Modeling the habitat suitability for deep-water gorgonian corals based on terrain variables

a r t i c l e i n f o The coral species Paragorgia arborea and Primnoa resedaeformis are abundant and widely distributed gorgonians in North Atlantic waters. Both species add significant habitat complexity to the benthic environment, and support a host of invertebrate species. Mapping their distribution is an essential step in conservation and resource management , but challenging as a result of their remoteness. In this study, three predictive models — Ecological Niche Factor Analysis, Genetic Algorithm for Rule-set Production and Maximum Entropy modeling (MaxEnt) were applied to predict the distribution of species' suitable habitat across a region of Røst Reef (Norwegian margin) based on multiscale terrain variables. All three models were successful in predicting the habitat suitability for both gorgonian species across the study area, and the MaxEnt predictions were shown to outperform other predictions. All three models predicted the most suitable habitats for both species to mainly occur along the ridges and on the upper section of the large slide, suggesting both species preferentially colonize topographic highs. Jackknife tests for MaxEnt predictions highlighted the seabed aspect in relation to P. arborea distribution, and the seabed relative position (curvature) in relation to the distribution of both species. Given the vulnerability of deep-water corals to anthropogenic impacts, further comparative study over a wider study area would be particularly beneficial for the management of the species. Paragorgia arborea and Primnoa resedaeformis are abundant and widely distributed gorgonian coral species observed in North Atlantic waters (Mortensen and Buhl-Mortensen, 2004; Tendal, 1992). The two species are among the largest deep-sea gorgonians, with P. arborea colonies reaching heights above the seafloor of 0.5–2.5 m and P. resedaeformis colony lengths of 0.5–1 m, with both providing complex biotic habitats for numerous invertebrate species (Buhl-Mortensen et al., 2010; Mortensen et al., 2008; Roberts et al., 2009). The deep-water gorgonians are long lived and slow growing species, and are fragile and vulnerable to damage which may result from anthropogenic activity such as bottom trawling and oil exploration (Mortensen and Buhl-Mortensen, 2005). Mapping the distribution of deep-water coral species is fundamental in assessing the potential risks to these ecosystems posed by these activities, and for developing management plans, particularly as species protection legislation such as the EC Habitats Directive stipulates protection of these habitats for all member states. However, such distribution mapping is challenging given the remoteness of these habitats, and predictive modeling techniques address …