Spatial, Ecological and Social Dimensions of Assessments for Bivalve Farming Management

The general purpose of assessment is to provide decision-makers with the best valuable data, information, and predictions with which management decisions will be supported. Using case studies taken from four scientific projects and dealing with the management of marine bivalve resources, lessons learned allowed identifying some issues regarding assessment approaches. The selected projects also introduced methodological or institutional frameworks: ecosystem approach to aquaculture (EAA), system approach framework (SAF), marine spatial planning (MSP), and valuation of ecosystem services (ES). The study on ecosystem services linked ES to marine habitats and identified ES availability and vulnerability to pressures. The results were displayed as maps of resulting potential services with qualitative metrics. The vulnerability value is an alternative to monetary valuation and, in addition to identifying the most suitable areas for each type of ES, this metric allows identifying the management strategies that will most probably maintain or affect each individual ES. The MSP example focused on bivalve farming activity and accounted for several criteria: habitat suitability, growth performance, environmental and regulation constraints and presence of other activities. The ultimate endpoint of such an approach is a map with qualitative values stating whether a location is suitable or not, depending on the weight given to each criterion. In the EAA case study, the indicator was defined by the growth performance of cultivated bivalves in different locations. This indicator is affected by distant factors – e.g. populations of marine organisms competing for the same food resource, nutrient inputs from rivers, time to renew water bodies under the action of tidal currents. The role and interactions of these factors were assessed with a dynamical ecosystem model. Examples illustrate that the assessment is often multi-dimensional, and that multiple variables would interact and affect the response to management options. Therefore, the existence of trade-offs, the definition of the appropriate spatial scale and resolution, the temporal dynamics and the distant effects of factors are keys to a policy-relevant assessment. EA and SAF examples show the interest of developing models relating response to input variables and testing scenarios. Dynamic models would be preferred when the relationship between input and output variables may be masked by non-linear effects, delay of responses or differences of scales. When decision-making requires economic methods, monetary values are often of poor significance, especially for those ecosystem services whose loss could mean the end of life, and appear to be a comfortable oversimplification of reality of socio-ecological systems which cannot be summarized in single numbers. Alternative methods, such as the ones proposed in the SAF and ES examples, would preferably consider institutional analysis or multicriteria assessment rather than single monetary values. Case studies also highlighted that credibility of assessment tools benefit from the association of stakeholders at different stages, among which: identification of the most critical policy issues; definition of system characteristics including ecological, economical and regulation dimensions; definition of modelling scenarios to sort out the most effective management options; assessment of models and indicators outputs.publishedVersio

Impact of Cultural Practices on the individual and Collective Economic Performances in Shellfish Farming: the Case of Oyster Farming in Baie Des Veys

The access regulation within the shellfish farming sector in France is based on a co-management system relying on both a national legislation, defining the general access conditions to maritime public grounds, and regional regulation systems, called “Regional Structural Schemes”. The latter specify the farming rules in cooperation with the administration, scientific and professional representatives. This regulation system, which aims at managing the common primary resources at the scale of a shellfish farming basin, is under review in the baie des Veys, on the Normandy coastline. In this context, biological modelling is used to assess the carrying capacity of the bay and to provide tools for modifying the RSS in a more sustainable way. Another objective of the study is to shift to bio-economic modelling, implying for the model to take into account extra technical and economical parameters. A specific survey has therefore been carried out for collecting detailed information on the cultural practices of the oyster farming companies, and for analysing the links with their structural characteristics and performance indicators, in terms of productivity and output. This article reviews the context of oyster farming in the baie des Veys from the environmental, socio-economic and institutional point of view. After the presentation of the methodology used for the survey, its results are analysed and a synthesis is made, leading to the identification of the main farming technical profiles. At this stage of the study, only theoretical developments on modelling are considered and outlooks in terms of collective management measures are discussed.Keywords: Aquaculture, Fisheries Economics, Aquaculture Efficiency and Managemen

Εισοδηματικές ανισότητες και φιλανθρωπία

<p>All variables were kriged on different variogram models depending on the data (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0044155#pone-0044155-t001" target="_blank">Table 1</a>). Geometrical scales were used to maximize the visualization of both gradients and the patchiness of the different variables. Mollusk maps are at different scales to account for the discrepancy in the data between the 2 samplings. <b>A, B</b>: Chl <i>a</i> concentration (µg.L⁻¹); <b>C, D</b>: SPiM amount (mg.L⁻¹). <b>E, F</b>: Bottom mean current velocities and direction at the 2 sampling periods, calculated by the MARS-3D hydrodynamic model.</p

