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EARTH SCIENCE | BIOSPHERE | ECOSYSTEMS | MARINE ECOSYSTEMS | COASTAL | KELP FOREST

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From 1 - 10 / 20
  • Benthic habitat annotations of stereo Baited Remote Underwater Video (Stereo-BRUV) and panoramic drop camera imagery, were completed as part of a report funded by the NESP Marine & Coastal Hub. This report focussed on an IUCN II zone in the South-west Corner Marine Park off the 'Capes region' near Margaret River. These data were analysed in TransectMeasure using a modified version of the CATAMI scheme.

  • Predictions of dominant habitats were completed as part of a report funded by the NESP Marine & Coastal Hub. This report focussed on an IUCN II zone in the South-west Corner Marine Park off the 'Capes region' near Margaret River. This modelling contains data from stereo Baited Remote Underwater Video and panoramic drop camera, and was completed using the FSS-GAM package in R. Predictions are at two different scales and resolutions, one using the broad 250m resolution Geoscience Australia bathymetry and the other using a 4m resolution multibeam survey from Geoscience Australia

  • Fish annotations of stereo Baited Remote Underwater Video and panoramic drop camera imagery, were completed as part of a report funded by the NESP Marine & Coastal Hub. This report focussed on an IUCN II zone in the South-west Corner Marine Park off the 'Capes region' near Margaret River. These data were analysed in EventMeasure using standard operating procedures for the annotation of remote stereo imagery.

  • Out-of-range observations of significant rafts of giant kelp (Macrocystis pyrifera) washing ashore in southern NSW in winter 2020. On 9 August 2020, two local marine naturalists on the south coast of New South Wales, Australia noticed a significant amount of a large unfamiliar kelp washed up on a local beach. Following some quick confirmations via phone and email, it was revealed that the unfamiliar seaweed was giant kelp (Macrocystis pyrifera): a species whose closest known populations are ~450 km away to the south (in Tasmania and western Victoria) and whose transport to New South Wales would have required oceanic rafting over several weeks and hundreds of kilometres against the prevailing south-flowing East Australian Current. Subsequent community-led searches over the following days confirmed four more locations of often-substantial amounts of giant kelp wrack, as well as many more anecdotal and unconfirmed accounts.

  • Ecosystems provide numerous services and benefits to society. While historically overlooked, these services are increasingly recognized and are now being mapped and accounted for. There are several approaches to mapping and evaluating these ecosystem services. In this report, we use two increasingly common approaches, Ocean Accounting and Welfare Economics, to evaluate ecosystem services for the Great Southern Reef. The Great Southern Reef is a network of rocky reefs dominated by temperate algal forests known as kelp. It spans over 8,000 Km of coastline and supports two thirds of the Australian population. Despite its presumed importance, there has been little work quantifying the extent and value of the ecosystem services provided by the Great Southern Reef. Through a systematic review we assessed the current state of knowledge of the ecosystem services provided by the Great Southern Reef. Using the Common International Classification of Ecosystem Services (CICES) framework, we created an overview of the ecosystem services (provisioning, regulating, and cultural) provided by the Great Southern Reef in New South Wales, Victoria, Tasmania, South Australia, and Western Australia. We then created metrics to quantify how these services benefit coastal societies in these five states. Highlight summaries include over 17 million Australians who live within 50 Km of the reef, 26 wild seaweed harvest companies, 115 tourism SCUBA operators, 1436 mapped dive sites, 18 million tourist visits each year, 16 temperate marine biology university programs, 43 books and films, key medical products, 23 tons of harvested seaweed, 1116 grams of carbon per m2 used for growth each year, 2,361 peer-reviewed scientific publications from 1976 to 2022, 186 marine protected areas, 2.16 million recreational fishers, and over 28 commercial fisheries with 20,000 tons of biomass taken each year. We then conducted economic evaluations using these biophysical values and the available information. Using a variety of approaches, we found that the total economic value of the Great Southern Reef was $11.56 billion each year. Individually the values were as follows, commercial fishing (producer surplus - $33.2 million), carbon sequestration (avoided damages - $37.8 million), nutrient cycling (avoided damages - $6,484 million), recreational fishing (consumer surplus - $1,668 million), diving and snorkelling (consumer surplus - $403 million), other recreational activities (consumer surplus $1,836 million), and the existence value (consumer surplus - $1,096 million).

