Leaping the Avon once again

Weirs on the Avon Water have been a barrier to spawning grounds for Atlantic salmon for over a century.  This summer, a flagship partnership project funded by Scottish Environment Protection Agency’s (SEPA’s) Water Environment Fund and the Heritage Lottery Fund supported Clyde and Avon Valley Landscape Partnership (CAVLP), will open up 200km of salmon spawning grounds in the Avon Water, that will see majestic Atlantic salmon leaping the Avon Water once again.  Today’s guest bloggers, Alan McCulloch from SEPA and Rob Mitchell of RAFTS,  look more closely at this good news.

The Atlantic salmon is one of the truly iconic species of Scotland and a source of considerable national pride.  The country is home to some of the finest salmon rivers in the world and these contribute significantly to the Scottish economy as a visitor attraction, a source of jobs and income in remote Scottish communities, and the provider of high quality world renowned salmon food products.

In the Autumn and early winter, salmon ‘steal the show’ as they make their way back from the ocean and leap spectacularly up river to their Scottish breeding grounds.  But not so in the Avon Water!

Atlantic salmon became virtually extinct in the Clyde in the 19th century.  Over the last 40 years, improved treatment of domestic and industrial wastes and reductions in industrial discharges have resulted in sufficient improvements in water quality in the lower rivers and upper estuaries of the Clyde to allow salmon to return.  But in some rivers including the Avon Water, barriers are preventing them from reaching their spawning grounds.  On the Avon, salmon are ‘queuing up’ under the Ferniegair Weir desperately trying to leap up river to spawn.  This is currently to no avail since Ferniegair Weir and the Millheugh Weir further upstream are impassable.

Imagine the excitement then to hear that Atlantic salmon will leap the Avon Water once more – a sight that has not been seen for over a century.

This is all down to a flagship partnership project between SEPA, Rivers and Fisheries Trusts Scotland (RAFTS), Heritage Lottery Fund Scotland, South Lanarkshire Council, Clyde River Foundation, anglers and local communities.  Natural rock fish passes will be installed at the Ferniegair and Millheugh weirs (built in late 19th century to serve local mills) in the summer of 2016, meaning that Atlantic salmon should be leaping the weirs in autumn 2016.

CAVP logoSEPA logoWEF logoRAFTS LogoHLFHI_CMYK

 

The fish passes will open up approximately 200km of salmon spawning grounds in the Avon Water and upgrade the Water Framework Directive status of 8 rivers in one fell swoop, six of which will achieve high status.  This gives the potential to create a whole new salmon fishery within the Clyde system bringing with it an increase in sports fishing and income from fishing permits and a boost to the local economy from fisherman and visitors using local amenities.

The project will also be a source of great excitement and pride for local communities.  The Clyde River Foundation works very closely with schools and communities in the Clyde area promoting fishing and the importance of healthy ecosystems and is planning a Clyde wide celebration of salmon homecoming when fish passage is secured across the Avon Water weirs.

 

The return of the iconic Atlantic salmon to the rivers of the Clyde symbolises the importance of Scotland’s magnificent environment to the Scottish people and economy.

“The watercourses of the Clyde and Avon valleys are an important and unique habitat for native wildlife.  For this reason, we have always viewed our involvement in this project as a vital part of delivering our overall Heritage Lottery Fund supported programme”, explains CAVLP Programme Manager Donna Marshall.

She continues, “A public meeting has been organised to allow local communities and anglers to find out more about the project and view the proposed designs.  Taking place in the Auditorium, Chatelherault Country Park Visitor Centre, Hamilton at 7pm on Tuesday 8 March, we would love to see as many people attend as possible and have the chance to ask questions about this exciting and vitally important project.”

 

For further information, please contact:

Alan McCulloch, Restoration Specialist – Water Environment Fund, Scottish Environment Protection Agency, Carrochan, Carrochan Road, Balloch, G83 8EG.     www.sepa.org.uk

Rob Mitchell, Barriers Programme Coordinator, Suite 1F40, 2 Commercial Street, Edinburgh, EH6 6JA.

