Dynamics of inorganic phosphorus in pelagic communities of the Sea of Okhotsk

• Published in: Journal of Plankton Research
• Main Author: Sorokin, Yu. I.
• Format: Text
• Language: English
• Published: Oxford University Press 2002
• Subjects: ORIGINAL ARTICLES; Okhotsk; okhotsk sea
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/24/12/1253; https://doi.org/10.1093/plankt/24.12.1253

Inorganic phosphorus uptake and regeneration in the Okhotsk Sea waters were investigated in July–August 1994 with the use of radioisotopic techniques. The rates of PO 4 -P uptake by microplankton in the upper mixed layer were between 1.5 and 6.6 μg P l−1 day−1 (average 2.75) in areas of diatom dominance, and between 0.68 and 1.68 μg P l−1 day−1 (average 1.16) in areas of intense warming and summer phytoplankton minimum. The residence time of PO 4 -P standing stock in water at different stations varied between 1.5 and 24 days (mean 9 days). The share of bacterioplankton contributing to total PO 4 -P uptake was ∼50% in areas of the summer phytoplankton minimum and 20–30% in areas of diatom dominance. The PO 4 -P regeneration rate was measured first time experimentally in the temperate sea. Its rates varied from 0.30 to 1.65 μg P l−1 day−1. In areas of diatom dominance, it compensated with 30–60% of PO 4 -P uptake. In zones of summer phytoplankton minimum and in the layers of deep chlorophyll maxima at 10–25 m depths, the PO 4 -P regeneration rate often exceeded its uptake. Primary phytoplankton production correlated well with PO 4 -P uptake values in the upper mixed layer, while no correlation was found between primary production and the ambient PO 4 -P content in water.