Limnology of Long Point Bay:

The water quality and ecological functioning of the Inner Bay are directly influenced by the limnological characteristics of Lake Erie and the quality of water and sediments entering from Big Creek. While Great Lakes wetlands have suffered some severe perturbations, the Inner Bay is unique in the Lower Great Lakes in that it does not receive point sources of pollutant loadings. Consequently, the Inner Bay has the highest water quality in nearshore Lake Erie.

The Inner Bay does however receive substantial quantities of diffuse-source nutrients and contaminants directly from Big Creek. Nutrient enrichment and the protected nature of the Bay have fostered the development of Long Point's extensive wetlands, thereby providing critically important habitat for waterfowl and fish. However, this has also contributed to the increased eutrophication of the Inner Bay. In extreme cases, increased eutrophication, or nutrient enrichment, causes algae to grow rapidly and the oxygen supply to be depleted. However, the combination of legislation to restrict phosphorus loadings, and the prolific filtering action of introduced zebra mussels (Dreissena polymorpha) have had a profound effect on the water quality of Long Point Bay and Lake Erie. Therefore, there is little threat that the Inner Bay will become over-enriched by the present level of Lake Erie water quality and nutrient inputs from Big Creek.

A large proportion of the contaminants that enter Long Point Bay do so directly through Big Creek. As the Big Creek watershed is primarily rural, wastes washed into Big Creek Marsh and Long Point Bay are primarily agricultural in nature. Consequently, the amount and type of contaminants entering the system are directly related to agricultural practices in the catchment. Elevated mercury, arsenic, lead, and manganese concentrations in the Big Creek Marsh are presumably associated with pesticide application in the catchment, the residues of which enter nearby tributaries and eventually, Big Creek and the Inner Bay. Once in the system, contaminants start to be transferred through trophic levels, ultimately becoming concentrated at often unhealthy levels in the fat and tissue of tertiary consumers such as birds. The introduction of zebra mussels with their prolific filtering capacities has drastically accelerated this process. Contaminants readily fuse to abiotic and biotic particles, and these particles are subsequently filtered/ingested by zebra mussels. The result is that mussels assimilate contaminants into their tissues, which in turn become readily available to higher level consumers such as waterfowl. This may be problematic for Lesser Scaup, Greater Scaup, and Buffleheads at Long Point, as they consume large quantities of zebra mussels.

The Outer Bay is deeper, colder and, compared to the Inner Bay, more strongly influenced by the hydrological conditions of Lake Erie than Big Creek. Therefore, while the Inner Bay is eutrophic, the Outer Bay is considered to be mesotrophic, and while the Inner Bay has been developed primarily for recreational activities, the Outer Bay has been the focus of localised industrial development.