The open waters of Lake Michigan are oligotrophic, and some near-shore areas are mesotrophic. Low nutrient levels, low biomass, high oxygen concentrations, and high transparency characterize oligotrophic lakes. These lakes are usually deep. Eutrophic lakes such as Spring Lake are highly productive with high nutrient levels, high biomass, low oxygen concentration in the bottom waters, and low transparency. The large volume of organic matter accumulated in bottom sediments depletes oxygen as it decomposes.
Mesotrophic lakes are between the other two trophic states in their characteristics.
The general flow of biomass in Lake Michigan is through trophic levels that include the producers, phytoplankton and aquatic plants, and consumers, zooplankton, forage fishes, predator fishes, and fish eating humans and other animals. Both webs are dependent upon the phytoplankton in the surface waters. Members of the pelagic food web include small invertebrates such as cladocerans and copepods. The biological integrity of the fish community that is dependent on pelagic and benthic species is no longer present. Increased pleasure and commercial fishing and human-induced environmental degradation have greatly altered the composition of fish species.