作者：A. Teittinen, P. Muukkonen and J. Soininen

The extent to which different taxonomic groups show congruent biodiversity patterns and whether their responses to environmental gradients differ remains unclear. Our aim is to examine whether phytoplankton and zooplankton show congruent patterns in taxon richness, taxonomic uniqueness of communities and community composition, and to identify the key factors influencing the observed patterns. We collected samples in June-July 2022 from 100 lakes in Finland, northern Europe. Taxonomic uniqueness of communities was calculated as local contributions to beta diversity (LCBD). We used linear regression to examine cross-taxon congruence in richness and LCBD. To identify the most important factors influencing richness and LCBD, we used a boosted regression tree approach. In addition, a Mantel test was used to explore the relationship between phytoplankton and zooplankton community composition. To evaluate the importance of individual explanatory variables on community dissimilarities, we conducted generalised dissimilarity modelling. There were significant, albeit weak, positive relationships between phytoplankton and zooplankton richness and LCBD. Water pH was identified as the factor most strongly associated with phytoplankton richness and LCBD. Zooplankton richness and LCBD were most strongly associated with water colour, soluble phosphorus and depth. Taxon richness and LCBD were negatively correlated within phytoplankton and also, separately, within zooplankton. Community composition of the two groups showed significant cross-taxon congruence. Phytoplankton community dissimilarities were primarily influenced by pH, whereas zooplankton dissimilarities were significantly driven by water colour and mean annual temperature. We found cross-taxon congruence for all studied aspects of phytoplankton and zooplankton biodiversity. Such positive relationships were weak, though, reflecting differing factors and responses to environmental gradients by the two groups, representing different trophic levels. This suggests that when monitoring lake plankton biodiversity, targeting only one planktonic group may be inadequate for obtaining a reliable view of the status of a lake. Our results further suggest that preserving species-poor lakes with unique community compositions in addition to highly diverse lakes may be essential to maintain biodiversity in lake ecosystems.

（来源：Freshwater Biology 2025 Vol. 70 Issue 6  723-741 DOI: 10.1111/fwb.70057）