Short-term fluctuations in dissolved silicate concentrations in the Gdansk Deep
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Diurnal fluctuations in dissolved silicate in the water column are discussed. The effect of temperature, salinity, depth and the time of day on silicate concentration was studied during the spring phytoplankton bloom. Maximum concentrations of silicate were recorded at night, minimal levels at noon and in the afternoon. Silicate was depleted down to a depth of 30 m. The sporadically recorded minimal silicate concentrations (0.07 - 0.28 *mol*dm-3) could have limited primary production. This observation is substantiated by the below-optimum Si:N and Si:P molar ratios in the euphotic layer. Silicate concentrations increased with depth, the maximum (30 - 60 *mol*dm-3) being measured in the near-bottom water. The pycnocline formed a barrier controlling silicate diffusion from the near-bottom water to the surface layer. Diurnal silicate fluctuations are also discussed with respect to biological processes.
Publication order reference
D.Burska, University of Gdansk, Institute of Oceanography Al. Marszalka Pilsudskiego 46, 81-378 Gdynia, Poland