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Marine Connectivity: Temperate Systems

Connectivity and Gene Flow in Temperate Alcyonacea (Octocorallia): Implications for Marine Protected Area (MPA) Designation


Connectivity between marine populations via larval dispersal determines genetic diversity, a high level of which is crucial for ecosystem function, resilience, and recovery from anthropogenic and climatic disturbance. Connectivity is therefore a key consideration in the design of marine reserve networks, as reserves must be appropriately sized and spaced to facilitate propagule dispersal between source and sink populations of taxa of conservation interest. However, the extent of connectivity between and within most marine ecosystems is poorly understood and data usually comprises inferred larval dispersal and is rarely derived from temperate or invertebrate taxa, many of which are heavily threatened by the fishing industry and climate change. Furthermore, some evidence suggests that colder temperatures characteristic of higher latitudes may prolong pelagic larval duration and therefore connectivity may depend upon temporal and spatial variation in life history traits in addition to physical processes, suggesting that existing guidelines established to design MPAs in tropical areas could be inapplicable in temperate regions.

To address this shortfall, this study will assess connectivity and gene flow of  the octocorals Eunicella verrucosa (the pink sea fan) and Alcyonium digitatum (dead mans fingers) using high-resolution molecular methods over a range of geographical scales. This data is vital to validate the effectiveness of boundaries of the MPA network proposed by the forthcoming UK Marine and Coastal Access Bill (2012), and will identify other areas in Europe where the octocorals may by threatened by reduced genetic diversity. We will determine if variation in dispersal potential of the two species affects the extent of connectivity, and we will assess the extent of inbreeding across the range of each species. Eunicella verrucosa is red listed by the IUCN and has a ‘vulnerable’ status; UK populations have suffered considerable decimation by trawling damage and are also subject to disease outbreaks. Baseline data concerning the connectivity between populations of both octocorals is currently inexistent and fundamental to the development of conservation strategies for these and other species with similar life history traits and ranges.

We have built a unique collection of octocoral specimens from southwest England, Wales, Ireland, France and Portugal, enabling us to assess connectivity between the British Isles and the waters of western Europe. This work was funded by Natural England, the NERC and the European Union Assemble Programme (agreement no. 227799).

Microsatellite markers to allow us to assess genetic connectivity within populations of these octocorals have recently been published in the journal Conservation Genetics Resources

  • Holland, L.P., D.A. Dawson, G.J. Horsburgh and J.R. Stevens (2013) Isolation and characterization of eleven microsatellite loci from the ubiquitous temperate octocoral Alcyonium digitatum (Linnaeus, 1758). Conservation Genetics Resources 5: 767–770.
  • Holland, L.P., Dawson, D.A., Horsburgh, G.J., Krupa, A.P. and Stevens, J.R. (2013) Isolation and characterization of fourteen microsatellite loci from the endangered octocoral Eunicella verrucosa (Pallas, 1766). Conservation Genetics Resources 5: 825–829. 
     

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