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Portbury Wharf Salt Marsh

Portbury Wharf Salt Marsh lies next to the nature reserve. It attracts and sustains a lot of wildlife and is crucial to the success of the nature reserve.  So we have dedicated a page to this really important habitat.

What is a salt marsh?

Salt marsh is an area of grassland that is regularly flooded by sea water but it is not just any grassland. Only plants that tolerate submersion in saltwater can grow here. Many of these plants are very nutritious and provide food as well as shelter for wildlife.  Though it is not just the plants that attract wildlife here.  The mud is the other star of the salt marsh as it is host to masses of small marine creatures loved by wading and shoreline birds. So it is not surprising that both the marsh and mudflats are a haven for wildlife. Around the globe, salt marshes sustain many wildfowl which are in decline.

High tides buffet the salt marsh twice daily. The water does not always cover the entire marsh, this only occurs on very high spring tides several times a year.

Tide rising across Portbury Wharf Salt Marsh

 

A Site of Special Scientific Interest

Portbury Wharf Salt Marsh is an important habitat. As a result it is designated a Site of Special Scientific Interest (SSSI). So scientifically it is more significant than the nature reserve which has no such designation.  The combination of salt marsh and nature reserve is great for wildlife which frequently move between the two.

This is not the only area of local coastline designated a Site of Special Scientific Interest (SSSI). The SSSI runs from Portbury Wharf Salt Marsh right down to Black Nore including Battery Point.

If that wasn’t enough, did you know that the salt marsh is also part of the Severn Estuary Special Area for Conservation (SAC), Special Protection Area (SPA) and Ramsar site? So this makes it of international, as well as national, significance for its wetland habitats and wildlife!

You can find out more at:

You can also use Natural England’s search tool to see maps and designations in the Severn Estuary and beyond.

Why are Salt Marshes so Important?

  • They are unique habitats for rare and unusual species of plants and animals
  • Salt marshes buffer the erosion effects of waves and protect the land behind from flooding
  • They capture and store carbon. So play a significant role in regulating local and global climate

The man-made salt marsh created in the Bristol Channel at Steart demonstrates the value of salt marshes. You can read more about it at:

Wildlife

Portbury Wharf Salt Marsh is rich in wildlife. At first glance you may not see much but look closer and you might be surprised. Hundreds of birds including wintering wildfowl and waders, roe deer and small mammals come here to feed and rest. In fact pretty much anything that visits the reserve is also likely to visit the salt marsh. There are probably larger numbers of ducks and wading birds on the salt marsh than on the reserve.

Some of our waders:

Winter is an especially important time on the salt marsh as many wildfowl migrate here between August and March. Species include curlew, redshank, dunlin, lapwing, common snipe, jack snipe, ringed plover, wigeon, teal, gadwall, shelduck and shoveler. When the ground elsewhere is frozen the salt marsh may be the only place where it is soft enough for waders to probe for food. So any disturbance that stops them feeding might be the difference between life and death for a featherweight.

Some of our ducks:

At other times of the year, especially in spring, listen out for the skylarks singing high above the marsh. We believe they nest here rather than on the reserve. The salt marsh is also a popular feeding area for flocks of starlings, linnets and goldfinches.

Roe Deer come to browse on the salt marsh plants as do smaller mammals like field voles.

Of course, these smaller mammals then attract birds of prey such as kestrels and even our barn owls come to hunt here. While other birds of prey such as peregrines and sparrowhawks will try to catch one of our feathered friends for their dinner.

 

What is under the water?

Have you ever stopped to think what wildlife comes in with the tide? We suspect that fish will feed on the salt marsh. We know that crabs visit here as we have found their empty shells left behind after moulting. Crabs have to moult in order to grow bigger, so they wriggle themselves out of their old shell backwards and “grow” a bigger shell. You can read more about this on the NOAA website.

