Spatio-Temporal Organization of the Pelagic Food Web in Northern and Central Lake Huron in 2017

Session: 29. - Preliminary Results from the 2017 CSMI Intensive Field Year on Lake Huron

Joann Cavaletto, NOAA GLERL, joann.cavaletto@noaa.gov
Henry Vanderploeg, NOAA GLERL, Henry.Vanderploeg@noaa.gov
Ed Rutherford, NOAA Great Lakes Environmental Research Laboratory, ed.rutherford@noaa.gov
David Wells, CIGLR, wellsdj@umich.edu
Paul Glyshaw, University of Michigan CIGLR, pglyshaw@umich.edu
David Fanslow, NOAA - GLERL, dave.fanslow@noaa.gov
Gregory Lang, Great Lakes Environmental Research Laboratory, Gregory.Lang@noaa.gov

Abstract

We examined the pelagic food web during diel surveys in early and late May, July, and September along nearshore/offshore transects in oligotrophic Thunder Bay and off shore Saginaw Bay, MI. We sampled organisms using traditional and advanced tools including a plankton survey system (PSS), multiple opening closing environmental sampling system (MOCNESS), and a variety of plankton nets. In addition, algal class profiles with a Fluoroprobe were done at sites along transects. The PSS mapped fine-scale diel vertical distributions of temperature, light, turbidity, and zooplankton biomass. Broad-scale vertical distribution of zooplankton species obtained with nets combined with PSS data allowed description of fine-scale vertical distribution of dominant zooplankton species. MOCNESS and traditional plankton nets provided site and depth-specific estimates of fish larvae and Mysis density. At both Thunder Bay and off shore Saginaw Bay, zooplankton biomass was low and similar between areas. In late May, plankton densities were highest in the epilimnion. By September, plankton densities were highest within the metalimnion. Consistent with results from a prior CSMI survey in Lake Huron (2012), Daphnia exhibited diel vertical migration in late summer. Calanoid copepods are the dominant zooplankton group in Thunder Bay, however Cyclopoid copepods appear to have increased since CSMI 2012.

1. Keyword
Lake Huron

2. Keyword
plankton

3. Keyword
zooplankton

4. Additional Keyword
CSMI 2017

5. Additional Keyword
Plankton Survey System (PSS)