Nutritional quality of two cyanobacteria: How rich is 'poor' food?

Katrin Schmidt*, Sigrún H. Jónasdóttir

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Cyanobacteria have often been described to be nutritionally inadequate and to interfere with zooplankton feeding. In laboratory experiments we offered 2 cyanobacteria, a unicellular Microcystis aeruginosa strain and the filamentous Nodularia spumigena, to the calanoid copepod Acartia tonsa as the sole diet and in food mixtures with the nutritious diatom Thalassiosira weissflogii. Egg production was used as criterion of food quality. The use of cyanobacteria alone was an insufficient diet. However, with increasing additions of M. aeruginosa and N. spumigena to the diatom, different effects were observed. Large additions of cyanobacteria resulted in lower egg production and often in elevated mortality of the females, but small additions of M. aeruginosa caused an increase of about 25% in egg production compared to a pure diatom diet. The influence of similar low concentrations of N. spumigena was weaker. We suppose that in the mixtures A. tonsa fed passively on M. aeruginosa, but not on the filaments of N. spumigena, and that ingested M. aeruginosa were used metabolically. As an additional test of the positive interactions between M. aeruginosa and T. weissflogii, different ratios of these species were offered to the copepods, while keeping the total food concentration constant in mixtures egg production was higher than expected from the proportion of T. weissflogii. The highest egg production rates were observed at a 3:1 mixture of T. weissflogii to M. aeruginosa. We conclude that mono-specific food experiments may give a false impression of the nutritional quality of phytoplankton species. Cyanobacteria, which when feel alone prove to be poor food, may supplement the diet of A. tonsa.

Original languageEnglish
Pages (from-to)1-10
Number of pages10
JournalMarine Ecology Progress Series
Volume151
Issue number1-3
DOIs
Publication statusPublished - 22 May 1997
Externally publishedYes

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology

Keywords

  • Acartia tonsa
  • Calanoid copepods
  • Cyanobacteria
  • Egg production
  • Microcystis aeruginosa
  • Nodularia spumigena
  • Nutritional quality

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