Lipid concentrations of Bythotrephes cederstroemi were compared among three Great Lakes, Erie, Huron, and Michigan, in an effort to investigate the phenotypic plasticity in size displayed among the lakes. Four developmental stages were measured in Lakes Erie and Huron and two stages were studied in Lake Michigan. With a gravimetric extraction method, the total lipid concentration range (μg lipid μg dry weight−1, expressed as percent) for Bythotrephes was estimated to be 10–19%. Statistically significant differences were found in lipid concentrations of Bythotrephes among lakes and developmental stages. Lake Erie had significantly higher lipid concentration values than Lake Huron for stages 2 through 4, and had similar values to Lake Michigan for the analyzed stages 1 and 4. The first instar had indistinguishable lipid concentrations among Lakes Erie, Huron, and Michigan. Even though animals from Lake Erie were significantly smaller, the data suggest that they were not less well nourished. We hypothesize that selective mortality imposed by visual predators on larger Bythotrephes and the lack of deep water refuges in Lake Erie has encouraged the smaller size of Bythotrephes found there in comparison to those found in Lakes Huron and Michigan.
- lipid concentration;