Climate change effects on deep-water corals – habitat suitability model input data

Deep-water corals are protected in the seas around New Zealand by
legislation that prohibits intentional damage and removal, and by marine
protected areas where bottom trawling is prohibited. However, these
measures do not protect them from the impacts of a changing climate and
ocean acidification. To enable adequate future protection from these
threats we require knowledge of the present distribution of corals and the
environmental conditions that determine their preferred habitat, as well
as the likely future changes in these conditions, so that we can identify
areas for potential refugia. In this study, we built habitat suitability
models for 12 taxa of deep-water corals using a comprehensive set of
sample data and predicted present and future seafloor environmental
conditions from an earth system model specifically tailored for the South
Pacific. These models predicted that for most taxa there will be
substantial shifts in the location of the most suitable habitat and
decreases in the area of such habitat by the end of the 21st century,
driven primarily by decreases in seafloor oxygen concentrations, shoaling
of aragonite and calcite saturation horizons, and increases in nitrogen
concentrations. The current network of protected areas in the region
appear to provide little protection for most coral taxa, as there is
little overlap with areas of highest habitat suitability, either in the
present or the future. We recommend an urgent re-examination of the
spatial distribution of protected areas for deep-water corals in the
region, utilising spatial planning software that can balance protection
requirements against value from fishing and mineral resources, take into
account the current status of the coral habitats after decades of bottom
trawling, and consider connectivity pathways for colonisation of corals
into potential refugia.