Improvement of Baltic Sea coastal ecosystems indicated by increased distribution of Fucus vesiculosus L. since 1984
(English)Manuscript (preprint) (Other academic)
Although there are several reports of continued eutrophication in the open Baltic Sea, we found increased distribution and depth penetration of Fucus vesiculosus in the coastal, phytobenthic system, indicating recovery. After a decline in depth penetration of Fucus in the Åland Sea by 3 m, from a maximum of 11.5 m in the 1940s to 8.5 m in 1984, the Fucus plants had again increased their depth distribution in 1992 and 1996, and in 2006 being back to the depths of the 1940s. Also, in the Askö area, data from the national monitoring programme show an increase of the Fucus maximum depth by 1 m between 1993 and 2009. We used Generalized Additive Models (GAM) to predict the change in percent cover of Fucus in the Askö area from 1993 to 2009. The largest change in Fucus coverage was predicted to occur in the inner parts of the archipelago, decreasing further out, thus being related to reductions in nutrient inputs from land sources. The field data however, showed the largest changes in the middle part since coverage and depth penetration of Fucus in the inner parts are limited by the quick change with depth from hard to soft substrates. In the Askö area the results in the inner archipelago could be linked to an increase in the spring Secchi depth since the beginning of the 1990s. The Secchi depth change was in accordance with the trends of decreasing spring primary production and chlorophyll-a concentration. As the most pronounced change in Secchi depth during the time period was a decrease in July and August, the summer conditions seem to have little influence on the depth distribution of Fucus.
Eutrophication, Baltic Sea, Fucus vesiculosus, depth distribution, SCUBA, monitoring
Research subject Marine Ecology
IdentifiersURN: urn:nbn:se:su:diva-54356OAI: oai:DiVA.org:su-54356DiVA: diva2:393440