Glucose uptake in ocean profiles with special reference to temperature

Abstract

Glucose uptake was measured at three different stations in the northwestern Pacific Ocean. The measurements were made at various temperatures (5° to 35°C) and glucose concentrations (3 to 100 μg glucose/l). The uptake of almost all samples taken from the surface to 1,500 m was affected primarily by temperature. The temperature dependence of samples from near the transition region between the Kuroshio and the Oyashio current waters was twice as large as that of both current samples. Furthermore, the samples from the former, transition, region and the aphotic samples of the latter, current, regions showed an optimal temperature 15° to 30°C higher than the in situ temperature; the optimal temperature was only 5° to 10°C higher in the photic samples of the stable region. The average potential glucose uptake at/near the optimal temperature was 0.026 μg glucose/l/h in the photic zone and 0.015 μg glucose/l/h in the aphotic zone. However, after correction by the in situ temperature, the uptake was 0.024 and 0.003 μg glucose/l/h, respectively.