Drivers of pH Variability in Coastal Ecosystems

Area of Science:

• Marine Chemistry
• Coastal Ecology
• Environmental Science

Background:

• Open-ocean acidification shows uniform trends due to atmospheric CO2.
• Coastal ecosystems display a wider range of pH changes, both increases and decreases.
• High pH variability in coastal areas is a significant concern.

Purpose of the Study:

• To synthesize long-term pH changes in coastal ecosystems.
• To contrast coastal pH trends with open-ocean acidification.
• To identify drivers of coastal pH variability and inform management.

Main Methods:

• Synthesis of data from 83 coastal ecosystems.
• Analysis of long-term pH trends, including nonlinear and seasonal variations.
• Identification of key drivers: land-based inputs, upwelling, and metabolic processes.

Main Results:

• Coastal pH trends range from -0.023 to 0.023 pH units yr-1, unlike uniform ocean trends.
• Majority of ecosystems showed nonlinear pH trends with significant seasonal/interannual variability.
• Land-based inputs (freshwater, nutrients, organic matter) and metabolic control were primary drivers.

Conclusions:

• Coastal pH is highly variable and influenced by land-based inputs and ecosystem metabolism.
• Management of nutrients, organic matter, and alkalinity can control coastal pH.
• Balancing eutrophication and acidification is crucial for coastal biodiversity and ecosystem services.