Rabaut M a rijn , M a g d a Vincx and Steven D e g rae r
M a rin e B io lo g y Section, B io lo g y D e p a rtm e n t, G h e n t U niversity (U G en t), K rijgslaan 2 8 1 , S8, B9 0 0 0 G e n t, Belgium
E -m ail: m a rijn .ra b a u t@ u g e n t.b e
M a rin e Protected Areas (MPAs) have been proposed as a va lu ab le too l to a pply the
ecosystem a pp ro a ch w hile the a m o u n t o f in fo rm a tio n needed to m anage systems in a
sustainable way is often perceived as insufficient. O u r study provides in form a tion on
how scientific data can be used and on how to deal with the com plexity o f the system.
The strategy focuses on sm all-scale, short-term studies on a lim ited set o f organism s.
O rganism s investigated are chosen because o f th e ir supposed horizontal and vertical
links with o th e r (groups of) organism s and because o f th e ir (direct o r indirect) e con o m ic
value. This strategy was a pp lie d fo r the Belgian part o f the N orth Sea using the b io ­
engineering polychaete Lanice conchilega. The e co lo g ica l im portance o f this species
relates to its m o d u la tio n m echanisms (such as the elevation, the co nso lid a tio n o f the
sedim ent, the spatial extent and the patchiness). Increased h ab ita t com plexity provides
fa vo u ra ble conditions fo r o th e r infaunal species. These species attract on the ir turn
o th e r predatory infauna. The analyses o f the associated species indicate tha t biodiversity
and productivity increase in areas where L. conchilega occurs (species richness
increases with fa c to r three, while the m a crobenthic density is seven times higher).
Analyses fo r the Belgian part o f the N orth Sea show tha t L. conchilega shapes the
com m unity com p ositio n by expanding the realized niche o f species tha t otherwise o ccu r
in low densities. Besides the horizontal and vertical interaction w ithin the benthic
ecosystem, interactions with o th e r ecosystem com ponents may occur. Therefore, the
interaction with juvenile flatfish
(often species o f high co m m e rcia l value) and the
resilience o f the p a rticu la r L. conchilega system to beam trawl flatfish fisheries is being
investigated in a set o f la b ora to ry experim ents. Results show that L conchilega is
relatively resistant to interm ediate fishing pressure. However, species tha t are strongly
associated with the L. conchilega agg re g atio n s are greatly im pacted a fter fisheries
disturbance. Intertidal field experim ents showed tha t the most d o m in a n t associated
species Eumida sanguinea was im pacted very severely and tha t also the a m p h ip o d
Urothoe poseidonis showed p ost-im p act effect. The in form a tion gathered in the case o f
L. conchilega is an exam ple o f ready-to-use in fo rm a tio n fo r the m arine m a n agem ent o f
the so ft-bottom area o f concern.