BSEP116B Biodiversity in the Baltic Sea - Helcom

some seaweeds the distance is at most 25 km. The
network should therefore take into account different
aspects of connectivity and not be focused
on one element or one species to the detriment of
others. The network design should also take into
account the different life history stages of species.
It has, however, been repeatedly suggested that, if
the network is not targeted to a certain species, an
average distance of 25 km can be used between
MPAs (Botsford et al. 2001, Shanks et al. 2003,
Palumbi 2003, Halpern et al. 2006).
Because the HELCOM database contains no
spatial information on habitat or species distribution
and such data are currently not available, an
approach using hypothetical straight-line connectivity
with a 20 km and a 50 km radius (i.e.,
40 km and 100 km connectivity distance) was
used in the HELCOM assessment (Figure 7.6). The
assessment showed areas of good connectivity
but also indicated major gaps, particularly in offshore
areas.
In the BALANCE project, connectivity was
assessed between protected patches of similar
benthic marine landscapes, both by using a fixed
25 km distance and by using a species-by-species
approach whereby the considered landscapes
and distances were set depending on the specific
requirements for selected species. With the
25 km distance, the landscape patches within the
BSPAs are relatively well-connected to each other
for most landscape types. However, the deep-sea
landscape types showed very low connectivity.
When using the species-specific approach,
the analysis showed relatively high connectivity
among landscape patches suitable for widespread
species with high dispersal abilities such as Baltic
telling (Macoma balthica). For short-distance dispersers,
however, the BSPA network is not wellconnected.
Furthermore, water currents affect
dispersal, either inhibiting or enhancing it, and
thus the fixed distances in the BALANCE assessment
should only be seen as a preliminary ‘rule of
thumb’.
The BALANCE analysis also showed that because
BSPAs, on average, are relatively large, the main
part of the connectivity reflects within-site connectivity
between landscape patches inside an
individual BSPA, whereas between-site connectivity
is much weaker. While between-site con-
Figure 7.6. Connectivity between the BSPAs (in darker green)
with a 20-km (light orange) and a 50-km (dark orange) radius
indicating 40 km and 100 km, respectively, connectivity distance
between the sites.
nectivity is important for long-distance dispersers,
the within-site connectivity is important for
short-distance dispersers. In addition, as most of
the BSPAs are situated in coastal areas, the connectivity
is very weak across the deeper offshore
areas of the Baltic Sea and the network does not
support good connectivity for species inhabiting
these areas.
7.3 Current status of the legal
protection and management
of the BSPA network
Establishment of an ecologically coherent and
well-managed network of Baltic Sea Protected
Areas requires relevant legal protection and
management measures. Most existing sites lack
implemented management plans or other means
of site management, and predominantly aim
to protect birds or terrestrial species. Although
many sites including in marine areas enjoy some
national protection, in most cases it is not clear
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