Marine plankton show threshold extinction response to Neogene climate change

Area of Science:

• Paleoceanography
• Marine Ecology
• Climate Change Science

Background:

• Climate change is predicted to alter marine plankton distribution.
• The ability of species to track shifting habitats and avoid extinction is uncertain.
• Radiolaria, a key zooplankton group, are sensitive indicators of oceanographic conditions.

Observation:

• During the late Neogene, amplified polar cooling caused significant declines in high-latitude radiolarian species richness.
• Ecological reorganization preceded the decline in species richness.
• The majority of affected radiolarian species (71%) did not migrate to lower latitudes but became extinct.

Findings:

• Many plankton species, exemplified by radiolaria, cannot successfully track optimal thermal habitats on a global scale.
• Local environmental thresholds are critical; exceeding them leads to assemblage restructuring and extinction, rather than successful migration.
• Extinction, not migration, is the primary response for a significant portion of affected plankton species.

Implications:

• Future climate change poses a substantial threat to high-latitude radiolarian diversity.
• The loss of radiolarian diversity may trigger cascading effects throughout marine food webs.
• Disruptions to plankton communities can impact global ocean carbon cycling.