The goal of the program was developing comprehensive inventories and maps of the distribution and abundance of physical and biological seabed habitats, seagrasses and benthic assemblages to provide baseline environmental mapping and a description of ecological patterns. The benthic habitat mapping was performed by utilising R/Python and Maxent software within the species distribution modelling domain. We correlated the probability of occurrence of individual benthic habitat classes with the environmental predictors developed form the multibeam hydroacoustic dataset. The data is presented as a maximum likelihood map incorporating all five prediction classes: (1- Macroalgae; 2- Filter Feeders; 3- Seagrass; 4- Hard Corals; 5- Bare seafloor). An updated version of this data are available (2022) Revised predictive benthic habitat map for Darwin Harbour. Report prepared for Department of Environment, Parks and Water Security. Australian Institute of Marine Science, Darwin, 127 pp.

This project updates the 2019 predictive benthic habitat map for this region, extending past the subtidal zone of the harbour to include intertidal habitats. The project worked with collaborators to synthesise existing data sets for inclusion in benthic habitat mapping process. Hydrodynamic model variables were updated and new digital elevation data included to provide a more accurate representation of the bed shear stress, waves and current. LiDAR surveys were conducted to fill in the gap between the IX bathymetric survey and the high tide water mark. The LiDAR survey data extended the existing bathymetry data. A total of 30 towed video transects were conducted in areas predicted to have a high probability of benthic fauna occurrence based on the existing predictive model. The benthic habitat model was updated to include NTG historical data, new towed video data, hydrodynamic and light data.

The CSIRO’s Oceans & Atmosphere Shallow Survey Internal Facility (SSIF) was contracted by the Institute for Marine and Antarctic Studies (IMAS) of the University of Tasmania (UTAS) in collaboration with Parks Australia, to undertake a hydrographic survey of the Boags Commonwealth Marine Reserve in the southwestern Bass Strait. This site was surveyed in conjunction with other smaller sites for Petuna Aquaculture, as part of a broader survey campaign. All of the sites covered in this campaign are located in the vicinity of the Hunter Group of Islands, off the north-western coast of Tasmania.

Biodiversity assessments of invertebrates within seagrass (Amphibolis antarctica and Posidonia australis) transplant plots, compared to adjacent bare sand and healthy meadows at Middle Bluff, Dubaut Point and Useless Loop, Shark Bay.

Assessment of Posidonia australis transplant survival at 3, 8, 12, 18, and 26 months (August transplant); and 3, 8, 12, 18, 26 and 30 months (April transplant), after planting at Middle Bluff, and Dubaut Point, Shark Bay.

Most research investigating how ocean warming and acidification will impact marine species has focused on visually dominant species, such as kelps and corals, while ignoring visually cryptic species such as crustose coralline algae (CCA). CCA are important keystone species that provide settlement cues for invertebrate larvae and can be highly sensitive to global ocean change. However, few studies have assessed how CCA respond to low emission scenarios or conditions. In a laboratory experiment, we examined the responses of temperate CCA assemblages to combined warming and acidification projected under low, medium, and high emissions. Net calcification and net photosynthesis significantly declined in all emissions scenarios, while significant reductions in relative growth rates and increases in percentage bleaching were observed in the highest emission scenario. The negative responses of CCA to both low and medium emissions suggest that they may be adversely impacted by combined warming and acidification by 2030 if current emissions are sustained. This will have far reaching consequences for commercially important invertebrates that rely on them to induce settlement of larvae. These findings highlight the need to take rapid action to preserve these critical keystone species and the valuable services they provide.

Genomic sampling locations and meadow indices for ribbon weed (Posidonia australis) and wire weed (Amphibolis antarctica) in Shark Bay (Gathaagudu)