Population Structure and Ecological Niches of Benthic Macroinvertebrates in the Upper Yarlung Zangbo River

The community structure and ecological niche of benthic macroinvertebrates in the upper Yarlung Zangbo River were analyzed in April and September 2023. The benthic macroinvertebrate community largely comprises aquatic insects, with Diptera accounting for approximately half. Commonly observed were Chironomus anthracinus, Tadamus sp.1, Piscicola geometra, species of the family Corixidae spp. and the genera Monodiamesa sp., Apatania sp., and Valvata sp. in April, and Orthocladius sp.1, Gammarus sp., Isoperla sp., Nais sp., Baetis sp., Monodiamesa sp., Tanytarsus sp., Ilisia sp., Nebrioporus sp. and species of the family Corixidae spp. in September. The α-diversity analysis showed significant seasonal differences (p < 0.05) in Shannon-Wiener diversity variable and Margalef richness variable. The Pielou evenness variable did not show seasonal effects (p > 0.05). The β-diversity April/September differences can be attributed to species turnover rather than to nestedness, indicating that benthic macroinvertebrate diversity protection strategies are critical to all areas of the river. In April, Chironomus anthracinus exhibited the broadest ecological niche, and, in September, the widest niche was observed in Gammarus sp. The largest observed ecological niche overlap values were between Chironomus anthracinus and Valvata sp. in April and Gammarus sp. and Ilisia sp. in September, indicating interspecific competition. The study clarifies the diversity status of benthic macroinvertebrates in the upper Yarlung Zangbo River and provides data for related research to facilitate formulation of biodiversity conservation policies.