HOW MANY DEMERSAL FISH SPECIES IN THE DEEP-SEA - A TEST OF A METHOD TO EXTRAPOLATE FROM LOCAL TO GLOBAL DIVERSITY

Grassle and Maciolek (1992) estimated that there were of the order of 10(7) species of benthic macroinvertebrates in the world's deep sea so ft sediments. Their estimate was extrapolated from the 798 species the y sampled and the pattern of species diversity observed along a. 176 k m transect on the continental slope of the northeast Atlantic Ocean. R elative to the deep sea invertebrate fauna, the deep sea fish fauna ha s been better sampled, at least in the upper 1500 m. To test the valid ity of the Grassle and Maciolek method of extrapolation, we applied it to data from a survey of fishes along the continental slope off weste rn Australia, a diverse and previously unsurveyed region. The resultin g global estimate for the deep sea demersal fishes - 60 000 species - was then compared with the number described to date, about 2650 specie s, and an estimate of total extant species. Our estimate, which consid ers the proportion of new species found in little-explored regions of the world ocean, such as off western Australia, and the number of new species expected in future taxonomic revisions, is a total of 3000-400 0 species. The Grassle and Maciolek method appears invalid as a means to extrapolate global biodiversity from local surveys.