Freshwater eutrophication drives sharp reductions in temporal beta diversity

Eutrophication has become one of the most widespread anthropogenic forces impacting freshwater biological diversity. One potentially important mechanism driving biodiversity changes in response to eutrophication is the alteration of seasonal patterns of succession, particularly among species with short, synchronous life cycles. We tested the hypothesis that eutrophication reduces seasonally driven variation in species assemblages by focusing on an understudied aspect of biodiversity: temporal beta diversity . We estimated the effect of eutrophication on by sampling benthic macroinvertebrate assemblages bimonthly for 2 years across 35 streams spanning a steep gradient of total phosphorus (P) and benthic algal biomass (as chlorophyll). Two widely used metrics of β diversity both declined sharply in response to increasing P and chl, regardless of covariates. The most parsimonious explanatory model for included an interaction between P and macroinvertebrate biomass, which revealed that was...