Spatfall in a changing environm ent: mind the HAB
De Rijcke M aarten1, Michiei B. Vandegehuchte1, Nancy Nevejan2, Julie Vanden Bussche3,
Lynn Vanhaecke3 and Colin R. Janssen1
1 Laboratory o f Environm ental T o xico lo g y and A quatic Ecology
Ghent University, J. Plateaustraat 22, B-9000 Ghent, Belgium
E-mail: m aarten.deriicke@ uqent.be
2 Laboratory o f A quaculture and A rtem ia Reference Center
Ghent University, Rozier 44, B-9000 Ghent, Belgium
3 Laboratory o f Chemical Analysis,
Ghent University, Salisburylaan IBB, B-9820 Merelbeke, Belgium
Due to the com bined effect o f overfishing, clim ate change, e utrophication and the dispersal o f
invasive species in the marine environm ent, harm ful algal bloom s (HABs) are steadily increasing in
frequency, inten sity and geographical scale. Yet to date, our understanding o f the effects o f HABs
on the recruitm en t o f marine organism s is lim ited. As shellfish fa rm ing is expected to play a crucial
role in the fu lfilm e n t o f the fu tu re global protein demand, a better understanding o f the risks that
HABs pose to the reproduction and developm ent o f bivalves is needed. This research therefore
aimed to investigate the acute to x ic effects o f harm ful algae and marine to x in s on the larval
viability, developm ent and innate im m une response o f bivalves. To th is end, em bryos o f the model
species M ytilus edulis (blue mussel) were exposed fo r 48 hours to a concentration series o f the
marine to xin s dom oic acid (DA) and okadaic acid (OA) as well as th e ir respective to x in -p ro d u cin g
algae Pseudo-nitzschia m ultiseries and P rorocentrum lim a. We found th a t neither bloom
concentrations o f dom oic acid, nor bloom densities o f P. m ultiseries displayed acute to x ic effects
on the v ia b ility and developm ent o f M. edulis larvae. Okadaic acid on the o the r hand sign ifican tly
reduced the v ia b ility o f veliger larvae at concentrations as low as 37.8pg.l ', which is a concentration
range likely to occur during dense bloom s o f OA producing algae This effect may be related to a
sign ifican t in h ib itio n o f larval protein phosphatases by OA as observed in vitro. P. lim a was not
found to affect the larval developm ent or v ia b ility b ut induced an increase in the phenoloxidase
innate imm une a ctivity which could not be a ttrib u te d to the occurence o f OA in the algae. A sim ilar
increase in PO a ctivity was detected fo r P. m ultiseries. This effect was strain dependent and could
partially be a ttrib u te d to the presence o f DA. As th is is the firs t study to investigate and detect the
activation o f the phenoloxidase innate im m une activity by harm ful algae and marine to xins, the
consequences o f these increases fo r the larval resilience to o the r stressors are unknown. Yet the
change o f the im m une a ctivity com bined w ith the reduced v ia b ility associated w ith OA warrants
closer investigation as HABs could possibly influence natural recruitm en t as well as the hatcherycultured production o f bivalves.
-
39-