Abstrakt
The mean cell sizes of microalgae vary in relation to the abiotic factors, such as nutrients, temperature, or water transparency. This study focused on the community cell size of desmids and diatoms, two dominant groups of the peatland phytobenthos.
Forty samples from various temperate European peatlands were investigated. The species composition and the species richness were controlled mainly by the pH levels.
Purely spatial factors also significantly affected the species composition. Interestingly, diatoms were more strongly geographically restricted than desmids.
The spatial control of the species composition was limited mostly to the large taxa, which indicated that dispersal limitation may be an important structuring factor for phytobenthos at a regional scale. The mean cell sizes of desmids were related to the ombro-minerotrophic gradient, pH, and Ca concentration.
Acidic, ombrotrophic bogs typically contained small cells, whereas minerotrophic fens had larger desmids. By contrast, the diatom size structure did not depend on the ombro-minerotrophic gradient.
Thus, the cell sizes of desmids in peatlands may be used as a proxy for important environmental processes, such as transition from minerotrophy to ombrotrophy, or acidification, whereas diatoms did not primarily respond to these processes and their size structure is driven by different factors, such as conductivity.