| Summary: | Progress Code: completed A hierarchical, 3-level, nested design was used. The highest hierarchical level consisted of six locations. Two of these locations, Brown Bay and Shannon Bay, have been contaminated with heavy metals (Stark et al., 2003; Snape et al., 2001); Brown Bay has also been contaminated with petroleum hydrocarbons (Snape et al., 2001). The remaining four locations are more distant from Casey Station and were used as control locations. These locations were Denison Island, Odbert Island, O'Brien Bay and Sparkes Bay. A full description of these sites is given below. Within each location two sites were selected approximately 100 m apart. Within each site, two plots were sampled (~ 10 m apart). Although the sampling program had been designed for four replicates within each plot, the patchy distribution of bottom sediments in the Windmill Islands restricted this to two replicate samples (~ 1 m apart) per plot. Samples were collected using an Eckman grab sampler, deployed from a boat. To minimise the potential influence of water depth, all samples were collected from 8 m water depth. Samples were collected within a three day period in early February when no sea-ice was present. Diatom data are presented as the relative abundances of benthic species. Samples are identified xyz where x = first initial of sample location (or first 2 initials where 2 locations start with the same letter), y = plot number (plots 1 and 2 represent site 1, while plots 3 and 4 are from site 2), and z = replicate number (a or b). Abbreviations used for species are shown in the separate file sp_list. This work was completed as part of ASAC project 1130 (ASAC_1130) and project 2201 (ASAC_2201). 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 ...
|
|---|