Large-amplitude cycles of Daphnia and its algal prey in enriched environments

E. McCauley, R.M. Nisbet, W.W. Murdoch, A.M. de Roos, William Gurney

Research output: Contribution to journalArticle

190 Citations (Scopus)

Abstract

Ecological theory predicts that stable populations should yield to large-amplitude cycles in richer environments1±3. This does not occur in nature. The zooplankton Daphnia and its algal prey in lakes throughout the world illustrate the problem4±6. Experiments show that this system its the theory's assumptions7±9, yet it is not destabilized by enrichment 6. We have tested and rejected four of ive proposed explanations 10. Here, we investigate the fifth mechanism: inedible algae in nutrient-rich lakes suppress cycles by reducing nutrients available to edible algae. We found three novel results in nutrient-rich microcosms from which inedible algae were excluded. First, as predicted by theory, some Daphniaedible algal systems now display large-amplitude predator-prey cycles. Second, in the same environment, other populations are stable, showing only small-amplitude demographic cycles. Stability is induced when Daphnia diverts energy from the immediate production of young. Third, the system exhibits coexisting attractors -a stable equilibrium and large-amplitude cycle. We describe a mechanism that flips the system between these two states.
Original languageEnglish
Pages (from-to)653-657
Number of pages5
JournalNature
Volume402
Issue number9
DOIs
Publication statusPublished - 19 May 1999

Keywords

  • daphnia
  • algal prey
  • large-amplitude cycles

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