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biota
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The threatened status of shellfish reefs has been well established globally (e.g Beck et al 2011) however the ecological consequences of these losses is still largely unknown. In Australia, shellfish reefs are one of the most imperilled marine habitat types (Gillies et al 2018), due to historical overharvest and widespread eutrophication of coastal waters through the use of fertilizers, livestock and human waste. Marine bivalves are important ecosystem engineers providing habitat, shelter and a food source for other species in benthic soft-sediment environments. In addition, filter-feeding bivalves link benthic and pelagic components of ecosystems through filtration and excretion. Through their filter feeding, they produce large amounts of faeces (digested seston) and pseudofaeces (rejected particles bound up in mucus) which are deposited on the benthos. This process brings energy and nutrients from the pelagic system to the benthic system (bentho-pelagic coupling). The removal of large quantities of seston can serve an important ecosystem function by improving water quality and clarity. The filtration of water performed by bivalves has been demonstrated to reduce water turbidity, improving light penetration and thereby enhancing growing conditions for seagrasses (Wall et al 2008). In systems where healthy populations of bivalves remain, they can filter a volume equivalent or larger than the entire estuary volume within the residence time of the water (zu Ermgassen et al 2013). While such densities of oysters are rare today, this highlights the critical ecosystem services that are lost when oyster reefs decline. Furthermore, it demonstrates the potential functions that can be regained through oyster reef restoration. Given the increasing awareness of the decline of these ecosystems, interest in restoration efforts to restore critical ecosystem functions has been growing. However, conservation and restoration decision making is underpinned by reliable quantification of relevant ecosystem services (zu Ermgassen et al 2016). For example, there are plans to restore some of the natural oyster reefs of Sydney Rock Oyster (Saccostrea glomerata) in Port Stephens, New South Wales. One of the main drivers motivating this restoration project is restoring lost ecosystem services. The filtration rates of Australian oysters has been demonstrated in aquarium studies using filtered water augmented with algae, yet little is known about filtration and biodeposition rates of oysters using raw seawater. In this study, we provide the first evaluation of the filtration and biodeposition rate of four species of bivalves using raw seawater, providing a proxy for natural biodeposition rates. As such, this study provides a first indication of the filtration/nutrient cycling function that may be restored following oyster restoration efforts.
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-- Layton et al. Chemical microenvironments within macroalgal assemblages: implications for the inhibition of kelp recruitment by turf algae. Limnology & Oceanography. DOI:10.1002/lno.11138 -- Kelp forests around the world are under increasing pressure from anthropogenic stressors. A widespread consequence is that in many places, complex and highly productive kelp habitats have been replaced by structurally simple and less productive turf algae habitats. Turf algae habitats resist re-establishment of kelp via recruitment inhibition; however little is known about the specific mechanisms involved. One potential factor is the chemical environment within the turf algae and into which kelp propagules settle and develop. Using laboratory trials, we illustrate that the chemical microenvironment (O2 concentration and pH) 0.0–50 mm above the benthos within four multispecies macroalgal assemblages (including a turf-sediment assemblage and an Ecklonia radiata kelp-dominated assemblage) are characterised by elevated O2 and pH relative to the surrounding seawater. Notably however, O2 and pH were significantly higher within turf-sediment assemblages than in kelp-dominated assemblages, and at levels that have previously been demonstrated to impair the photosynthetic or physiological capacity of kelp propagules. Field observations of the experimental assemblages confirmed that recruitment of kelp was significantly lower into treatments with dense turf algae than in the kelp-dominated assemblages. We demonstrate differences between the chemical microenvironments of kelp and turf algae assemblages that correlate with differences in kelp recruitment, highlighting how degradation of kelp habitats might result in the persistence of turf algae habitats and the localised absence of kelp.
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NOTE THIS IS AN ARCHIVED VERSION OF THE GLOBAL FISHERIES LANDING DATA. The current version of the data is available from https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/5c4590d3-a45a-4d37-bf8b-ecd145cb356d and should be used for all future analyses from 16/01/2019. For any questions about version changes to this dataset, please contact the Point of Contact nominated in this record. Global fisheries landings supplied by a number of agencies (FAO/UN, CCAMLR, NAFO, ICES etc) are mapped to 30-min spatial cells based on the range/gradient of the reported taxon, the spatial access of the reporting country's fleets, and the original reporting area. This data is associated with types of fishing gears. Estimates of illegal, unreported and unallocated landings are included as are estimates of the weight of fisheries products discarded at sea. Mapping the source of fisheries capture allows investigation of the impacts of fishing and the vulnerability of fishing (with its associate food security implications) to climate change impacts.
