Contributed Session.
Lead Organizer: Laura Treible, Savannah State University (laura.treible@gmail.com)
Co-organizers:
Katalin Patonai, Université de Montréal (kati.patonai@gmail.com)
Presentations
06:00 PM
EPISYMBIOTIC INFECTION ON CYCLOPOID COPEPODS DURING THE STAGNATION PERIOD OF 2018-2022 IN LAKE BIWA, JAPAN (8771)
Primary Presenter: Taiabur Rahman Tuhin, The University of Shiga Prefecture (tuhin.rahman78@gmail.com)
Epibionts impact the biology and ecology of host zooplankton, and therefore, more information is necessary on these associations to better understand lake ecosystems. In this study, we investigated the morphological characteristics of the epibionts to identify the species and the year-to-year and seasonal variations of their infection rates on crustacean zooplankton in Lake Biwa. Zooplankton samples were collected monthly with a vertical net haul from the bottom to the surface in the north basin of Lake Biwa from January 2018 to December 2022. Temperature, dissolved oxygen, and chlorophyll-a were simultaneously measured throughout the water column. Two epibiont species were identified, i.e., epizoic flagellate Colacium vesiculosum and peritrich ciliate Epistylis anastatica, throughout the study period. Both the epibionts just infested adult and copepodites of Cyclopoida spp. No such infections were found in any other crustacean zooplankton species. The lake water was stratified from June to October every year. An oxygen-minimum layer was formed below the thermocline from July to September, just after the massive phytoplankton bloom in June. Episymbiotic infestation was generally found from May to December every year but not from January to April. The infestation prevalences were high from August to November. The infestation prevalence was positively correlated with temperature or host abundance while negatively with dissolved oxygen, suggesting a stable interaction between abiotic and biotic ecological processes related to the stratification of the lake water.
06:00 PM
Analysis of variability in zooplankton metabolism and morphology for biogeochemical modeling (9125)
Primary Presenter: Sem Docekal, Arizona State University (sdocekal@asu.edu)
Zooplankton respiration plays a crucial role in marine biogeochemical cycling, and its relationship to organismal dry mass has long been described by allometric models. These models, which predict physiological processes based on mass, temperature, and broad taxonomic assignment, have been the foundation in simplifying complex ecosystem functions. There has recently been an expansion in the use of image-based sampling techniques, and to use these datasets for physiological estimates requires a conversion between observed biovolume and the historically more commonly measured biomass measurements, as well as a further exploration of the variability in metabolic rate among regions. The objective of this project is to analyze a suite of physiological, environmental, biovolume and biomass datasets from six distinct oceanic biomes. By comparing observed rates with the calculated values generated with current allometric models, we identified key factors that drive deviations from expected patterns. Our results suggest that regional differences play a significant and unaccounted for role in influencing zooplankton respiration. This highlights the importance of incorporating seasonal and regional variability to improve predictions of zooplankton metabolism and carbon cycling in marine ecosystems. In contrast, although biovolume to biomass relationships have some regional variability, simplified models are possible and our data provides confidence intervals for a global versus regional parameterization.
06:00 PM
Do gravel highways affect water quality and invertebrate communities in Arctic lakes? (9190)
Primary Presenter: Derek K. Gray, Wilfrid Laurier University (dgray@wlu.ca)
Gravel roads are a common feature in developed areas of Canada’s Arctic. These roads can be a source of calcareous dust that drifts to roadside lakes, causing significant changes in conductivity, calcium, and pH levels. In this study, we examined if road proximity was associated with differences in water quality and invertebrate communities in lakes along the Dempster and Inuvik-Tuktoyaktuk Highways in the Northwest Territories, Canada. We collected biological and water quality data from 18 lakes selected using a stratified random sampling design, with distance from the road (0-300 m, 300-600 m, and > 600 m) and region of study (boreal forest, tundra) as the two factors. We hypothesized that lakes closer to the road would exhibit differences in water quality and invertebrate communities associated with road dust pollution and other stressors caused by roads. We found no clear differences in water quality or invertebrate communities among lakes based on distance from the highways. In addition, while there were differences between regions, these did not appear to be related to the effects of the roadways. Our results suggest that variability in lake morphometry and water quality in this region might be more important than the influence of roads.
