COMPOSITION AND DISTRIBUTION OF MACROBENTHO AND MEIOBENTHO AROUND SUBLITTORAL HYDROTHERMAL VENTS IN THE BAY OF PLENTY, NEW-ZEALAND

The composition and distribution of macro- and meiobenthos, and the mo rphology of dominant mollusc species were studied in zones of shallow- water gasohydrothermal vents in the Bay of Plenty, New Zealand: near W hale and White Islands and in the area of underwater gasohydrothermal activity ''Calypso''. Near gasohydrothermal vents of McEwans Bay (Whal e Island) we found bacterial, algobacterial, and diatom mats with low rates of oxygen consumption. On the silty sand bottom of this bay, den se populations of the bivalve Tawera spissa and the gastropod Cominell a adspersa were found. The abundance of meiofauna increased closer to the vents, nematodes being dominant. The ''Calypso'' area and the volc anic depression near Whale Island are characterised by intensive metha ne seepage: here we found the pogonophore Siboglinum sp., in the volca nic depression at a silt temperature of 65-degrees-C. The abundance an d diversity of bottom fauna decreased with an increase of bottom tempe rature. Overall, the composition of bottom fauna in the zones of volca nic activity was similar to that beyond these zones. Only in the zones of gasohydrothermal vents were stilbonematine nematodes and pogonopho res found.