BENTHIC COMMUNITIES WEST OF GREAT MERCURY ISLAND, NORTH- EASTERN NEW ZEALAND by Roger V. Grace* and Anne B. Gracef *36 Sussex ... from the Royal New Zealand Navy Hydrographic Office chart number N.Z. 5318 , aGreat Mercury Island to Mercury Baya, October, 1971. ... The dredge was hand- hauled from a 12-foot aluminium dinghy with 18 horsepower outboard motor. ... The sediment in each sample was briefly described, and passed over a 2mm wire sieve.