Limnocalanus macrurus (Copepoda: Calanoida) retains a marine arctic lipid and life cycle strategy in Lake Michigan
Limnocalanus macrurus , an omnivorous calanoid copepod with strong carnivorous tendencies that invaded fresh water during the Pleistocene glaciation, retains a marine arctic lipid and life cycle strategy in the hypolimnion of Lake Michigan. Its maximum lipid concentration of 67% of dry mass—consisti...
| Published in: | Journal of Plankton Research |
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| Main Authors: | , , , |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
1998
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| Subjects: | |
| Online Access: | http://plankt.oxfordjournals.org/cgi/content/short/20/8/1581 https://doi.org/10.1093/plankt/20.8.1581 |
| Summary: | Limnocalanus macrurus , an omnivorous calanoid copepod with strong carnivorous tendencies that invaded fresh water during the Pleistocene glaciation, retains a marine arctic lipid and life cycle strategy in the hypolimnion of Lake Michigan. Its maximum lipid concentration of 67% of dry mass—consisting largely of wax esters—is the highest reported for freshwater zooplankton and is among the highest reported for marine polar species. The high lipid concentration of L.macrurus runs counter to the paradigm that high wax ester concentrations are found in herbivorous, but not in carnivorous, polar species. Lipids are drawn down to extremely low levels (10% of dry mass) during the reproductive period, November–May. Reproduction in this univoltine species appears to be timed so that the new generation develops during the high abundance of prey (crustacean microzooplankton and net phytoplankton) in spring. A high wax ester content may allow egg production to start in winter when the prey concentration is low. In contrast to many polar species, the new generation moves through all copepodid stages to adult without diapausing. Copepodid 5 females have a low lipid concentration, and lipids are slowly built up in new generation adults during summer and fail before reproduction commences. This lipid and life cycle strategy may have given L.macrurus an advantage over potential freshwater competitors, such as the arctic freshwater cyclopoid copepod Cyclops scutifer , in the hypolimnia of glaciated lakes. |
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