In this study we used catch and effort data from a commercial fishery to generate habitat suitability models for Port Phillip Bay, Victoria, Australia. Species modelled were King George whiting (Sillaginodes punctata), greenback flounder (Rhombosolea tapirina), Australian salmon (Arripis trutta and A. truttaceus), and snapper (Pagrus auratus). Locations of commercial catches were reported through a grid system of fishing blocks. Spatial analyses in a Geographic Information System (GIS) were applied to describe each fishing block by its habitat area. A multivariate approach was adopted to group each fishing block by its dominant habitats. Standardized catch per unit effort values were overlaid on these groups to identify those that returned high or low catches for each species. A simple set of rules was then devised to predict the habitat suitability for each habitat combination in a fishing block. The spatial distribution of these habitats was presented in a GIS. These habitat suitability models were consistent with existing anecdotal information and expert opinion. While the models require testing, we have shown that in the absence of adequate fishery-independent data, commercial catch and effort data can be used to produce habitat suitability models at a bay-wide scale.

This paper was prepared for presentation at the 1998 SPE European Petroleum Conference held in The Hague, The Netherlands, 20-22 October 1998.

Nutrient addition experiments are one way of testing the importance of nutrients in ecological systems and can be undertaken relatively easily in soft sediments. We added nutrients (Osmocote ® ) at 2 sites in Port Phillip Bay, Australia, which differed in proximity to sources of nutrient loading. Changes in faunal assemblages were assessed over an 18 wk experimental period in 1998. At the Sand Island site, nitrate levels were elevated in the high dose treatments and 3 taxa showed responses to nutrient additions, with differences in densities between control and dosed plots of between 50 and 600%. Assemblage-level measures of total abundance and diversity were approximately 20 to 80% greater in dosed plots relative to controls at the end of the experimental period. In contrast, at the more enriched Western Treatment Plant site, 3 of the 10 most dominant taxa were affected by the nutrient additions, with changes of between 50 and 200% observed during the course of the experiment. At this site none of the assemblage level measures of abundance, biomass and diversity reflected an effect of the dose treatments. These results are broadly consistent with other studies that suggest that in areas of low ambient nutrient availability diversity is likely to increase, while in areas with high background nutrient loadings there is likely to be a decrease. At Sand Island, changing the nutrient status of the area is liable to result in rapid changes in several deposit-feeding populations. At the Western Treatment Plant, the same absolute change in N may have less impact on the invertebrate fauna.

Advances in wastewater treatment have greatly improved the quality of municipal wastewater effluents in many parts of the world, but despite this, treated wastewaters can still pose a risk to the environment. Licensing plays a crucial role in the regulation of municipal wastewater effluents by setting standards or limits designed to protect the economic, environmental and societal values of waterbodies. Traditionally these standards have focused on physical and chemical water quality parameters within the discharge itself, however these approaches do not adequately account for emerging contaminants, potential effects of chemical mixtures, or variations in the sensitivity and resilience of receiving environments. In this review we focus on a number of industrialised countries and their approach to licensing. We consider how we can ensure licensing is effective, particularly when considering the rapid changes in our understanding of the impacts of discharges, the technical advances in our ability to detect chemicals at low concentrations and the progress in wastewater treatment technology. In order to meet the challenges required to protect the values of our waterways, licensing of effluents will need to ensure that there is no disconnect between the core values to be protected and the monitoring system designed to scrutinise performance of the WWTP. In many cases this may mean an expansion in the monitoring approaches used for both the effluent itself and the receiving waterbody.

A wide variety of endpoints or metrics are commonly employed in pollution monitoring situations but, to date, there have been very few experimental field studies aimed at assessing links between a putative pollutant and established soft sediment assemblages. We carried out a manipulative field experiment whereby intact assemblages were transplanted from control areas to sites adjacent to drains discharging secondary treated sewage effluent at 3 intertidal outfall locations in Port Phillip Bay, Victoria, Australia. We found that the ability of different measures to detect impacts varied, although multivariate methods were able to discriminate the effects of treatment, and population level measures tended to be more sensitive than assemblage level measures of abundance, biomass and diversity. Integrated measures, such as average individual biomass, were found to provide a sensitive detection tool plus an insight into the biological consequences of observed changes. We consider our findings in the light of conceptual models of pollution-induced change in soft sediment assemblages.

Understanding biological responses to nutrient enrichment under different environmental conditions is integral for the effective management of eutrophication in coastal environments. However, current conceptual models of nutrient enrichment are limited as they are based on studies that only consider a single source of nutrients, when in reality it is more likely that enrichment is a result of multiple sources. Here, we test the hypothesis that biological responses to nutrient enrichment in intertidal mudflat assemblages depend on the source by comparing enrichment from a controlled release fertilizer with that from decomposing macroalgae. Sediment at two sites in Port Phillip Bay, Victoria, were dosed with the different nutrient sources and monitored through time. After six weeks, the macroalgae-enriched plots had significantly higher abundances and biomass of some taxa of deposit-feeding polychaetes. In the fertilizer-enriched plots, the porewater nutrients increased but there was no detectable change in abundances or biomass of infauna, suggesting that the nutrients did not assimilate into the foodweb. The rate of assimilation of anthropogenic nutrients potentially occurs over longer time scales compared with the rapid assimilation and biological responses to decomposing macroalgae. Responses to the different nutrient sources provide new insights into the complexity of nutrient enrichment models that are applied to the management of aquatic ecosystems worldwide.

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