Trends in total phosphorus and chlorophyll in Lake Erie: insights from two monitoring programs.

Session: 32. - Long-Term Monitoring: Achievements, Challenges, and Solutions

Courtney Winter, ORISE, EPA - GLNPO, [email protected]
Patrick Kocovsky, U.S. Geological Survey, [email protected]
Eric Osantowski, US EPA, GLNPO G-17J, [email protected]
Paris Collingsworth, Purdue University, US EPA, [email protected]

Abstract

The EPA Great Lakes National Program Office (EPA-GLNPO) has operated a continuous monitoring program focused on offshore waters throughout the Great Lakes since the early 1980’s.  One common critique of this program is that the EPA-GLNPO monitoring program lacks the temporal resolution necessary to characterize seasonal nutrient trends, particularly in a dynamic system such as Lake Erie.  To supplement the EPA-GLNPO monitoring program the Lake Erie Committee Lower Trophic Level Task Assessment (LEC-LTLA) has operated a nearshore monitoring program collecting samples bi-weekly since the late 1990’s.  Here, we compare trends in total phosphorus and chlorophyll in Lake Erie using data collected by both programs to provide a more complete picture of lower trophic level dynamics in the system.  The EPA-GLNPO and LEC-LTLA data sets are combined into a single time series showing basin-specific estimates for the three basins of Lake Erie.  Separate Bayesian statistical analyses were conducted for spring (March – May) and summer (August) surveys.  The results from the Bayesian analysis highlight any interannual differences in trends that are linked to environmental conditions such as tributary run-off and lake warming rates. 

1. Keyword
Lake Erie

2. Keyword
nutrients

3. Keyword
monitoring