Sarah O’Sullivan, Communications Assistant at Clyde and Avon Valley Landscape Partnership sarah.osullivan@clydeandavonvalley.com

Posted in biodiversity | Tagged , , , ,

Saving the world isn’t just for the movies…

Will you be an everyday hero by taking small steps to help fight climate change? Changes can be as simple as turning your thermostat down just one degree, washing your clothes at 30°C, leaving the car for shorter journeys and recycling your food waste.

ENERGY CONSUMPTION Social Media Image

Seems easy! And in fact, these small changes can make a big difference.

  • The Energy Saving Trust point out that turning your thermostat down from 22°C to 21°C saves 310kg – 360kg of carbon dioxide every year. You could also save £85 – £90 a year in fuel bills.
  • Washing your clothes at 30°C instead of 40°C uses around 40% less energy, and drying your clothes on a line instead of in a tumble dryer can make a big difference.
  • 23% of car journeys are under 1 mile, and another 33% under 2 miles. Walking or cycling shorter distances can make a big difference to reducing car use.
  • We waste 600,000 tonnes of food and drink per year. Sending food waste to landfill causes the release of harmful greenhouse gases like methane. Recycling your food waste through the council or composting it in a compost bin in your garden makes sure that it doesn’t go to waste. Through your council it can either be composted or sent off for anaerobic digestion, where waste is turned into energy for homes. By not wasting food, each person could save £470 and 610kg of CO2e.

Reducing emissions in our everyday lives is important because a massive 42% of our emissions come from things that we have control over – our energy use, travel choices, food choices, and the things we buy. Changing our behaviour can go a long way towards limiting climate change, making heroes out of us all.

Climate heroes: staff cycle to work, Image credit: Lorne Gill/SNH

Climate heroes: staff cycle to work, Image credit: Lorne Gill/SNH

Why do we need to limit climate change?

Recent weather events have highlighted the sorts of effects that we’re likely to see more of in future because of rising average global temperatures and changing weather patterns. From flooding to droughts, to impacts on agriculture and our food supply around the world, the effects of climate change will be felt by us all.

Flooding on the River Isla near Coupar Angus, January 2016, Image credit: Lorne Gill/SNH

Flooding on the River Isla near Coupar Angus, January 2016, Image credit: Lorne Gill/SNH

For nature too, climate change has a big impact. The timings of natural events such as flowering and reproduction is changing for some species, having knock-on effects to other aspects of nature. Some species may benefit, though others may no longer thrive in areas where they are usually found – and some of our best loved species may struggle to survive at all. We may see more pests and diseases as the climate becomes more suitable for them, and we may see some new invasive species. For more information see the Biodiversity climate change impacts report card.

The mountain ringlet butterfly is one of the species whose range is thought to be restricted by climate change (Source: Biodiversity report card) Image credit: Ken Willmott

The mountain ringlet butterfly is one of the species whose range is thought to be restricted by climate change (Source: Biodiversity report card) Image credit: Ken Willmott

In the marine environment, carbon dioxide may be causing oceans to acidify. This is potentially harmful for many marine creatures like corals and molluscs and crustaceans, including the prawns and mussels that we enjoy eating. These rely on the ocean’s alkaline properties to build up their shells and skeletons. Emissions from our cars and energy use emit carbon dioxide, which is then absorbed by the oceans. For more information on the expected effects on our oceans, see the Marine climate impacts report card.

A stormy sea and big waves at Lybster harbour, Image credit: Lorne Gill/SNH

A stormy sea and big waves at Lybster harbour, Image credit: Lorne Gill/SNH

Scientists agree – human behaviour has caused climate change. It is now our responsibility to protect ourselves, each other, and the environment around us from the worst effects.

Your mission should you choose to accept it: to live a little greener in 2016.

 

If can’t see the video within this blog please go to …

http://www.greenerscotland.org/climate-change

 

Look out for the hashtag #emissionsimpossible

Posted in climate change | Tagged , ,

Glasgow’s water voles

Today’s guest blog comes courtesy of Robyn Stewart, Glasgow’s Water Vole Ambassador. The discovery of thriving populations of water voles in a residential area of Glasgow away from traditional habitat is considered to be of national significance. SNH are supporting Glasgow City Council and the University of Glasgow, who are working in the local community, to help conserve this unique population, and Robyn leads that work. 

