Relationships between environmental factors and macroinvertebrate community indicators across spatial scales in rivers
Date Issued
2014
Date
2014
Author(s)
Chin, Yu-Chi
Abstract
Stream systems are affected by complex processes interacting with each other at multiple scales due to the hierarchical systems. Identifying the relationships between the environment and aquatic communities at different spatial scales is an essential research issues for enhancing our understanding of the ecosystem patterns and processes. In this study, we investigated the relationships between environmental variables and benthic macroinvertebrate communities in river ecosystem at multiple spatial scales including state-, subregion-, and catchment-levels. The data we used were extracted from the Round One Survey of U.S. Maryland Biological Stream Survey (MBSS) database which was conducted during 1995-1997 and comprised of 422 sites in 18 catchments in Maryland. There were 23 environmental variables including 17 physical habitat variables and 6 water chemistry variables and 82 biological taxa containing 78 families and 4 orders of benthic macroinvertebrates. Multivariate statistical analysis was used to determine the variation of environmental characteristics, community compositions of benthic macroinvertebrates, and the relationships of benthic macroinvertebrate communities and environmental variables of multiple spatial scales. Principal component analysis (PCA) results indicated that the altitude was the most important environmental variables on characterizing the environment at multiple scales since altitude was a composite variable of environmental condition. Non-metric multidimensional scaling (NMDS) demonstrated that Chironomidae was the dominant family in Maryland at multiple scales and it also affected the benthic macroinvertebrate community structure across different spatial scales. Canonical correspondence analysis (CCA) and multidimensional overall pattern (BVSTEP) showed that the benthic macroinvertebrate community structure tended to be controlled by the environmental variable such as the riffle habitat quality at catchment-scale (5.03%-40.65%), after then at subregion-scale (2.57%-6.54%) or state-scale (1.86%) due to influences of the riffle habitat quality. Riffle habitat quality was a composite variable simultaneously influential by the velocity, stream depth, and substrate as quantifying the habitat complexity at catchment-scale. Also, higher abundance and richness of the benthic macroinvertebrate communities were found in sites with high riffle habitat quality in Maryland. Therefore, the benthic macroinvertebrate community structure showed higher dependence upon the environmental variables at catchment-scale. Moreover, the results of BVSTEP also presented that Ephemerellidae (ρ=0.285-0.446) and Hydropsychidae (ρ=0.506-0.568) were correlated with the environment at subregion- and catchment-scales. In addition, Ephemerellidae was highly correlated with DOC and SO4 concentration, and Hydropsychidae was particularly correlated with discharge, velocity/depth diversity, and riffle habitat quality. This research suggested that monitoring the variation of the small-scale environmental variables could be essential for understanding the biological response in river ecosystem and we could use Ephemerellidae and Hydropsychidae as the ecological indicators for habitat quality in response to organic pollutions and hydraulic comditions of Maryland freshwater ecosystems.
Subjects
大型無脊椎動物
空間結構
理化因子
河川階層
高層
淺瀨棲地品質
搖蚊科
小蜉科
紋石蛾科
Type
thesis
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