Exotic marine algae blooms in Great Lakes

In late summer 2003, researchers at MSU first observed nuisance levels of macroalgae blooming in Muskegon Lake (W43.23 N86.29), a coastal water body of Lake Michigan. Upon further inspection, this algae was identified as Enteromorpha, an exotic marine algal genus. The algae covered 5-70% of the littoral zone in Muskegon Lake, and was later found washed up on the shoreline (see photos below).

Two Enteromorpha subspecies were identified:

	E. flexuosa subsp. flexuosa		E. flexuosa subsp. paradoxa
	cells arranged in longitudinal rows unbranched (<0.5 cm broad)		branched, microscopic branches uniseriate at tip
4X
20X
40X
100X

Regionally, this algae has subsequently been observed in Mona Lake (~6 km to south) and White Lake (~16 km to north). All sites where Enteromorpha were observed have experienced a high level of industrial activity and currently have hazardous waste sites (Part 111, Michigan's Natural Resources and Environmental Protection Act, 1994 PA 451) in their watersheds.

We found low epiphytic diatom densities on Enteromorpha, which is a concern in systems where epiphytic diatoms may be important components of the food web.

Epiphyte load on Cladophora (left) compared to Enteromorpha (right).

(Lougheed, V.L. and Stevenson, R.J. 2004. Exotic marine algae reaches bloom proportions in a coastal lake of Lake Michigan. Journal of Great Lakes Research. 30(4):538-544).

For more information contact: Vanessa Lougheed (vlougheed@utep.edu).