The Data Interrogation and Visualisation Environment (DIVE) is a graphical tool to interactively explore and visualise a diverse range of datasets. These datatsets range from 1-dimensional point data (e.g. species biomass) to 4-dimensional time-varying volumetric datasets (e.g. model output).

Here we predict oceanographic connectivity among four geographical locations in the south west of Western Australia using hydrodynamic modelling of larval dispersal and test these predictions against genetic descriptions of population structure, population boundaries and estimates of larval migration in two co-distributed sea urchin species. Sea urchins are excellent models for characterising marine population connectivity because of their commonness, diversity of larval life histories, ease of sampling, and ecological importance as grazers in coastal benthic habitats. Our study sampled two species, Heliocidaris erythrogramma and Phylocanthius irregularis. H. erythrogramma spawns predominantly in summer and its lecithrotrophic larvae are free swimming for 3-4 days in laboratory observations. In contrast, little is known about spawning time and larval duration in P. irregularis. The south-west corner of Australia is dominated by the Leeuwin current system, the worlds only poleward-flowing western continental boundary current. The Leeuwin current (LC) is particularly strong in the late autumn and winter months and is weaker in the summer. Strong seasonal contrasts in the LC flow pattern make it possible to generate testable predictions about the predominant direction of larvae-mediated gene flow in H. erythrogramma. Comparison of genetic structure with oceanographic model predictions allowed us to make predictions about the possible larval biology of the less well characterised urchin P. irregularis.

The dynamics of the seasonal evolution of chlorophyll a at the continental shelf break around 32 degrees south has been investigated using a one-dimensional numerical BGC model at shelf and lagoon scales. The results show that a combination of vertical mixing associated with the Leeuwin Current and surface cooling during the winter months is responsible for the wintertime increase in chlorophyll a concentration at the shelf break (Greenwood and Soetaert, 2008). In addition, variation in the timing and magnitude of the winter increase in chlorophyll is shown, for the first time, to relate to the strength of the Leeuwin Current. A nitrogen budget for the southwest WA shelf has been derived by diagnosing the simulated fluxes of particulate and dissolved nitrogen from the 3-D model across the shelf boundaries (across two cross-shelf transects at 27S and 34.5S and across the 100 m isobath) as well as deposition and release of nitrogen at the seafloor.

The Science Plan for WAMSI Node 1 Project 1 characterised the south west Australian marine coastal and shelf ecosystem structure and function. Mooring progam An array of instruments was deployed four times between July2007 and May 2008, recovered after 4-6 weeks each time to download data, and service the instruments. CTD Surveys During the course of the mooring program a ctd survey of the region was completed at approximately monthly intervals using the RV Linnaeus. In the first 2 surveys a grid of 25 stations was occupied after which a further 5 stations were added to the northern end of the grid.

Within this experiment the blue mussel ( Mytilus edulis ) is being used as a proxy indicator to understand rates of secondary production across the continental shelf off Marmion WA. The experiment is being run at 5m depth intervals between 0 and 40 meters. Length and width of valves and wet/dry weights of tissue matter are being measured to compare condition and growth rates of individuals from different depths. Stable isotope values are obtained to compare relative C13 and N15 values, to understand if there is a difference in diet across the shelf. Water sampling is also being carried out and regular intervals whilst the experiment is deployed to investigate differences in Particulate organic matter, Chl-a, HPLC and isotope values of organic matter in the water column, to aid in explaining variation in growth and diet patterns.

Summary Although ecosystem structure and function can be influenced by both bottom up (primary productivity) and top-down (predation) processes (ref), top-down processes (predation) have been demonstrated to account for over 70% of the variation in the some temperate kelp communities (Halpern et al in press). Removal of key predators such as fish and lobsters, has been shown to have the potential to result in trophic cascade effects in which grazers may take over the system, producing massive changes to ecosystem structure. (Babcock et al 1999, Shears et al 2003, Steneck et al 2004). Locally, it has been suggested that predation by western rocklobster Panuluris cygnus may be particularly important in the structuring of local ecosystems. Abundances of P.cygnus have been shown to be strongly negatively correlated with the abundance of large (>2cm) trochid gastropods (Edgar 1990) and adult P.cygnus are known to feed readily on a wide range of locally abundant crustaceans and molluscs (James and Tong 1997, James et al 2001, Power et al 2005). Despite this, understanding about the linkages between lobster predation and local macroinvertebrates populations is still currently very limited. Here we contrast differences in the rates of predation on locally abundant blue mussels Mytilus edulis (Lamarck 1819), using fished and unfished areas as the principal source of contrast. Methods Predation rates on mussels, Mytilus eduli, were measured by adapting predator exclusion methods first described in Edgar 1990. To test the hypothesis that large predators, including P.cygnus, may be controlling abundances of molluscs, caged and uncaged mussels were deployed inside and outside fished reserves at Marmion, Rottnest Island and Jurien Bay. At each of the three locations, 12 similar sized mussels (70mm total length) were attached to a series of 8 plastic mesh grids, with 4 of the grids being fully enclosed to prevent predator access and 4 of the grids remaining open to allow predator access. (Fig. 1) 8 grids were attached to concrete blocks using cable tiestm and blocks deployed in approximately 4m water depth on seagrass substrate immediately adjacent high relief limestone reef. At Marmion and Jurien Bay, 3 blocks containing attached mussels were deployed outside reserves and 2 blocks with mussels were deployed inside reserves. At Rottnest Island 3 blocks were deployed both inside and outside of reserves. After a deployment period of seven days all grids were retrieved and the mussels on each plastic grid recorded as either alive, dead or missing

Thirty hard corals of the species Plesiastrea versipora have been collected from Marmion Reef for sectioning and x-ray analysis to provide measurements of growth. These data will be combined with coral population structures collected in 2006-2007 invertebrate surveys, enabling us to independently validate models of patch dynamics (including patch longevity) using estimated coral ages.

A) Rates of primary productivity for reef macroalgal and sediment microalgal communities will be determined from measurements of oxygen release (and/or CO2 consumption) collected from reef (3x) and bare sand/microphytobenthos (3x) communities using benthic chamber incubations. B) Nutrient enrichment experiments - response of macroalgae will be measured in terms of N assimilation in algal tissue, changes to species composition and changes in abundances. The response of consumers (abundance and other aspects of population dynamics, biomass, feeding biology and fecundity) will also be investigated, using video for mobile (fish) grazers, and quadrat sampling for less mobile grazers (eg. gastropods on reefs, urchins in sediments). Variations in the isotopic composition of the algae and consumers will be used to assess nutrient exposure and subsequent energy flow pathways into secondary production.