Trevor Ward

SELECTING MARINE RESERVES USING HABITATS AND SPECIES ASSEMBLAGES AS SURROGATES FOR BIOLOGICAL DIVERSITY

We compare the value of using habitat categories and species assemblages as surrogates for marine biological diversity in the context of choosing a set of representative areas for a marine reserve network. Habitat categories were based on interpretation of aerial photographs and maps, and on local knowledge. Species assemblages were created from comprehensive survey data on 977 taxa (mainly species), derived from an intensive three- year study of a temperate marine embayment, and classified into plant, fish, and invertebrate assemblages. Reserves were selected using a heuristic iterative algorithm to simulate a marine reserve network based on 10-80% representation of each surrogate. The effective- ness of each surrogate was evaluated by comparing the number of taxa that would be coincidentally included in each simulated reserve for the bay. Areas selected to represent 10% or 20% of the surrogates were best chosen using fish or invertebrate assemblages, because by spatial coincidence, they included 60-80% of all available taxa. However, areas selected to represent ?40% of the surrogates were generally best derived from habitat categories, because they included ?93% of all available taxa. Plant assemblages were generally poor surrogates for overall species richness. These findings suggest that habitat- level surrogates may be a highly cost-effective method for initial identification of high- priority areas to manage marine diversity of coastal ecosystems.

Use of assemblages derived from different taxonomic levels to select areas for conserving marine biodiversity

One of the main reasons for establishing networks of marine protected areas (MPAs) is to conserve and manage biodiversity. Of the many elements to biodiversity, representation of species diversity is a common target. As preparing a complete inventory of all marine species is impractical, surrogates to represent species diversity have been sought. One such surrogate is lower taxonomic resolution. Based on the distributions of 977 taxa of fish, invertebrates and plants in a temperate marine bay, we used species richness as a measure of biodiversity to examine the value of using assemblages generated from species, genus, family and class level data as surrogates in a selection process for MPAs. Genus assemblages resulted in selection of areas with a similar number of species to those obtained by using species assemblages, provided the selected set of areas represented 60% or more of the assemblage occurrences. Results using family and class assemblages varied. Because spatial scale, geographic location and the identity of the taxonomic group are all likely to affect the efficacy of using lower taxonomic resolution as a surrogate for species diversity, we argue that there is no universally preferred level. This requires further study at different spatial scales and among different locations, using a range of taxonomic groups, and we therefore suggest that the use of lower taxonomic resolution survey data to select MPAs should be approached with caution.

Temporal variation of metals in the seagrass Posidonia australis and its potential as a sentinel accumulator near a lead smelter

Temporal variation in the concentrations of Cd, Cu, Mn, Ni, Pb and Zn in leaves of the seagrass Posidonia australis was studied at three sites near a lead smelter on the shore of Spencer Gulf, a large hypersaline marine embayment in South Australia, on four occasions from October 1980 to September 1981. Concentrations of Cd, Mn, Pb and Zn of up to 541, 537, 379 and 4241 μg g-1, respectively, were found in leaves collected from the site nearest to the smelter. A substantial temporal variation in the concentrations of these metals in samples from all sites resulted from the combined effect of leaf age and collection strategy. Concentrations of Cd, Cu and Zn in the leaf epibiota were lower than those in the leaves, but the reverse was true for Mn and Ni. The use of seagrass leaves as sentinel accumulators for Cd, Pb and Zn must be based on collections made at the same time of year, or otherwise account for the effect of leaf age on concentrations of the metals in the samples.

