Physical, Chemical, and Biotic Effects on Arctic Zooplankton Communities and Diversity

We examined how physical and chemical factors and fish populations affected the presence and density of zooplankton species in 104 Alaskan arctic lakes. Five fish species and nine zooplankters were sampled from the lakes. Lakes depth was related to the distribution of zooplankton in that smaller zooplankton species were found in deep lakes and large species in shallow lakes. Neither ionic strength nor chlorophyll was a major factor in zooplankton presence or absence. When fish were present, few, if any, very large zooplankton occurred together. However, the relationship between the presence and density of smaller-sized zooplankton species and the presence of specific species of fish was complex and did not fit anticipated patterns. The diversity of zooplankton in these arctic lakes was not related to chemistry of fish distribution, but species richness increased with increasing lake area and depth. For a few zooplankters (notably Holopedium gibberum), the fraction of lakes containing the zooplankter varied by region.