A stoichiometric analysis of the zooplankton-phytoplankton interaction in marine and freshwater ecosystems

• Published in: Nature (London) 1994-07, Vol.370 (6486), p.211-213
• Main Authors: Elser, James J, Hassett, R. Patrick
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Aquatic ecosystems; Aquatic habitats; Biological and medical sciences; Ecosystems; Freshwater ecosystems; Fundamental and applied biological sciences. Psychology; General aspects; Humanities and Social Sciences; letter; Marine ecosystems; multidisciplinary; Phytoplankton; Plankton; Science; Science (multidisciplinary); Synecology; Zooplankton
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/370211a0

IN the 35 years since A. C. Redfield's classic paper 1 , the use of elemental ratios has become widespread in marine and freshwater phytoplankton studies 2,3 . But nutrient ratios have only recently been studied elsewhere in pelagic ecosystems, such as the producer-consumer interface 4,5 . Here we report the results of the first study, to our knowledge, of N:P ratios in pelagic producers and consumers (phytoplankton and zooplankton) in lacustrine and marine habitats. The N:P ratio of phytoplankton was higher in lakes than in marine sites; however, N:P ratios were higher in marine zooplankton than in freshwater zooplankton. The elemental imbalance of the phytoplankton–zooplankton interaction (N:P food –N:P consumers ) in lakes was positive and exceeded the negative imbal-ance in marine sites; thus P-deficient food may limit zooplankton growth in lakes but not in oceans. Stoichiometric calculations 6 indicated that consumer-driven nutrient recycling ratios in lakes may be 4–6 times higher than in marine systems. Consistent with this difference, phytoplankton P-limitation was more prevalent in lakes than in marine sites. Thus, the ecological stoichiometry of the zooplankton–phytoplankton interaction differs qualitatively in freshwater and marine ecosystems.