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Phosphorus limitation in Daphnia: Evidence from a long term study of three hypereutrophic Dutch lakes
Author(s) -
DeMott William R.,
Gulati Ramesh D.
Publication year - 1999
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1999.44.6.1557
Subject(s) - seston , bosmina , daphnia , abundance (ecology) , zooplankton , biomanipulation , ecology , biology , branchiopoda , phytoplankton , detritus , lake ecosystem , cladocera , environmental chemistry , environmental science , nutrient , ecosystem , chemistry
The Loosdrecht lakes comprise three shallow, interconnected hypereutrophic lakes in The Netherlands. A lake restoration project conducted during the 1980s resulted in reduced phosphorus loading. However, no changes in phytoplankton abundance or species composition were noted, although seston carbon:phosphorus (C:P) ratios increased. Filamentous cyanobacteria and detritus continued to dominate the seston. Moreover, planktivorous fish were very abundant. Relationships between zooplankton abundance and seston abundance and stoichiometry (C:P and carbon:nitrogen ratios) were analyzed using data collected during 9 yr of intensive study of the three lakes. Analysis based on annual means shows surprisingly strong and consistent inverse relationships between Daphnia abundance and the seston C:P ratio for two of the three lakes. In these two lakes (Loosdrecht and Vuntus Lakes), the annual mean abundance of Daphnia cucullata ranged from 104 to 0.7 individuals L −1 over a range in mean seston C:P ratios from about 250 to 500 (molar). In the third lake, Breukeleveen, Daphnia abundance was higher for a given seston C:P ratio, especially during the 2 yr following a biomanipulation project in this lake. Analysis of seston C:P ratios and Daphnia abundance in individual samples provides further evidence that high seston C:P ratios constrained Daphnia abundance in all three lakes. In contrast to Daphnia , the abundances of zooplankters with low P requirements, including Bosmina spp. and cyclopoid copepods, show little relationship to seston C:P ratios. These results suggests that the abundance of Daphnia in the Loosdrecht lakes was determined by the variable P content of their diets and consistently strong fish predation.