Ecosystem Health Assessment of Lower Jinsha River Based on the Phytoplanktonic Index of Biotic Integrity(P-IBI)
In this study,we evaluated the aquatic ecosystem health of the cascaded reservoirs in the lower Jinsha River before the cascaded hydropower stations began operating.The evaluation was based on the phytoplanktonic index of biotic integrity(P-IBI)developed as part of this research.The aim of the study was to provide technical and data support for early warning and ecological restoration evaluation of the cascaded reservoirs.The P-IBI evaluation system was based on a phytoplankton investigation carried out at 30 sampling sites in the dry and wet seasons in 2017-2018(5 reference sites and 25 conservation sites)in the lower Jinsha River.A total of 86 phytoplankton species(genera)were identified,reflecting high spe-cies diversity.The phytoplankton community structure belonged to the Bacillariophyta-Chlorophyta-Cy-anophyta type,dominated by Bacillariophyta(43 species,50％),and retaining the composition characteris-tics of phytoplankton in natural rivers.Using the distribution range,discriminant analysis,and Pearson correlation,five core indices(total taxonomic units,cyanobacteria taxonomic units,percentage of Bacil-lariophyta to total taxonomic units,cell density of Bacillariophyta,Chlorophyta cell density as a percent-age of total cell density)were selected from 27 candidate metrics to establish the P-IBI evaluation system.Based on the 25％percentile value of reference sites,the evaluation standard for ecosystem health in the lower Jinsha River was established and five P-IBI grades were set:P-IBI＞3.81,healthy;3.03-3.81,sub-healthy;2.67-3.03,fair;2.28-2.66,poor;P-IBI＜2.28,very poor.River health was then assessed at each of the 30 sampling sites.During the wet season 1 site was healthy,4 sites were sub-healthy,9 sites were fair,8 sites were poor,and 8 sites were very poor.During the dry season,no sites ranked as healthy,5 sites were sub-healthy,8 sites were fair,8 sites were poor,and 9 sites were very poor.In general,the health sta-tus of the lower Jinsha River was poor,and the ecological condition in the wet season was better than that in dry season.River health evaluation using the P-IBI well reflected conditions before the cascaded hydro-power stations began operations and will support efforts to manage and improve the ecology of the lower Jinsha River.
phytoplanktonindex of biotic integrityecosystem health assessmentcascaded reservoirsthe lower Jinsha River
万方数据
维普
