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ALEXANDRE MEINESZ

Maerl beds

In Dive.Explo360: Mediterranean · Northeast Atlantic · Atlantic Ocean

Seen up close, maerl resembles a mosaic of pink branches scattered over the seabed. These calcified algae, reinforced by natural calcium carbonate, build valuable habitats for fish, crustaceans and molluscs over decades. Their slow growth makes them a fragile marine heritage.

Habitat de Maerl beds Habitat
Sand, Gravel, Maerl
Profondeur de Maerl beds Depth
30-60 m
Groupe biologique de Maerl beds Group
Red alga
Rôle écologique de Maerl beds Role
Primary producer, Ecosystem engineer

WHAT DOES IT LOOK LIKE?

Maerl resembles small fragments of pink stone, but is actually a calcareous red alga. Unattached to the seabed, it takes the form of small stiff, branching pieces. Its colour varies from pink to purple and turns white when dead. It grows extremely slowly, around a few millimetres a year. As the fragments accumulate, they form beds sheltering a great diversity of organisms.

WHERE DOES IT LIVE?

Maerl lives on soft seabeds such as sand or gravel in well-lit areas. It is generally found from a few metres down to around forty metres deep, depending on water clarity. It grows in environments with good water renewal and moderate hydrodynamics.

WHAT DOES IT EAT?

Like all algae, maerl produces its own organic matter through photosynthesis. It uses light, carbon dioxide and nutrients in the water.

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Other species — Red alga

Cartilaginous Branched Red Alga Coralligenous Habitat Purpurean weed

Same habitat and depth

Sandy seabed species Gravel seabed species Maerl bed species

Same ecological role and depth

Producer species Ecosystem engineer species

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