ÖVERGÖDNINGENS OCH METALLUTSLÄPPENS PÅVERKAN PÅ MAKROALGERNA GRÖNSLICK [CLADOPHORA GLOMERATA) OCH ULLSLEKE [CERAMIUM TENUICORNE) / The influence of eutrophication and metal contamination on the seaweeds Cladophora glomerata and Ceranium tenuicorne

The changes in the state of equilibrium between the two common Baltic sea-algae Cladophora glomerata and Ceramium tenuicorne as a result ofeutrofication and the discharge of metals has been studied. The results show that C. glomerata is more capable than C. tenuicorne to utilize an enhanced content of nutritive substances for growth. C. glomerata shows a higher rate of growth than C. tenuicornein more nutrified water. The results also indicate that C. glomerata is about ten times more tolerant towards the toxic metals, copper and zinc, than C. tenuicorne. The method used in another experiment closely simulated the conditions in nature; the ability of young sporophytes to establish and grow under competition from C. glomerata. The results from this experi- ment support the hypothesis from the other experiments that C. glomerata outrivals C. tenuicorne. According to this work, C. glomerata is more resistant to toxic metals and is better at utilizing enhanced contents of nutritive substances. There is therefore a risk that other algae, such as C. tenuicorne will be driven out of competition by C. glomerata. This in turn may have negative consequences for the crustaceans and fish living and feeding in the algal belt. One example is herring, the Baltic’s most valuable species from an economical aspect. Herring is strongly dependent on the C. tenuicorne-belt in which its roe are hatched. Other species, for instance cod and salmon, which feed on herring would also be affected.