Name:	Dr Cliff Law
	Institution:	Plymouth Marine Lab/ NIWA
	Address:	(current contact details) National Institute of Water and Atmospheric Research (NIWA) 301 Evans Bay Parade, Greta Point, PO Box 14-901, Kilbirnie, Wellington New Zealand
	Telephone:	64-4-386-0478
	Fax:	64-4-386-2153
	E-Mail:	c.law@niwa.co.nz

Ecosystem manipulation experiments are commonly used in the terrestrial environment to determine resource limitation, but have previously been excluded in the ocean by advection and dispersion. The deployment of advanced sensitive tracer technology has allowed PML to track surface water masses for periods exceeding two weeks and distances greater than 1400 km, from the addition of small quantities of a gaseous tracer, sulphur hexafluoride (SF6). This technique has been proven within the IRONEX studies in the Equatorial Pacific and SOIREE in the Southern Ocean, and we will provide this capability for the CYCLOPS In situ Phosphate enrichment experiments during Year 2 and 3. The SF6 tracer will act as a label for the phosphate enriched water, and thereby act as a proxy for the phosphate when it is no longer detectable. As the tracer patch is mapped in near-real time, it will be used to identify vertical profiling sites in both enriched and control regions, and so provide the framework for the in situ studies. In addition valuable information concerning dispersal and exchange will be obtained, with estimates of vertical diffusivity, lateral diffusivity and air-sea exchange.