FSML: New technology for measuring lower trophic levels in lakes

Cornell University, Ithaca NY

Investigators

Abstract

Spatial structure affects most ecological interactions in lakes and elsewhere, including predator-prey dynamics, primary production, algal blooms, and grazing by zooplankton. This facilities improvement proposal will add the capability to measure fine-scale spatial structure of algae and zooplankton in lakes to the available instrumentation at the Cornell Biological Field Station (http://www.cbfs.dnr.cornell.edu). The equipment that will be acquired are a laser optical plankton counter used to measure zooplankton from about 0.2 mm to 3 mm in length. This range includes most of the crustacean zooplankton in lakes. A fluoroprobe, that uses a set of different wavelengths of light to separate the contributions of several algal groups in the phytoplankton; a small research vessel to transport the fluoroprobe and optical plankton counter to different sites in the lake, and finally a FlowCam, a laboratory instrument that take pictures of particles in a sample and organize pictures using image recognition software. This automation allows many more samples to be processed than with standard microscopy techniques. These instruments will be used to evaluate the role of spatial structure in fish-zooplankton and grazer (zooplankton and mussels)-algae interactions in Oneida Lake and elsewhere, including the Great Lakes. The Cornell Biological Field Station has been involved with studies on the Oneida Lake ecosystem for over half a century and the resulting data set is one of the best long-term data sets reaching from nutrients to fish in a temperate lake in North America, if not the world. The new instruments will further improve the value of this data set and associated research projects. For more detailed spatial and temporal analyses of lower trophic levels, the acquisition of equipment to measure zooplankton, phytoplankton and dreissenid mussel distributions at a finer spatial scale than what is currently possible at the Cornell Biological Field Station at Shackelton Point is necessary. The needed equipment includes a new boat with hydraulics to conduct more frequent and detailed benthic sampling (including boat motor and trailer), a laser optical plankton counter for measuring zooplankton distributions, a fluoroprobe to measure group specific phytoplankton biomass, and a FlowCAM for more detailed taxonomic analyses of phytoplankton and smaller zooplankton. Although CBFS has been a leader in developing hydroacoustics for spatial analyses of fish interactions, equipment for similar analyses of lower trophic levels is lacking. The new instruments and an appropriate boat for their deployment would remedy this situation. Research at CBFS is primarily in two areas: 1) investigations of the ecology and fisheries of Oneida Lake, a 200 km2 shallow mesotrophic lake in central New York, and 2) studies of the spatial and temporal dynamics of Great Lakes ecosystems and how those dynamics affect ecosystem processes. Both areas of research rely on long term data sets collected and/or analyzed at CBFS to understand functional mechanisms and ecosystem services as impacted by ongoing ecological changes in these systems. The availability of these long term datasets makes CBFS one of only a handful of sites in the world where research questions about lake ecology can be framed in the context of the large time scales required to understand the impacts of perturbations such as invasive species and changing climate. Long-term studies of the ecological processes in natural systems are vital to society if we are to understand the dynamics of ecological disruptions, establish the mechanisms that influence these dynamics, and differentiate the influence of human activities from natural variability. Demand for use of the CBFS facility has increased and includes NSF funded and pending proposals, as well as research funded from various other sources. Broader impacts of CBFS activities include educational opportunities for visiting undergraduate and graduate students, an undergraduate intern program which partly focuses on under-represented minorities, connections with management agencies and advice on ecosystem fisheries management including participating in management committees, and a program for increasing use of Oneida Lake in the science curriculum for K-12 public schools in the area. All these broader impacts are ongoing and will continue for the duration of this project.