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  • This record provides an overview of the NESP Marine and Coastal Hub Research Plan 2023 project "Delineation and estimation of the Maugean skate population in Macquarie Harbour, Tasmania". For specific data outputs from this project, please see child records associated with this metadata. -------------------- The endangered Maugean skate is now only found in Macquarie Harbour, which has a long history of environmental degradation, and recent research suggests that the population may be declining. However, our current abundance estimation tools are inadequate to determine population status and a new method is needed. This project will use next generation genetic sequencing and novel imaging survey tools to delineate and estimate the size of the Macquarie Harbour Maugean skate population to inform conservation strategies. There is also a need to investigate the evolutionary potential of the Maugean skate to adapt to the changing environmental conditions. This research will address these needs by examining the skate's genetic diversity and fine-scale population structure using whole genome typing, and developing a high-resolution dataset of genome-wide single nucleotide polymorphisms. This genetic approach will help inform adaptive management strategies, such as captive breeding, and enhance our ability to detect differentiated lineages with adaptive potential. Outputs • Tissue sampling results and genome-wide population genetic structure [dataset] • Adaptive resolution imaging sonar (ARIS) and lidar water column scanning [dataset] • Final project report [written]

  • This record provides an overview of the NESP Marine and Coastal Hub emerging priorities study - "Application of environmental DNA to survey Bathurst Harbour Tasmania for the endangered Maugean skate". For specific data outputs from this project, please see child records associated with this metadata. -------------------- The Maugean skate (Zearaja maugeana) is listed as Endangered under Tasmania’s Threatened Species Protection Act and the Commonwealth Environmental Protection and Biodiversity Conservation Act 1999. Its known population is small (~3,000 individuals, Macquarie Harbour, 2016) and highly restricted, having only been recorded in two isolated estuaries: Bathurst Harbour and Macquarie Harbour in south-western/western Tasmania. This constitutes one of the most limited distributions of any known extant elasmobranch. Although the skate was first discovered in Bathurst Harbour, most knowledge of the species stems from the Macquarie Harbour population. Only four individuals have been reported in Bathurst Harbour, with the last reported sighting in 1992. Environmental conditions in Macquarie Harbour have changed markedly since then due to anthropogenic activities in and around the estuary including historical mining, hydro-electric generation and alteration of natural river flows, and marine fish farming. Previous research has shown clear signs of population stress and evidence of detrimental impacts of degraded environmental conditions on the Maugean Skate in Macquarie Harbour. Understanding the potential population status of the Maugean Skate in Bathurst Harbour will assist in determining conservation actions. This study used Environmental (e) DNA to determine the presence/absence of the endangered Maugean skate (Zearaja maugeana) in Bathurst Harbour, strengthening the evidence base for effective conservation plans and specific recovery actions. Outputs • Maugean skate eDNA sampling data and inferred species distribution (presence/absence) [dataset] • Final Project Report, including a short summary of recommendations for policy makers of key findings [written]

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    Dive surveys were conducted in 2014 and the same sites resurveyed annually until 2022 (excluding 2021), to establish a baseline and monitor the status of the critically endangered spotted handfish (Brachionichthys hirsutus) population. This dataset is a summary of all surveys season 2014 to 2022 (excluding 2021) in which the 11 sites across the Derwent Estuary and D'Entrecasteaux Channel were assessed. The data describes the search effort (transect length, swathed area) and counts of handfish observed on each transect, including size measurements (total length) and depth records for each sighted fish.

  • This record provides an overview of the NESP Marine and Coastal Hub small-scale study - "Conservation of spotted handfish". For specific data outputs from this project, please see child records associated with this metadata. -------------------- Spotted Handfish (Brachionichthys hirsutus) were once common across the bays and estuaries of South-eastern Tasmania. By 1996, however, populations had declined and the species was listed as Critically Endangered under Australia’s Environment Protection and Biodiversity Conservation Act 1999. The species is relatively short-lived, (5–10 years) and matures at more than two years’ old. This leaves a short window for reproduction, which relies on egg masses laid on seafloor structures such as stalked ascidians. If spawning fails, population declines may occur rapidly. With no planktonic life stage to aid dispersal, and low adult dispersal, outside recruitment to re-establish collapsed populations is unlikely. Analysis of 23 years of Spotted Handfish survey data (1997–2019) supported by previous NESP Marine Biodiversity Hub work (project A10) helped develop a time-series of survey data, increasing biological understanding and contributing to effective management actions. This project recommenced surveys of multiple local populations, after a two-year gap, to ensure that the potential impacts of development of the Derwent estuary and surrounds handfish populations or their habitats can be detected. Included in the population surveying was identification of suitable locations to plant Artificial Spawning Habitats (ASH) where natural spawning structures have declined. This will continue to support the species' captive breeding program with industry and foster engagement with the indigenous and broader community through participation, talks, outreach, publications, and the National Handfish Recovery Team (NHRT). Outputs • A consolidated database of all available data on spotted handfish imagery, length frequency, and GPS regions to 2022 [time-series database] • Final Project Report, including a short summary of recommendations for policy makers of key findings [written]

  • 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. Australia’s giant kelp forests are listed as a Threatened Ecological Community under the Environment Protection and Biodiversity Conservation Act 1999. Habitat restoration is a potential tool for the conservation and management of giant kelp ecosystems. For habitat restoration to be effective, the cause of habitat decline must be understood and overcome. 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 (Project E7, Marine Biodiversity Hub) identified warm-tolerant strains of giant kelp from remnant patches in eastern Tasmania, where the species has experienced precipitous declines due to ocean-warming. These strains have high potential to assist with ‘future-proofing’ kelp forest restoration, however it is still unclear what the physiological mechanisms are that provide their improved thermal tolerance. This work cultivated the warm-tolerant strains of giant kelp previously identified, along with giant kelp strains of normal tolerance, at both cool (16 °C) and warm temperatures (20 °C). The juvenile kelp was then harvested, and a suite of physiological traits that may be responsible for their differences in thermal tolerance were examined. These included 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. This work demonstrated for their first time that the improved thermal performance of these strains 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, these 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. The 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 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. Only four individuals have ever been reported in Bathurst Harbour, with the last known sighting occurring in 1992. This study used environmental DNA (eDNA) to determine the presence/absence of the Maugean skate in Bathurst Harbour on the southwest coast of Tasmania. Water samples were collected from the seafloor 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.

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    Fixed position oxygen and water temperature logger data from the Macquarie Harbour World Heritage Area (WHA). Two Hobo oxygen data loggers are positioned at approximately 15 m depth at different sites within the WHA, with the intent of monitoring representative mid-bottom water oxygen values in the WHA as these were identified in previous studies to be naturally low due to limited seawater exchange at the harbour entrance, and thus likely to be most susceptible to anthropogenic factors that may increase oxygen demand and alter WHA conservation values. These values include core habitat of the Maugean Skate, a listed threatened species. This work is funded by WHA advisory board via the Nature Conservation Branch of DPIPWE and is part of a larger study being conducted by IMAS undertaking a biological baseline study of the biodiversity of the Macquarie Harbour WHA. This data spans 08/11/14 to present (most recent update 02/02/17).