The role of Phyllophora antarctica in structuring macrofaunal communities at Cape Evans

Benthic suveys indicate that Phyllophora is the only attached macroalga present at Cape Evans. Attached and drift algal biomass was quantified in quadrats (61) between 0 - 30m depth using stratified random sampling. The alga formed an extensive cover (mostly occurring as loose-lying accumulations) at all depths sampled. All algae were dried and weighed. Two techniques were used to determine the photosynthetic activity of the seaweeds, PAM fluorometry in situ using a diver operated submersable fluorometer and seven patches of algae were measured on five replicate fronds from the top to the bottom of each plant. Each measurement was taken at a standard distance of 5mm from the plant surface and within 5cm of the apical tip of each frond. Benthic core samples were taken from under the drift algae to assess the structuring effect of drift Phyllophora accumulations on underlying macrofaunal communities. Macrofauna cores were sieved, preserved in 70% isopropyl alcohol, stained with Rose Bengal, sorted and identified to the lowest taxonomic level possible. Sediment cores were also taken and analysed for sediment particle size, organic matter, benthic chlorophyll a content and stable isotope signature of carbon and nitrogen.