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dataset

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    Water quality and biological data was collected from four tide-dominated river estuaries indicative of catchments with varying levels of human impacts to: 1) assess draft indicator levels for water quality, and 2) investigate biological indicators of estuarine health in NW Tasmania. The data represented by this record was collected in the Black River.

  • This dataset comes from the Floating Forests project (http://floatingforests.org). Floating Forests is an online citizen science project attempting to map the cover of surface-canopy forming kelps, primarily the giant kelp Macrocystis pyrifera, using Landsat data. To acquire the data, citizen scientists were given tiles of images taken from the Landsat series of satellites (https://landsat.usgs.gov/) scenes that had been manipulated to make kelp more visible. Landsat has a roughly two week repeat time for the entire globe and a 30m resolution, although given variability in weather quarterly aggregation is recommended. Each image was scene at minimum four times. If no kelp was noted, then it was retired and scored as a zero. If kelp was noted in the first four classifications, then an individual image was shown to fifteen people total. The polygons of kelp beds presented here represent consensus classifications from the platform and are tagged with minimum number of users who classified pixels in the polygons as kelp. For example, at the five user threshold, each area represents pixels where at least five users - not neccesarily the same five users - said there was kelp present. This consensus classification has been shown to match very closely to expert classifications. For more information and links to outputs, see http://blog.floatingforests.org in addition to the main project site. Or go to the main project site, and start a conversation in the "talk" section of the site.

  • 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. This data spans from 1984 to present. Note that Emma has completely fabricated this abstract, and requires direct input from KEEN.

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    Temperature loggers have been deployed at a range of sites statewide in waters ranging between 6 and 22m depth. From 2012, 27 sites around Tasmania are being monitored. This record shows data collected from 2004 up to December 2020. Data is still being collected (April 2023) and will be added to this collection as it becomes available.

  • Categories  

    These data describe quantitative exposure indices generated using cartographic fetch methods on a 0.01 degree grid across temperate Australia (South Australia, Victoria and Tasmania). Two indices are reported: openness and bathymetry-altered fetch. Openness is a measure of the distance of a site to the nearest coastline in all directions and describes potential exposure to locally generated seas and undefined swell. Bathymetry-altered fetch attempts to account for the attenuation of wave energy as waves move into shallow waters and encounter friction with the seafloor.

  • Categories  

    The spatial extent of C. rodgersii "barrens" was estimated by surveying rocky reef habitat with a towed underwater video system. Sampling took place at 13 regions along the east coast of Tasmania, each comprising 3 subsites, this dataset refers to the Nubeena region, and its 3 subsites: Cape Raoul, Salters Point and Wedge.

  • Categories  

    A research program jointly conducted by Alginates (Australia) P/L and C.S.I.R.O. Division of Fisheries and Oceanography was set up to investigate the relationship between kelp: Macrocystis pyrifera (Linnaeus) C. Agardh 1820 and crayfish larvae. Alginates (Australia) P/L, based at Louisville in the Mercury Passage, were harvesting kelp at this time. This study was initiated to address concerns regarding the effect of harvesting on crayfish stocks. The survey results are taken from an unpublished interim report presenting the results of the work at that stage (1965). Apparently an aerial survey was used to determine stock distributions although this is not specified in the report.

  • Categories  

    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.

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    The effect of barrens formed by the long spined sea urchin, Centrostephanus rodgersii, on the standing stocks of southern rock lobsters (Jasus edwardsii) and black lip abalone (Haliotis rubra) was estimated by divers using underwater visual census methods to compare lobster and abalone abundance in barrens with that in adjacent kelp habitat. Abalone (H. rubra) and rock-lobster (J. edwardsii) populations were compared on C. rodgersii barrens and in adjacent algal-dominated habitat at the same depth and on the same substratum type at three sites in eastern Tasmania (Elephant Rock:Binalong Bay, St Helens Is, and Mistaken Cape:Maria Island). At Elephant Rock and St Helens Island , the barrens are extensive and well established Type 1 barrens, while at Mistaken Cape the barrens in 8-14 m are incipient Type 4 barrens, comprising small barren patches in the algal bed (see FRDC report for classification of barren types). Note that while there are extensive barrens in deeper water (>18 m) at Mistaken Cape, at these depths working time is limited and it was difficult to locate intact macroalgal beds on equivalent substrata.

  • Categories  

    The spatial extent of C. rodgersii "barrens" was estimated by surveying rocky reef habitat with a towed underwater video system. Sampling took place at 13 regions along the east coast of Tasmania, each comprising 3 subsites, this dataset refers to the St Helens region, and its 3 subsites: Binalong Bay, St Helens Island and St Helens Point