Regional geochemistry of metal-contaminated surficial sediments and seagrasses in upper Spencer Gulf, South Australia

Surficial sediments, shallow sediment cores and seagrass samples were collected over an area of about 600 km2 of upper Spencer Gulf, South Australia, adjacent to a major lead-zinc smelter. Regional variation in heavy metal contents was studied in relation to different pathways of contamination from the smelter complex, and geochemical association with natural constituents of the sediments. About 300 km2 were contaminated to some extent. Areas of appreciable contamination (10 × background) were greatest for Cd and least for As, with Pb and Zn intermediate. Regional trends of heavy metals in the sediment reflected inputs of pollutants from both liquid effluents and atmospheric fallout, modified by tidal currents. Total accessions to Germein Bay were estimated to be at least 25 000 tonnes each of Pb and Zn and 500 tonnes of Cd and As. Arsenic differed both in its distribution with sediment depth and in its geochemical associations when compared to Pb, Zn and Cd. Correlation of Cd with the fine fraction (< 20 μm) permitted a normalization of data which accounted for marked regional variations in sediment grain size and provided a better basis of assessing the regional impact of pollution. Metal concentrations in Posidonia leaves were highly correlated with total and EDTA extractable metal concentrations in the sediments, and may provide a more sensitive indicator of metal dispersion. Background levels of metals in Posidonia were not found in our study area.

Indicators for assessing the sustainability of Australia's marine ecosystems

Principles of integrated ecosystem-based management have been used to derive 61 potential environmental indicators for reporting on Australia’s marine and estuarine ecosystems. They are focused on tracking the condition of marine ecosystems in the face of a variety of uses and pressures, and are consistent with approaches used for assessment of public- and private-sector environmental activities, and with the international standard. The in icators cover issues in protected species, common habitats, renewable and non-renewable resources, water and sediment quality, and integrated management. Gaps in knowledge and technical capacity include: knowledge of the nature of the ecosystems is incomplete (ineffective indicators may be selected); scientific understanding of environmental issues is limited (the wrong cause may be identified); the resolving capacity of a monitoring programme cannot be determined (monitoring may falsely infer that no changes have occurred, or provide an answer to the wrong question); procedures for synthesis and aggregation of data across spatial, temporal and taxonomic scales, or for estimating uncertainty in national summaries are lacking; case-study trials, reference sites, and suitable interpretative models are needed; and an established procedure for revising and updating the indicators as new knowledge accrues, or if new issues arise, is lacking.

A strategy for assessment and management of marine ecosystems: Baseline and monitoring studies in Jervis Bay, a temperate Australian embayment

Abstract Jervis Bay is a temperate marine embayment that is highly regarded for its environmental quality and has recently been listed on the Register of the National Estate. Although it is considered relatively pristine, the bay is subjected to a diverse set of existing uses and may be subjected to a number of new uses. These existing and proposed uses include a National Park, tourist developments, urbanization and Department of Defence training exercises. Concern about the possible impacts of the existing and proposed uses of the bay led to the development of a set of baseline studies and a plan for monitoring the ecology of the bay. The lack of successful strategies for assessing and managing impacts in marine systems forced the development of a new strategy based on adaptive management principles. Key features of the strategy include system attributes, measurable indicators, inventory and baseline studies, a monitoring programme and a database. Experience from studies of Jervis Bay suggests that: • •|subjective considerations in choosing attributes and indicators may be unavoidable but should be explicit; • •|static inventories of ecosystems are an insufficient background for detection of environmental change; • •|monitoring is the key link between inventory, baseline and process research and various management options; • •|monitoring should be optimized, with all choices made explicitly; and • •|monitoring should respond adaptively to increased knowledge and changed management requirements.

The response of southern hemisphere saltmarsh plants and gastropods to experimental contamination by petroleum hydrocarbons

