Science and Technology Production

Reporte técnico: Zooplankton Ecology of Lake Tahoe: Composition, Migration, and Influence on Plankton Particle Sizes Final Report

Technical Report

Authorship:

Sudeep Chandra ; Erin Suenaga ; Carina Seitz ; Katie Senft ; Emily M. Carlson ; Zachary Bess ; SCORDO, FACUNDO ; Michael Lam

Summary *

The study reveals that while most zooplankton exhibit diel vertical migration, specific taxa (e.g., Bosmina, Epischura, and Diaptomus) Display different behaviors depending on the site and season sampled. Also, analyzing the vertical and spatial concentration of macro- and microzooplankton, we found significant day-night differences across nearshore and offshore environments, demonstrating the complexity of their migration patterns with potential combined vertical and horizontal migration patterns. In short, day-to-night samplings need to occur in time and space to develop more accurate mean concentrations for different zooplankton taxa. This more accurate representation can then be used to assess the role of zooplankton on the lake?s water quality and clarity. Using seminatural experiments with lake water from the nearshore and offshore habitats, we observed minimal impacts of grazing by zooplankton on the finer particle fractions, which are known to control clarity. The higher zooplankton densities may influence the dissolved organic carbon and nutrient concentration within the water, which could affect the functional processes related to microbes and phytoplankton. Exploring the influence of zooplankton and the 4 contributions of organic carbon and nutrient cycling via similar experiments over time that capture the much higher densities we observed during the monitoring, combined with bioenergetic modeling to understand the role of zooplankton excretion processes on microbe or phytoplankton growth is warranted before making strong conclusions about the role of zooplankton on the ecosystem dynamics in the lake. This study reinforces the idea that zooplankton populations are largely heterogenous in Lake Tahoe in horizontal and vertical space and time, adding to a notion that relying on a few stations to characterize zooplankton in the lake may lead to erroneous conclusions about their dynamics (e.g., density, composition) and role in the lake. Specific methods that quantify the density and composition must also consider the mesh size, depth of plankton collections, and preservation methods. In addition, comparing traditional (microscopy) to modern tools (metagenomics for ciliates and rotifers) may allow for a more functional characterization of the role of zooplankton within the lake. Finally, experiments that quantify the influence of zooplankton coupled with monitoring of natural populations in space and time could allow for an understanding of the fate of particles in the presence of different larger and smaller zooplankton taxa or the role of zooplankton in driving pelagic processes like bacterial and phytoplankton growth. Information provided by the agent in SIGEVA