CBFS graduate student Toby Holda, working with Watkins, Rudstam, Boynton from CBFS, and collaborators from EPA (Scofield), Univ Michigan (Jude), NOAA (Pothoven), USGS (Warner, O’Brien) and DFO Canada (Currie, Bowen), analyzed the abundance patterns of mysid shrimps in all five of the Laurentian Great Lakes from 1990s to 2019. This analysis was published this year in the Journal of Great Lakes Research (49:1179-1189). Holda and colleagues show that mysid abundance is related to food resources but that low abundances in two lakes, Lake Huron and Erie, are likely due to higher predation rates on mysids. Mysids are an up to 25 mm long freshwater crustacean, also known as the opossum shrimp because it carries young in a brood pouch for as long as months. It is the largest of the freshwater zooplankton in the Great Lakes and can contribute up to 30% by weight of zooplankton biomass. The species is a major prey of fish, but also a predator on other zooplankton. It migrates from the bottom of the lakes to the water column each night and are therefore sampled by nets at night. The importance of this species is highlighted by a new ecosystem indicator of mysid shrimps for the State of the Great Lakes by US EPA and Environment Canada. This indicator will be based on Holda’s work and the information from the Great Lakes program at CBFS led by Jim Watkins.
Holda, TJ, JM Watkins, AE Scofield, SA Pothoven, DM Warner, TP O'Brien, KL Bowen, WJS Currie, DJ Jude, PV Boynton, and LG Rudstam. (2023). Intra-lake trends and inter-lake comparisons of Mysis diluviana life history variables and their relationships to food limitation. Journal of Great Lakes Research 49:1179-1189.
