Zooplankton structure and its contribution to open water diversity is driven by macrophyte patch attributes in floodplain lakes

Abstract

Aquatic macrophytes play a key role in structuring aquatic communities by providing diverse resources. We hypothesized that the role of macrophytes in structuring zooplankton communities in floodplain shallow lakes depends on the diversity-related characteristics of the macrophyte patches. We analyzed zooplankton biomass, taxonomic and functional diversity across a gradient of vegetated, transitional, and open areas in eight floodplain lakes, assessing environmental factors and their relationships with zooplankton diversity and macrophyte patch characteristics.Zooplankton biomass, species richness, H´, D´, and FRic were highest in vegetated areas, where β-diversity occupied a larger functional space, driven primarily by nestedness. Key environmental factors structuring zooplankton in vegetated areas included phenolic compounds, NH4+, conductivity, dissolved oxygen, soluble reactive phosphorus, and chlorophyll-a, whereas open areas lacked specific structuring factors. Macrophyte richness best predicted zooplankton taxonomic richness, H´, and D´, while macrophyte cover explained functional richness. Our results suggest that macrophyte patches offer favorable conditions for zooplankton diversity and act as a zooplankton source for open areas. These findings not only highlight the crucial role of macrophytes in structuring aquatic microinvertebrate biodiversity but also reveal that this structuring role is complex and depends on the specific characteristics of macrophyte patches.