Persistent spatial structuring of coastal ocean acidification in the California Current System

Area of Science:

• Marine chemistry
• Ecosystem dynamics
• Climate change impacts

Background:

• Coastal upwelling ecosystems face significant chemical changes due to ocean acidification (OA).
• Understanding the spatial distribution of OA is crucial for effective management strategies.
• Current knowledge on OA exposure in nearshore habitats remains limited.

Purpose of the Study:

• To investigate the spatial patterns of ocean acidification in coastal upwelling ecosystems.
• To assess the duration and severity of suboptimal conditions for marine life.
• To identify potential refuge areas for marine organisms facing OA.

Main Methods:

• Deployment of a novel coastal ocean acidification observing network.
• Monitoring of nearshore habitats across 1,000 km of the California Current Large Marine Ecosystem.
• Analysis of water chemistry, including pH variability and penetration of acidified waters.

Main Results:

• A persistent spatial mosaic of OA exposure was observed in nearshore habitats.
• Hotspots experienced suboptimal conditions for calcifying organisms for up to 56% of the summer season.
• Some of the lowest and most variable surface ocean pH levels were recorded in these hotspots.
• Persistent refuge areas with less severe OA conditions were identified.

Conclusions:

• Spatial heterogeneity in OA is a key feature of coastal upwelling systems.
• Management actions must consider the observed spatial patterns of OA exposure.
• Identified refuge areas offer opportunities for local adaptation to ocean acidification.
• This research provides critical data for conserving productive coastal ecosystems under climate change.