Potential Impact of DOM on Fish Biodiversity in the Jinshui River Basin Environment

Water quality is crucial for the ecological health of rivers. However, assessing environmental stressors in large river basins has been challenging due to limited biodiversity monitoring tools. Combining environmental DNA and water quality monitoring presents new possibilities for evaluating the impact of dissolved organic matter (DOM) on fish diversity. Case studies from the Jinshui River, Futou Lake, and Gan River in the Jinshui River Basin demonstrated that eDNA biomonitoring reached 84.62% OTU asymptote (176 OTUs) and 91.06% species asymptote (49 species). The Gan River had 1.21 and 1.26 times more fish OTUs than Futou Lake and the Jinshui River, with 20 overlapping species among the areas. We identified typical excitation-emission matrix (EEM) components of DOM and three PARAFAC fluorescent components: C1 (microbial humic-like), C2 (terrestrial humic-like), and C3 (tryptophan-like). Sequence diversity was positively correlated with EC, TDS, pH, NH3-N, DO, CODMn, biological index (BIX), and freshness index (β/α). Taxonomic diversity positively correlated with spectral slope ratio (SR) and C3. Functional diversity positively correlated with SR but negatively correlated with humification index (HIX). The combined eDNA and DOM monitoring approach shows promise for future assessments of fish biodiversity in river basin environments.