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This dataset contains physiological measurements collected from sand flathead (Platycephalus bassensis) to examine regional differences in thermal performance between Tasmania’s heavily fished southern population and the more lightly fished northern population. Fish were captured from both regions and acclimated for three weeks under common laboratory conditions before measurements were taken. The dataset includes standard metabolic rate (SMR), maximum metabolic rate (MMR), and aerobic scope (AS) recorded during acute thermal exposure at 12.5°C, 15°C, and 20°C using intermittent‑flow respirometry. To assess longer‑term thermal tolerance, critical thermal maximum (CTmax) was measured after a 14‑day acclimation to each test temperature. The purpose of the study was to determine whether populations with different histories of fishing pressure exhibit divergent thermal sensitivities and metabolic responses to warming. This information contributes to understanding how exploitation history may influence physiological resilience to climate change in coastal fisheries.
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This dataset describes seagrass at 34 individual meadows from surveys of Dugong and Turtle habitats in the North-West Torres Strait for November 2015 and January 2016. The data includes information on seagrass species, biomass, diversity, and BMI and algae percent cover. This meadow (polygon) layer provides summary information for all survey sites within the 34 individual seagrass meadows mapped in 2015-2016 with information including individual meadow ID, meadow location (intertidal/shallow subtidal/subtidal), meadow density based on mean biomass, meadow area, dominant seagrass species, seagrass species present, survey dates, survey method, and data custodian. ESRI and Landsat satellite image basemaps were used as background source data to check meadow and site boundaries, and re-map where required. The data described by this record is current as of 01/12/2016 for use in the Seamap Australia project. Newer versions of the data, additional 'point' data for 853 sites, and alternative download formats are available from eAtlas. http://eatlas.org.au/geonetwork/srv/eng/metadata.show?uuid=034ce816-0777-4bbd-aefc-8b73bd540245
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Mesozooplankton community composition and structure were examined throughout the D’Entrecasteaux Channel, Huon Estuary and North West Bay, Tasmania, from November 2004 to October 2005, the data represented by this record was collected on the 11/02/2005. The composition of the mesozooplankton community was typical of inshore, temperate marine habitats, with seasonally higher abundance in summer and autumn and lower numbers in winter and spring. Copepods were the largest contributors to total abundance across all seasons and stations, while cladocerans and appendicularians were proportionally abundant in spring and summer. The faecal pellets of these three main groups, along with those of krill and amphipods, also contributed significantly to material recovered from sediment traps. Meroplanktonic larvae of benthic animals showed short-term peaks in abundance and were often absent from the water column for long periods. Spatially, North West Bay and the Channel had a higher representation of typically marine species, including Calanus australis and Labidocera cervi, while truly estuarine species, such as the copepod Gladioferens pectinatus, were more important in the Huon Estuary.
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Abalone growth data include estimates from growth increment data from tagging studies, and from shell ageing studies. Data has been collected from all Tasmanian state waters since 1986.
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Mesozooplankton community composition and structure were examined throughout the D’Entrecasteaux Channel, Huon Estuary and North West Bay, Tasmania, from November 2004 to October 2005, the data represented by this record was collected on the 10/03/2005. The composition of the mesozooplankton community was typical of inshore, temperate marine habitats, with seasonally higher abundance in summer and autumn and lower numbers in winter and spring. Copepods were the largest contributors to total abundance across all seasons and stations, while cladocerans and appendicularians were proportionally abundant in spring and summer. The faecal pellets of these three main groups, along with those of krill and amphipods, also contributed significantly to material recovered from sediment traps. Meroplanktonic larvae of benthic animals showed short-term peaks in abundance and were often absent from the water column for long periods. Spatially, North West Bay and the Channel had a higher representation of typically marine species, including Calanus australis and Labidocera cervi, while truly estuarine species, such as the copepod Gladioferens pectinatus, were more important in the Huon Estuary.
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This global meta-analysis documents data from underwater visual surveys used to determine the effect of kelp bed disturbance and canopy density on the abundance and structure of fish communities. Spatial, temporal and ontogenetic variability of many key fish species was examined at various levels of kelp disturbance at sites spanning a global temperate distribution. Rocky reef habitats and fisheries management regimes of sites were also examined as covariates.
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Aerial surveys of southern right whales (Eubalaena australis) were undertaken off the southern Australian coast to monitor the recovery of this endangered species following extreme 19th and 20th Century commercial whaling. The aerial survey was undertaken in the coastal waters from Perth (Western Australia) to Ceduna (South Australia) between the 12th and 17th August 2021, to maintain the annual series of surveys and inform the long-term population trend. The maximum whale counts for each leg of the survey flights between Cape Leeuwin and Ceduna, and consisted of a total 643 southern right whales sighted across the survey area (270 cow-calf pairs and 103 unaccompanied whales). The subsequent population estimate for the Australian ‘south-western’ population is 2,549 whales, which represents the majority of the Australian population given the very low numbers in the ‘south-eastern’ subpopulation. The population long-term trend data is indicating recent years (from 2007) are showing greater inter-annual variation in whale counts. To evaluate the recovery of the southern right whale population, it will be critical to collect long-term data on the annual variability in whale numbers related to the non-annual female breeding cycle and identify possible impacts on this by short-term climate dynamics, longer-term climate change and/or anthropogenic threats.