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Abundance of biota

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    The spatial and temporal dynamics of seagrasses have been studied from the leaf to patch (100 m**2) scales. However, landscape scale (> 100 km**2) seagrass population dynamics are unresolved in seagrass ecology. Previous remote sensing approaches have lacked the temporal or spatial resolution, or ecologically appropriate mapping, to fully address this issue. This paper presents a robust, semi-automated object-based image analysis approach for mapping dominant seagrass species, percentage cover and above ground biomass using a time series of field data and coincident high spatial resolution satellite imagery. The study area was a 142 km**2 shallow, clear water seagrass habitat (the Eastern Banks, Moreton Bay, Australia). Nine data sets acquired between 2004 and 2013 were used to create seagrass species and percentage cover maps through the integration of seagrass photo transect field data, and atmospherically and geometrically corrected high spatial resolution satellite image data (WorldView-2, IKONOS and Quickbird-2) using an object based image analysis approach. Biomass maps were derived using empirical models trained with in-situ above ground biomass data per seagrass species. Maps and summary plots identified inter- and intra-annual variation of seagrass species composition, percentage cover level and above ground biomass. The methods provide a rigorous approach for field and image data collection and pre-processing, a semi-automated approach to extract seagrass species and cover maps and assess accuracy, and the subsequent empirical modelling of seagrass biomass. The resultant maps provide a fundamental data set for understanding landscape scale seagrass dynamics in a shallow water environment. Our findings provide proof of concept for the use of time-series analysis of remotely sensed seagrass products for use in seagrass ecology and management.

  • This data is part of the 2013 report "Synthesis of seagrass mapping studies conducted by the Water Science Branch of the Department of Water".

  • [This data has been superseded by a synthesised global dataset which includes additional ecological data contributed by non-RLS entities (National Reef Monitoring Network). Please visit the corresponding NRMN Collection (IMOS - National Reef Monitoring Network Sub-Facility - Global off-transect species observations || Global reef fish abundance and biomass) for the most current version of this data. See "Downloads and Links" section below.] This dataset contains records of bony fishes and elasmobranchs collected by Reef Life Survey (RLS) divers along 50m transects on shallow rocky and coral reefs, worldwide. Abundance information is available for all records found within quantitative survey limits (50 x 5 m swathes during a single swim either side of the transect line, each distinguished as a Block), and out-of-survey records are identified as presence-only (Method 0). Although surveys are undertaken as part of monitoring programs at particular locations (mostly in Australia), this dataset contains does not include repeat surveys of sites.

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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 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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    Zooplankton samples were collected at inshore coastal waters of south eastern Tasmania, between the years 1971 and 1972. Three stations were selected to cover the D'Entrecasteaux Channel, mouth of the Derwent River and the Storm Bay areas. Surface, midwater and bottom zooplankton samples were collected monthly for a period of twelve months during the day as well as night time, using horizontal tows. Data for temperature and salinity were also obtained from the stations.

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    Annotations of canopy forming seaweed derived from towed video at selected key abalone blocks along the east coast of Tasmania. The purpose of the study was to examine the patch dynamics of seaweeds and urchin barrens and to provide validation for the identification of urchin barrens from multibeam surveys.

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    Dive surveys using strip transects are used to determine species composition, size structure and abundance of scallops, with surveys conducted pre- and/or post fishing season. In addition, post season telephone surveys of recreational scallop dive licence-holders are conducted to collect information about scallop diving activity (including days fished, location and success), and a range of management-related issues (eg. attitudes to management options, communication strategies).

  • This data is part of the 2013 report "Synthesis of seagrass mapping studies conducted by the Water Science Branch of the Department of Water".

  • This data is part of the 2013 report "Synthesis of seagrass mapping studies conducted by the Water Science Branch of the Department of Water".

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    Zooplankton was counted and identified from three sites over the 5-year period. The net used (200 m Bongo net) was designed to catch meso-zooplankton with an integrated vertical tow through the water column. One net from each of the paired Bongo samples was analysed and the data expressed as numbers per m3. Copepods dominated the zooplankton, with other groups such as salps, krill, appendicularians, cladocerans, chaetognaths and meroplanktonic larvae being seasonally dominant.