A discarded shell – the shell splits at the back and the moulting crab wriggles out backwards

Wildlife and People

There is a footpath running along the sea wall at the top of Portbury Wharf Salt Marsh. With such wonderful views it is understandably a popular path with runners, cyclists and walkers. So as not to spook the wildlife we suggest keeping to the path and keeping dogs under control. This is especially true in winter when birds need peace and quiet to feed and rest. So we have come up with some Walking the Dog suggestions to enable dog walkers to protect the wildlife.

In September 2019, Natural England proposed that this path becomes part of the official England Coast Path.  The England Coast Path is a national long-distance trail following the coastline of England.  If this route along the salt marsh path is agreed by the Secretary of State this area may become even more popular. So in order to lessen the impact on this vital habitat, Natural England will put up signs encouraging us to keep off the salt marsh and leave it to the wildlife.

 

Salt Marsh Plants

The salt marsh plants are a crucial part of this habitat. They have to survive relentless battering by the waves and smothering by tidal debris. Some of these plants, like spartina happily grow in the wetter zone along the tide line. Others like sea lavender prefer a “dryer” spot higher up the marsh.

The plants growing on each salt marsh can vary depending on the age of the marsh and its height above sea water. The latter will affect how often it is covered by the tide and therefore the plants that grow there. At Battery Point salt marsh, just a hop, skip and a jump down the estuary, there is an abundance of Sea Lavender and Samphire but not so at Portbury Wharf.

While many salt marsh plants are edible, we would not recommend eating the plants here. Leave them for the wildlife!

 Never eat a wild plant unless you are 100% certain that it is safe to eat and you know that you have identified it correctly. 

Some of the key Salt Marsh Plants

NB Click or hover over the images below to see more.

 

 

 

CATTLE ONCE GRAZED HERE

The cattle that once grazed this salt marsh would have been partial to this herb . . .

. . . but too much would make them sick.

Sea Arrow Grass (Triglochin maritima)

Sea Arrow Grass has long slender arrow like leaves and spikes of flowers from May.

From a distance you might not give it a second glance but up close the flowers are jewel like.

Sea Arrow Grass is sometimes known as Sea Coriander due to its similar taste. However, this plant can be toxic! In certain dry conditions, cyanide builds up in its leaves.

 

 

A GOOD YEAR FOR SEEDS

In some years there are so many sea aster seeds the salt marsh turns white. There was certainly a feast for the birds at Battery Point in 2017!

Sea Aster  (Aster tripolium)

Growing up to 50 cm tall, Sea Aster flowers from July to September. It is abundant on Portbury Wharf salt marsh and grows from the very top of the marsh to the bottom, coping well even on the tide line.

The leaves are fleshy and the flowers, which attract many insects, are either purple rayed, or yellow rayless.  They flower long into autumn so are a good source of nectar for late flying insects and butterflies. Then there is the rare Sea Aster mining bee.  It is only found in the UK on the east coast and sometimes the south coast. There are no records of this bee here but it is always worth looking out for just in case!

In autumn masses of tiny seeds are borne in white clusters. Like most fine, “thistlely” seeds they are a very important food for seed eating birds such as goldfinches and linnets.

Parts of the Sea Aster are edible with a delicate, salty taste similar to samphire apparently.

Sea Lavender (Limonium vulgare)

This is a lovely plant with gorgeous mauve flowers July to September. It is perhaps the showiest of all the salt marsh flowers. Sea Lavender is also known as Marsh Rosemary but it is not actually related to either lavender or rosemary.

The flowers are a good food source for insects and are pollinated by flies and bees as well as the wind.

There is a small patch of Sea Lavender at Portbury Wharf but it grows more abundantly at Battery Point.

Sea Milkwort (Lysimachia maritima)

Formerly Glaux maritima has a number of common names including sea milkwort and black saltwort. It is a low growing perennial whose small flowers can carpet the salt marsh between June and August. Though this creeping plant is often hidden beneath taller plants.