 

Juvenile male water vole caught and microchipped as part of mark-recpature study to estimate population density. Pringles tubes aid handling the animal. (Photo courtesy of Stef Scott)

Juvenile male water vole caught and microchipped as part of mark-recpature study to estimate population density. Pringles tubes aid handling the animal. (Photo courtesy of Stef Scott)

Water voles need water right? Surely the clue is in their name….but if I were to tell you that there is a thriving population alongside the M8, Scotland’s busiest motorway, you could be forgiven for doubting my wildlife identification skills.

The east end of Glasgow is a far cry from the pristine image of wetland habitat we associate with water voles yet remarkably high densities are being found here several kilometres away from water in grassland habitat such as road verges, brownfield sites, and even the occasional back garden.

Typical grassland habitat in the east end of Glasgow

Typical grassland habitat in the east end of Glasgow

Water voles have long been associated with water and their distribution is usually considered to be limited to the distribution of wetland habitat. Their movements are often quoted as rarely exceeding two meters beyond the riverbank and they are also notoriously fussy: they like dense vegetation which they both eat and hide in, soft banks to burrow into and the flow of the water must be not too slow but not too fast either.

While their habitat preferences have been relatively well researched it is surprisingly little known that European populations of the water vole, from which our water voles originated when they colonised the UK during the last Ice Age, have long been known to be capable of living in non-aquatic habitats. These non-aquatic voles are normally found in grassland habitats and this behaviour is termed fossorial in reference to their predominately subterranean existence.

In fact, the grassland populations found in some upland areas in mainland Europe can peak at 1000 water vole per hectare, a truly mindboggling image given as even a fraction of these numbers is unheard of in the UK. In contrast, most of our water vole colonies are spread linearly along a water course and even reed bed populations only reach a maximum of 40-50 animals per hectare.

An adult female caught as part of the mark-recapture study. Traps are baited with carrots and apples, particular water vole favourites.

An adult female caught as part of the mark-recapture study. Traps are baited with carrots and apples, particular water vole favourites.

In addition to this, water vole populations have also undergone one of the fastest declines of all our native mammal species in recent years, dropping 88% UK-wide and up to 98% at a local scale in some areas.

Their decline started in the 1900’s as land use changed considerably resulting in the loss of wetland margins with the move towards intensive agricultural and the overall UK trend towards urbanisation. However, the catastrophic decline that we see nowadays started in the 1950’s with the accidental introduction of the non-native, semi-aquatic American mink: water voles have no way to evade these efficient hunters with mink being small enough to enter the burrows that water voles dig in order to have a safe place to hide from predators.

As American mink spread from one water course to another, a crash in water vole numbers would soon follow. Water vole populations simply could not recover from the combined effects of heavy predation on top of widespread habitat loss and fragmentation. As a result, water voles are now protected in the UK and a priority biodiversity species for many local authorities and wildlife conservation organisations.

All captured water voles were weighed, measured, sexed and microchipped.

All captured water voles were weighed, measured, sexed and microchipped.

So when the east end water voles came to light back in 2008 after a single animal was accidentally caught in a rat trap set in a housing estate in the east end, Glasgow City Council reacted quickly. Surveys revealed extensive water vole field signs, such as burrows and feeding remains, in grasslands throughout the area which prompted the Council to fund a research project alongside the University of Glasgow to map the distribution of the fossorial animals and investigate their habitat preferences.

It also couldn’t be more timely given the initial surveys revealed thriving water vole populations were located on the exact brownfield sites being targeted in the much needed regeneration plan of Glasgow’s east end by the Scottish Government and Glasgow City Council.

So what did the study reveal? Firstly, two distinct types of water vole exist in Glasgow with the habitat mosaic of east end providing habitat for both the fossorial water vole as well as the more familiar wetland type. Multiple fossorial breeding colonies were found throughout the east end and some were over 1800m from the nearest wetland habitat. Secondly, the distribution of fossorial populations was strongly linked to the M8 corridor and surrounding grassland patches in an almost linear fashion.

