Relating crustacean zooplankton community structure to residential development and land-cover disturbance near Canadian Shield lakes

Abstract

We applied the land-cover cascade (LCC) concept to evaluate whether human disturbance affects crustacean zooplankton community in 13 nutrient-poor lakes of the Laurentian region along a gradient of residential development and land-cover disturbance. Zooplankton biomass responded indirectly to residential disturbances within the watershed based on path analysis. In most LCC models, total phosphorus enrichment was a strong intermediate element linking residential disturbances to increased biomass of small crustaceans ( Bosmina , Ceriodaphnia , and Diaphanosoma ) and Daphnia species ( D. g. mendotae , D. dubia , and D. ambigua ). Zooplanktivory index was also an intermediate element in LCC models of crustacean functional groups and an independent element in daphnid-based LCC models. Low zooplanktivory was associated with higher biomass of large Daphnia ( D. pulicaria and D. catawba ). However, residential disturbance and select environmental factors (phosphate enrichment, zooplanktivory index, lake depth, littoral macrophytes) explained only 42% and 57%, respectively, of among-lake variation in crustacean community and Daphnia assemblages. Variation partitioning analysis suggested that planktivory had a similar or greater influence than human disturbance and phosphate enrichment. Our study improves the knowledge of crustacean zooplankton responses to increasing residential development and land-use disturbances near Canadian Shield lakes.