Funding Program: Contaminant Biology

Statement of Problem: Early life stage mortality in salmonines of the Great Lakes continues to be problematic. Thiamine deficiency, related to the thiaminase content of planktivorous alewives, has been causally linked to early-life stage mortality. The factors responsible for spatial and temporal differences in thiaminase in the food web that influence thiaminase in alewives are unidentified. This project is designed to assess the dynamics of planktonic thiaminase and determine the risk of current levels to juvenile lake trout.

Objectives: Primary Invasive Species goal: (6)Determine effects of invasive species and susceptibility of habitats to invasions (Effects Goal) Secondary FAER Goal: Quantify and describe functional relationships among aquatic species and habitats to provide information to conserve or restore aquatic community structure and function. Major changes in the food webs of the Great Lakes have occurred over the past two decades. Among the many factors involved, numerous non-native species have become established, concentration of inorganic phosphorus has declined, and climate change has altered the Great Lakes aquatic environment. Especially the increase in non-native species has resulted in significant alteration of nutrient dynamics in lake food webs resulting in a greater occurrence of blue-green algae. Blue-green algae are known to produce thiaminase and may represent an important source of thiaminase in the Great Lakes. Our hypothesis is that these changes in the food web have lead to an increase in thiaminase and as a result, impacts on salmonines. We will address this hypothesis by investigating the following questions: 1. Are spatial and temporal trends in zooplankton thiaminase associated with biological, physical or chemical limnological variables? 2. Does dietary thiaminase within the range observed in zooplankton pose a risk to the survival of juvenile fish?