Abstract

Invertebrates make up a large part of the world's biological diversity and perform essential ecological functions. Many invertebrates are under threat of extinction due to extreme transformations of habitats. Crayfish are one such threatened invertebrate. Crayfish are keystone species in many freshwater systems. Keystone species are those species most important in shaping the ecology of a system. Crayfish are an important resource for many animals and affect species diversity and abundance. Specifically, crayfish can adversely affect ecosystems by removing plants, making the water turbid. They also prey on fish eggs reducing their numbers. There are 415 species of crayfish in North America of which eight are found in Michigan. We examined crayfish biodiversity and distribution within the Grand River system. Our study identified three species of crayfish and the invasive zebra mussel that could alter crayfish populations.