HR: 0800h
AN: OS11A-0186    [Abstracts]
TI: Proving the Ocean Nourishment Concept
AU: * Jones, I S
EM: ian.jones@otg.usyd.edu.au
AF: Ocean Technology Group, University of Sydney, Sydney, NSW 2006, Australia
AB: Vast regions of the sea are barren because of a lack of essential nutrients. Ocean Nourishment is the concept of injecting nutrients into the photic zone of the ocean to store carbon and increase the base of the marine food web. It is elaborated in Jones & Young (1997). The first step in demonstrating this concept is to see if the limiting nutrients can be recognised and provided to the oligotrophic ocean. To this end water samples from three sites were collected in ultraclean polycarbonate culture bottles and enriched with various mixtures of nutrients. They were then placed in a water bath and subjected to natural sunlight for a number of days. Fluorescence levels were measured daily. Previously Thomas (1969) carried out enrichment experiments in and out of high nutrient water in the North Pacific and again Thomas (1970) cultured on the deck of his ship nutrient poor waters in the Pacific. He found nitrogen was the most important limiting nutrient in the poor waters but that micronutrients produced growth in the nutrient rich waters. Ryther and Dunstan (1971) in the Atlantic cultured coastal water with only nitrogen and phosphorus separately. The addition of nitrogen without phosphate produced growth in all cases. To increase the geographic coverage of enrichment experiments, samples were collected off Morocco twice, in the Tasman Sea and in the Sulu Sea. The samples enriched with different concentrations of urea (typically 10 microM) and phosphorous. An increase concentration of chlorophyll is the result of growth of phytoplankton exceeding death and grazing by zooplankton. At five sites an increase of chlorophyll was observed in the macronutrient enriched bottles over that in the control. At the sixth site the control grew at much the same rate as the enriched sample possibly due to contamination by the fluorometer. The maximum chlorophyll level was observed after 4 or 5 days. Replicate samples showed different levels of chlorophyll growths. It was concluded that there were sufficient micronutrients present to support some additional photosynthesis at the sites investigated. These results suggest that it will be practical to nourish broad regions of the ocean to increase primary production. References Jones, I. S. F. and H. E. Young (1997) Engineering a large sustainable world fishery.Environmental Conservation, 24, 99-104. Ryther, J.H. and W. M.Dunstan (1971) Nitrogen, Phosphorus and Eutrophication in the coastal marine environment, Science, 171, 1008-1013. Thomas, W H (1970) Effect of Ammonium and Nitrate Concentration on Chlorophyll increase in Natural Tropical Pacific Phytoplankton Populations, Limnology and Oceanography, 15, 386-394. Thomas, W.H., (1969). Phytoplankton nutrient enrichment experiments off Baja California and in the eastern equatorial Pacific Ocean. J. Fish Res. Bd. Can., 26: 1133-1145. Acknowledgement A Eddington made a number of the obsevations. The Ocean Nourishment Corporation Pty Ltd funded some of the reearch.
UR: http://www.otg.usyd.edu.au
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
DE: 4845 Nutrients and nutrient cycling (0470, 1050)
DE: 4855 Phytoplankton
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting