Overcoming Ostrea edulis seed production limitations to meet ecosystem restoration demands in the UN decade on restoration

The European flat oyster, Ostrea edulis, is a habitat-forming bivalve which was historically widespread throughout Europe. Following its decline due to overfishing, pollution, sedimentation, invasive species, and disease, O. edulis and its beds are now listed as a threatened and/or declining species and habitat by OSPAR. Increasing recognition of the plight of the oyster, alongside rapidly developing restoration techniques and growing interest in marine restoration, has resulted in a recent and rapid growth in habitat restoration efforts. O. edulis seed supply is currently a major bottleneck in scaling up habitat restoration efforts in Europe. O. edulis has been cultured for centuries, however, research into its culture declined following the introduction of the Pacific oyster, Crassostrea gigas to Europe in the early 1970 s. Recent efforts to renew both hatchery and pond production of O. edulis seed for habitat restoration purposes are hampered by restoration project timelines and funding typically being short, or projects not planning appropriately for the timescales required for investment, research-and-development and delivery of oyster seed by commercial producers. Furthermore, funding for restoration is intermittent, making long-term commitments between producers and restoration practitioners difficult. Long-term, strategic investment in research and production are needed to overcome these bottlenecks and meet current ambitious restoration targets across Europe

Mussel production carrying capacity : the need for an in situ and multidisciplinary approach

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Interacting climate change effects on mussels (

The physiological response of two species of mussels (Mytilus edulis and M. galloprovincialis) and two species of oysters (Crassostrea gigas and Ostrea edulis) to temperature, oxygen levels and food concentration, factors likely to vary as a result of climate change, was determined experimentally. Bivalves of similar size from different origins were exposed to six temperatures (3, 8, 15, 20, 25 and 30 °C) at two food regimes (2 and 10 μg Chl a L−1) for 6 weeks. In a parallel running experiment M. edulis from the same batches were exposed to three different temperatures (15, 20 and 25 °C) and three different oxygen levels (30, 50 and 100%) at two food regimes (2 and >8 μg Chl a L−1) for 3–4 weeks. Survival during the experiment ranged from 93% to 100% except for the mussels exposed to 30 °C which showed 100% mortality after three to 32 days. Higher food conditions showed higher optimal temperatures for growth of mussels and oysters. In addition, at the high food treatment, reduced O2 saturation resulted in lower growth of mussels. At the low food treatment there were no differences in growth among the different O2 levels at the same temperature. At high food concentration treatment, M. edulis growth was higher with low temperature and high oxygen level. Condition index was higher at higher food concentrations and decreased with increasing temperature. In addition, condition was lower at low oxygen saturation. Lower clearance rates were observed at high food concentrations. At 100% saturation of oxygen, mussel clearance rate increased with temperature at High food regime, but not at Low food regime. Mussel clearance rates were significantly reduced with low oxygen concentrations together with high temperature. Oxygen consumption significantly increased with temperature. Oxygen saturation was the main factor affecting mussel clearance rate. High temperature and low oxygen concentration combined significantly reduced clearance rate and increased oxygen consumption. These response curves can be used to improve parameterisation of individual shellfish growth models taking into consideration factors in the context of climate change: temperature, food concentration, oxygen concentration and their interactions. The observation that abiotic factors interact in affecting mussels and oysters is an important result to take into account

Futurs possibles d'un système d'acteurs : formalisation et génération automatique de scénarios

RJCIA 2022National audienceL'étude des futurs possibles d'un système d'acteurs par la génération de scénarios est un moyen d'anticipation et d'aide à la décision pour les organisations. Les méthodes existantes, le plus souvent participatives, produisent en général un nombre restreint de scénarios. Une génération systématique et automatisée de scénarios permettrait à la fois d'élargir l'ensemble des résultats produits et de limiter les biais inhérents à la réflexion des participants. Nous présentons ici un modèle formel permettant de définir un système et ses composantes (acteurs, principes moraux, variables...) et de générer et d'analyser des scénarios, en particulier lorsque des conflits se produisent pour un acteur (conflit moral) ou entre plusieurs acteurs (conflit logique)