MICROBIAL DIVERSITY AND ECOSYSTEM FUNCTION

The nature and scale of ecosystem functions, such as carbon-fixation a nd nutrient cycling in a freshwater pond, appear to be governed by com plex reciprocal interactions involving physical, chemical and microbio logical Factors. Moreover, these interactions continuously create new microbial niches that are quickly filled from the resident pool of rar e and 'cryptic' (and probably cosmopolitan) microbial species. This co uld mean that microbial activity and diversity are both a part of, and inseparable from, pond ecosystem function, and that concepts such as 'redundancy' of microbial species, and the 'value' of conserving biodi versity at the microbial level have little meaning.