Statistical analysis of polychaete population density: dynamics of dominant species and scaling properties in relative abundance fluctuations

We consider here the dynamics of two polychaete populations based on a 20 yr temporal benthic survey of two muddy fine sand communities in the Bay of Morlaix, Western English Channel. These populations display high temporal variability, which is analyzed here using scaling approaches. We find that population densities have heavy tailed probability density functions. We analyze the dynamics of relative species abundance in two different communities of polychaetes by estimating in a novel way a "mean square drift" coefficient which characterizes their fluctuations in relative abundance over time. We show the usefulness of using new tools to approach and model such highly variable population dynamics in marine ecosystems

La préservation du patrimoine naturel littoral dans le processus de la gestion intégrée des zones côtières : éléments de réflexion pour l'élaboration d'un projet et perspectives

The coastal zone is an area of conflicting processes reflecting its position at the interface between the terrestrial and marine environments. This area needs further study and an enforcement of co-ordinated conservation policy for the implementation of effective protection. A multidisciplinary team (law, ecology, biology, and geography) has published a book, which assembles the elements of current politics involved with the preservation of the natural heritage of the coasts of mainland France. Part 1 deals on the definition of the coastal zone, the dispositions for the preservation of the natural heritage, the institutions concerned with its knowledge about and management and the objective criteria and methods for the choice or separation of zones to be protected. Part 2 gives the characteristic heritage aspects of the three coastal chosen regions. Part 3 gives perspectives to set up a more management model for the preservation of the natural heritage. It is necessary to have a clarification of current expertise resulting in a harmonization and institutional co-ordination of organisms linked to the coastal zone. The reform of the status of the CELRL increases its intervention in the maritime public domain. It offers prospects to consolidate this organization in its role in the protection of the littoral natural patrimonyInterface entre le milieu terrestre et le milieu marin, le littoral est une zone conflictuelle où les usages sont contradictoires, et un espace où il existe des besoins de connaissances et où il faut mettre en place une politique coordonnée de protection. Un ouvrage vient d'être réalisé par une équipe pluridisciplinaire (droit, écologie, biologie, géographie) en réponse au programme LITEAU du MATE. Il recense les éléments de la politique de préservation du patrimoine naturel de la France métropolitaine. Il prend pour exemples trois littoraux. Le Temps 1 s'ordonne autour des définitions du littoral, des institutions impliquées dans sa connaissance et sa gestion, des critères et méthodes objectives pour choisir ou délimiter des zones à préserver. Le Temps 2 traite des particularités patrimoniales des trois régions choisies. Le Temps 3 donne des perspectives pour construire un modèle de gestion satisfaisant du patrimoine naturel littoral à partir de l'analyse de l'existant. Les nombreuses interactions entre les intervenants multiples sur le littoral imposent une clarification des compétences, une harmonisation et une coordination institutionnelle. La réforme du statut du CELRL prévoit son intervention au domaine public maritime ; elle offre des perspectives pour le conforter dans son rôle d'acteur de la protection du patrimoine naturel littoral

Ecological impacts of non-native Pacific oysters (Crassostrea gigas) and management measures for protected areas in Europe

Pacific oysters are now one of the most ‘globalised’ marine invertebrates. They dominate bivalve aquaculture production in many regions and wild populations are increasingly becoming established, with potential to displace native species and modify habitats and ecosystems. While some fishing communities may benefit from wild populations, there is now a tension between the continued production of Pacific oysters and risk to biodiversity, which is of particular concern within protected sites. The issue of the Pacific oyster therefore locates at the intersection between two policy areas: one concerning the conservation of protected habitats, the other relating to livelihoods and the socio-economics of coastal aquaculture and fishing communities. To help provide an informed basis for management decisions, we first summarise evidence for ecological impacts of wild Pacific oysters in representative coastal habitats. At local scales, it is clear that establishment of Pacific oysters can significantly alter diversity, community structure and ecosystem processes, with effects varying among habitats and locations and with the density of oysters. Less evidence is available to evaluate regional-scale impacts. A range of management measures have been applied to mitigate negative impacts of wild Pacific oysters and we develop recommendations which are consistent with the scientific evidence and believe compatible with multiple interests. We conclude that all stakeholders must engage in regional decision making to help minimise negative environmental impacts, and promote sustainable industry development

