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The Workshop on Bay of Biscay and Iberian Coast Aquaculture Overview (WKBoBICAO) was established to assemble and synthesize aquaculture related data and information and to inform the aquaculture overview for this ecoregion. The geographic extent of the Bay of Biscay and Iberian Coast ecoregion is extensive and ranges from southern Brittany in France through northern and northwestern Spain, it includes the entire coastline of Portugal (mainland) and culminates in the Gulf of Cadiz in southern Spain. It covers a wide range of habitat types and climatic conditions, which has a bearing on the types of aquaculture practiced in the ecoregion. Aquaculture is practised throughout much of the ecoregion. Both intertidal and subtidal waters are utilized in addition to terrestrial pond culture. The aquaculture production within the ecoregion is dominated by shellfish which are largely produced in France (Oysters and Mussels) and Spain (mussels). Portugal production comprises a mix of shellfish, finfish and crustacean culture and while lower in terms of tonnage produced and value than the other countries. In 2021, the aquaculture sector in the ecoregion reached 310,000 Tons produced and €775 million in value. Shellfish are the most produced in the ecoregion and contribute to almost 75% of total value. Crustacean production in Spain and shellfish and finfish production in Portugal show a clear increase since 2010, other species are static in terms of production. Spain produces the greatest tonnage but is second to France in terms of economic value. A number of other species (e.g. finfish, polychaete worms for bait) in addition macroalgae are also grown at smaller scales throughout the ecoregion. In the ecoregion, aquaculture licencing, regulation and policy are the responsibility of the member state. While overarching policy is defined at the EU level, licensing can be different in the various countries. In Portugal a single federal body is responsible for licensing. In Spain and

Since the beginning of the industrial revolution, atmospheric carbon dioxide (CO2) concentrations have risen steadily and have induced a decrease of the averaged surface ocean pH by 0.1 units, corresponding to an increase in ocean acidity of about 30 %. In addition to ocean warming, ocean acidification poses a tremendous challenge to some marine organisms, especially calcifiers. The need for long-term oceanic observations of pH and temperature is a key element to assess the vulnerability of marine communities and ecosystems to these pressures. Nearshore productive environments, where a large majority of shellfish farming activities are conducted, are known to present pH levels as well as amplitudes of daily and seasonal variations that are much larger than those observed in the open ocean. Yet, to date, there are very few coastal observation sites where these parameters are measured simultaneously and at high frequency. To bridge this gap, an observation network was initiated in 2021 in the framework of the CocoriCO(2) project. Six sites were selected along the French Atlantic and Mediterranean coastlines based on their importance in terms of shellfish production and the presence of high- and low-frequency monitoring activities. At each site, autonomous pH sensors were deployed, both inside and outside shellfish production areas, next to high-frequency CTD (conductivity-temperature-depth) probes operated through two operating monitoring networks. pH sensors were set to an acquisition rate of 15 min, and discrete seawater samples were collected biweekly in order to control the quality of pH data (laboratory spectrophotometric measurements) as well as to measure total alkalinity and dissolved inorganic carbon concentrations for full characterization of the carbonate system. While this network has been up and running for more than 2 years, the acquired dataset has already revealed important differences in terms of pH variations between monitored sites related to the in

Ocean acidification (OA), a consequence of the increase in anthropogenic emissions of carbon dioxide, causes major changes in the chemistry of carbonates in the ocean with deleterious effects on calcifying organisms. The pH/PCO2 range to which species are exposed in nature is important to consider when interpreting the response of coastal organisms to OA. In this context, emerging approaches, which assess the reaction norms of organisms to a wide pH gradient, are improving our understanding of tolerance thresholds and acclimation potential to OA. In this study, we deciphered the reaction norms of two oyster species living in contrasting habitats: the intertidal oyster Crassostrea gigas and the subtidal flat oyster Ostrea edulis, which are two economically and ecologically valuable species in temperate ecosystems. Six-month-old oysters of each species were exposed in common garden tanks for 48 days to a pH gradient ranging from 7.7 to 6.4 (total scale). Both species were tolerant down to a pH of 6.6 with high plasticity in fitness-related traits such as survival and growth. However, oysters underwent remodelling of membrane fatty acids to cope with decreasing pH along with shell bleaching impairing shell integrity and consequently animal fitness. Finally, our work revealed species-specific physiological responses and highlights that intertidal C. gigas seem to have a better acclimation potential to rapid and extreme OA changes than O. edulis. Overall, our study provides important data about the phenotypic plasticity and its limits in two oyster species, which is essential for assessing the challenges posed to marine organisms by OA.

La mer nous a toujours nourri-e-s. Nous avons longtemps cru qu’ils pouvaient pêcher ou récolter sans risque d’épuiser ses ressources. L’histoire et la biologie ont montré qu’il n’en était rien. La pêche est devenue l’activité humaine impactant le plus les océans. La mer nourrit, mais elle stocke aussi l’essentiel des gaz à effet de serre et le réchauffement produits par les activités humaines. Le dérèglement climatique d’origine humaine devrait devenir la pression principale sur les écosystèmes marins, s’ajoutant aux effets de la pêche, des autres pollutions, et de la destruction de zones sensibles. Dans ces conditions, la mer va-t-elle rester nourricière ? Tout dépend des actes que nous posons aujourd’hui. Afin d’éclairer nos choix, une démarche prospective a été menée dans le cadre du projet FORESEA 2050 de l’Ifremer. L’objectif était d’écrire des scénarios décrivant des futurs possibles pour la pêche et de l’aquaculture en France en 2050. Comme des balises sur une carte marine, ces scénarios aident à esquisser aujourd’hui les trajectoires les plus souhaitables pour demain. Comme dans l’océan, vous pouvez choisir d’en explorer les profondeurs, ou de rester en surface. La carte est entre vos mains. Faires en bon usage, et bonne exploration. Pour que la mer reste nourricière.

Ocean acidification caused by anthropogenic carbon dioxide emissions alters the growth of marine calcifiers. Although the immediate effects of acidification from global ocean models have been well studied on calcifiers, their recovery capacity over a wide range of pH has never been evaluated. This aspect is crucial because acidification events that arise in coastal areas can far exceed global ocean predictions. However, such acidification events could occur transiently, allowing for recovery periods during which the effects on growth would be compensated, maintained or amplified. Here we evaluated the recovery capacity of a model calcifier, the Pacific oyster Crassostrea gigas. We exposed juveniles to 15 pH conditions between 6.4 and 7.8 for 14 days. Oyster growth was retarded below pH 7.1 while shells were corroded at pH 6.5. We then placed the oysters under ambient pH > 7.8 for 42 days. Growth retardation persisted at pH levels below pH 7.1 even after the stress was removed. However, despite persistent retardation, growth has resumed rapidly suggesting that the oysters can recover from extreme acidification. Yet we found that the differences in individual weight between pH conditions below 7.1 increased over time, and thus the growth retardation cannot be compensated and may affect the fitness of the bivalves.