[Niche and Interspecific Association of Phytoplankton Dominant Species at Different Hydrological Periods in Xiaoche River, Guizhou Province].

Abstract

To understand the niche and interspecific association of phytoplankton in different hydrological periods of the Xiaoche River in Guizhou Province, phytoplankton samples were collected in two different hydrological periods （dry period and wet period） from 2020 to 2022. The niche width （B_i），niche overlap（O_ik），variance ratio method（VR），chisquare test（χ²）, AC test, and Jaccard index （JI） were used to analyze the niche and interspecific association of phytoplankton dominant species. The results showed that a total of 7 phyla and 50 species of phytoplankton were identified in the Xiaoche River, with 4 phyla and 12 species being the dominant species. The combination analysis of niche width and FG functional group showed that the water environment of the Xiaoche River in a medium eutrophic state. The dominant species could be divided into broad niche species, medium niche species, and narrow niche species, and the niche width of the dominant species varied between 1.278 and 4.849. No significant difference exists in the three years of niche overlap value, with the proportion of O_ik>0.6 being 50.00% （2020）, 42.86% （2021）, and 53.49% （2022）, respectively, indicating that there were close to the same or more common species occupying environmental resources in a highly similar way. The dominant species showed a significant positive correlation overall, and the community was relatively stable. The chi-square test showed that only four pairs of 66 dominant species had significant associations； the AC test showed that 33 pairs had significant associations； and the Jaccard index showed that 41 pairs had significant associations, all of which showed more negative than positive associations, indicating that the phytoplankton community in the Xiaoche River was in the early stage of succession.