Geographic and seasonal patterns and limits on the adaptive response to temperature of European Mytilus spp. and Macoma balthica populations

Seasonal variations in seawater temperature require extensive metabolic acclimatization in cold-blooded organisms inhabiting the coastal waters of Europe. Given the energetic costs of acclimatization, differences in adaptive capacity to climatic conditions are to be expected among distinct populations of species that are distributed over a wide geographic range. We studied seasonal variations in the metabolic adjustments of two very common bivalve taxa at European scale. To this end we sampled 16 populations of Mytilus spp. and 10 Macoma balthica populations distributed from 39° to 69°N. The results from this large-scale comprehensive comparison demonstrated seasonal cycles in metabolic rates which were maximized during winter and springtime, and often reduced in the summer and autumn. Studying the sensitivity of metabolic rates to thermal variations, we found that a broad range of Q10 values occurred under relatively cold conditions. As habitat temperatures increased the range of Q10 narrowed, reaching a bottleneck in southern marginal populations during summer. For Mytilus spp., genetic-group-specific clines and limits on Q10 values were observed at temperatures corresponding to the maximum climatic conditions these geographic populations presently experience. Such specific limitations indicate differential thermal adaptation among these divergent groups. They may explain currently observed migrations in mussel distributions and invasions. Our results provide a practical framework for the thermal ecophysiology of bivalves, the assessment of environmental changes due to climate change and its impact on (and consequences for) aquaculture

Assessment of coastal management options by means of multilayered ecosystem models

This paper presents a multilayered ecosystem modelling approach that combines the simulation of the biogeochemistry of a coastal ecosystem with the simulation of the main forcing functions, such as catchment loading and aquaculture activities. This approach was developed as a tool for sustainable management of coastal ecosystems. A key feature is to simulate management scenarios that account for changes in multiple uses and enable assessment of cumulative impacts of coastal activities. The model was applied to a coastal zone in China with large aquaculture production and multiple catchment uses, and where management efforts to improve water quality are under way. Development scenarios designed in conjunction with local managers and aquaculture producers include the reduction of fish cages and treatment of wastewater. Despite the reduction in nutrient loading simulated in three different scenarios, inorganic nutrient concentrations in the bay were predicted to exceed the thresholds for poor quality defined by Chinese seawater quality legislation. For all scenarios there is still a Moderate High to High nutrient loading from the catchment, so further reductions might be enacted, together with additional decreases in fish cage culture. The model predicts that overall, shellfish production decreases by 10%–28% using any of these development scenarios, principally because shellfish growth is being sustained by the substances to be reduced for improvement of water quality. The model outcomes indicate that this may be counteracted by zoning of shellfish aquaculture at the ecosystem level in order to optimize trade-offs between productivity and environmental effects. The present case study exemplifies the value of multilayered ecosystem modelling as a tool for Integrated Coastal Zone Management and for the adoption of ecosystem approaches for marine resource management. This modelling approach can be applied worldwide, and may be particularly useful for the application of coastal management regulation, for instance in the implementation of the European Marine Strategy Framework Directive

Projet OGIVE. Outils d’aide à la Gestion Intégrée et à la Valorisation des Ecosystèmes conchylicoles de Basse-Normandie. Rapport final d’activités - Phase I (2005-2008)

L’objectif général du projet OGIVE est d’acquérir des connaissances sur le fonctionnement des écosystèmes conchylicoles de Basse-Normandie dans le but d’établir une plateforme de données communes à l’ensemble des partenaires du projet. Ces connaissances sont ensuite utilisées pour développer des outils novateurs permettant de fournir des avis et expertises aux gestionnaires du Domaine Public Maritime. Le projet a ainsi pour objectif de contribuer au développement durable de la filière conchylicole en Basse-Normandie en optimisant la production conchylicole et en préservant la qualité environnementale des écosystèmes qui supportent cette activité. Le projet OGIVE a été structuré initialement autour du développement de trois outils : 1) Un outil empirique sous Système d’Information Géographique destiné à répondre aux questions de gestion relatives aux restructurations à l’échelle d’une concession, 2) Un outil de modélisation non spatialisé (i.e. modèle d’écosystème biologique) permettant d’estimer la capacité de support trophique (i.e. biomasse maximale à mettre en exploitation compte tenu de la nourriture disponible dans l’écosystème) de chacun des sites de production bas-normands, 3) Un outil de modélisation spatialisé (i.e. modèle d’écosystème couplant les processus physiques & biologiques) permettant d’affiner les estimations de capacité de support trophique et de tester différents scénarios de réaménagement des zones d’élevage. Le présent rapport est dédié à la présentation des résultats acquis au cours de la première phase du projet (2005-2008)