New insights in the structuring role of Lanice conchilega reefs in

New insights in the structuring role o f Lanice conchilega reefs in
intertidal food webs: a focus on epi- and hyperbenthos
Bart De Smet', An-Sofie D’H ondt', Pieterjan V erhelst1, Jérôme Fournier23, Laurent Godet4, Nicolas
Desroy5, M arijn Rabaut1, Magda V in cx1 and Jan Vanaverbeke1
1 D epartm ent o f Biology, Marine Biology Section
Ghent University, Krijgslaan 281 /S8, 9000 Ghent, Belgium
E-mail: badsmet.desm et@ uqent.be
2 CNRS, UMR 7208 BOREA
Muséum National d ’H istoire Naturelle 75231 Paris Cedex 05, France
3 Muséum National d ’H istoire Naturelle
Station Marine de Dinard, 35800 Dinard, France
4 CNRS, UMR 6554 LETG-Nantes G éolittom er
Université de Nantes, 44312 Nantes Cedex 3, France
3 IFREMER Laboratoire Environnem ent et Ressources FBN
CRESCO, 35800 Dinard, France
In recent years, the interest in d isentangling food webs in marine environm ents is grow ing due to
an increasing dem and fo r a sustainable use o f aquatic resources. Moreover, the presence o f healthy
and abundant food webs is crucial to ensure the survival o f species. M onitoring the status and the
trends o f marine food webs is essential in ord er to collect inform a tion needed to assess the current
situation and im plem ent the necessary conservation measures. A marine species which was shown
to be very useful w ith in a conservation co nte xt is Lanice conchilega. This tu be -b u ild in g polychaete
can fo rm dense populations, often called biogenic reefs, which prom ote m acrobenthic co m m un ity
change and constitute feeding grounds fo r secondary consum ers such as fla tfis h and waders.
A lthough L. conchilega is studied quite elaborately, up to now little or no attention has been paid to
the entire intertida l epi- and hyperbenthic com m unities associated w ith the reefs. Therefore, th is is
to our knowledge - the firs t study which focusses on the effect o f L. conchilega reefs on the entire
associated benthic assemblage (i.e. including the macro-, epi- and hyperbenthic com m unity) over a
larger geographic scale. A ll three com m unities were sampled w ith in a L. conchilega reef and control
area at tw o locations in France: the bay o f the M ont Saint-Michel (BMSM) and Boulogne-sur-Mer
(Boulogne).
Independent o f the geographical location, the L. conchilega reef structures all three associated
benthic com m unities, although the e xten t o f the structuring effect varies between them . We suggest
th a t th is is due to the d ifferen tia l dependency o f the macro-, epi-, and hyperbenthic com m unities to
the seafloor. The m acrobenthic com m unity, which is m ost intim ately connected w ith the sedim ent,
is m ost notably affected by the presence o f L. conchilega, w hile the hyperbenthos o f the lower w ater
colum n is the least structured by the reef. The increased abundances o f animals in all three benthic
reef com m unities a ttract and sustain higher tro p h ic levels such as (com m ercial) fish and wader.
Hence, L. conchilega reefs do not o nly affect abundances and d ive rsity but they su bstantially steer
the structure o f the intertida l sandy beach food web including benthic, pelagic and air-borne
com ponents. Moreover, the reef effect is applicable on a larger geographical scale, which is an
im p o rta n t fin d in g tow ards the im plem entation o f widespread conservation measures in the future.
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