Today is World Saltmarsh Day (11 June) when we celebrate the superpowers of this amazing wetland habitat. Cleethorpes’ very own protected habitat of saltmarsh begins behind the Leisure Centre and extends along the shore towards the Fitties.
Saltmarsh is a delicate eco-system that needs to remain undisturbed, but right now you can walk along the designated dune path and see an abundance of wildlife, including sea thrift, sea lavender, sea milkwort, sea arrow grass and lesser sea spurrey. This area is delicate so please stick to the path.
Saltmarsh is nature’s hidden weapon in the battle against climate change. In the spring it is believed to take a huge breath in, locking away the greenhouse gases that are destroying our planet in layers of mud. It also plays a vital role in flood defences by slowing the incoming tide.
The Humber’s muddy appearance (turbidity) is due to suspended sediment. This comes mainly from the eroding boulder clay cliffs along the Holderness coast and also river sediments. The Humber drains a fifth of England, and this sediment is vital for the estuary’s function and every tide carries over 1,500 tonnes.
It is this deposited sediment that maintains the estuary’s important habitats such as, mudflats, sandflats and the saltmarsh. The Humber supports a rich variety of habitats and species and is recognised as one of the most important estuaries in Europe for overwintering birds. It supports 31 species of international importance.
The estuary’s important habitats and species are the reason it has been given a number of nature conservation designations under UK, European and International law.
Our saltmarsh is part of the Humber SSSI (Site of Special Scientific Interest), which is protected under UK law. It is also part of the internationally designated and protected Special Area of Conservation (SAC), a Special Protection Area (SPA), an internationally important wetland site under the Ramsar Convention, and a European Marine Site.
This is because of the 150,000 winter migratory birds that depend on it for food, shelter, and rest. The wintering birds fly for hundreds, some thousands, of miles, and need to spend their time here feeding and resting to ensure they can make it back to their summer breeding grounds. The birds feed on the molluscs, worms, invertebrates, and fish that live in and around the saltmarsh and mudflats.
Saltmarsh is also the first line of defence against flooding and provides a natural flood defence (or soft defence as opposed to hard defence such as a concrete sea wall).
In storm surges, salt marsh can reduce the height of damaging waves by almost 20% by dissipating the energy in the wave, and 60% of the reduction in the wave energy is due to the presence of marsh plants alone. The plants create friction as the wave moves over them, which reduces the energy of the wave and, therefore, the height and distance it will travel inland. This is important in light of climate change and sea-level rise.
Defra and the Environment Agency have shown that a seawall without saltmarsh costs £5,000 per metre, and an 80m wide saltmarsh can provide a saving of £4,600 per metre because of the reduced wave height.
If saltmarsh remains constant, healthy, and functioning then no management, and associated costs, are required, and it can respond to change and adapt to most physical changes, such as sea-level rise.
Saltmarsh is also a vital carbon store. Only 3% of the world’s land surface is saltmarsh and it sequesters 50% more carbon than all of the world’s forests.
Saltmarsh reduces pollution by acting as a sink for a number of pollutants, including herbicides, pesticides, and heavy metals. These are largely attributed to human activity and, if left to remain in the water and sediment, can pose an environmental risk, such as contamination of shellfish stocks in estuaries.
Nutrient cycling within saltmarshes can also have a significant effect on coastal and estuarine water quality. In this respect, healthy, functional saltmarsh habitat may have an important role to play in the control of nutrients, such as nitrogen and phosphorous, which are important in determining water quality and, ultimately, human health.
There are around 300 species of terrestrial invertebrates that live in saltmarsh, and around 150 of those are found exclusively in saltmarsh. There are varied and abundant marine species that occur in and under the salt marsh, ranging in size from the smallest mud-dwelling mollusc to quite large burrowing crabs.
Saltmarshes are also particularly important for the smaller passerines, such as skylark, twite, reed bunting, rock pipit and Lapland bunting, some of which are winter visitors. Saltmarsh is used by fish as nurseries and breeding areas, and they feed on the invertebrates that live there.
Saltmarshes support a wide range of plants and animals, many of which are specially adapted to the rigours of an environment where they are regularly covered by the tide. Consequently, many of the species present are found nowhere else. Furthermore, many of the larger estuarine saltmarshes represent some of the most extensive areas of natural and semi-natural habitat in an intensively used landscape. As such, they are important wildlife areas, because they are extensive, diverse, rare, ‘natural’ and vulnerable.
Colletes halophilus, the Sea Aster Bee, is classified as Nationally Scarce, found only in a handful of places on the East Coast, Cleethorpes being one of them. They are scarce because they rely on feeding their young with Sea Aster pollen, which grows in saltmarsh, and burrow and live in the bare sand of dunes.
Marvel at our incredible saltmarsh, enjoy it from the dune pathway, but please leave it undisturbed to continue its vital role in nature.
Find out more about Life on the Saltmarsh by visiting Life on the Saltmarsh
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