Seasonal oxygen cycles and biological new production in surface waters of the subarctic Pacific Ocean

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Abstract
Seasonal cycles of oxygen, temperature and salinity at Ocean Weather Station P in the subarctic Pacific Ocean reveal a regular 4–6% supersaturation of oxygen in the surface waters during the summers of the 10‐year period 1969–1978. The main processes causing super‐saturation are surface water heating and the net effect of primary production and community respiration. The biological and heating signals are separated using a mixed layer model and estimates for the air‐water gas exchange rate calculated from empirical correlations to wind speed. Biological new production during the summer (mid‐May to mid‐August) is estimated to be 100–300 mg C m−2 d−1. These values are within the range of independent estimates calculated from the summer nitrate depletion. There is a factor of 3 variation in the new production estimates during the period 1969–1978 with a minimum in 1973–1975. This trend is positively correlated with the interannual variation in zooplankton standing stock at station P.