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Nutrients and the Great Lakes Nearshore, Circa 2002-2007
Citation:
KELLY, J. R. Nutrients and the Great Lakes Nearshore, Circa 2002-2007. In Proceedings, SOLEC, Niagara Falls, ON, CANADA, October 22 - 23, 2008. US Environmental Protection Agency, Cincinnati, OH, 49-56, (2009).
Impact/Purpose:
Nearshore nutrient impressions were largely limited to observations of local spatial trends from a few site-specific studies and some temporal trends at a set of Canadian water intake locations (later summarized in Nicholls et al. 1999). Lacking a systematic information base for the nearshore, Edsall and Chartlton (1997) used data from existing open water surveillance and monitoring programs (Environment Canada [EC] and U.S EPA Great Lake National Program Office [GLNPO]) to describe decadal trends in the lakes leading up to the mid-1990s.
Description:
Nearshore nutrient impressions were largely limited to observations of local spatial trends from a few site-specific studies and some temporal trends at a set of Canadian water intake locations (later summarized in Nicholls et al. 1999). Lacking a systematic information base for the nearshore, Edsall and Chartlton (1997) used data from existing open water surveillance and monitoring programs (Environment Canada [EC] and U.S EPA Great Lake National Program Office [GLNPO]) to describe decadal trends in the lakes leading up to the mid-1990s. Their impressions of the mid-1990s included the following related to the nearshore: (1) Nutrients and chlorophyll tended to be elevated closer to shore and decrease moving offshore. (2) Exceedance of TP guidelines (10 15 ìg/L) were noted in Lake Ontario (nearshore) and Lake Erie (nearshore and offshore). (3) The levels of nearshore chlorophyll a relative to Total Phosphorus (TP) were low after dreissenid mussel infestation (which occurred in late 1980s in Lake Erie, thereafter in other lakes), compared to observations at those same locations pre-mussel invasion. (4) Long-term declines in TP and chlorophyll at shallow ( ~3-17 m) water intake stations were evident for all the lakes from the 1970s through the late 1980s. Some chlorophyll declines may have continued into the 1990s, whereas further TP declines were less apparent. (5) The reappearance of the attached benthic (bottom-dwelling) alga Cladophora in shallow waters was being noted in the mid/late 1990s. Cladophora was a problem in former decades, prior to P abatement, when excessive growth and later drift to shorelines lead to widespread problems of beach fouling/odor. This chapter revisits these themes, using recent information. As initial background for SOLEC 2008, this is not an exhaustive review, but intended to capture the flavor of conditions in the nearshore in the current decade.
