The Daily Bulletin Archive

Please join the Great Lakes Center for the seminar "The Benthic Nepheloid Layer in the Great Lakes: What Is It, and Where Did It Go?" presented by Richard Barbiero, former senior environmental scientist at General Dynamics Information Technology, on Thursday, November 17, at 11:00 a.m. in Science and Mathematics Complex 172. All are welcome.

Abstract
The existence of near-bottom layers of increased turbidity (benthic nepheloid layers - BNLs) are a widespread and persistent feature of many regions of the ocean. Such regions have also been reported from the deeper parts of all five Laurentian Great Lakes; however, there have previously been no consistent comparative studies across all five lakes documenting their extent and magnitude. Neither has the potential impact of dreissenid colonization on BNLs been examined across all five lakes. Using long-term monitoring data from GLNPO’s water quality surveys, Dr. Barbiero's research has shown the BNL to be a consistent and extensive pre-dreissenid feature of the offshore, stratified waters of all Great Lakes except Lake Superior. In recent years, though, the BNL has been all but eliminated in all areas except for central Lake Erie, with reductions in bottom phosphorus also seen. Initiation of changes in the BNL almost invariably preceded the appearance of Dreissena in the offshore, suggesting that dreissenid impacts on the reductions in the BNL were largely remote. These post-invasion reductions in the BNL have the potential to alter both overall phosphorus dynamics in the lakes and competitive outcomes among benthic species.