Dissolved Silicate and Particulate Iron Content in Different Water Types

Abstract

CONSIDERABLE information regarding the complex circulation pattern which exists in the waters surrounding the Hawaiian island chain has been obtained through the analysis of surface waters at a station near Koko Head on the Island of Oahu which has been monitored by the U.S. Bureau of Commercial Fisheries since 1956. Temperature and salinity data, together with information gathered in six oceanographic surveys made since 1949 in the vicinity of the high islands of the Hawaiian archipelago, have shown that the islands are surrounded by the cooler and more saline water of the Western North Pacific in winter and by the warmer and intermediate salinity water of the California Current Extension in the summer¹. The boundary between these two layers of water as shown by a relatively high salinity gradient moves north and south through the island chain and is responsible for the seasonal variations in water type. The Hawaiian waters, being subtropical in nature, are not normally subject to appreciable changes in standing crops of phytoplankton. Consequently, it seemed of interest to investigate the possibility that variations in trace metals and other chemical species might reflect changes in water type.