Surprisingly, despite the huge amount of disturbance from the motorway traffic, the long grasses which characterise the motorway verge provide the water voles with a continuous swath of grassland habitat in which they can move freely without breaks or barriers, something of a rarity in the environment these days. The fossorial water voles actually preferred habitats which were in close proximity to people because human presence created the road verges, parks and gardens which provided soft banks to burrow into and dense grassland swards full of palatable, disturbance-tolerant grasses like Yorkshire fog and Bent grasses. Even though it was completely by accident, urbanisation in this particular instance was an actual benefit to wildlife.

Water vole feeding remains of Yorkshire fog grass.

Water vole feeding remains of Yorkshire fog grass.

I am often asked what caused the east end water vole populations to move into grasslands but to be honest it is still somewhat of a mystery and difficult to ascertain without genetic analysis. It is possible that populations here are a relic of those once found along the Monkland Canal prior to it being filled in for the creation of the M8 which may in turn have forced the water voles into surrounding grasslands.

Regardless of the origin of this behaviour, it gives the water voles one huge advantage: grasslands act as a refuge from the American mink because they are so far from the mink’s normal wetland hunting grounds. There was no evidence that moving into grasslands was a behavioural adaptation to avoid mink however, as there are no records that American mink and water vole were found in the same area.

Dawn trap check. (Photo courtesy of Cath Scott)

Dawn trap check. (Photo courtesy of Cath Scott)

Indeed, evidence from this study lends more weight to the theory that moving into grasslands is the expression of an ancestral behaviour from their founding European colonisers. The fossorial water vole may be far more common than we realise because current survey guidelines are limited to wetland habitats. Records of fossorial behaviour in the UK do exist, dating back to the 1900s and studies at the University of Aberdeen revealed extensive populations in grasslands on small islands in the Sound of Jura.

Off the back of the University of Glasgow study has come some fascinating ground-penetrating radar research mapping the subterranean burrow system of the fossorial water vole with geophysicist experts at RSK. Preliminary findings have shown that the burrow system varies considerably from the normal wetland water vole arrangement, with an outer ring of burrows connected to the central nest chamber in a pattern also linking up food stores and bolt holes.

Geophysicists from RSK carrying out ground-penetrating radar scans of fossorial water vole burrows.

Geophysicists from RSK carrying out ground-penetrating radar scans of fossorial water vole burrows.

 

The area occupied by a fossorial water vole territory also appears to be much smaller, an area of 8 x 10m, compared to the 30-150m length of river margin required by the wetland type.

These findings, along with the main study, are going to inform habitat management and creation guidelines for Glasgow City Council as they face the difficult task of balancing the protection of these incredible fossorial populations alongside the regeneration of the east end. The Council are being hugely proactive though and incorporating water vole distribution into their city masterplan which will go to inform future development decisions.

All in all, the east end water voles are a beacon of hope for the future preservation of water voles as grasslands tend to be a product of urbanisation rather than one under threat from it, and are also comparatively cheap to produce and manage, and crucially mink-free.

 

Photos, unless otherwise stated, courtesy of Robyn Stewart.

 

 

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Species of the month – Brandt’s bat

Bats are notoriously tricky beasts to study. They’re small, nocturnal, can fly fast and many of the species look very similar. And when they’re not out and about, they are experts at hiding away in small cavities in buildings and trees or underground, making them very difficult to detect.

Consequently it is not surprising that we are not sure how many species there are in Scotland – eight, nine, ten (or more)? One species, the Brandt’s bat (Myotis brandtii) has long been suspected to occur in southern Scotland as it is resident in neighbouring Cumbria and Northumberland, but until recently there was only one confirmed record from Scotland – a specimen in Perth museum, possibly collected in the Black Wood of Rannoch in 1874, however, there are conflicting published accounts of both the locality and the year of collection. It was originally identified as a whiskered bat, but later confirmed as Brandt’s.

