Ten+Â years gone: Continued degradation of offshore planktonic communities in U.S. waters of Lake Erie's western and central basins (2003-2013)

Mounting evidence exists to indicate that Lake Erie is once again experiencing eutrophication. Such signs include increases in both the incidence of harmful algal blooms in the western basin and the re-emergence of large hypoxic areas in bottom waters of the central basin. Towards further assessing Lake Erie's health and the degree to which this ecosystem has become more eutrophic, we calculated a Planktonic Index of Biotic Integrity (P-IBI) for the western and central basins of Lake Erie during 2003-2013 and compared values to P-IBI values from previous periods of heightened eutrophy (1970) and the recovery from eutrophy (1995-2002). As expected, P-IBI scores in the eutrophic/hypereutrophic range (< 3) have predominated in both the western and central basins during 2003-2013. This decline in P-IBI scores (and hence, ecosystem health), however, has been more evident in the western basin than in the central basin.