of a long-term study stream (+0oC), +2oC, and +4oC. Early results indicate the complex nature of temperature effects on LL development. The number of canal neuromasts is not significantly impacted by temperature but the terminal neuromast number and more advanced stages of canal formation are reached sooner at higher temperatures. The rate of increase in neuromast size differs between canals and reflects the asynchronous process of canal enclosure. Canal neuromasts in the supraorbital canal, one of first canals to enclose, grow at similar rates across temperature treatments. However, the neuromasts in the mandibular canal, one of the last canals to enclose, grow more slowly at higher temperatures. With temperatures increasing in brook trout native ranges due to global climate change, this accelerated development may have critical consequences (e.g., metabolic demand, LL-mediated behaviors) and may affect the long-term viability of their populations. |