Ecosystem services provided by the Baltic Sea ... - Naturvårdsverket

SWEDISH ENVIRONMENTAL PROTECTION AGENCY
Report 5873 • Ecosystem services provided by the Baltic Sea and Skagerrak
Economic Marine Information
cial fish are found. Lately, soft-bottom habitats are gradually becoming covered by
filamentous algae, an undesired development potentially resulting in reduced diversity,
limited provision of food (reduced catches of plaice have already been documented)
, enjoyment of recreation and aesthetic value.
Offshore banks
Offshore banks are shallow environments, often dominated by hard bottoms. The
distance from shore typically makes them less impacted by human-induced stress
and thus they provide unique habitats, of particular importance for organisms subjected
to increasing levels of threat along human-impacted coastlines. For example,
juvenile stages of some commercially important fishes are essentially restricted to
offshore banks. Offshore banks also play important roles for sea birds. Offshore
banks southwest of Gotland, for example, constitute the most important locality for
wintering long-tailed duck (Clangula hyemalis). Given the recent interest in offshore
banks shown by the wind power industry, SEPA has undertaken marine geological
investigations of 19 offshore banks (77). As a result, three Skagerrak banks
have been listed, while another seven Baltic banks have been proposed for listing,
within the Natura 2000 network. Currently, the government has assigned SEPA
with investigations of an additional 20 shallow offshore banks.
Cold-water coral reefs
Coral reefs in the deep waters of Skagerrak were only discovered in the last century;
today most of them have succumbed to human impact. Cold-water reefs can
be extensive in size and provide habitat for a multitude of species (78). However,
they are susceptible to disturbance, particularly to destructive fishing methods such
as trawling. As a result, only one of the six known Swedish reefs contains living
colonies. Although only Lophelia pertusa is a true reef builder, other non-reef
building corals also provide complex structures, which likewise contribute to habitat
and biodiversity. Besides being affected by mechanical disturbance, like trawling,
the slow-growing corals are sensitive to reduced oxygen concentration (as a
result of eutrophication), invasive non-indigenous species, pollution and acidification.
Despite current research in the field of reef restoration, the near-future of
cold-water reefs appears grim. Restoration of cold-water corals might take 50 - 100
years and estimates of restoration costs based on current knowledge and technology
are estimated to at least 53 000 € (79.).
Swedish Environmental Objective No 10 - A Balanced Marine Environment,
Flourishing Coastal Areas and Archipelago
“The North Sea and the Baltic Sea must have a sustainable productive capacity, and
biological diversity must be preserved. Coasts and archipelagos must be characterized
by a high degree of biological diversity and a wealth of recreational, natural and cultural
assets. Industry, recreation and other utilization of the seas, coasts and archipelagos
must be compatible with the promotion of sustainable development. Particularly valuable
areas must be protected against encroachment and other disturbance”
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