Rapid Assessment of Biodiversity using 'Biological Diversity Technicians'

"March 1992".

Project Number: Rapid biodiversity assessment, freshwater environments - M/04/1757, YH/6/14/3.

MDFRC item.

Associated publications - Cranston, P.S. and Hillman, T.J. (1992) Rapid assessment of biodiversity using 'biological diversity technicians'. Australian Biologist 5(3): 144-155.

The efficacy of biotic surveys limited in time, taxonomic range, and specialist survey and identification skills was measured. Benefits and drawbacks to the use of 'biological diversity' technicians in biodiversity estimation were assessed. Technicians were students basically trained in systematics and invertebrate biology but without specific aquatic experience. Running and standing waters in the upper Murray River drainage were sampled because extensive prior surveys allowed reasonable estimates of total diversity. Using several traditional sampling techniques, aquatic immature stages of Odonata (damselflies and dragonflies), Ephemeroptera (mayflies) and Chironomidae (midges) were assessed; These groups were chosen because of (i) their frequent use as biological indicators and potential to represent total aquatic biodiversity, (ii) the availability of identification keys and (iii) the availability of local taxonomic expertise to scrutinise the technicians' identifications. Sampling followed laboratory protocol and effectively recovered much of the fauna predicted from previous studies. Some organisms restricted to more cryptic substrates were unrepresented. Samples of floating midge pupal exuviae indicated a more diverse community than did larval samples. Taxonomic accuracy varied between taxonomic groups. Amongst the odonates, failure to recognise instar differences led to an overestimate of species number. The correct number of mayfly taxa was generally assessed but the technicians' failure to recognise a replacement between sites by a similar but ecologically distinctive genus would lead to erroneous site comparison. The greatest diversity in the samples carne from the Chironomidae, which represented the greatest departure from accuracy in the technicians efforts, with many more species than the technicians' estimates. Species recognition was slightly less unrealistic for chironomid pupal exuviae than larvae. A labour force such as these 'biological diversity' technicians would be a valuable aid in routine and regular sampling according to specified guidelines, and in sorting to at least ordinal, perhaps family, or, in some groups, to even more refined taxonomic levels. Such a system operates in many aquatic research laboratories worldwide. However, the skills required to make accurate decisions about species delimitation do not come 'off-the-shelf', no matter how much we would like it so. Mis-estimation of species number and identity has serious consequences for biodiversity studies, where site comparability is essential. We question the transfer to biodiversity studies of the concept of "indicator" groups as applied in biological monitoring, where selected organisms act as indicators of environmental health on our behalf. The expectation that diversity of any group or groups should in some sense represent total community diversity, requires testing. Until such time, the more neutral term “selected groups" ought to be used. Design of biodiversity projects must involve integration of specialist taxonomists' skills from inception onwards, thereby involving mutualism rather than a undirectional 'service' function.