Contrasting patterns of population structure and gene flow facilitate exploration of connectivity in two widely distributed temperate octocorals

This is the final version of the article. Available from Springer Nature via the DOI in this record.Connectivity is an important component of metapopulation dynamics in marine systems and can influence population persistence, migration rates and conservation decisions associated with Marine Protected Areas (MPAs). In this study, we compared the genetic diversity, gene flow and population structure of two octocoral species, Eunicella verrucosa and Alcyonium digitatum, in the northeast Atlantic (ranging from the northwest of Ireland and the southern North Sea, to southern Portugal), using two panels of thirteen and eight microsatellite loci, respectively. Our results identified regional genetic structure in E. verrucosa partitioned between populations from southern Portugal, northwest Ireland, and Britain/France; subsequent hierarchical analysis of population structure also indicated reduced gene flow between southwest Britain and northwest France. However, over a similar geographical area, A. digitatum showed little evidence of population structure, suggesting high gene flow and/or a large effective population size; indeed, the only significant genetic differentiation detected in A. digitatum occurred between North Sea samples and those from the English Channel/northeast Atlantic. In both species the vast majority of gene flow originated from sample sites within regions, with populations in southwest Britain being the predominant source of contemporary exogenous genetic variants for the populations studied. Unsurprisingly, historical patterns of gene flow appeared more complex, though again southwest Britain appeared an important source of genetic variation for both species. Our findings have major conservation implications, particularly for E. verrucosa, a protected species in UK waters and listed by the IUCN as ‘Vulnerable’, and for the designation and management of European MPAs.We thank Natural England (project No. RP0286, contract No. SAE 03-02-146), the NERC (grant No. NE/L002434/1) and the University of Exeter for funding this research. Additional funding for sample collection, travel and microsatellite development was provided by the EU Framework 7 ASSEMBLE programme, agreement no. 227799, and NERC grant No. NBAF-362

Spearfishing Regulation Benefits Artisanal Fisheries: The ReGS Indicator and Its Application to a Multiple-Use Mediterranean Marine Protected Area

The development of fishing efficiency coupled with an increase of fishing effort led to the overexploitation of numerous natural marine resources. In addition to this commercial pressure, the impact of recreational activities on fish assemblages remains barely known. Here we examined the impact of spearfishing limitation on resources in a marine protected area (MPA) and the benefit it provides for the local artisanal fishery through the use of a novel indicator. We analysed trends in the fish assemblage composition using artisanal fisheries data collected in the Bonifacio Strait Natural Reserve (BSNR), a Mediterranean MPA where the spearfishing activity has been forbidden over 15% of its area. Fish species were pooled into three response groups according to their target level by spearfishing. We developed the new flexible ReGS indicator reflecting shifts in species assemblages according to the relative abundance of each response group facing external pressure. The catch per unit effort (CPUE) increased by ca. 60% in the BSNR between 2000 and 2007, while the MPA was established in 1999. The gain of CPUE strongly depended on the considered response group: for the highly targeted group, the CPUE doubled while the CPUE of the untargeted group increased by only 15.5%. The ReGS value significantly increased from 0.31 to 0.45 (on a scale between 0 and 1) in the general perimeter of this MPA while it has reached a threshold of 0.43, considered as a reference point, in the area protected from spearfishing since 1982. Our results demonstrated that limiting recreational fishing by appropriate zoning in multiple-use MPAs represents a real benefit for artisanal fisheries. More generally we showed how our new indicator may reveal a wide range of impacts on coastal ecosystems such as global change or habitat degradation