OTHER: Trophic Dynamics of a Changing Zooplankton Community

密歇根湖正受到一种新来的捕食者的入侵。1984年12月，在劳伦斯五大湖中首次发现了白纹伊蚊。到1986年8月，这种物种已经蔓延到密歇根州南部湖，而且每10天数量就会翻一番。Bythotrephes正在咄咄逼人地入侵，特别是在近海地区，但到目前为止，它们正在避开冰川残存物种占据的栖息地。作为加入现有群落的入侵浮游生物物种，这是研究中等营养层食物链操纵的难得机会。从它在欧洲深湖中的持久性和成功来看，Bythotrephes很可能成为近北区浮游动物群落的永久成员。这项建议试图研究这种社区级扰动的营养动态，跨越近岸和近海区域之间的物理和生态梯度。

Lake Michigan is being invaded by a predator new to the Nearctic. Bythotrephes cederstroemii, was first found in the Laurentian Great Lakes in December, 1984. By August 1986, the species had spread to Southern Lake Michigan, and was doubling in abundance every 10 days. Bythotrephes is invading aggressively, particularly in the offshore region, but is so far avoiding habitats occupied by glaciomarine relict species. As an invading plankton species joining an existing community, it represents a rare opportunity to study manipulation of a food web at the middle trophic level. Judging from its persistence and success in deep European lakes, Bythotrephes will probably become a permanent member of zooplankton communities in the Nearctic. This proposal seeks to study the trophic dynamics of this community-level perturbation across the physical and ecological gradients between inshore and offshore regions.