Until recently, quantitative data on the benthic fauna along the coast of Victoria, south-east Australia, were restricted to those few areas (potentially) receiving commercial and industrial effluent. Collectively, studies in these areas covered ∼50 to 60 km of a coastline that extends for 1000 km. Recently, samples were taken from depths of 10, 20 and 40 m along the entire coast, and analysis of these made it possible to examine benthic community structure throughout the region. Species richness is high along the entire length of the coast, supporting the argument that species richness in temperate areas is not always higher in the deep sea than in shallow water. The major factor influencing species richness was depth. Although slightly more individuals were collected from stations at 10-m depth than from stations at 40-m depth, almost three times as many species were found at the deeper stations. Sediment type also influenced species richness. For the stations at 40-m depth, species richness was ∼25% higher in medium and coarse sands than in fine sand. Pattern analysis suggested some bioregionalisation of the fauna, but the effect of geographical location on affinities among sample stations was much less than the effects of depth and sediment type.Additional keywords: benthos and species richness, depth and species richness, sediment and species richness.

Quantitative sampling of macrobenthos and fouling organisms in the estuarine reaches of the Calliope River and Auckland Creek, Gladstone, Australia has been conducted since November 1974, and includes the recovery period (1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981) following severe flooding (and flood-induced scouring) in December 1973/January 1974 . Changes in numbers of the 18 most abundant species of benthic polychaetes and one encrusting serpulid (Ficopomatus uschakovi) are examined. Numbers of F uschakovi settling on fouling panels showed a regular seasonal pattern, with a late summer maximum and a winter minimum throughout this period . The total numbers of individuals for all taxa in benthic samples followed a clear colonization pattern, with super-imposed seasonality ; plateau densities were reached five years after flooding . Total numbers of the 18 most abundant polychaetes showed a similar recolonizational pattern including the seasonal variation.Generally, those species of polychaetes with similar trophic strategies displayed similar patterns of abundance throughout the period : (i) The suspended detritus feeders (F uschakovi, Branchiomma sp ., Lysilla pacifica, Amaena trilobata and Terebellides stroemi) formed a constant proportion of the population ; (ii) Mobile surface detrital feeders (Glycera americana, Nephtys mesobranchia, Lumbrineris sp ., Sthenolepis sp. and Poecilochaetus serpens) initially formed a high proportion of the population which diminished with time ; (iii) The stationary surface detrital feeders (Magelona dakini, Paraprionospio sp ., Isolda pulchella and Pseudopolydora kempi) initially formed a low proportion which increased to a maximum four to five years after flooding and subsequently declined ; (iv) The sole surface deposit feeder examined (Leitoscoloplos normalis) had two peaks -in early 1975 and 1978 ; (v) The subsurface deposit feeders (Cossura sp., Sternaspis scutata, Euclymene sp . and Mediomastus sp.) initially formed a small proportion increasing continuously to become the most abundant group at the end of the period . It is suggested that these changes reflect changes with time in the substrate since the flood-induced scouring of these estuaries, particularly the gradual accumulation of detrital material, and the changing availability of food for the different trophic groups .

Quantitative sampling of the macrobenthos of the cooling water discharge canal of the Gladstone Power Station has been conducted monthly from September 1976 to July 1980 (sampling times 1-47), to provide information on (i) the effects of an initially small but increasing thermal discharge on this biota, and (ii) the likely effects that could be expected to occur in the Calliope River, which will ultimately receive a 65-m3 s-1 thermal discharge with a maximum temperature differential of 8.2� C when the power station is fully commissioned. Considerable fluctuation was found in the biotic data; however, the number of benthic organisms correlates more closely with flow rates in the canal than with any other abiotic factor, showing a positive correlation for sampling times 1-32, followed by a negative correlation for times 33-47. Times classification also indicated a major dichotomy at times 32-34. It is concluded that the changes in the benthos of the canal can be attributed primarily to changes in flow rates, which, in turn, have altered the sediment composition. This is supported by a change in the benthic fauna, with a gradual replacement of species of known sandy mud affinities by species living on or in stiff clays. With a design maximum temperature differential of 8.2� C and with lower water velocities outside the canal, the present data suggest that it is unlikely that the benthic fauna of the Calliope River, adjacent to the power station, will be markedly altered as a result of the thermal discharge; however, because of abiotic and biotic differences between thecanal and the river, the testing of this extrapolation must await the analysis of the 'post-thermal' data presently being collected.