Connectivity between MPAs: selecting appropriate taxa and assessing genetic connectivity in two benthic marine invertebrates

Abstract

Connectivity is fundamental for the persistence of many populations of marine species and is formally identified as one of five key principles for designing an ecologically coherent network of Marine Protected Areas (MPAs) in European waters. However, the process of assessing connectivity between MPAs, and which taxa to include in assessments of connectivity, is challenging. Managers of MPAs have typically concentrated their efforts on species that are endangered or rare, or on so-called 'umbrella', 'keystone' or 'flagship' species; however, these species may not always be the best candidates for assessing connectivity of a MPA network. In this thesis, a meta-analysis was firstly conducted to study genetic patterns across a broad range of coastal marine taxa in the northeast Atlantic. This meta-analysis provided insights into the biological and methodological information needed to ascertain which taxa may be considered as good candidates for assessing genetic connectivity between MPAs across Britain and the wider northeast Atlantic. The knowledge gained from this literature survey facilitated the design of a set of criteria that identified ideal traits of a candidate species for assessments of genetic connectivity between MPAs; subsequently, based on these criteria, two species were selected to assess connectivity between MPAs in the British network: the pink sea fan (Eunicella verrucosa) and the European lobster (Homarus gammarus). Using 13 microsatellites and 3,743 SNPs, the results for the pink sea fan indicated the presence of three distinct genetic groups, partitioned between sites from western Ireland, southern Portugal and Britain-France. For the European lobster, 86 SNPs indicated strong genetic differentiation between the northeast Atlantic, the middle Mediterranean and the eastern Mediterranean (Aegean Sea). In addition, there was a pronounced genetic cline across the northeast Atlantic, suggesting that connectivity in the European lobster follows a stepping-stone model of dispersal, which was supported by simulations of larval dispersal. Taken together, the results from these two studies suggests that the MPA network in Britain is sufficient to maintain connectivity in the pink sea fan and the European lobster, and possibly other species living in comparable habitats with similar life histories and dispersal traits. Moreover, the criteria applied in this thesis to select species appears to facilitate the identification of ideal surrogate taxa to assess connectivity between MPAs, which could easily be applied to assessments of MPA network connectivity in other seas and oceans around the world.