The nutrient regime of Bass Strait

Abstract

Charts of temperature, salinity, nitrate plus nitrite, inorganic phosphate, silicate, ammonia, total phosphorus, and chlorophyll a are presented for Bass Strait for all seasons, based on seven cruises from August 1979 to November 1981. Temperature and salinity observations are consistent with eastward flow in winter and weak or westward flow in summer. Nutrient concentrations in Bass Strait are low (< 1 µM) throughout the year but rise to somewhat higher levels at the western edge, and to considerably higher levels (up to 7 µM) at the eastern edge, during winter. Chlorophyll a concentrations are also low (generally <0.5 µg I^-1) but show highest concentrations over the shelf just inside both edges, again in winter. It is suggested that nutrient input to Bass Strait occurs from the deeper waters in the east and west, and that the nutrients are used as soon as they enter Bass Strait, leaving a very limited nutrient supply for the interior of Bass Strait.