Diatom data for transects at 4 locations in the Windmill Islands

Sediment samples were collected from four locations within the Windmill Islands (Cloyd Island, Odbert Island, Shannon Bay and Brown Bay). Within each location three parallel transects were created, with samples taken at set depths along each transect. At the time of collection, both surface and benthic irradiance levels were measured, and the % of surface irradiance that reached the sediment-water interface was calculated. Samples were analysed for benthic diatom abundances (expressed as relative abundances), and grain-size (expressed as % of total weight). The diatom spreadsheet (diatom_data)lists the relative abundance of benthic species. The abbreviation used to identify species are explained in the separate file called sp_list. Samples are identified XTYZ where X is the first letter of the location, Y indicates the sampling position along the transect and z indicates the transect (a, b or c). The benthic sheet is the relative abundances of benthic species. The greater than 2% sheet lists all the species that reach abundances greater than2% in at least 1 sample. The table sheet has the same info as greater than 2% but arranged by the individual locations. In this sheet (tables), measurements in m represent the depth of the water column overlying the position where the sediment samples were collected. (ie it was at different locations, not different water depths in the one spot). Sampling positions reflect increasing depth. At Brown Bay and Odbert Island, sediment samples were collected below water columns/water depths of 1, 2, 4, 8 and 12 m. At Cloyd Island, samples were collected from 4,6,8 and 12 m water depths. At Shannon Bay samples were collected from 2, 4, 8, and 12 m water depths. Details of the environmental parameters examined (grainsize and light) are given in the file labelled 'env_data' This work was completed as part of ASAC project 1130 (ASAC_1130). Public summary from project 1130: Algal mats grow on sea floor in most shallow marine environments. They are thought to contribute more than half of the total primary production in many of these areas, making them a critical food source for invertebrates and some fish. We will establish how important they are in Antarctic marine environments and determine the effects of local sewerage and tip site pollution. We will also investigate the impact on the algal mats of the additional UV radiation which results from the ozone hole. The fields in this dataset are: Diatom Spreadsheet Species Site Location Transect Depth (m) Environmental Data Spreadsheet Location Transect Depth (m) Grain size Gravel Sand Mud Light