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
Supporting ecosystem services
S5: Maintenance of habitat
Definition
Marine habitat typically refers to benthic or littoral habitat structure and habitat
forming biota. In a broader perspective, habitat is simply the environment in which
an organism occurs. From this definition, it should be obvious that habitats – of all
kinds - are essential to maintain ecosystem diversity and function. Nevertheless,
some habitats are often highlighted as of particular value. For instance, structurally
complex habitats like algal beds or biogenic reefs, as opposed to plain sand or mud,
are often particularly important, as they provide refuges against predation as well
as a variety of different food resources.
Related processes and services
By supporting diversity and function, essentially all ecosystem services are dependent
on the maintenance of habitat directly, or indirectly. The provision of fish
for consumption is dependent on presence of habitats used for spawning, feeding,
breeding and growth to maturity – but not only for the fish consumed; the habitat
requirements of the fish that fed the fish are just as important. This indirect dependence
on a variety of habitats is illustrated by the complexity of the food web
(chapter S3). Coastal habitats appear particularly important. Among both commercial
and recreational fish landings, species associated with coastal habitats comprise
77 % (by weight) (60). In coastal waters, certain habitats are dominated by
one species; this habitat provider is often crucial to numerous species. Key habitat
builders in our marine environments include marine algae like Fucus and Furcellaria,
sea-grass (Zostera sp.) and blue mussels (Mytilus edulis). The tourism industry
benefits from all habitats supporting attractive wildlife such as marine mammals
and birds, but also habitats that in themselves attract e.g. divers and recreational
boaters. In summary, the maintenance of a multitude of habitats safeguards
against ecological surprises while providing the best possible conditions for maintaining
diversity, resilience and options for current or future human use.
Not only do habitats affect species distributions; various organisms, including fish,
may also modify their habitat. The grazing of algae, the filtering of water, the defecating,
the feeding on invertebrate that in turn feed on algae – are all examples of
ways in which marine animals influence their habitat, and the habitat of others.
This reciprocal influence should be considered in all aspects of e.g. monitoring,
management and exploitation.
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