| Summary: | Progress Code: completed Increased ultraviolet radiation (UV-A and/or UV-B) may impact on the establishment and structure of a shallow water benthic invertebrate assemblages. A global experiment in more than 8 countries, using an identical methodology (transparent UV filters) will add significantly to our understanding of the impacts of anthropogenically induced global change on natural systems. To appraise the effects of increased UVR on shallow marine benthic assemblages, five experimental rafts were deployed in protected bays west of Shirley Island near Casey Station, Antarctica (66.16oS 110.30oE). Each raft consisted of eight experimental units, each of which contained a colonization panel (ceramic tile) positioned horizontally and submerged 4-6 cm underwater. Irradiation treatments were randomly assigned to each unit with the use of UV cut-off filters. The treatments were as follows: No UVR (transmits photosynthetically active radiation or PAR, 400-700nm), No UVB (transmits PAR + UVA, 320-700nm), Perspex (full spectrum, 280-700nm, procedural control), or No filter (full spectrum, treatment control). In addition there were three levels of consumer treatments: With consumption (container sides removed), without consumption (container sides perforated with 4 mm holes), and a control (3 sides perforated, 1 side removed). After seven weeks tiles were removed to the laboratory for examination. All tiles were dominated by diatoms and no sessile invertebrates were apparent. The first trial has been completed, but several other panels are still in place. A conference will be held in early 2002 between participating countries to discuss results and findings. The 2001\2002 summer season consisted of experimental designs divided up into three separate projects. The aims were all to provide a corrollary to the previous seasons data. Project 1 consisted of the extraction and redeployment of settlement depth arrays situated in Geoffrey's Bay and Hollin Island Channel. Due to prevailing weather conditions resulting in ...
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