06:00 PM
TROPHIC NICHE BREADTH OF DAPHNIA PULEX IN AN ABANDONED AND SUBMERGED MICA MINE (9333)
Primary Presenter: Lucine Gonnet, Université du Québec à Montréal (gonnetlucine@gmail.com)
Quebec has the largest number of metal mines in Canada. Before the enactment of a restoration law in 1988, many mines were abandoned after resource depletion without any reclamation obligations. As a result, groundwater flooded mining pits and underground tunnels, creating new artificial aquatic habitats. These hostile environments were subsequently colonized by microorganisms from gallery surfaces and water, along with macroinvertebrates, including zooplankton. Since most mining lakes are only a few decades old, studies on their zooplankton communities remain limited. This study aims to assess how depth-related abiotic factors influence the diversity, community composition, and δ¹³C and δ¹⁵N ratios of Daphnia pulex food resources and to evaluate its trophic niche breadth across depths in an abandoned mine pit lake in Val-des-Monts. Eukaryotic and prokaryotic communities within particulate organic matter (POM) were characterized through rRNA gene sequencing (18S and 16S). To determine D. pulex's trophic niche, isotopic analyses of carbon-13 and nitrogen-15 were conducted on both D. pulex tissues and POM across a depth gradient. Depth-related shifts in microbial community composition and δ¹³C and δ¹⁵N signatures of POM revealed a transition from photosynthetically derived carbon at the surface to microbially processed carbon at greater depths. In response to these environmental gradients, D. pulex exhibited a wider C-isotopic trophic niche breadth in the mixolimnion, likely reflecting greater food resource diversity and availability. Finally, D. pulex did not exhibit diel vertical migration, possibly due to anoxic conditions in the monimolimnion and the absence of fish predation.
06:00 PM
HOW DORMANCY STRATEGIES IMPACT COMMUNITY ASSEMBLY AND GENETIC STRUCTURE OF ROCK POOL TARDIGRADES (9521)
Primary Presenter: Michael Matthews, University of Texas at El Paso (mamatthews5@utep.edu)
As ephemeral aquatic habitats face frequent desiccation, survival strategies are a necessity for organisms inhabiting them. Limno-terrestrial tardigrades are exemplary in this regard, as most are capable of anhydrobiosis while others encyst. There is likely a difference in efficiency, however, as encystment requires more energy to produce multiple layers of cuticle, and there is a shorter window to ‘escape in time’ due to its longer duration. These differences may influence community assembly and genetic structure of populations by facilitating or hindering dispersal and gene flow via anemochory. We aim to characterize (1) community composition of rock pools at two regional protected sites and (2) population structure of two tardigrade species, anhydrobiotic Mesobiotus huecoensis and encysting Pseudobiotus kathmanae. We hypothesize that M. huecoensis will have greater dispersal potential, resulting in lower genetic distances. We compared genetic variation within and among populations using two molecular markers (ITS2, COI). Initial findings show minimal genetic difference among three populations of P. kathmanae based on ITS2 region divergence (0.13%). Phylogenetic analyses using COI sequences (n=23) with 2.3% divergence, reveal clades that are not clustered by rock pool, suggesting that encysting individuals are not dispersal limited. Bdelloid rotifers were dominant in all rock pools; tardigrade species did not co-occur. Further genetic analysis of both species will confirm how dormancy strategies and dispersal ability shape community development and evolutionary processes.
CS23P - Zooplankton Ecology and Physiology
Description
Time: 6:00 PM
Date: 29/3/2025
Room: Exhibit Hall A