Global Habitat Suitability for Framework-Forming Cold-Water Corals

Abstract

Predictive habitat models are increasingly being used by conservationists, researchers and governmental bodies to identify vulnerable ecosystems and species' distributions in areas that have not been sampled. However, in the deep sea, several limitations have restricted the widespread utilisation of this approach. These range from issues with the accuracy of species presences, the lack of reliable absence data and the limited spatial resolution of environmental factors known or thought to control deep-sea species' distributions. To address these problems, global habitat suitability models have been generated for five species of framework-forming scleractinian corals by taking the best available data and using a novel approach to generate high resolution maps of seafloor conditions. High-resolution global bathymetry was used to resample gridded data from sources such as World Ocean Atlas to produce continuous 30-arc second (∼1 km2) global grids for environmental, chemical and physical data of the world's oceans. The increased area and resolution of the environmental variables resulted in a greater number of coral presence records being incorporated into habitat models and higher accuracy of model predictions. The most important factors in determining cold-water coral habitat suitability were depth, temperature, aragonite saturation state and salinity. Model outputs indicated the majority of suitable coral habitat is likely to occur on the continental shelves and slopes of the Atlantic, South Pacific and Indian Oceans. The North Pacific has very little suitable scleractinian coral habitat. Numerous small scale features (i.e., seamounts), which have not been sampled or identified as having a high probability of supporting cold-water coral habitat were identified in all ocean basins. Field validation of newly identified areas is needed to determine the accuracy of model results, assess the utility of modelling efforts to identify vulnerable marine ecosystems for inclusion in future marine protected areas and reduce coral bycatch by commercial fisheries.

Coralligenous and maërl habitats: predictive modelling to identify their spatial distributions across the Mediterranean Sea

“…water temperature, salinity, depth, nutrient concentrations, seabed types, etc), which are typically easier to record and map across vast expanses (i.e. regional, global scale) in contrast to species and habitat data [42][43][44] . Despite inherent limitations and associated uncertainties, predictive modelling is a cost-effective alternative to field surveys as it can help identifying and mapping where sensitive marine ecosystems may occur.…”

Cold-Water Coral Habitats in Submarine Canyons of the Bay of Biscay

“…The size of coral habitats, of which most segments measured less than 100 m, compared to the resolution of the environmental factors, ranging from 100 m to 0.083 • latitude (∼10 km) easily explain the difficulty to discriminate particular environmental settings for the different coral habitats. The observed pattern also points out the limits of habitat suitability models which were based on a rather low resolution of oceanographic parameters (0.04 • -1 • latitude) (Davies et al, 2008;Davies and Guinotte, 2011;Yesson et al, 2012). Limited resolution understandably causes uncertainties in habitat mapping and suitability models (Davies and Guinotte, 2011;Rengstorf et al, 2012) whereby some local features, such as individual coral habitats, could be missed.…”

“…Several habitat suitability models have predicted that the canyons are indeed (highly) suitable for octocorals , antipatharians (Yesson et al, in press) and colonial scleractinians (Davies and Guinotte, 2011), but temperature, salinity, water density, slope, rugosity and bathymetric position index (BPI) came out as important factors in these models controlling the distribution (Davies and Guinotte, 2011;Howell et al, 2011;Yesson et al, 2012, in press;Robert et al, 2015). Most "habitat" suitability models were, however, devoted to predict occurrences of the coral (sub)order or species only and the results may not be the same if the suitability of habitats is being predicted (Howell et al, 2011), similarly to the model of Robert et al (2015) predicting abundances, species richness and diversity.…”

“…There is a high overlap between the predicted suitable areas of these coral orders/species, including the canyons for all corals (Davies and Guinotte, 2011;Yesson et al, 2012, in press). This pattern is emphasized by the present study as the environmental factors (e.g., temperature), as well as the derivatives of the 100 m resolution bathymetry do not discriminate a specific environment for each coral habitat.…”

Environmental forcing of the Campeche cold-water coral province, southern Gulf of Mexico

“…The biodiversity associated with these ecosystems may be comparable to that found in tropical coral reefs (Roberts et al, 2006), and they occur almost worldwide except for the highest latitudes (Davies and Guinotte, 2011). The availability of advanced deep-sea technologies (e.g., remotely operated vehicles) greatly supported the discovery and investigation of large, thriving and (so far) unknown CWC ecosystems in remote places.…”