Nutrient Dynamics in the Celtic Sea during the 18 Month UK Shelf Seas Biogeochemistry Programme

Malcolm S Woodward1, Amandine Sabadel2,3 and Carolyn Harris2, (1)Plymouth Marine Laboratory, Plymouth, PL1, United Kingdom, (2)Plymouth Marine Laboratory, Plymouth, United Kingdom, (3)Dunedin University, Chemistry, Dunedin, New Zealand
Shelf Seas are highly productive areas when compared to the open ocean, which makes them important with regard to understanding the nutrient cycling of the major macro nutrients (Nitrate, Silicate, and Phosphate). These Seas are also influenced by anthropogenic nutrient loading, climate change, and other impacts. The Continental Shelf to the west of the UK is relatively poorly understood with regard to the fundamental biogeochemical processes, like the role of shelf seas in the global cycles of key nutrients, and in determining primary and secondary production. We report results from an 18 month intensive survey to the Celtic Sea and the deep off-shelf Atlantic waters, with data from a series of 10 research cruises to the area, and investigate the nutrient changes and cycling, from the mixed water column winter conditions, to the spring bloom in April where the nitrate and phosphate were taken up from the water column, into the summer season where nitrate was undetectable. Following through to the autumn/winter, with the nutrients being replenished again and a mixed water column once again established. Exchanges with the deep Atlantic water onto the Shelf are studied by a series of transects onto the Shelf during the different seasons.