Biodiversity Fact File: Eel grass and Maerl

Thursday 1st December 2016

Eel Grass. Polly Whyte, Earth In Focus

Our Island has a brilliant array of biodiversity and Manx Wildlife Trust works hard to protect it for future generations to enjoy.

Our biodiversity fact files aim to bring often lesser-known but threatened species to our attention and explain the incredible lives that they lead.

We have a rich variety of marine life all around us here on the island and, although often out of view, it has a big impact on our lives, whether it is the eelgrass beds which can help take the energy out of winter storms, or the massive forest like kelp beds which lie off our coast.

Eel grass
Eel grass marine habitats are few and limited in area on the Island, they occur at Port Lewaigue, Langness and the South end of Laxey bay.

Eel grass looks just like an undersea long grass meadow, only this grass is the only undersea flowering plant. It is also a perennial, it has a winter die back period and sprouts new growth in the spring. It expands by underground rhizomes as well as seeds and grows in estuaries and shallow bays.

Its biggest bonus is that it supports algae growth and microscopic diatoms, as well as marine invertebrates, juvenile fish, including salmon, and juvenile shellfish too.

Eel grass can up take nutrients in the sea water and help control troublesome algae blooms and water clarity, as well as fixing loose sediment on the seafloor. All in all, quite an amazing habitat.

Our next important species and priority habitat is maerl, this is a coralline red seaweed which creates a spiky mat-like layer on the sea bed creating a beautiful pink/purple coloured layer.

Maerl is fragile, easily damaged and slow growing, but has been proven to be a fantastic habitat for juvenile scallops, which hide from predators in the holes created between individual maerl. Lots of shellfish, sea urchins, anemones and worms burrow in the maerl gravel beneath this living maerl mat.

Wave action can create a landscape very like a ridge and furrow cultivated landscape with living maerl in the furrows and dead maerl gravel accumulating on the ridges. In the past, because maerl is lime rich, it was gathered and used for soil improvement, but this is no longer done.

Tagged with: Biodiversity, Eel grass, Maerl, Marine