Flow-related disturbances in forested and agricultural rivers: Influences on benthic macroinvertebrates

Abstract

Flow disturbances and conversions of land-use types are two major factors that influence river ecosystems. However, few studies have considered their interactions and separated their individual effects on aquatic organisms. Using monthly monitoring data from two streams with different land-use types (i.e. forest and agriculture) in the subtropical Central China over three years, we accurately predicted the changes of macroinvertebrate communities under flood disturbances and land-use type conversions. The dominant taxa and main community metrics significantly declined following flash floods. Several mayflies and chironomid had rapid rates of recovery, which could reach high abundance in three months after floods. And most of the community metrics recovered more rapidly in the forested river than that in the agricultural river. Stepwise multiple regression (SMR) models were used to investigate the relationships between biotic metrics and hydrological and temporal variables. For example, SMR revealed that floods reduced the stability of benthic communities, and the length of low flow period was of considerable importance to the recovery of the fauna. Two-way ANOVA indicated that intra-annual fluctuation had more (e.g. the total abundance and wet biomass), equal (e.g. total richness, EPT richness, percent EPT abundance, and Margalef index), or less (e.g. tolerant value) influence on macroinvertebrate communities than land-use types. Consequently, the effects of floods on macroinvertebrates should be taken into account when macroinvertebrates are used as indicators for assessing river ecosystem. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.