کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4399370 1306733 2009 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Recent increases in the large glacial-relict calanoid Limnocalanus macrurus in Lake Michigan
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
Recent increases in the large glacial-relict calanoid Limnocalanus macrurus in Lake Michigan
چکیده انگلیسی

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.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Great Lakes Research - Volume 35, Issue 2, June 2009, Pages 285–292
نویسندگان
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