Brandt’s bat

Brandt’s bat

Brandt’s bat is one of the smallest British species and one the most difficult to identify; even experts find it hard to separate it from the closely-related whiskered bat. The most reliable method of identifying it is by DNA sequencing, but the pre-molar teeth and the shape of the male Brandt’s bats’ genitals can also be used. Because of the similarity between Brandt’s and whiskered bats, quite a few records for these species have been classed just as ‘whiskered/Brandt’s bats’.

In late 2013, however, during an inspection of a Forestry Commission building near Newton Stewart, evidence was found indicating that the building had been used as a bat roost. As all bats and their roost are legally protected, any work affecting them or their roost would require a licence from SNH, hence the need for a bat survey of the building.

Different bat species produce slightly different droppings and, despite being quite old (and therefore less likely to yield usable DNA for identification), the droppings were considered to be worthy of further investigation. A few were sent to the University of Warwick for DNA analysis. The results came back as Brandt’s bat!

Ttwo Daubenton’s bats (left and middle) and a Brandt’s/whiskered bat on the right, in hibernation

Ttwo Daubenton’s bats (left and middle) and a Brandt’s/whiskered bat on the right, in hibernation

The existence of droppings in a building strongly suggests that the bats were using the building as a roost, and its location, no further north than the known resident English population, implies that the bats were not just vagrants from England (or elsewhere) ending up in Galloway by accident. (Vagrant bats do occasionally turn up in some very unlikely places, including North Sea oil rigs and Shetland, which has no resident bats).

The presence of Brandt’s bats in this building suggests that they could occur over a wider area of southern Scotland. If so, it brings the number of Scottish species to nine and probably ten, because another species of uncertain status – the Nathusius’ pipistrelle – is regularly recorded during bat surveys across Scotland, but a confirmed roost of this species has yet to be found.

Bats play an important role: not only do they eat a lot of midges, but they can also show us how healthy our habitats are as whole. If bats are doing well, it’s more likely plants and insect populations are also thriving.

Find out more about Bats on our website at http://www.snh.gov.uk/protecting-scotlands-nature/protected-species/which-and-how/mammals/bat-protection/

Read our Bats and People leaflet @ http://www.snh.org.uk/pdfs/publications/wildlife/bats%20and%20people%20leaflet.pdf

 

Image 1 is (c) and courtesy of John Haddow, image of three bats is (c) and courtesy of Marlot Jonker.

 

 

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Capercaillie counting

Our guest blogger today is Sarah West.  Sarah is the Capercaillie Project Assistant,  joint-funded by RSPB, Scottish Natural Heritage and Forestry Commission Scotland.  Here she gives us a brief insight to the fifth national survey of this elusive bird; an RSPB and SNH project.

Capercaillie (Tetrao urogallus) male displaying in snow-laden forest, Scotland ©Pete Cairns/2020VISION

Capercaillie (Tetrao urogallus) male displaying in snow-laden forest, Scotland ©Pete Cairns/2020VISION

The capercaillie is a large but rarely seen grouse that makes its home in the pine forests of the Scottish highlands. They are generally shy and avoid contact with humans, disappearing into the trees before you realise that they are there.

However, capercaillie are quite famous for their springtime get-togethers where males dance to attract hens to mate with. This communal dance is known as ‘lekking’, and every year we monitor the number of birds attending these leks. However, this does not provide us with an accurate population estimate as many birds won’t attend the lek sites, or will only visit sporadically. Therefore, the national survey was devised to count birds seen in a representative portion of capercaillie habitat across Scotland which could then be extrapolated to provide an idea of the population size of these beautiful birds, and to see how this changes over time.

Capercaillie (Tetrao urogallus) male displaying, Scotland ©Pete Cairns/2020VISION

Capercaillie (Tetrao urogallus) male displaying, Scotland ©Pete Cairns/2020VISION

The first national survey was carried out in the winters of 1992-1994 and produced an estimate of 2200 birds, a decline of 90% since the 1970’s and a serious cause for concern. The second national survey took place in the winter of 1998/99 and showed a further decline to just 1073 birds, proving that, without help, capercaillie would once again face UK extinction.

