The Northern Baltic Sea, off the southern coast of Finland, and Green Bay, off Lake Michigan in Wisconsin, both experience large toxic cyanobacteria blooms, especially during the summer and early fall months. Nodularia spumigena is the toxic algae in the Baltic Sea and produces the toxin Nodularin. Nodularin is a toxin that has branched from the toxin Microcystin, which is produced by Microcystis, the toxic algae forming blooms in Green Bay. While the toxin often acts as a defense mechanism to deter zooplankton from grazing, the calenoid copepod Eurytemora affinis, with populations in both the Baltic and Green Bay, does feed and consume these toxic algal cells and is able to survive. The consequences in terms of reproductive success from the consumption of this toxin are relatively unexplored. This study focuses on whether or not the two populations have similar responses to feeding on each of these toxic algae in laboratory studies. In both locations, the copepods were collected from the field and put through grazing experiments to examine their grazing and filtration rates in addition to their egg production in various food treatments. Both populations were able to feed and survive but had decreased egg production in a treatment consisting of a mixture of toxic algae and algae considered a good food source (Rhodomonas in Baltic experiments; Scenedesmus in Green Bay experiments). When exposed to the mixture of the good food source with the filtrate of the toxic algae, the Baltic population had a 43% decrease in survivorship, but egg production was comparable to that of the Rhodomonas control. The filtrate treatment had a 91% survivorship in Green Bay and nearly a double increase in egg production compared to the Scenedesmus control. This leads to the need for further investigation of the effects of the intracellular and intercellular toxins on both copepod populations.
Level of Honors
Bart De Stasio
Dwyer, Amanda, "Comparison of the Effects of Toxic Cyanobacteria on the Reproductive Success of Eurytemora affinis Populations in the Baltic Sea and Green Bay, Wisconsin" (2013). Lawrence University Honors Projects. Paper 34.