Lake Ontario water quality during the 2003 and 2008 intensive field years and comparison with long-term trends

Aquatic Ecosystem Health & Management
By: , and 

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Abstract

Phosphorus loading declined between the 1970s and the 1990s, leading to oligotrophication of the offshore waters of Lake Ontario during that time period. Using lake-wide data from the intensive field years of 2003 and 2008 and from available long-term data sets on several trophic state indicators (total phosphorus [TP], soluble reactive silica [SRSi], chlorophyll a and Secchi disc transparency [SDT]), we tested the hypothesis that oligotrophication of the offshore waters of Lake Ontario has continued in the 2000s. Significant differences between 2003 and 2008 include higher spring (April) TP, SRSi, and SDT in 2008, lower summer (July–August) SDT in 2008, higher summer chlorophyll a in 2008, and lower fall (September) TP, SRSi, and chlorophyll a in 2008. The decline in SRSi from spring to summer was greater in 2008 than in 2003. Change point and regression analyses on the long-term data revealed no trend in spring TP since 1996, in summer chlorophyll a since 1994, in spring SDT since 1998, in spring SRSi or SRSi decline from spring to summer since 1999, or in summer SDT since 2001. Neither the comparison of the 2003 and 2008 surveys nor the analysis of the long-term data supported our hypothesis of continued oligotrophication of the offshore of Lake Ontario in the 2000s.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Lake Ontario water quality during the 2003 and 2008 intensive field years and comparison with long-term trends
Series title Aquatic Ecosystem Health & Management
DOI 10.1080/14634988.2015.1000787
Volume 18
Issue 1
Year Published 2015
Language English
Publisher Taylor & Francis
Contributing office(s) Great Lakes Science Center
Description 11 p.
First page 7
Last page 17
Country Canada, United States
Other Geospatial Lake Ontario
Online Only (Y/N) N
Additional Online Files (Y/N) N
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