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Seagrass meadows cover only about 0.1% of the seafloor, yet they account for roughly a tenth of the carbon buried in ocean sediments. Seagrasses are flowering plants that grow underwater along coasts.

NOAA

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The story behind the card

Unlike seaweeds, which are algae, seagrasses have roots, leaves and flowers, and they grow in shallow coastal water on every continent except Antarctica. Their leaves slow the current so fine particles settle, and their roots bind the seabed. Dead leaves and roots are buried in mud with little oxygen, where they rot very slowly, so their carbon can stay locked away for centuries. Carbon stored by coastal plants in this way is called blue carbon. In the Mediterranean, including the Turkish coast, Posidonia oceanica meadows build thick mats of roots and sediment over thousands of years. Since the late nineteenth century, more than a fifth of the world's known seagrass area has been lost to dredging, pollution and coastal building.

Türkçe oku
Deniz çayırları deniz tabanının yalnızca binde birini kaplar, ama okyanus tortullarına gömülen karbonun yaklaşık onda biri onların payıdır. Deniz çayırları kıyı sularında, su altında yetişen çiçekli bitkilerdir.

Alg olan deniz yosunlarının aksine deniz çayırlarının kökü, yaprağı ve çiçeği vardır; Antarktika dışındaki bütün kıtaların sığ kıyı sularında yetişirler. Yaprakları akıntıyı yavaşlatır, böylece ince tanecikler dibe çöker; kökleri de deniz tabanını bir arada tutar. Ölen yapraklar ve kökler oksijeni az olan çamura gömülür ve orada çok yavaş çürür; bu yüzden içlerindeki karbon yüzyıllarca hapsolabilir. Kıyı bitkilerinin bu yolla depoladığı karbona “mavi karbon” denir. Türkiye kıyıları da dahil olmak üzere Akdeniz'de Posidonia oceanica çayırları, binlerce yıl boyunca kök ve tortudan kalın katmanlar örer. 19. yüzyılın sonlarından bu yana dünyada bilinen deniz çayırı alanlarının beşte birinden fazlası tarama, kirlilik ve kıyı yapılaşması yüzünden yok oldu.

Sources and further reading

Background reading: Seagrass
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