Temporal β-diversity of zooplankton at various time scales in a small mountain lake

To examine how compositional changes in a community vary depending on time scales, we estimated temporal β-diversity of zooplankton in Lake Hataya Ohnuma, a small lake in Yamagata, Japan. The zooplankton community was monitored for 9 years with monthly samplings. We estimated the inter-annual, inter-seasonal, intra-seasonal, and inter-month β-diversity with the magnitude of sampling errors, and examined relative contributions of these time scales on changes in the zooplankton community structure. The temporal β-diversity was high at the inter-seasonal scale than at the intra-seasonal and inter-annual time scales, suggesting that taxonomic turnover in the zooplankton community was regulated by seasonally changing parameters such as water temperature. Indeed, the temporal β-diversity is related significantly to water temperature, although no significant relationship was detected between the temporal β-diversity and chlorophyll-a concentrations. In addition, the large inter-month β-diversity with significant inter-annual β-diversity indicated that the phenology of the zooplankton community changed depending on years, especially before and after 2012. These results indicate that temporal β-diversity is a useful gauge for detecting phenological changes and for quantifying the temporal stability of plankton communities at various time scales.