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2022

40 record(s)
 
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    Here, we hypothesize that Fe uptake rates by sea-ice algae and under-ice phytoplankton are higher than the rates reported for open ocean phytoplankton in the SO. We performed 55Fe and carbon (14C) short-term uptake field measurements in, on and under Antarctic sea ice. We collected under ice seawater, melted snow and sea-ice cores. We then spiked them with 14C or 55Fe radiotracers to measure Fe and C uptake rates by sea-ice algae. Samples were then filtered, and residual radioactivity on the filters measured liquid scintillation counter (Packard).

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    Seagrass meadow extent and meadow-scape was mapped using two alternative approaches at Green Island, a reef clear water habitat, in the Cairns section of the Great Barrier Reef, in November 2020. Approach 1 included mapping seagrass meadow-scape using imagery captured during low spring tides with a DJI Mavic 2 Pro UAV at an altitude of 100 m, with a resolution of 2.45cm/pixel. Approach 2 used PlanetScope Dove imagery captured on 05 November 2020 coinciding as close as possible to the field-surveys from 25 to 27 November 2020, with 3.7 m x 3.7 m pixels (nadir viewing) acquired from the PlanetScope archive. This record describes meadow extent data collected using Approach 2 (PlanetScope imagery). View the original metadata record at https://doi.pangaea.de/10.1594/PANGAEA.946605 for the full data collection.

  • 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.

  • An increasing number of studies are considering Fe and ligand concentrations, providing data of trace element availability across the remote Southern Ocean region (Ardiningsih et al., 2021, Gerringa et al., 2020, Hassler et al., 2017, Thuroczy et al., 2012, Thuroczy et al., 2011, Caprara et al., 2016 and references therein). However, studies seldom focus on polar coastal environments which are especially sensitive to climate-induced changes. To anticipate how these changes may impact Fe availability, we must first understand the drivers of ligand supply to the Antarctic coast and offshore. The newly compiled Southern Ocean Ligand (SOLt) Collection includes all publicly available Fe complexation datasets for the Southern Ocean including dissolved Fe concentrations, Fe-binding ligand concentrations, and complexation capacities for 25 studies between 1995 - 2019.

  • 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.

  • Decision makers seek to account for the socioeconomic values of environmental assets. However, understanding the available frameworks and data can be a barrier. We address this here by summarizing the data used across four case studies (3 geographic regions and 3 socio-economic value frameworks) to demonstrate what data are available and how they are applied to support decisions in varied contexts.

  • Data collected from Southern Ocean phytoplankton laboratory culture experiments to examine the effect of iron limitation on the Chlorophyll fluorescence (F) to chlorophyll (Chl) ratio. Irradiance levels at which cultures were grown are indicated by the photon flux density (PFD). Growth rates of Fe limited cultures (-Fe) relative to Fe replete cultures (+Fe) are referred to as μ / μmax (unitless).

  • Collection of processed BGC-Argo float profiles, used to calculate phytoplankton phenology from chlorophyll, phytoplankton carbon and nitrate.

  • The Maugean Skate Zearaja maugeana is a micro-endemic species known from only two isolated estuaries, Bathurst and Macquarie Harbours in southwestern/western Tasmania. This constitutes one of the most limited distributions of any known extant elasmobranch. As a result, the species is listed as ‘Endangered’ under the Threatened Species Protection Act (Tasmania) and the Environmental Protection and Biodiversity Conservation Act (Commonwealth). Even though it was first discovered in Bathurst Harbour, most of what is known about the species comes from the Macquarie Harbour population. In fact, only four individuals have ever been reported in Bathurst Harbour, with the last known sighting occurring in 1992. This study aimed to use eDNA to determine the presence of the Maugean skate in Bathurst Harbour on the southwest coast of Tasmania. Water samples were collected within 1 m from the sea floor in Bathurst Harbour in November 2021 and February 2022, and in Macquarie Harbour (control samples) in December 2021. Samples were filtered using a self-preserving eDNA sampling system. Following each survey DNA from the samples was extracted and analysed through qPCR amplification. Mitochondrial primer pairs from two gene regions were used to detect the presence of Maugean skate DNA in the samples. Where possible, positive detections were sequenced, and their identity verified.