Protection & Restoration of Ecosystem Services
MOCNESS in the Great Lakes: Gear Efficiency Comparisons and Estimates of Fine-Scale Vertical Spatial Structure of the Food Web
Overview and Objectives
CILER will support NOAA-GLERL in the use of the MOCNESS sampling gear to selectively sample fine-scale (<5 m) vertical structure of the water column to capture densities and food web interactions of the lower food web in Lake Michigan. Gear efficiency tests also will be conducted to compare catches of plankton in the MOCNESS with those collected with traditional gears.
Recent studies at NOAA-GLERL (Vanderploeg et al. 2015) have shown that there is extreme diel vertical migration of zooplankton, micronekton, and fishes, and their densities are highly concentrated in relatively thin layers associated with thermal structure and phytoplankton concentrations that can be sampled well only by new technology. Despite extensive sampling of the food web by traditional methods, critical nagging questions remain regarding vertical position and movement of zooplankton, Bythotrephes, Mysis, larval fish, and fish predators relative to light, temperature, and chlorophyll. Precise definition and quantification of spatial structure and density are critical to understanding food web structure and function, and for ecosystem forecasting. New sampling equipment is needed to sample the food web at fine horizontal and vertical scales. To address this gap in our understanding of the spatial distribution of lower food web organisms, the MOCNESS (Multiple Opening Closing Nets Environmental System Sampler) was purchased by NOAA-GLERL to sample fine-scale (<5 m) vertical and horizontal distributions of mesozooplankton, Bythotrephes, and micronekton including Mysis and larval fishes.
In FY 15, the expected outcomes were to set up, test and operate the MOCNESS system, and conduct efficiency studies. Other expected outcomes included seasonal MOCNESS sampling of the Lake Michigan food web to contribute to the EcoDyn Spatial Structure study. We were able to acquire, set up and use the MOCNESS, but didn’t test it because of a faulty depth sensor. In FY16, a reliable pressure sensor will be used and gear efficiency tests will be conducted to incorporate MOCNESS into EcoDyn science studies.
Vanderploeg, H.A., D.B. Bunnell, H.J. Carrick, and T.O. Höök. 2015. Complex interactions in Lake Michigan’s rapidly changing ecosystem. Journal of Great Lakes Research 41 (Supplement 3):6 (DOI:10.1016/j.jglr.2015.11.001).