The planktonic diatom, Asterionella formosa, is an excellent indicator of enrichment, being abundant in meso- and eutrophic lakes. It is presumed to reproduce clonally as sexual reproduction has never been observed. Populations are often genetically diverse reflecting selection processes, including parasitism by chytrids that appears to promote genetic diversification.
In addition, evidence for cryptic speciation suggests that local adaptation leads to differentiation, despite the potential for widespread dispersal of micro-organisms. The deposition of silica skeletons (frustules) in sediments makes it possible to track the dynamics of A. formosa within lakes over time by measuring abundances and morphological change in response to changing environments.
This multidisciplinary project will integrate studies in morphometrics, genetic diversity, differentiation and gene flow within and between populations to examine how A. formosa responds to a gradient of eutrophication over space and time. Water bodies in the English Lake District offer an excellent system for study.