37 Demography and Conservation of Deep Corals: The Study of Population Structure and Dynamics

The science of demography was developed for the study of human populations, but the theoretical framework and analytical techniques can be easily applied to animal populations, giving powerful instruments for conservation and management. Demography is then a paradigmatic example of the advantages of interdisciplinary approaches which allow transferring the techniques developed in one field (e.g. human population studies) to different fields (e.g. nature conservation and management). Cold-water corals have been approached relatively recently by scientist due to the technical constrains linked to the deep habitat where they live. However the fast development of underwater observation technologies is allowing to gather data on those deep and not easily accessible ecosystems, showing their paramount role in the ecosystem functioning. Due to the peace at which environmental changes are threatening natural ecosystems, increasing our knowledge on cold-water corals is urgent and time constrained. Due to the slow life cycles of the cold-water coral species, forecasting capacity is needed to understand the dynamics of their populations. Demography can give this forecasting capacity but, up to now, the paucity of data from deep coral populations still not allowed to apply demographic models to those environments. Fortunately, the application of demographic models to other species with similar characteristics can help a fast development of similar instruments to cold-water corals. The present chapter aims at introducing demography from an historical point of view, showing how this science evolved from the study of human populations to the conservation of animal populations. We then review the application of demographic modeling to coral populations and in particular we focus on the case study of the Mediterranean red coral (Corallium rubrum). This species is endemic to the Mediterranean Sea and besides it is not considered as a cold-water coral species, it dwells in relatively cold environment and can be found at considerable depths.