After this poor result, more effort was put into research and forest management to benefit capercaillie; areas of suitable forest habitat were expanded and joined together, deer fences have been removed or marked to avoid collisions, and predators are controlled to increase chick survival. The national survey is repeated every six years and this positive management for capercaillie has been reflected in its results, with the 2003/04 survey turning up 1980 birds, and the most recent survey in 2009/10 revealing 1285 birds. The extreme winter weather and long-lying snow in 2009/10 meant that many areas were inaccessible.

Capercaillie tracks

Capercaillie tracks

This year marks the fifth national capercaillie survey, taking place over the winter of 2015/16. Six people were recruited to complete this survey, which covers all capercaillie areas in Scotland; from Easter Ross to the Trossachs. The survey itself is made up of over 700 triangular ‘transects’ (2 km long routes to walk whilst counting capercaillie). These transects are randomly distributed across capercaillie areas, with many in remote forests or crossing difficult terrain, often involving long walks into each survey area.

The national survey runs over winter in part to avoid the breeding season when capercaillie are most sensitive to disturbance, but this can make things tricky for the surveyors. Rain, snow and high winds all conspire to make this a difficult survey, especially considering the short day-length and more than 700 transects to complete. Add to that forest bogs, windthrown trees, deer fences and rocky terrain and you’ve got one tough survey!

In addition, capercaillie sightings are not guaranteed as they are a scarce species and, despite their large size, they are shy and well camouflaged so are often difficult to spot as they remain hidden in trees as you approach, staying perfectly still and hoping that you don’t see them. Usually the only sighting that you’ll get is the tail end of a bird as it bursts from a tree in an explosion of noise and frantic wingbeats, out of sight in a few seconds. But every encounter with a bird is important for the survey so that we can get an accurate estimate of capercaillie numbers in Scotland.

Sarah West

Sarah West

The national survey fieldwork runs until the end of March 2016, followed by some serious number-crunching so we won’t know the new population estimate until the following year but we are hoping for a good result – an increase in birds.

 

Photo credits.  Images 1 and 2 ©Peter Cairns/2020VISION , Images 3 and 4 © Sarah West.

Posted in biodiversity, Birds | Tagged , , ,

Deadwood … good wood

There is great ‘natural’ value in deadwood, as Sarah Smyth of our Ecoystems and Biodiversity team explains.

Trees contribute a huge amount as living organisms providing shelter and ecosystem services such as carbon sequestration, pollution reduction, water runoff reduction , aesthetic and cultural value as well as potentially providing food and shelter.  Periodically stormy winds batter us and trees, and branches fall down. There is a huge temptation to tidy up the fallen materials. But before you do, spare a thought for all the animals that use piles of deadwood for shelter and food.

Wood stacked in to a logpile for biodiversity. ©Lorne Gill/SNH

Wood stacked in to a logpile for biodiversity. ©Lorne Gill/SNH

Deadwood can persists for as long as it was alive, supporting a new range of species.  Rather than tidy up all fallen wood and logs, leave a small pile tucked away and very quickly it will become home to lots of animals.  About 20% of woodland species need dead wood at some point for food or shelter.  No matter what stage of rotting the deadwood is at – there will be an insect or fungi that will be ready to take hold and turn it into dinner.

A wood wasp. ©Lorne Gill

A wood wasp.
©Lorne Gill

The good news is that this means less work for the gardener, rather than clearing messy deadwood from a area, tuck it into a pile in a shady corner somewhere and leave it be, very soon, fungi, lichens and bryophytes will establish, these in turn provide protection for lots of invertebrates, which can provide a tasty snack for birds, mammals and amphibians, look out later in the year for hedgehogs nestling under the wood.

Over time the logs will break down as they are nibbled and burrowed into – natures clearing squad do their job and you don’t need to.

Long-horn beetle, Taynish NNR, Argyll. ©Lorne Gill/SNH

Long-horn beetle, Taynish NNR, Argyll. ©Lorne Gill/SNH

Deadwood in sunny areas does also has a value – to different species. So it shouldn’t be disregarded. Species such as wasps, ichneumons in particular like dry, warm, wood to gather material, for nest building and to lay their eggs in. Also certain deadwood invertebrates need habitat in warmer spots. So, as is often the case, it’s about having a “bit of everything” if possible.

