Effects of marennine, the blue pigment synthesized by the diatom Haslea ostrearia, on early developmental stages of the mussel Mytilus edulis and the sea urchin Sphaerechinus granularisCharlotte FALAISE1, Patrick CORMIER2, Jean-Luc MOUGET1, Vincent LEIGNEL1, Yann HARDIVILLIER1, Karine Lemarchand3, Réjean TREMBLAY3

1Laboratoire Mer Molécule Santé (EA 2160, FR CNRS 3473 IUML), Le Mans Université, France

2Laboratoire de Biologie Intégrative des Modèles Marins (UMR 8227, UPMC/CNRS), Station Biologique de Roscoff, France

3 Institut des Sciences de la Mer, Université du Québec à Rimouski, Canada.

Keywords: Diatom, Haslea ostrearia, marennine, bivalve, echinoderm, larval development, embryonic development

The marine diatom Haslea ostrearia can accumulate in the cell apices and release in its surrounding environment a blue pigment called marennine. This pigment has been well known for centuries in oyster farms in western France as it provides a blue-green color to the gills of oysters, conferring the label ‘fine de claire verte’ and increasing their market value. The chemical nature of marennine is still unknown and is currently being studied through several research programs*, yet various biological activities were demonstrated by this pigment such as antiviral, antifungal or antioxidant1. Recent studies also demonstrated the capacity of marennine to limit in vitro the growth of pathogenic bacteria from the genus Vibrio2 and to improve in vivo the survival of mussel and scallop larvae challenged with a pathogenic Vibrio3. Such results reinforced the interest of H. ostrearia and its pigment for a potential use in aquaculture to stabilize larval rearing. However, little is known about the effects of marennine on early developmental stages of marine invertebrates, while such studies are essential to determine the marennine concentrations that can be delivered without toxicity or adverse effect on larvae. In this context, we carried out two series of experiments with two different models, the mollusc Mytilus edulis and the echinoderm Sphaerechinus granularis. In M. edulis, a dose-response effect was observed, with the earliest developmental stages appearing more sensitive to marennine. In sea urchin S. granularis, we observed a reversible effect when embryos were rinsed, suggesting a non-permanent toxicity of the pigment. These results underline the potent biological activity of marennine, from beneficial (coloring or anti-pathogen agent) to harmful (cell development inhibition), and the need to consider dose of the pigment and sensitivity of target organisms for applications in aquaculture.
*RFI-Food for tomorrow program and European Union's Horizon 2020 research and innovation program (grant agreement No 734708 / GHANA / H2020-MSCA-RISE-2016).

1. Gastineau, R. et al. Marennine, promising blue pigments from a widespread Haslea diatom species complex. Mar. Drugs 12, 3161–3189 (2014).
2. Falaise, C. et al. Antimicrobial Compounds from Eukaryotic Microalgae against Human Pathogens and Diseases in Aquaculture. Mar. Drugs 14, 159 (2016).
3. Turcotte, F. et al. Prophylactic effect of Haslea ostrearia culture supernatant containing the pigment marennine to stabilize bivalve hatchery production. Aquat. Living Resour. 29, 401 (2016)