Bonnet, S.

Collard, M.

Dubois, Ph.

Open Marine Archive

 - 20 -
OCEAN ACIDIFICATION IMPACTS ON THE PHYSIOLOGY AND ADHESIVE 
PROPERTIES OF THE STARFISH ASTERIAS RUBENS 
Collard Marie*, Stéphanie Bonnet* and Philippe Dubois 
Marine Biology Laboratory, Université Libre de Bruxelles, 50 avenue F.D. Roosevelt,  
1050 Brussels, Belgium 
E-mail: macollar@ulb.ac.be ; sbonnet@ulb.ac.be 
The increase in atmospheric CO
2
 due to anthropogenic activity is an acidification of the ocean which 
could lead to pH as low as 7.7 and 7.4 by 2100 and 2300, respectively. The impact of this 
phenomenon will depend on the considered organisms and ecosystems. In particular little is 
currently known on the effects of acidification on temperate ecosystems. The intertidal rocky shores 
are of great interest in this context as intertidal organisms face tidal pH and temperature changes. 
They may harbor organisms pre-adapted to the changes predicted for the coming years and 
centuries. Furthermore, the intertidal environment will be more affected as shallow waters will face 
the highest decrease in seawater pH. Therefore, we studied the effects of ocean acidification on 
Asterias rubens, the common starfish of the Belgian coast which is known to structure some 
intertidal shores through its predator activity. Effects on the physiology but also on the adhesion 
capacities of the organism were investigated using organisms maintained at pH 8.1, 7.7 and 7.4 for 
periods of 15 and 31 days. Our results showed that Asterias rubens did not regulate its acid-base 
balance as no accumulation of HCO
3
- was observed and no dissolution of the skeleton as a buffer 
was detected by measures of Mg2+ and Ca2+ in the coelomic fluid. However, the starfish showed no 
consequence from the decrease of the coelomic fluid pH as all activities measured (respirometry, 
adhesion capacities) were not significantly affected by seawater pH decrease. Equilibration of the 
coelomic pH with the seawater pH was fast (typically less than 24 hours). The former was always 
lower than the latter. This suggests an accumulation of respiratory CO
2
 inside the organism which 
creates a respiratory acidosis and so a decrease of the pH. In conclusion, it seems that Asterias 
rubens withstands the effects of ocean acidification, at least for short terms (one month). If this is 
confirmed, the balance between the predator and its prey (Mytilus edulis, the blue mussel) may shift 
with time as many studies have shown deleterious effects on the latter. The rocky intertidal shores 
may face changes in the coming centuries and move to a new equilibrium. 
 
Keywords: ocean acidification; echinoderms; acid-base regulation. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
*These authors have contributed equally to this work. 
 
 


Ocean acidification impacts on the physiology and adhesive properties of the starfish <i>Asterias rubens</i>

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