Connectivity is crucial for helping species adapt to climate change. When that adaptation includes moving to a new location, connectivity facilitates range shifts by allowing species to move to a more suitable habitat. In the ocean, connectivity between habitats can happen on two planes– vertically across ocean depths, and horizontally within depths.
Ocean habitats can be fragmented by anthropogenic activities (like fishing and pollution) and by changing environmental conditions such as increasing water temperature. Climate impacts, habitat connectivity, and anthropogenic stresses are all likely to vary by ocean depth. To understand how ocean species will respond to climate change, it’s important to determine how will species adapt to the combined pressures of climate change and anthropogenic activities across ocean depths.
Lin, Y., Chen, Y., Liu, X., Lin, X., Laws, E.A., Zhou, Y., Xiang, Z., Zhang, X., Chen, Z., Li, Y., and Y. Lu. 2025. Climate-driven connectivity loss impedes species adaptation to warming in the deep ocean. Nature Climate Change 15: 315–320.
In a new study, researchers modeled the combined impact of anthropogenic activities and climate change on the connectivity of four ocean depths: the Sunlight Zone (epipelagic), Twilight Zone (mesopelagic), Midnight Zone (bathypelagic) and Abyssal Zone (abyssopelagic). They looked at whether marine species are likely to adapt to these increasing pressures using a climate connectivity framework that included multiple habitats, multiple climate scenarios, and distribution data for over 32,000 marine species across the globe.
They found that connectivity is likely to be more impacted as ocean depth increases, meaning that species will be less likely to find suitable habitats under climate change at the greatest ocean depths. The area in which habitats will be unconnected under climate scenarios was estimated to be 32% in epipelagic zones, 46% in mesopelagic zones, 61% in bathypelagic zones, and 74% in abyssopelagic zones. They also found that 68–80% of the unconnected regions across all strata and scenarios would experience disruptions in connectivity before 2050, with those disruptions occurring before 2030 at depths greater than 1,000 meters.
The ranges of species that inhabit deeper zones were estimated to shrink under warming as well. In the epipelagic zone, only 2.4% of species inhabited ranges where 50% or more species were estimated to experience irreversible loss of connectivity. While this figure was higher for the mesopelagic zone (13%) and bathypelagic zone (26%), it skyrocketed to 95% in the abyssopelagic zone. Unlike this wide range in connectivity loss, species across all four zones had similar capacities to offset warming stress through movement, ranging from offsetting 64-69% of global warming.
Overall, this research shows that connectivity will be most affected in deeper ocean depths. While deeper zones have the potential to act as climate refugia, they’re still likely to experience significant disruptions in connectivity. In addition to management decision that tackle climate warming, marine protected areas (MPAs) that extend to deeper ocean depths and form extensive networks are a crucial component of maintaining connectivity and conserving biodiversity in the ocean.
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