Inner Long Point Bay is one of the most important waterfowl staging areas in North America, and provides essential fish spawning and nursery habitat as well as recreational and economic opportunities (see Chapter 8). This can be attributed to the fact that the Bay is shallow (mean depth of 1 m), supports dense stands of submergent and emergent vegetation (Wilcox and Knapton 1994) and is protected from destructive wave energy by the Long Point spit and a sandbar that extends from Pottohawk Point almost to Turkey Point. 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 (Leach 1981). However, the water quality and ecological functioning of the Inner Bay is directly influenced by the amount and type of suspended load carried by Big Creek as well as the water quality of Lake Erie. Dedrick Creek and Forestville Creek also drain into the Inner Bay but have substantially smaller watersheds than Big Creek. More recently, the prolific filtering action of introduced zebra mussels (Dreissena polymorpha) has had a profound effect on the water quality of Long Point Bay and Lake Erie.
Due to the fact that Big Creek primarily drains directly into Inner Long Point Bay (Figure 1.1), Big Creek Marsh retains only a portion of the nutrient and contaminant load transported by Big Creek. The resultant diffuse-source suspended load transported from the Big Creek drainage basin into the Inner Bay can be substantial (Stone et al. 1991). While fostering the development of extensive wetlands, this nutrient enrichment and the protected nature of the Bay have contributed to the eutrophication of the Inner Bay (Berst and McCrimmon 1966; Leach 1981). Consequently, an increase in the suspended nutrient or contaminant load from Big Creek could substantially alter the ecology of the Inner Bay. Despite the shallow depth and abundance of macrophytes in the Inner Bay, dissolved oxygen appears to be adequate in summer; this has been attributed to thermal stratification and macrophyte photosynthesis (Leach 1981). The water levels in the Inner and Outer Bay fluctuate closely with the annual, seasonal and short term changes in Lake Erie (Berst and McCrimmon 1966) and this flushing action, much like in Big Creek Marsh, is necessary to sustain wetland productivity (Ball 1985; Kaminski et al. 1989; Neill 1990).
The Outer Bay is deeper, colder and, relative to the Inner Bay, more strongly influenced by the hydrological conditions of Lake Erie than Big Creek. Consequently, the water in the Outer Bay has a lower chlorophyll a standing crop, a lower total phosphorus content, and a higher secchi disc transparency, all indicating that it is less productive than the Inner Bay (Leach et al. 1977). 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. The Nanticoke industrial complex was developed on the northeast shore of the Outer Bay in the early 1970s (Figure 1.1). The Ontario Hydro Thermal Generating Station, the Stelco Steel Mill, and the Imperial-Esso Oil Refinery have been established at Nanticoke. This industrial development has somewhat increased the thermal, contaminant and nutrient loading of the Outer bay (Haymes and Dunstall 1989).