Does culture supernatant of Haslea ostrearia containing marennine affect short-term physiological traits in the adult blue mussel Mytilus edulis?

Marennine, the blue-green pigment excreted by the pennate diatom Haslea ostrearia has potential for applications as a natural antimicrobial agent in bivalve aquaculture. However, utilization of this pigment should be assessed further prior to its application in bivalve hatcheries. The present study aims to investigate the effect of the culture supernatant of H. ostrearia containing marennine (Blue Water, BW) on physiological rates of adult mussel Mytilus edulis. The hypothesis tested in this study was that BW could alter clearance and respiration rates of adult M. edulis as indicative physiological traits. Furthermore, the effect of BW on veligers and pediveligers larvae was assessed in physiological experiments to determine whether the fixation of marennine by the larvae can influence larviphagy in this species. Our results showed that BW significantly lowered CR by 43% and reduced the oxygen consumption by 30% in adult mussels, as compared to control. In larviphagy experiments, mussels ingested veliger and pediveliger larvae without discrimination between greened or non-greened larvae. Moreover, fixation of BW in bivalve gills at 3 mg L-1 affected the physiological rate but not intensity of larviphagy in adult M. edulis. This study thus provides an insight into the necessity to determine the potential effect of marennine on adult bivalve for the future utilization of this pigment in bivalve hatcheries.