| Autor: |
Elliot W. Jackson, John T. Lehman, Jonathan P. Doubek, Jeffrey S. Schaeffer |
| Rok vydání: |
2013 |
| Předmět: |
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| Zdroj: |
Journal of Great Lakes Research. 39:404-408 |
| ISSN: |
0380-1330 |
| Popis: |
Reported population biomass of Limnocalanus macrurus in Lake Huron has been underestimated by several-fold owing to application of an inappropriate length–weight regression model. During August and September the underestimates can exceed three-fold, suggesting that secondary production of the species in the lake is greater than previously thought. Increased representation of the species in the plankton community in recent years is associated with a decrease in its trophic level deduced through nitrogen stable isotope analysis of specimens from opportunistic samples obtained in 1993, 1995, and 2009. Limnocalanus 15 N enrichment relative to primary herbivores appears to have decreased by 1.5‰ over this time period. Similarly, Diaptomus 15 N enrichment relative to primary herbivores appeared to decrease by 1.1‰ from 1993 to 2009. Our data offer at least two possible explanations for this shift. (1) Limnocalanus has adopted a more herbivorous diet in response to the ecological changes in Lake Huron or (2) hypolimnetic Diaptomus have adopted a more herbivorous diet and Limnocalanus is relying in part on Diaptomus as a food source. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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