Genetic hotspots for conserving Southern Ocean benthic biodiversity

As climate change intensifies, maintaining genetic diversity of natural populations is crucial to safeguard ecosystem integrity and adaptive potential. The Southern Ocean encompasses 10% of the Earth's oceans¹ and contains a taxonomically diverse ecosystem with an extraordinarily high level of endemism (50%-90%).²^,³^,⁴ As one of the fastest-changing regions on Earth, the Southern Ocean is currently under threat from climate change⁵ and anthropogenic stressors, including fishing and tourism.⁶ Targeted marine protected areas (MPAs) are popular and effective mechanisms for limiting anthropogenic stressors in sensitive marine ecosystems.⁷ Approximately 78% of Southern Ocean species are benthic invertebrates,⁴ and most modern benthic taxa radiated in situ over the last 14 million years,⁸ alongside adaptation to withstand polar conditions.⁹ However, their genetic information has not yet been synthesized across the region to determine priority areas for genetic conservation. Using a multi-species genetic landscape approach from 28 benthic marine invertebrate species examined at a population level, we identified hotspots of nucleotide diversity, haplotype diversity, genetic divergence, and genetic connectivity comprising 3,455,799 km² of the Southern Ocean. Only ∼28% of all identified genetic hotspots are currently being protected by established MPAs. Maintaining established and adopting proposed MPAs would protect ∼54% of all hotspots. The Southern Ocean is likely to face a high risk of ecosystem failure unless ecosystem resilience is sustained.¹⁰ Targeted areas to safeguard Southern Ocean benthic biodiversity, informed by genetic knowledge, are now readily available for conservation assessments.