UC Santa Barbara

Horizontal distribution patterns of three trophic levels were investigated at Mono Lake, California, USA during the autumns of 1980 and 1981. Coefficients of variation for Anemia monica and grebes peaked in October of both years, whereas coefficients of variation for phytoplankton declined from August to November. Stable population gradients were observed in the Anemia population. In contrast, grebes were very mobile and their distributional patterns changed between sampling dates. Anemia and phytoplankton were negatively correlated during 1980, but no significant correlations occurred in 1981. Grebes and Artemia were positively correlated in October 1980 and 1981, suggesting active prey tracking by the grebes. Interactions between trophic levels may have contributed to the creation and maintenance of patchiness, although these effects appeared to be intermittent. © 1986 IRL Press Limited.