Factors driving the seasonal dynamics of Pseudo-nitzschia species and domoic acid at mussel farming in the SW Mediterranean Sea

ABSTRACT

The seasonal variations in Pseudo-nitzschia species and domoic acid (DA) concentration were investigated, at three shellfish farms in SW coastal Mediterranean. In parallel, the toxicity of mussels was tested. Two distinct groups of species were enumerated according to morphology and size (Pseudo-nizschia delicatissima and P. seriata groups). DA was detected over a nine-week period from July to October 2012 in the Lagoon, with a maximum concentration recorded in July (12.71 ng DA L⁻¹). DA was positively correlated with the presence of P. seriata-group and P. delicatissima-group and was mostly occurred during P limitation period in seawater. No DA was found in mussels that were collected during the period of DA absence in seawater. Our results suggest that temperature, salinity, inorganic and organic nutrients were significant for the seasonal dynamics of P. seriata and P. delicatissima groups, but that the P limitation was the most driving factor for DA production in these areas. The relative influence of environmental factors should be further studied to better understand the recent surfacing of massive blooms of toxigenic Pseudo-nitzschia in SW Mediterranean coast.

KEYWORDS:

• Domoic acid
• Pseudo-nitzschia
• diatoms
• Mediterranean lagoon

Acknowledgments

We thank the owners of shellfish farms Bizerte lagoon which we give access to their shellfish farms. We also wish to thank the entire team of the IRTA for the DA analyses. English text was edited by native speaker. The authors thank the two anonymous reviewers for their constructive and helpful comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Sondes Melliti Ben Garali is Professor in phytoplanktonology and marine ecology.

Inès Sahraoui, Assistant at Faculté des Sciences de Bizerte, Université de Carthage, Bizerte, Tunisia. His research examines Phytoplankton Ecology especially the toxic diatoms of the genus Pseudo-nitzschia. His research aims to understand the toxic effect diatoms on bivalves.

Pablo de la Iglesia, Analytical chemist, specialist in marine toxins, chromatographic and mass spectrometric methods. His research on toxins and microalgae with duties from the official shellfish monitoring programme and from the quality system as technical responsible of the ISO 17025 IRTA's accreditation.

Mohamed chalghaf, Aquaculture engineer in Ecloserie de Bivalves de l'Institut supérieur de Pêche et d'Aquaculture de Bizerte: [email protected]/[email protected] BP,15 Errimel Menzel Jemil 7080 Bizerte; Tunisie.

Jorge Diogène, Head of the Marine and Continental Waters programme. His research focuses on The Marine and Continental Waters programme of IRTA focuses research and conducts environmental monitoring of rivers, wetlands, estuary and coastal areas.

Jamel Ksouri, General Director at the Higher Institute of Fisheries and Aquaculture of Bizerte, Bizerte, Tunisia his research is focused on the Science and Technology of Fishing and Aquaculture.

Asma Sakka Hlaili, Professeur at Faculté des Sciences de Bizerte, Université de Carthage, Bizerte, Tunisia. His research activities focus on the dynamics, diversity and ecotoxicology of planktonic communities as well as their responses to natural and anthropogenic forcings (climate change, industrial and terrestrial pollution, atmospheric deposition,…).