Abstract
ABSTRACT: Identifying the underlying mechanismsthat explain the spatial variation of stream macroin-vertebrate assemblages is crucial for the protectionof species diversity. Consequently, questionsregarding how much variance in macroinvertebratecommunity structure is related to spatial dispersaland local environmental factors, and which envi-ronmental vari ables are the key drivers havebroad research and management implications.Based on data from 22 stream sites within the Qin-jiang River watershed, Guangxi, China, we exam-ined the variation in macro invertebrate communitystructure attributable to local environmental factors(i.e. stream physical habitat and water chemistry)vs. spatial dispersal factors (i.e. overland andwatercourse spatial eigenvectors among samplingsites) using variation partitioning procedures. Over-all, we found that stream macro invertebrates areinfluenced both by local environmental factors andspatial dispersal factors. The most important envi-ronmental factors structuring macro invertebrateassemblages were current velocity, dissolved oxy-gen, conductivity, total phosphorus, and physicalhabitat quality. Both overland and watercourse dis-persal pathways had a similar influence onmacroinvertebrate assemblages. These results dem -onstrate that stream macroinvertebrates within thestudied landscape are constrained by local envi-ronmental conditions and dispersal factors, andhence comply with the niche-based species sortinghypo thesis in the context of metacommunity ecol-ogy.KEY WORDS: Macroinvertebrate · Spatial factors ·Local environment · Stream · China
Highlights
An important goal for community ecology is to identify major patterns of community structure, and to characterize and predict changes in those patterns in relation to environmental gradients (Soininen et al 2004)
We investigated the influences of spatial factors as well as environmental variables on macroinvertebrate community structures in a metacommunity context in the Qinjiang River watershed, Guangxi Zhuang Autonomous Region, China
All local environmental variables (i.e. V, datadissolved oxygen (DO), conductivity, total phosphorus (TP) and HQI) identified by the forward selection procedure were significantly correlated with macroinvertebrate composition (Fig. 4)
Summary
An important goal for community ecology is to identify major patterns of community structure, and to characterize and predict changes in those patterns in relation to environmental gradients (Soininen et al 2004). A recently developed theory defines ‘metacommunity’ as a set of local communities that are linked by dispersal of multiple potentially interacting species with a few key processes pertaining to patch dynamics, species sorting, mass effect, and neutrality (Hanski & Gilpin 1997, Leibold et al 2004) This concept has successfully explained the distribution patterns of aquatic organisms and the drivers determining such patterns (Thompson & Townsend 2006, Heino & Mykrä 2008, Jacobson & Peres-Neto 2010, Heino 2013). We investigated the influences of spatial factors as well as environmental variables on macroinvertebrate community structures in a metacommunity context in the Qinjiang River watershed, Guangxi Zhuang Autonomous Region, China. Our specific objectives were to (1) quantify the amount of spatially structured variation in stream macroinvertebrate communities, (2) examine the proportion of variation in macroinvertebrate community structure explained by local environmental variables and by spatial factors, both jointly and separately, and (3) identify the major environmental variables that determine macroinvertebrate distribution patterns in the Qinjiang River watershed
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