Biological traits and community functional diversity analysis offer valuable insights into ecological changes. Research on the functional diversity of ciliate communities has primarily focused on benthic ciliates, and studies on the functional structure of planktonic ciliate communities have been based mainly on feeding type or body size. We conducted a year-long sampling survey at eight sites within the ecological floating bed of Sesuvium portulacastrum in Putian to reveal community-, traits-, and species-level responses to various environmental changes. Community composition exhibited temporal variation, with the relative abundance of Tintinnopsis showing variation with sampling time, Strombidium and Euplotes displayed relatively stable proportions (except in April). The biological traits remained relatively stable, except for the presence of sand shells. Furthermore, species and trait composition demonstrated similar clustering patterns in principal coordinates analysis. Both species diversity and functional diversity reached the lowest levels in April. Mantel analysis revealed a significant positive correlation between these diversity indices and salinity, electrical conductivity (EC), and total dissolved solids (TDS). RLQ and fourth-corner analyses were used to investigate the response of functional traits to environmental factors. Our findings suggested significant associations between feeding type and the presence of sand shells with salinity, EC, and TDS; body size showed a significant correlation with ammonium nitrogen.

planktonic ciliate communities, biological trait analysis, functional diversity