16 / BIG OCEAN QUESTION

Why are seagrass meadows ocean nurseries?

These ordinary-looking underwater lawns shelter young animals, hold shorelines together and bury carbon beneath the mud.

THE SHORT ANSWER

Seagrass meadows slow water, trap particles, anchor sediment and create nursery and feeding habitat. Their roots and oxygen-poor soils can store organic carbon for long periods, making loss important far beyond the plants themselves.

Three things to know

Seagrass is
A flowering plant
It evolved from land-plant ancestors and produces flowers, pollen and seeds.
Carbon store
Mostly soil
Buried roots, rhizomes and trapped particles build long-lived stocks.
Habitat users
Turtles to sharks
Meadows feed grazers and shelter juvenile fish and invertebrates.
01

A submerged grassland

Leaves capture sunlight in shallow water while rhizomes spread through sediment. Unlike seaweeds, seagrasses have roots and internal vascular tissues. They require enough light, so turbidity and algal growth can set their depth limit.

02

The meadow changes the water around it

Dense blades slow currents and waves, encouraging particles to settle. Roots and rhizomes bind the bottom. This can improve water clarity and reduce erosion, creating feedbacks that help the meadow persist when conditions remain suitable.

03

Loss can unlock stored carbon

Dredging, poor water quality, heat stress, propeller scars and disease can fragment beds. When soils erode or become oxygenated, stored organic matter may decompose more quickly. Protection therefore preserves habitat and avoids some emissions; it is not a substitute for reducing fossil-fuel carbon.

What people usually ask

Is seagrass the same as seaweed?

No. Seagrasses are true flowering plants; seaweeds are algae.

Do seagrasses grow in the deep sea?

No. They need sunlight and are mostly restricted to shallow coastal waters.

WANT TO CHECK US?

Here’s where the answer came from

Open the original government science or research-institution source behind this page.

01
NOAA Ocean Service — Coastal blue carbon

Carbon storage and coastal-ecosystem functions.