Will krill fare well under Southern Ocean acidification?

Area of Science:

• Marine Biology
• Oceanography
• Climate Change Research

Background:

• Antarctic krill (Euphausia superba) are a keystone species in the Southern Ocean ecosystem.
• Ocean acidification, driven by increased atmospheric carbon dioxide (CO₂), poses a significant threat to marine life.

Purpose of the Study:

• To investigate the impact of elevated partial pressure of carbon dioxide (pCO₂) on the early developmental stages of Antarctic krill.
• To assess the potential consequences of projected ocean acidification levels on krill survival and development.

Main Methods:

• Experimental exposure of Antarctic krill embryos and larvae to varying pCO₂ levels (380, 1000, and 2000 µatm).
• Observation and analysis of embryonic development and larval behavior.
• Modeling of future Southern Ocean pCO₂ under IPCC scenarios.

Main Results:

• No significant effects on embryonic development or larval behavior were observed at 1000 µatm pCO₂.
• At 2000 µatm pCO₂, 90% of embryos showed disrupted development before gastrulation, with no successful hatching.
• Model projections indicate Southern Ocean surface pCO₂ could reach 1400 µatm by 2100 under the IS92a scenario.

Conclusions:

• Elevated pCO₂ levels, consistent with future ocean acidification projections, severely impair Antarctic krill early development.
• Urgent research is needed to understand the full pCO₂-response relationship for krill across all life stages.
• The findings highlight a critical vulnerability of this key species to ongoing climate change, with potential cascading effects on the Southern Ocean ecosystem.