Contribution of microspatial factors to benthic diatom communities

Abstract

Spatial factors can play important and potentially confounding roles governing the presence, the absence, and the abundance of the diatom species and consequently influence the diatom-based bioassessment. To examine how spatial factors affect diatom community and biomonitoring, diatom community was sampled in three catchments with similar river length and watershed area across a large spatial scale along the Yangtze River, China. Redundancy analysis (RDA) showed that patterns of diatom distribution could be attributed not only to environmental variables (e.g., NO3–N, TN, WT, and COD), but also to spatial factors (e.g., elevation, latitude, and longitude). Partial RDAs partitioned the total variance of diatom data explained (64.7%) into three parts: pure spatial variables contributed the highest proportion (19.8%), followed by pure environmental variables (5.4%), and the shared effects by environmental and spatial sets explained a large proportion of diatom variance (39.5%). Recognizing the potential influences of spatial factors, further accumulations of diatom data within different regions would allow for the development of better diatom-based monitoring methods for watershed diagnosis and management.