Lipid content of Mysis diluviana in the offshore region of southeastern Lake Michigan in 2009–2010

The lipid content of Mysis diluviana in the offshore region of southeastern Lake Michigan was determined in 2009 and 2010. Total lipids (mg) increased with Mysis length, but percent lipids (% dry weight) did not. Increases in lipids for juveniles (< 10 mm) were related to increases in structural lipids (i.e., phospholipids and sterols), whereas increases in total lipids for adults were related to increases in storage lipids (i.e., triacylglycerols). Percent lipids varied seasonally, and were in general, highest in spring or late fall for juveniles and small adults (< 15 mm). For the largest adults (16+ mm), % lipid content did not vary much over the year in 2009, but in 2010, % lipids peaked in July. The rate of lipid retention differed among cohorts of juveniles, but it did not differ among cohorts of adults. In 2009 and 2010 respectively, 14% and 40% of Mysis > 13 mm had lipid content < 14%, a value associated with a high percentage of docosahexaenoic acid that may reflect starvation for this size of Mysis. Food availability (chl a levels or zooplankton biomass) was not correlated with Mysis lipid content for any size group of Mysis. Seasonal gradients in food availability might not be large enough to elicit strong responses in lipid content of Mysis.

► Total lipids (mg) increased with Mysis length, but percent lipids did not.
► Increases in lipids for juveniles were related to increases in structural lipids.
► Increases in total lipids for adults were related to increases in storage lipids.
► Food availability was not correlated with Mysis lipid content.
► 14–40% of adult Mysis had lipid content that may reflect starvation conditions.