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.

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.

Laterals of kelp Ecklonia radiata were cut from healthy individuals, photographed, placed on reefs for 2-3 days, then collected and re-photographed. Area loss was calculated from photographs.

Between Dec 06 and Feb 07 the number and size (estimated maximum diametre cm) of sessile invertebrates (sponges, corals) were recorded across 14 different habitat types within Marmion lagoon. 16 sites within 4 locations (inshore, inner-mid, outer-mid, offshore)were surveyed using 1 x 25m UVC belt transects. Survey data has been used to investigate the abundances of potentially important fauna across differeing habitat types and have confirmed that patch structure is an important and ubiquitous characteristic of Marmion Lagoon benthic communities, with strong implications for biodiversity and productivity.

During November 2007 three study sites were established that form the basis of repeated observations of natural temporal variability in habitat patch dynamics. The sites are located on reefs in the Marmion Marine Park with each site approximately 2500 m2 in extent. The sites are comprised of a patchy mosaic of kelp forest, mixed algal canopy, and low foliose algal assemblages. At each site nine circular areas measuring 3m in diametre have been cleared of all algae and changes in percent cover of algae monitored over an 18 month period using photo quadrats (0.25m2). The successional process observed within circular clearances have been used to help understand the causal mechanisms underlying patch formation and maintenance at Marmion Reef.

Field surveys were undertaken at Marmion, Rottnest Island and Jurien Bay to measure the biomass of key taxa and benthic functional groups. Surveys of fish, invertebrate and western rock lobster were completed at 32 sites across the three regions. Within each of these three key regions, sites were identified as being either reef or seagrass habitat.