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Hair mercury levels increase with the amount of fish in the diet and the amount of mercury in the fish species consumed. If hair mercury levels in people throughout the world were monitored by a standard analytical procedure, the results would indicate locations where people's body burden of mercury is high enough to be subclinically unhealthy and where controls on environmental emissions might be beneficial. The relationship of hair mercury concentration to the method of sampling and analysis of hair, the analysis of the results, the amount of fish consumed, the country and location from which samples were taken and the age, sex and occupation of the donor is discussed.

In October 1981, relatively high concentrations of surface phytoplankton (chlorophyll a-1.5 fig 1-I relative to a background of -0.4 pg 1-I) were observed in a cyclonic crescent of cool water along the south-eastern margin of a warm-core eddy in the south-westem Tasman Sea. Associated with this phytoplankton peak were relatively high concentrations of surface nitrate (-50 fig I-'), low concentrations of oxygen (<90% satn), and a population of a copepod (Calanoides carinatus) often associated with upwellings. The salinity, oxygen and nitrate distributions suggest that an upwelling-downwelling circulation cell existed at the interface between (anticyclonic) eddy and (cyclonic) crescent. Biological enrichment was greater at the site of the crescent than where the margin of the eddy was comparatively straight. The hypothesis is advanced that such enrichment may be the basis for the association that exists between schools of southern bluefin tuna and sharp surface temperature fronts.

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