Linking zooplankton richness with energy input and insularity along altitudinal and latitudinal gradients

Abstract

AbstractAltitudinal and latitudinal gradients are excellent venues for investigating the direct and indirect effects of air temperature, solar irradiance, and insularity on spatial patterns of aquatic biodiversity. The findings can be used to predict how lake communities will respond to increasingly extreme climate events. We explored hypotheses of energy/climate, geography, and glacial history explaining patterns in species richness in a historical dataset of crustacean zooplankton communities from 436 lakes in the Canadian Rocky Mountains. GIS‐based estimates of solar and thermal energy inputs combined with habitat area and insularity provided the best prediction of local species richness. Energetic and geographic factors explained a moderate proportion of the total variation in species richness (Generalized R2 = 0.50), and were sufficient to account for both altitudinal and latitudinal gradients in zooplankton diversity. History of deglaciation was not supported as a predictor of patterns in species richness. A post hoc analysis with a smaller dataset also found strong support for lake pH, and some support for fish presence as predictors of species richness, but these only increased the proportion of the total variation explained very slightly relative to the model including only energetic and geographic factors (Generalized R2 = 0.55 vs. 0.53). Our findings highlight the multiplicity of local and regional factors of zooplankton species richness in mountain lakes, forecasting that it will increase under a scenario of warmer and drier (i.e., less cloud cover) conditions, especially in high connectivity lakes that cease to be fed by rapidly disappearing glaciers.