Recent increases in the large glacial-relict calanoid Limnocalanus macrurus in Lake Michigan

Journal of Great Lakes Research
By: , and 



Since 2004, population density of the large hypolimnetic calanoid Limnocalanus macrurus Sars. has increased dramatically in Lake Michigan. The average summer biomass of this species between 2004 and 2006 was roughly three times that of the period 1984–2003, and at levels unprecedented in our 22-year dataset, making L. macrurus the dominant zooplankter in the lake in terms of biomass. These increases have been accentuated by coincident population declines of the main daphnid, Daphnia mendotae, in the lake with the result that in 2006, L. macrurus accounted for 75% and 50% of the large (> 0.9 mm) crustacean biomass in the northern and southern basins of Lake Michigan, respectively. The increases in L. macrurus populations have closely coincided with equally dramatic increases in summer water clarity. Recent extinction coefficients are among the lowest recorded for the lake, and deepening light penetration has permitted increases in the size of the deep chlorophyll layer. In addition, planktivorous fish populations have declined coincidently with the increases in L. macrurus. It seems likely that an increase in sub-epilimnetic production has resulted in increased food resources for the deep-living L. macrurus, while low planktivore abundances have reduced predation loss, permitting L. macrurus to respond to these increases in sub-epilimnetic production.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Recent increases in the large glacial-relict calanoid Limnocalanus macrurus in Lake Michigan
Series title Journal of Great Lakes Research
DOI 10.1016/j.jglr.2008.12.006
Volume 35
Issue 2
Year Published 2009
Language English
Publisher Elsevier
Contributing office(s) Great Lakes Science Center
Description 8 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Great Lakes Research
First page 285
Last page 292
Country United States
Other Geospatial Lake Michigan
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