For more information on managing deadwood see Managing deadwood in forests and woodlands http://www.forestry.gov.uk/pdf/FCPG020.pdf/$file/FCPG020.pdf

You might also enjoy : http://www.rspb.org.uk/makeahomeforwildlife/advice/gardening/deadwood.aspx

 

Did you know ?

Most dead wood recycling is done by hundreds of different fungi because they are the only species that produce enzymes that can break down wood!

Posted in biodiversity, Fungi, Insects | Tagged , , , , , ,

Eelgrasses – flowers beneath the tide

Eelgrasses (Zostera species) are amongst the very few flowering plants that live in seawater. Two (or possibly three) species grow around Scotland. They form beautiful underwater meadows that are havens for marine wildlife, and nursery areas for commercially important species, including plaice and flounder, so they are another of our special conservation priorities in Scotland.

A dense subtidal seagrass bed in shallow water in the Sound of Barra marine SAC

A dense subtidal seagrass bed in shallow water in the Sound of Barra marine SAC

What are eelgrasses?

Eelgrasses belong to a group of plants known as seagrasses. Although they look grass-like, they are probably more closely related to the freshwater pondweeds. As well as the large species of eelgrass (Zostera marina), two smaller varieties have been recognised in the past: narrow-leaved eelgrass (Z. angustifolia) and dwarf eelgrass (Z. noltei).  The latest classifications group Z. marina and Z. angustifolia as a single species (Z. marina). The rather similar tasselweeds (Ruppia species) also grow in brackish ditches and pools, but belong to a completely different family.

Where do they grow?

Eelgrasses grow on sheltered gravelly, sandy or muddy seabeds, or with maerl, from areas exposed at the lowest tides down to depths of about 4 metres. They often inhabit places with a gentle tidal current. They can grow in full-strength seawater, or in brackish lagoons and lochans where the seawater is diluted with freshwater.

Why are they vulnerable?

In the 1930s, almost 90% of the eelgrasses around Britain died from a wasting disease, which may have been caused by a fungus. Eelgrasses grow best in undisturbed, clean water, and high levels of nitrates (from urban wastewater or farm run-off) have been linked to declines in Zostera in a number of sites around Scotland. .

A stalked jellyfish on seagrass in Loch Gairloch

A stalked jellyfish on seagrass in Loch Gairloch

Why are they important?

Many different fish live amongst the beds of eelgrass, sheltering between the swaying leaves of the plants to escape detection

Several species of flatfish use eelgrass beds as nursery areas, to lay their eggs and shelter their newly hatched young. These may include commercially important species like plaice and flounder. Eelgrasses are also important food for wildfowl, such as wigeon, in estuaries.

Many small invertebrates, particularly sea firs and sea squirts, attach to the leaves of eelgrass, while burrowing anemones, bivalve molluscs and burrowing urchins lie buried in the sand beneath. Some rare seaweeds lie unattached between the plants, and native oysters, once common in Scotland but now very rare, grow in some eelgrass beds. The roots of eelgrass bind the sand, helping to prevent erosion of the seabed.

A native oyster amongst a stand of seagrass in the Loch Sween Nature Conservation MPA

A native oyster amongst a stand of seagrass in the Loch Sween Nature Conservation MPA

For all these reasons, it is critically important for us to protect eelgrass beds. That means keeping them free of trampling and dredging, and from coastal development close to where they grow. We also need to ensure that the waters in which they grow remain clean and unpolluted, and to protect their habitat from non-native invasive species, such as cord-grasses (Spartina species). Seagrass beds are a Priority Marine Feature (PMF) in Scottish waters and are a designated feature of nature conservation interest within a number of our Marine Protected Areas.

A small hermit crab on a blade of seagrass in Gruinard Bay on the west coast of Scotland

A small hermit crab on a blade of seagrass in Gruinard Bay on the west coast of Scotland

SNH flickr account contains many more marine images. Why not have a look @ https://www.flickr.com/photos/snh-iyb2010/albums/with/72157646742700048

 

Posted in biodiversity, Marine | Tagged , , ,