Field experiments examined the response of two common perennial saltmarsh plants and their gastropod epifauna to the effects of weathered petroleum hydrocarbons. Application of the petroleum hydrocarbons to the saltmarsh mimicked an accidental spill, but confined the contamination to small areas. Populations of the perennial chenopod, Sarcocornia quinqueflora, and the perennial grass, Sporobolus virginicus, showed little inertia and senesced rapidly after the application of weathered Bass Strait crude oil and diesel (11· m−2). No resprouting from underground stems or recruitment of seedling was detected up to 17 months after the application of hydrocarbons to Sarcocornia. Dead stems of the perennial grass Sporobolus persisted in areas treated with oil and diesel for up to 12 months, but showed no signs of resprouting from basal shoots or rhizomes originating from culms within the treated areas. Slow recovery from rhizomes originating outside the plots was evident after a few months but tiller growth appeared to be inhibited by residual hydrocarbons. No recruitment of seedlings was observed in the denuded plots and no other macrophytes were observed to colonise these areas until the end of the study (17 months). The response of saltmarsh gastropods to petroleum hydrocarbons shows greater inertia and stability than the vascular plants. Initial mortality was high, but migrations from the edges of the treated areas restored densities to control and pre-treatments levels within a few months. The reduction in cover of plants apparently had little effect on the abundance of gastropods although residual effects of the hydrocarbons may have inhibited predators of gastropods from the openings created by the death of saltmarsh plants. We predict that the widespread contamination of saltmarshes in south-eastern Australia by spills of crude oil or diesel would result in the loss of vegetation cover and reductions in the abundance of gastropod epifauna.

Australia's Oceans Policy: Sink or Swim?

In 1999, Australia introduced an ecosystem-based oceans policy. This article analyzes the issues that must be addressed in implementing this policy. Institutional arrangements and regional marine management plans are the keys to translating ecosystem management principles into day-to-day operation. The proposed institutional arrangements have the potential to overcome the historical problems of coordination and jurisdictional disputes, but implementation has further polarized federal and state agencies and stakeholders. Even if these issues are resolved, the authors note that substantial development is required in the areas of designing nested ecosystem-based management frameworks at the appropriate geographic scales, methods for integrating across the range of users and ecosystem values, and tools for evaluating and assessing ocean management decisions before the policy will affect the ecologically sustainable use of Australias ocean estate.

Diel periodicity of Metanephrops australiensis and other deep-water crustaceans of northwest Australia

Abstract The diel patterns in catch rate and, by inference, activity of eight deep-water crustacean species have been assessed by repeated trawling at a location with a depth of 430 m on the continental slope of northwest Australia. The patterns of catch rate identified show that, despite the depth, one highly valued commercial species, Metanephrops australiensis, had peaks of catchability near dusk and dawn. In general, male M. australiensis of all sizes displayed similar diel patterns in catch rate, while the females were more variable. Four species, including Metanephrops andamanicus, showed no detectable diel changes in catch rate. Two caridean shrimps and a penaeid prawn were caught in greater numbers during daylight hours, which suggests a substantial nocturnal vertical migration.

Effects of metals and sediment particle size on the species composition of the epifauna of Pinna bicolor near a lead smelter, Spencer Gulf, South Australia

Abstract Pinna bicolor (Mollusca: Pelecypoda) were transplanted between four sites near a lead smelter. The species composition of their epifauna (sessile and mobile) was examined in relation to characteristics of both sediments and seston at the sites. Seventy-two taxa were distinguished in the epifaunal community. Substantial differences were found in the short-term sensitivity of some of the species to concentrations of Cd, Pb and Zn in sediments and to sediment particle size. The short-term sensitivity of many species to metals or sediment particle size explained their long-term distribution pattern. Twenty-three taxa were identified as significantly characterizing the faunal differences. Of these, eleven (four molluscs, four bryozoans, two barnacles and one ascidian) were affected by both sediment metal concentration and particle size, and eight (four molluscs, one bryozoan, one polychaete, one hydroid and one barnacle) were affected by metal contamination but not particle size. Of all fauna examined, the Bryozoa were the most metal-sensitive. Four species, Smittina raigii (Bryozoa), Galeolaria sp. 1 (Polychaeta), Epopella simplex (Cirripedia) and Monia ione (Pelecypoda) were identified by their short- and long-term sensitivity to metal contamination, and absence of sensitivity to sediment particle size, as suitable species for monitoring the effects of metal contamination on the epifauna. The implications of the results for toxicity-testing are discussed.