Implications for the conservation of deep-water corals in the face of multiple stressors: a case study from the New Zealand region

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The waters around Aotearoa New Zealand are a global hotspot of biodiversity for deep-water corals. Deep-water corals, like many other seafloor species, are vulnerable to climate-related stressors and from the damaging effects of bottom-contact fisheries, yet we are not aware of any practical examples of multiple stressors being quantitatively accounted for in marine spatial planning.

We addressed this gap in knowledge by using recently developed habitat suitability models for 12 species of deep-water corals predicted for current and future climatic conditions (climate change scenarios SSP2-4.5 and SSP3-7.0). We explored marine conservation scenarios by assessing the impact of bottom trawling on predictions of current distributions of deep-water corals, and the effectiveness of possible protection for deep-water corals under future climatic conditions. We found that bottom trawling was predicted to impact all species, but particularly the reef-forming corals, and that suitable habitat was predicted to decrease under future climatic conditions. We demonstrated that when designing protection using current day predictions of suitable coral habitat alone (which is akin to the “usual approach”), spatial marine protection was unlikely to provide adequate conservation for deep water-corals in the future due to distribution shifts associated with climate change and fishing.

However, in the analyses where we accounted for future distributions of suitable coral habitat, areas were identified which may provide climate refugia for corals whilst still providing efficient protection for current distributions (despite being impacted by bottom trawling). These gains in conservation value may be particularly important given the predicted reduction in suitable habitat for deep-water corals from the cumulative impacts of bottom fishing and climate change.