  • This record described kelp growth and ecophysiological data relevant to the thermal tolerance of specific warm-tolerant and 'normal' family-lines of giant kelp (Macrocystis pyrifera) from Tasmania, Australia. For habitat restoration to be effective, the cause of habitat decline must be understood and overcome. But this is problematic when climate change is driving habitat loss, since it cannot be reversed or ameliorated prior to restoration. A previous NESP project, led by this team, identified warmwater-tolerant strains of giant kelp (Macrocystis pyrifera) from remnant patches in eastern Tasmania, where the species has experienced severe declines over the past half-century due to climate change and ocean-warming. While these strains have high potential to assist with ‘future-proofing’ of kelp forest restoration activities, it is still unclear what the physiological mechanisms are that provide their improved thermal tolerance. Here we cultivated the warm-tolerant giant kelp strains, along with giant kelp strains of normal tolerance, at both cool (16 °C) and warm temperatures (20 °C). We then harvested the juvenile kelp, and examined a suite of physiological traits that may be responsible for their differences in thermal tolerance, including nutrient usage (carbon and nitrogen content), cellular membrane processes (fatty acid contents), and photosynthesis (PAM fluorometry and photosynthetic pigments). The cultivation trials again illustrated the improved ability of the warm-tolerant strains to develop at stressful warm temperatures relative to normal giant kelp. For the first time, we also demonstrate that their improved thermal performance may extend to the development and fertilisation of the earlier kelp ‘gametophyte’ life-stage. Despite the clear differences in growth between the two test groups, the physiological assessments illustrated a complex pattern of responses, some of which are contrary to expected based on prior knowledge of thermal performance in kelps. Nonetheless, our results indicate that the warm-tolerant strains of giant kelp have a greater capacity to alter the composition of their fatty acids and may be more efficient users of nitrogen (a key nutrient for growth and development). This new information will help inform ongoing kelp breeding and selection programs for future-proofing kelp restoration in Australia and globally. This improved understanding of the physiology of kelp thermal tolerance might also help with identifying individuals and populations of Macrocystis, and other kelps, that may be resilient to (or especially threatened by) ocean warming and climate change.

  • The recruitment of mussels and microphytobenthic (MPB) algae to 28 experimental artificial reefs supporting different patch sizes and density of kelp (Ecklonia radiata) off Maria Island, Tasmania. The recruitment of mussels was assessed using rope fibre habitats, and the recruitment of MPB algae was assessed using microscope slides, positioned across the artificial reef and collected in November 2015. These data were collected to examine how the patch size and density of kelp influences the establishment of MPB algae and mussels.

  • Biogenic marine habitats are increasingly threatened by a multitude of human impacts, and temperate coasts in particular are exposed to progressively more intense and frequent anthropogenic stressors. In this study, the single and multiple effects of the urban stressors of nutrification and sedimentation on kelp bed communities were examined within Australia’s largest urbanised embayment (Port Phillip Bay, Victoria). Within this system, grazing by sea urchins (Heliocidaris erythrogramma) plays an important role in structuring reef communities by overgrazing kelp beds and maintaining an alternative and stable urchin barrens state. It is therefore important to explore the effects of urban stressors on kelp bed dynamics related to urchin abundance, and test the relative strengths of bottom-up and / or physical drivers (e.g. elevated nutrients and sediment) versus top-down (e.g. urchin grazing) forces on kelp bed community structure. The interactions of these drivers were assessed to determine whether their combination has synergistic, antagonistic, or additive effects on kelp beds. It was found that kelp responds positively to nutrient enhancement, but when combined with enhanced abundance of grazing sea urchins, the local positive effect of nutrient enhancement is overwhelmed by the negative effect of increased herbivory. Turf-forming algae behaved very differently, showing no detectable response to nutrification, yet showing a positive response to urchins, apparently mediated by overgrazing of canopy-forming algae that limit turf development. No direct effects of enhanced sediment load (at twice the ambient load) were found on intact kelp beds. Collectively, the results demonstrate that the ‘top-down’ control of urchin grazing locally overwhelms the positive ‘bottom-up’ effect of nutrient enhancement, and that intact kelp beds demonstrate resilience to direct impacts of urban stressors.

  • Sea urchins have the capacity to destructively overgraze kelp beds and cause a wholesale shift to an alternative and stable ‘urchin barren’ state. However, their destructive grazing behaviour can be highly labile and contingent on behavioural shifts at the individual and local population level. Changes in supply of allochthonous food sources, i.e. availability of drift-kelp, is often suggested as a proximate trigger of change in sea urchin grazing behaviour, yet field tests of this hypothesis are rare. Here we conduct a suite of in situ behavioural surveys and manipulative experiments within kelp beds and on urchin barrens to examine foraging movements and evidence for a behavioural switch to an overgrazing mode by the Australian sea urchin Heliocidaris erythrogramma (Echinometridae). Tracking of urchins using time-lapse photography revealed urchin foraging to broadly conform to a random-walk-model within both kelp beds and on barren grounds, while at the individual level there was a tendency towards local ‘homing’ to proximate crevices. However, consistent with locally observed ‘mobile feeding fronts’ that can develop at the barrens-kelp interface, urchins were experimentally inducible to show directional movement toward newly available kelp. Furthermore, field assays revealed urchin grazing rates to be high on both simulated drift-kelp and attached kelp thalli on barren grounds, however drift-kelp but not attached kelp was consumed at high rates within kelp beds. Time-lapse tracking of urchin foraging before/ after the controlled addition of drift-kelp on barrens revealed a reduction in foraging movement across the reef surface when drift-kelp was captured. Collectively results indicate that the availability of drift-kelp is a pivotal trigger in determining urchin feeding modes, which is demonstrably passive and cryptic in the presence of a ready supply of drift-kelp. Recovery of kelp beds therefore appears possible if a sustained influx of drift-kelp was to inundate urchin barrens, particularly on reefs where local urchin densities and where grazing pressure is close to the threshold enabling kelp bed recovery.

  • The abundance of macroinvertebrates associated with 28 experimental artificial reefs supporting different patch sizes and density of kelp (Ecklonia radiata) off Maria Island, Tasmania. Macroinvertebrates were assessed by diver-based visual census conducted between November 2015 and December 2016. This data was collected to examine how the patch size and density of kelp influences the establishment of macroinvertebrate assemblages.