Regulation of rotifer densities by crustacean zooplankton in an oligotrophic montane lake in British Columbia
- Institute of Animal Resource Ecology and Department of Zoology, The University of British Columbia, V6T 1W5, Vancouver, B.C., Canada
To examine the relative demographic effects of predation and competition for food in rotifers during spring and summer in an oligotrophic lake, predator and competitor densities and food supplies were experimentally altered inside large enclosures. Abundances of rotifer species were positively correlated with experimental densities of fourth instar Chaoborus trivittatus larvae, a major crustacean predator in 1976. Experimental alteration of the densities of Daphnia rosea and Diaptomus leptopus and D. kenai in 1978 produced highly significant increases in rotifer biomass only under Daphnia removal, but not under copepod removal. Inorganic fertilizer additions to enclosures in 1978 and 1979 revealed minimal rotifer increases unless pulsed additions were large or Daphnia were also excluded. Large demographic reponses of rotifers to low fertilizer loadings in the absence of Daphnia confirmed the pre-eminence of competitive food limitation in producing rotifer scarcity in summer.
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences biologiques fondamentales et appliquees. psychologie
- 4 - vecteurs d'importance medicale, nuisances, depredateurs des denrees et materiaux: surveillance des populations et lutte
- 1 - Life Sciences ; 2 - Agricultural and Biological Sciences ; 3 - Ecology, Evolution, Behavior and Systematics