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The stoichiometry of dissolved organic carbon, nitrogen, and phosphorus release by a planktonic grazer, Daphnia
Author(s) -
Frost Paul C.,
Xenopoulos Marguerite A.,
Larson James H.
Publication year - 2004
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.2004.49.5.1802
Subject(s) - daphnia , dissolved organic carbon , daphnia magna , phosphorus , environmental chemistry , cladocera , plankton , branchiopoda , ecological stoichiometry , nitrogen , biology , chemistry , ecology , nutrient , zooplankton , toxicity , organic chemistry
We examined the relationship between Daphnia release rates and ratios of dissolved organic carbon (DOC), nitrogen (N), and phosphorus (P) and the elemental composition of algal food. We constructed a three‐element (C, N, and P) mass‐balance model to explore the relationships between food elemental composition and Daphnia release of DOC, N, and P. The model predicts that Daphnia DOC:N and DOC: P release ratios will increase with increasing food C:N and C: P ratios, respectively. These effects on DOC:N and DOC: P ratios are dependent, however, on the availability of the third element (P and N respectively) in our model. In addition, we experimentally measured the mass‐specific release of DOC, ammonia (NH 4 ), and soluble reactive phosphorus (SRP) from Daphnia magna fed food of contrasting C:N: P ratios. Daphnia release rates of DOC were not significantly affected by algal C:N or C: P ratios. However, high C:N and C: P ratios in algal food raised the DOC:NH 4 and DOC:SRP ratios (respectively) released from Daphnia . Our results, experimental and modeling, show a strong dependence of DOC: N and DOC: P release ratios by Daphnia on food C:N and C: P ratio. Thus, elevated C:N or C: P ratios in food can cause imbalanced release of DOC and NH 4 or SRP, respectively, by Daphnia with potentially strong feedback on microbial heterotrophs in planktonic food webs.