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Chapter 26,052

Untersuchungen uber Produktions- und Lebensbedingungen in norwegischen Austern-Pollen

Gaarder, T.

Bergens Mus Arbok Naturvidenskapelig Rekke 2: 6-64

1932


Accession: 026051833

Most abundant plankton forms in 3 Norwegian oyster pools in the summer of 1931 were a blue-green alga 1-2/[mu], and a green alga 3[mu]. Optimum light conditions occurred from 0.5 to 2 meters deep. The green algae thrive best near the surface and in salinity < 19%0 with a pH range 8.5-9.1. The blue greens thrive in reduced light below the surface with salinity > 1Q%O and a pH range of 7.7-8.6. Copper occurred in open fjord water up to 0.004 mg. per liter, while in the three pools it was not over 0.008. Lack of copper may hinder the attachment of oyster larvae but in concentrations above 0.02 mg. per liter the growth of the algae is inhibited. The larvae of O. edvlis thrive best with 0.015-0.04 mg. copper per 1. At pH approximating 9 the oyster larvae are injured, above 9.1 they die in a few days. Iron, manganese, and humus do not appear as factors limiting productivity in the oyster pools. With increase in nitrate and phosphate light becomes the limiting factor, but increase in algae raises the pH to a point where further production is inhibited.

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