Document Type

Honors Project

Publication Date



Bythotrephes longimanus, also known as the spiny water flea, is an invasive planktonic crustacean in the Great Lakes. Bythotrephes competes with fish for smaller planktonic prey. We sampled southern Green Bay, WI during the summers of 2017 and 2018 to determine population structure and dynamics of zooplankton in this important body of water. The biomass of Bythotrephes in 2017 express high numbers in mid-June and experience a mid-summer crash in early-July. Biomass then began to rise steadily until reaching their peak in late-August and September. We observed this crash in biomass for Bythotrephes and Leptodora in both 2017 and 2018. Our data concludes a negative correlation between Bythotrephes and native herbivorous zooplankton species in the summer of 2017. During the summer of 2018, Bythotrephes first appeared in low numbers in June and increased slightly between late July and early August. By early September the population declined drastically while biomass of the native zooplankter Leptodora kindtii increased. It is hypothesized that juvenile Leptodora are also being preyed upon by Bythotrephes, leading to the reciprocal population dynamics between the years.

Level of Honors

cum laude




Bart De Stasio