Methane emissions from macrophyte beach wrack on Baltic seashores

Area of Science:

• Environmental Science
• Marine Biology
• Climate Science

Background:

• Beach wrack, composed of marine macrophytes, is a common feature on coastlines worldwide.
• The potential for beach wrack to emit greenhouse gases, particularly methane, is not fully understood.

Purpose of the Study:

• To quantify methane (CH4) emissions from beach wrack under various environmental conditions.
• To assess the seasonal variability and temperature-dependence of these emissions.
• To evaluate the impact of wrack management practices on greenhouse gas release.

Main Methods:

• Field measurements of methane fluxes from beach wrack depositions across different seasons, ages, and locations.
• Correlation analysis between methane emissions, temperature, and wrack moisture content.
• Calculation of average seasonal fluxes using historical temperature data.

Main Results:

• Methane emissions from beach wrack varied significantly, ranging from 0 to 176 mg CH4-C m-2 day-1.
• Emissions showed a strong positive correlation with temperature, peaking in summer above 20°C.
• Wet wrack emitted more methane than dry wrack.
• Accumulated wrack heaps away from the water exhibited near-zero emissions.

Conclusions:

• Waterlogged beach wrack is a significant source of methane emissions.
• Global temperature increases may lead to drastically higher methane emissions from beach wrack.
• Collecting beach wrack into heaps away from the shoreline effectively mitigates methane release.