Genetic connectivity and conservation of temperate and cold-water habitat-forming corals

Abstract

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 understanding 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 subpopulations, 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 conceptual framework for optimizing and planning effective studies on genetic connectivity is provided, including general recommendations on sampling design, key species and new molecular markers to use with a special emphasis on the "nextgeneration" DNA sequencing technologies.