An influence of mesohabitat structures (pool, riffle, and run) and land use pattern on the index of biological integrity in the Geum River watershed
BackgroundPrevious studies on the biological integrity on habitat and landuse patterns demonstrated ecological stream health in the view of regional or macrohabitat scale, thus ignored the mesoscale habitat patterns of pool, riffle, and runs in the stream health analysis. The objective of this study was to analyze influences on the mesohabitat structures of pool, riffle, and run reaches on the fish guilds and biological integrity in Geum River Watershed.ResultsThe mesohabitat structures of pool, riffle, and run reaches influenced the ecological stream health along with some close relations on the fish trophic and tolerance guilds. The mesoscale components altered chemical water quality such as nutrients (TN, TP) and BOD and these, then, determined the primary productions, based on the sestonic chlorophyll a. The riffle reach had good chemical conditions, but the pool reach had nutrient enrichments. The riffle reach had a predominance of insectivores, while the pool reach has a predominance of omnivores. Also, the riffle reach had high proportions of sensitive fish and insectivore fish, and the pool reach had high proportions of tolerant species in the community composition. The intermediate fish species in tolerance and omnivorous fish species in the food linkage dominated the community in the watershed, and the sensitive and insectivorous fishes decreased rapidly with a degradation of the water quality. All the habitat patterns were largely determined by the land use patterns in the watershed.ConclusionsTrophic guilds and tolerance guilds of fish were determined by land use pattern and these determined the stream health, based on the Index of Biological Integrity. This study remarks the necessity to include additional variables to consider information provided by mesohabitats and land use distributions within the selected stream stretch. Overall, our data suggest that land use pattern and mesohabitat distribution are important factors to be considered for the trophic and tolerance fish compositions and chemical gradients as well as ecological stream health in the watershed.