Mapping diversity in temporary aquatic habitats: the distribution and occurrence of microphyte communities Supervisors: Dr Roger Flower (Geography, UCL) and Professor John Birks (Visiting Professor in Quaternary Palaeoecology, Geography, UCL) Seasonally wet areas and especially temporary ponds constitute an important habitat type that sustains a highly adaptable biota often comprising unusual and/or endemic species. Although seasonal changes in water availability impose a major constrain on these habitats, more usual characteristics of aquatic habitats (nature of the substratum, water chemistry, morphometry and site aspect) are also influential factors affecting species abundances. The significance of temporary aquatic habitats for diversity has only recently been recognised and is now a research topic within the new EU Framework Programme 7. Initial research has focused on the relevance of these specialized habitats to invertebrates and to amphibians but microphyte communities have received little attention. Diatoms (micro-algae with siliceous cells walls) are one group of microphytes that are excellent indicators of water quality and are used extensively in environmental change research including biomonitoring of permanent waters, as indicators of ecological quality (cf. the Water Framework Directive) and in palaeoecology. Other microphyte groups include the bryophytes and green algae. This research projects sets out to understand more about the distributions of, in the first instance, diatom species in ephemeral wet habitats. It is proposed to sample and enumerate diatom species in a variety of these sites, both natural and artificial, in upland and lowland areas in the UK and in the seasonally drier country, Morocco. The environmental factors that influence species occurrences and abundances are of special interest as are those that control species diversity locally and regionally. Various hypotheses about these controls and include environmental quality and niche size, biogeography, and population dynamics will be tested using diatoms, and possibly other microphytes, from an array of habitats types. It is proposed to compare and evaluate and biodiversity patterns in various temporary aquatic habitats using numerical techniques and identify the main factors influencing species diversity in both climatic zones. Whilst the results will be most relevant to assessing floristic diversity and interpreting the occurrences and abundances of diatom species, they should also help test the ‘rules' which control community composition. The work could also have relevance to other fields including palaeoecology, forensic science and geoarcheaology where diatoms are used to infer environmental attributes.