The importance of algal cultures for the assessment of the eutrophication of the Oslofjord
- O. M. Skulberg1
© Biologischen Anstalt Helgoland 1970
1. Assay experiments with unialgal cultures have been carried out in connection with an investigation of the Oslofjord 1962 to 1965. The test algae included the following species:Selenastrum capricornutum Printz,Chlorella ovalis Butcher,Skeletonema costatum (Grev.)Cl. andPhaeodactylum tricornutum Bohlin.
2. In the Oslofjord three different types of water are mixed: sea water from the open sea, fresh water from the tributaries, and polluted discharges. The algal growth assays have given information on the amounts and availability of plant nutrients in the water. The quality of the water for algal growth was determined.
3. The results indicated that the water of the inner part of the fjord was in a condition where a significant increase in sewage load gave a relatively small increase in algal growth. Conversely, it was found that for water samples from the outer Oslofjord, a small addition of sewage would give relatively high increase in growth.
4. Enrichment experiments with essential nutrients showed that the supply of compounds of nitrogen, phosphorus and iron was important for the resulting yield of algae. It was not possible to ascribe the main fertilizing effect to any single one of the components.