Sea Plantain (Plantago maritima)

The leaves of Sea Plantain can sometimes be confused with Sea Arrow Grass but they are broader and often toothed. It is also known as Goose Tongue and its strong tap root anchors it to the salt marsh. It flowers between June and August and close up the flower spikes are rather attractive. The young succulent leaves are edible and probably enjoyed by grazing Canada geese, wigeon and roe deer.

Sea Purslane  (Halimione portulacoides)

Sea Purslane is a grey-green, woody shrub growing to about 50 cm high. Its edible leaves are thick, fleshy and crunchy. There is a small amount growing at Portbury Wharf salt marsh.

Frosted Orache (Atriplex laciniata)

Frosted Orache (pronounced Orak) is a sprawling annual plant which flowers between August and September. It can grow 30 cm tall but often the stems lie horizontally leaning against other plants. In autumn the ripened triangular fruits, leaves and stems turn to gloriously vivid yellows and pinks.

 

 

 

STRANGE BUT BEAUTIFUL

This is an eye-catching plant, especially when sunlit from behind.

It sometimes grows in single stems, like asparagus but when established it is multi-stemmed growing in miniature forests.

Marsh Samphire  (Salicornia Europaea)

Marsh Samphire, also known as Sea Asparagus, is edible and has become a fashionable delicacy in recent years. However a world away from the dinner table, its other name is Glasswort as when burnt it creates soda ash which was used in the making of glass and soap. It was first called Glasswort in the 16th century when there was a resurgence in English glassmaking.

Marsh Samphire just loves gooey mud so grows right down on the tide line. This is one of the first plants, together with Spartina, to colonise mud and create salt marshes. It grows well at Battery Point.

 

 

 

DID YOU KNOW?

Scurvy Grass was used in the Befuddlement Draft at Hogwarts in the Harry Potter series.

English Scurvy Grass  (Cochlearia anglica)

It is not actually a grass at all but has spoon shaped leaves so is also known as Spoonwort.  These fleshy, succulent leaves are very rich in vitamin C and they were once eaten by sailors to ward off scurvy. Scurvy is a disease caused from a lack of fresh fruit and vegetables in the diet. If a sailor was at sea for months or even years they would have had a very poor diet after their fresh supplies had run out.  So when the ship was close to land they would row ashore to harvest this nutritious plant and perhaps others on the salt marsh.

Scurvy grass thrives in salty environments and will grow equally well in the mud at the bottom of the marsh to the drier areas at the top. It will also grow on roadsides that have been treated with salt in the winter.

 

 

DID YOU KNOW?

Sea Thrift is the county flower of the Isles of Scilly

Sea Thrift  (Armeria maritima)

Also known as Sea Pink, it grows in low clumps with long stems supporting pink flowers. It tolerates salt well so will grow in wet or dry saline places from salt marshes to sea cliffs.

It flowers in April and May on this salt marsh with globes of pink flowers varying from strong to delicate shades of pink.

Spartina

This is one of the first species to colonise mud so is fundamental in establishing salt marshes. It can withstand long periods of immersion in salt water and its deep roots stabilise the mud. Spartina grows quickly and often forms large dense colonies.

Sea Spurrey  (Spergularia maritima)

Sea Spurrey is a low growing, spreading plant. So it is quite hard to find hidden beneath the tangle of taller salt marsh plants. Small, jewel-like pink flowers appear between June and August.

The Mud

The mud has it’s own important ecosystem, brimming with life, but we do not know too much about it. So if there are any sediment experts out there we would love to hear from you so you can fill in the gaps!

 

We hope you love Portbury Wharf Salt Marsh

as much as we do!

 

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References and further reading:
https://en.wikipedia.org/wiki/
https://theseashore.org.uk/theseashore/Saltmarsh%20section/Saltmarsh%20introduction.html
Severn Estuary Regulation 33 Advice.pdf