Genetic diversity and local connectivity in the mediterranean red gorgonian coral after mass mortality events

Estimating the patterns of connectivity in marine taxa with planktonic dispersive stages is a challenging but crucial task because of its conservation implications. The red gorgonian Paramuricea clavata is a habitat forming species, characterized by short larval dispersal and high reproductive output, but low recruitment. In the recent past, the species was impacted by mass mortality events caused by increased water temperatures in summer. In the present study, we used 9 microsatellites to investigate the genetic structure and connectivity in the highly threatened populations from the Ligurian Sea (NW Mediterranean). No evidence for a recent bottleneck neither decreased genetic diversity in sites impacted by mass mortality events were found. Significant IBD pattern and high global F-ST confirmed low larval dispersal capability in the red gorgonian. The maximum dispersal distance was estimated at 20-60 km. Larval exchange between sites separated by hundreds of meters and between different depths was detected at each site, supporting the hypothesis that deeper subpopulations unaffected by surface warming peaks may provide larvae for shallower ones, enabling recovery after climatically induced mortality events

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

Genetic Connectivity and Conservation of Temperate and Cold-Water Habitat-Forming Corals

Recent explorations of rocky habitats from 40 to about 6,000 m depth disclosed the role of gorgonian and scleractinian corals as habitat formers in tropical, temperate, and polar deep waters. Deep biogenic habitats host high species richness and complexity and their conservation requires a profound understand- ing of biological and ecological features of sessile species inhabiting them, such as the habitat-forming corals. In sessile species, earliest life history stages and larval processes (e.g., reproduction mode, larval development, behavior, and feeding mode) ensure the exchange of individuals within and among subpopula- tions, supporting species and habitat resistance and resilience. Genetic studies allow investigating larval processes when direct observations cannot be used. Parameters such as genetic connectivity, gene flow, and levels of genetic diversity are essential to monitor health and resilience of populations under current and future scenarios of anthropogenic environmental changes. In this chapter a review of studies on genetic connectivity of temperate and cold-water habitat-forming corals and associated invertebrate species will be presented. Among them, two case studies, Desmophyllum dianthus, a deep-sea worldwide-distributed scleractinian, and Corallium rubrum, a harvested Mediterranean and Eastern Atlantic alcyonacean with a wide bathymetric distribution, will be discussed in detail. This chapter will also show how these studies contributed to develop, implement, and recommend future conservation strategies and management plans. Existing gaps in literature on genetic connectivity of habitat-forming corals and other invertebrates have been also stressed and discussed. Finally, a concep- tual framework for optimizing and planning effective studies on genetic connec- tivity is provided, including general recommendations on sampling design, key species and new molecular markers to use with a special emphasis on the \u201cnext- generation\u201d DNA sequencing technologies