Eelgrass (Zostera marina)

Our species of the month for March is Eelgrass (Zostera marina). This marine plant forms small pockets of lush underwater meadows in the shallow coastal waters around Alderney.

Eelgrass meadows are among the most productive and important habitats on Earth. Although they only cover around 0.1% of the ocean floor, they support thousands of marine species. They improve water quality by filtering, cycling and storing pollutants, reducing contamination in seafood and storing up to 18% of the world’s oceanic carbon ¹. Eelgrass meadows can also protect coastal communities by reducing wave energy during storms and flood events ².

Since eelgrass is sensitive to pollution and declining water quality, it is often considered a sentinel species, with its presence indicating a healthy marine environment. Despite their importance, seagrasses are in global decline due to coastal development, nutrient pollution, dredging, boating activity and climate change; since the 1930s an estimated 7% of seagrass habitat has been lost each year.

Highlighting the urgent need to conserve these vital underwater ecosystems, March the 1^st was declared World Seagrass Day by the United Nations General Assembly in 2022.

If you’re out exploring Alderney’s coastline this month and you spot eelgrass washed ashore, we’d love to see your photos!

1. United Nations. World Seagrass Day 1 March 2026 [Available from: https://www.un.org/en/observances/seagrass-day].

2. Sierra JP, Gracia V, Castell X, García-León M, Mösso C, Lin-Ye J. Potential of transplanted seagrass meadows on wave attenuation in a fetch-limited environment. Journal of Marine Science and Engineering. 2023;11(6):1186.