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.

Map of cumulative sound exposure from shipping in the GBR for winter 2015 (June-September).

This record provides an overview of the NESP Marine and Coastal Hub small-scale study - "A photo-identification study of southern right whales to update aggregation area classification in the southwest of Australia". For specific data outputs from this project, please see child records associated with this metadata. -------------------- The population of Southern Right Whales (SRW) in the Southern Hemisphere has been recovering slowly from near extinction due to its decimation from whaling before its ban in the mid-1970’s. The population that visits the Australian coast each year to breed is estimated to have increased by about 4–5% per year in the past two decades, bringing the total population to approximately 3,500 whales. As the population increases, the whales extend their breeding areas into previously occupied suitable habitat. As the species recovers, there is increasing evidence of expansion of aggregation areas. Consequently, there is a need to update known established aggregation areas and Biologically Important Areas (BIAs) and update relevant Marine Parks management plans based on new evidence. Flinders Bay and Geographe Bay off south-western Western Australia were likely to have been important calving areas before commercial whaling began. Much of this habitat is popular for recreational boating and other marine activities. This project collated and completed photo-ID matching of southern right whale images collected between 2010 to 2020 in the southwest of Australia, and uploaded these to the Australasian Right Whale Photo-Identification Catalogue (ARWPIC). The photo-ID matching outcomes provide evidence that Flinders Bay and Geographe Bay now fit the criteria to be recognised nationally as Biologically Important Areas (BIAs) for Southern Right Whales. Outputs • Photo-identifications of individual whales in southwestern Australia for 1991-2021 (photo-matches contributed to ARWPIC) • Final Project Report, including evidence and recommendations for updating aggregation area classification in the southwest of Australia according to the Commonwealth criteria [written]

Growth (shoot count) of Amphibolis antarctica and Posidonia australis following transplant to Middle Bluff and Dubaut Point, Shark Bay. Plants were transplanted by the Malgana people with assistance from UWA staff then assessed for shoot counts after 8 months.

The goal of our study was to split the Australian maritime Exclusive Economic Zone (EEZ) into a set of smaller acoustic zones, whereby each zone is characterised by a set of environmental parameters that vary more across than within zones. The environmental parameters chosen reflect the hydroacoustic (e.g., water column sound speed profile), geoacoustic (e.g., sound speeds and absorption coefficients for compressional and shear waves), and bathymetric (i.e., seafloor depth and slope) parameters that directly affect the way in which sound propagates. Mean zone parameters and shape files are available for download. The zones may be used to map, for example, underwater sound from commercial shipping within the entire Australian EEZ.

Total organic carbon (TOC) sediment stocks as a CO2 mitigation service require exclusion of allochthonous black (BC) and particulate inorganic carbon corrected for water–atmospheric equilibrium (PICeq). For the first time, we address this bias for a temperate salt marsh and a coastal tropical seagrass in BC hotspots that represent two different blue carbon ecosystems of Malaysia and Australia. Seagrass TOC stocks were similar to the salt marshes with soil depths < 1 m (59.3 ± 11.3 and 74.9 ± 18.9 MgC ha-1, CI 95% respectively). Both ecosystems showed larger BC constraints than their pristine counterparts did. However, the seagrass meadows’ mitigation services were largely constrained by both higher BC/TOC and PICeq/TOC fractions (38.0% ± 6.6% and 43.4% ± 5.9%, CI 95%) and salt marshes around a third (22% ± 10.2% and 6.0% ± 3.1% CI 95%). The results provide useful data from underrepresented regions, and, reiterates the need to consider both BC and PIC for more reliable blue carbon mitigation assessments.

In coastal ecosystems, seaweeds provide habitat and a food source for a variety of species including herbivores of commercial importance. In these systems seaweeds are the ultimate source of energy with any changes in the seaweeds invariably affecting species of higher trophic levels. Seaweeds are rich sources of nutritionally important compounds such as polyunsaturated fatty acids (PUFA) and are particularly rich in long-chain (≥ C20) PUFA (LC-PUFA). In southern Australia, the ‘Great Southern Reef’ has one of the most diverse assemblages of seaweeds in the world, which support highly productive fisheries and have been recognised as a promising resource of omega-3 LC-PUFA. Despite this, there is little information on the biochemical composition of most species and how it varies between sites and seasons. To address this knowledge gap, we undertook a survey to assess seasonal variability in the biochemical composition (fatty acids and nitrogen content) of abundant understory seaweeds across three sites in eastern Tasmania. The availability of nutritional compounds differed between sites and was primarily driven by differences in the biomass and the biochemical composition of the nutritious red seaweeds at each site. This variability may explain regional differences in the productivity of commercial fisheries. At the species level, seasonal changes in fatty acid composition were highly variable between species and sites, indicating that multiple environmental drivers influence fatty acid composition of seaweeds in this system. This finding suggests that commercial harvest of seaweeds from eastern Tasmania will need to consider species and site-specific variability in fatty acid composition.

NESP Marine Biodiversity Hub Project E7. Results from the outplanting of lab-selected and cultivated warm-adapted genotypes of giant kelp (Macrocystis pyrifera), at two trial restoration sites. A third restoration trial site had no surviving kelp, so those data were not included here. Data and details from lab-selection experiments can be found in the associated dataset - "NESP Marine Hub Project E7 - Macrocystis pyrifera thermal tolerance testing" https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/0b91d7fd-7d29-452f-954a-78cf75151035