An independent, non-commercial site to collect and disseminate information on the natural history of Shetland

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Nature in Shetland

winner of a Shetland Environment Award 2004


Shetland Biological Records Centre



Marine Plants

Shetland’s wildlife is internationally renowned and attracts many visitors to the islands.  Those elements that live on land – such as birds, mammals and plants – are relatively well known.  However, we know a great deal less about our marine wildlife for the simple reason that it is very difficult to observe.  Two important plants that grow around the coast of Shetland are eelgrass and maerl.  In the right conditions both eelgrass and maerl can grow to form dense beds which support a wide range of other marine plants and animals. As a result they make an important contribution to the biodiversity of the islands. 

Shetland Biological Records Centre is keen to find out more about Shetland’s marine life.  Please help us by recording your sightings of eelgrass and maerl on the survey form at the bottom of this page and returning it to SBRC.

Photo right - surveying the eelgrass beds at Whiteness Voe.

EELGRASS - Zostera marina

Although eelgrass grows in the sea, it is not a seaweed, but a group of marine flowering plants.  However, it is unlikely that you will ever see the flowers because they are very small and usually hidden at the bottom of the leaves.  Eelgrass grows in shallow coastal seas around the world generally in water less than 10m deep.  It is usually found on sandy or muddy areas sheltered from strong tides and currents.

Eelgrass is only patchily distributed around the UK.  This is partly due to a wasting disease in the 1930s which wiped out populations in many areas.  Although eelgrass is nationally scarce, in the right conditions it can form dense beds known as meadows.  Other plants that are often found associated with eelgrass meadows include sugar kelp and bootlace weed, together with burrowing animals such as razor shells and heart urchins.

Beds of eelgrass are important for a number of reasons.  They provide a wide range of habitats for many other plants and animals, including sheltered nursery areas for some types of fish.  The plant roots form a dense network which stabilises the seabed, helping to reduce coastal erosion.  In addition, decomposing plants support food chains both inside and outside the beds.

Only one species of eelgrass occurs in Shetland, Zostera marina, known locally as ‘Marlie’.  At present three eelgrass beds are known in Shetland, at South Voe, West Burra, Marlee Loch at the head of Brindister Voe, and in Whiteness Voe.

Photos - eelgrass


Maerl is the name given to several species of red seaweeds which have hard calcium skeletons.  It grows as free living nodules on the seafloor and is one of the slowest growing plants in the North Atlantic, growing only a few millimetres each year.  Maerl tends to grow best in tidal flows associated with rapids and in sounds between islands, such as in Bluemull Sound.

Maerl is found from the Mediterranean to Scandinavia, although it is a relatively scarce habitat.  It can occur as simply a few scattered nodules, right through to extensive beds.  Maerl beds develop very slowly and are usually made up of a mixture of live and dead nodules, although the proportion can vary greatly between areas.  Large beds tend to be made up of a bottom layer of dead maerl gravel overlain by a thin layer of live nodules.  It is easy to tell the difference between the two: live maerl is pink, but this colour fades gradually when dead.

Both live and dead maerl provide habitats for a wide range of plants and animals, some of which are rare and largely confined to maerl beds.  Keep a look out for different species living in and around maerl beds.  These may include sugar kelp, an anemone called Cerianthus lloydii, common sea urchins, hermit crabs and harbour crabs.

Please look out for maerl or eelgrass when you are diving.  Have you found a few scattered individuals or been lucky enough to come across a large and well established bed?  As well as looking at the two plants, try and record other plants and animals that live on or in these habitats, especially if they appear to be particularly common.  For maerl, also have a look at how much is living (pink) and how much dead (cream coloured).

Please describe the location of the maerl or eelgrass very carefully  -  give a grid or chart reference if possible.  And, remember, if you see anything else interesting underwater, please let us know.

Photos - maerl


The following is the information required for the eelgrass and maerl survey, please fill in as much as you can. You can either copy and paste this information into a document or download this form as an Adobe Acrobat file (PDF).

Name and address of recorder:

Site name:                                              Date of dive:                        

Site location: (either OS grid reference or latitude/longitude)

Time of dive          Start:                     Finish:

Underwater visibility:                          Current speed:

Sketch of dive profile and where the maerl/eel grass has been found:

Please include some indication of the abundance of the plants and how big an area they cover and for maerl the % of live maerl/dead maerl/other sediments.

Sea floor type:     

Depth range of habitat:      

Other plants or animals present: 

Please fill in the form with as much detail as possible and return to:

SBRC, Garthspool, Lerwick, Shetland ZE1 0NY Tel. (01595) 694688


This site is not directly connected to any of the organisations mentioned, so comments  may not necessarily reflect the views of the organisations, clubs or societies  involved. The pages on this website remain the intellectual property of the authors. They may be freely downloaded, quoted or used for any purpose, providing acknowledgement is given to the website and/or the author/s. No liability is accepted for the accuracy of this information.