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
lier in the year. As a consequence, clam larvae are faced with double jeopardy; they
have no access to food, yet they are still subject to predation.
How to maintain food web dynamics
In order to counteract severe disruption of food web dynamics, particularly in the
light of climate change and marine acidification, the following management considerations
are crucial:
Sustainable harvest
Application of the ecosystem approach
Habitat protection
Taking preventive measures against introduced species
The maintenance of food web dynamics can only be achieved through awareness
and sustainable use of other more apparent ecosystem services. The most straight
forward manner to restore food webs, disrupted by over-extraction, is to reduce
exploitation. Where disruption requires more drastic measures, biomanipulation
has been put forward as an option, albeit risky. Per definition, biomanipulation
introduces considerable amounts of uncertainty into the ecosystem and the outcome
in demand may be accompanied by others, less desirable impacts. Two different
biomanipulation experiments have been discussed in regard to the Baltic Sea; the
introduction of predatory zander (Sander lucioperca) and intensive fishing for sprat
(25) are both aimed at reducing sprat dominance. Breaking the sprat dominance
might be the only way to increase zooplankton abundance, phytoplankton control,
increase water transparency and ultimately provide the conditions for improved
recruitment success of Baltic cod.
Typically, the presence of non-indigenous species goes unnoticed until economic
consequences become apparent. Recently, however, awareness has increased and
both IMO, UN:s maritime organisation, and ICES have declared the transport of
alien species as an imminent threat to marine ecosystems worldwide. AquAliens
constituted a Swedish five-year research project with the objective to clarify the
most important factors for the survival and establishment of alien organisms in a
new environment. The final report from the AquAliens project, presented in 2008,
promoted risk analyses and increased public awareness (45). Currently, in a joint
project between various affected authorities (Swedish Board of Fisheries (SBF),
SEPA, Swedish Species Information Centre, Swedish Board of Agriculture, Swedish
Forest Agency, Swedish Customs and the Swedish Maritime Administration), a
strategy and action plan for alien species are under development in Sweden and
will be presented during 2008.
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