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Copepods

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    Zooplankton samples were collected at two sites in south eastern Tasmania, between the years 2000 and 2001 using two types of plankton net. Samples were collected using horizontal hauls during the daytime only. All copepods, salps and chaetognaths were identified and enumerated.

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    Mesozooplankton community composition and structure were examined throughout the D’Entrecasteaux Channel, Huon Estuary and North West Bay, Tasmania. The data represented by this record was collected as part of a grazing study conducted in North West Bay (1-2 October, 2006). The grazing impacts of microzooplankton and mesoplankton on the phytoplankton communities were examined during several process studies. Experiments with mesozooplankton grazers were restricted to dominant omnivorous copepods (e.g. Acartia tranteri, Paracalanus indicus, Centropages australiensis) cladocerans and appendicularians. Grazing rates of microzooplankton reached as high as 96% of daily primary production, while that of mesozooplankton herbivours was never greater than 20%. Trophic interactions between the species are complicated by the recent arrival of the heterotrophic dinoflagellate Noctiluca scintillans to the region. This species grazes heavily on phytoplankton, smaller zooplankton and faecal pellets. Noctiluca scintillans accounted for up to 20% of mesozooplankton abundance in autumn and it is capable of both suppressing zooplankton abundance and reducing the sedimentation of faecal pellets to the seafloor.

  • This metadata record contains the results of two bioassays testing the response of Antarctic marine copepods to both individual and combined metals via 14 day toxicity tests. The tests were conducted during the 2012-2013 season at Davis Station, East Antarctica. Three metals (cadmium, copper and zinc) were tested singularly and in metal mixture combinations. The concentrations used in the two tests are outlined in the excel spreadsheet (AAS4100_12-13_MixedMetalTox.xlsx). Tests were carried out in 70 mL plastic vials (exposure vials) that contained 50 mL of test solutions. Test solutions were prepared by mixing stock solutions with filtered (0.45 microns) sea water and were stored in a constant temperature cabinet at 0 plus or minus 1 degree C for at least 2 hours prior to the start of tests in order to get to the required test temperature. Each treatment included four replicates and each test included eight controls. Within each replicate vial, 9-12 copepods were carefully added. No additional air, food or water was provided over the test period. At five days a water change was completed by removing the old test solution and replacing it with freshly prepared test solution at the same concentration. The tests were carried out in a constant temperature cabinet set at 0 plus or minus 1 degree C on a 16:8 light:dark photoperiod over 14 days. The number of surviving copepods were counted in each test container, at the same time each day, for 10 days and then a final count was completed on day 14. Mortality was determined by observing the copepods over 20 seconds and if there was no movement they were considered dead. Test solutions were sampled four times during the tests for measurement of metal concentrations. Samples were collected at day 0, day 5 pre-water change, day 5 post-water change and at day 10. Concentrations of the three test metals were determined in theses samples using Inductively-Coupled Plasma Optical Emission Spectrometer (ICP-OES) with appropriate matrix matched standards and blanks to ensure quality control. For all analyses, measured metal concentrations (as opposed to nominal concentrations) were used. Point estimates, including LC10 and LC50 values, were determined using the maximum likelihood-probit method using the software ToxCalc (version 5.0.26 Tidepool Scientific Software). Point estimates were calculated at 4, 7, 10 and 14 days of exposure. Whenever the assumptions for the maximum likelihood-probit method were not met then the Trimmed Spearman-Karber Analysis was used. Data are provided in an Excel workbook (filename: AAS4100_12-13_MixedMetalTox.xlsx). The first worksheet ("/Test Conditions") provides descriptive details for the tests and a key to abbreviations and units. Each worksheet includes a "This worksheet provides..." statement to assist interpretation of the data. A second data file is provided (filename: AAS4100_12-13_ToxCalc.xlsx) containing relevant test data from AAS4100_12-13_MixedMetalTox.xlsx, for input to ToxCalc software for analysis. This file also contains subsequent ToxCalc outputs, with key data (LC10 and LC50 values) provided in a summary worksheet. Other support files provided are seven images of the test species (images by Frances Alexander) and two figures showing copepod response to test solutions (% survival) over the exposure period of the two tests. Copepod samples were collected from the nearshore environment of Prydz Bay, offshore from Davis Station, on two days: 20 December 2012 and 9 January 2013. The 20 December collection was composed of Tisbe sp., collected from benthic habitats and the 9 January collection was composed of Paralabidocera Antarctica, collected from surface waters. Two 14-day laboratory-based toxicity tests were conducted in the Davis laboratories. The test dates were: 2 - 16 January 2013 (test 01; using Tisbe sp., collected 20 December 2012) and 10 - 24 January 2013 (test 02; using P. Antarctica, collected 9 January 2013).

  • This dataset contains samples collected at O'Gorman Rocks and Ellis Fjord near Davis station from December 1997 to March 1998. Depth-stratified zooplankton samples were obtained for determination of zooplankton abundance and biomass. Water samples were collected for the determination of chlorophyll a concentration, protist identification and abundance, and the concentration of particulate and dissolved organic carbon. Sediment trap material was collected for the analysis of faecal pellets (identification and CHN analyses), protist identification and abundance, and the measurement of particulate organic carbon concentration. Zooplankton grazing experiments were performed in the laboratory at Davis station and zooplankton were also collected for CHN analyses. Data from this project arose from projects ASAC 963 and ASAC 2229.