An Analysis of the Biotic Community in a Kumaun Himalayan Lake, Nainital (U. P.), India

Abstract

AbstractA comprehensive study of phyto‐ and zooplankton and macrozoobenthic components in Lake Nainital showed that species richness was high for plankton and low for macrozoobenthos. The algal biomass was dominated by greens (54 %) and blue‐greens (31 %), the zooplankton population by copepods (84 %), and the macrozoobenthic community by a Tubifex‐Chironomus association constituting≥95 % of the annual number of the macrobenthic invertebrates. Respiration (807.5g C m−2 year−1) surpassed gross production (630.5 g C m−2 year−1). The mean annual ratio between phyto‐ and zooplankton biomass is 3.3 and between phytoplankton and herbivores it is 4.6. If biomass is treated as a measure of crude production, the relationship among the three trophic levels suggests that herbivory is inefficient while carnivory is efficient, because part of the primary production remains unutilized by dominant herbivorous zooplankters, whereas Mesocyclops leuckarti, the sole carnivore, feeds efficiently on rotifers and juveniles of other copepods. The low diversity of different biotic components and the P/R ratio of less than 1 perhaps suggest that the lake is passing through the stage of heterotrophic succession.