Saltmarshes

Birds of the saltmarsh

Saltmarsh is an excellent habitat for birds and provides a feeding ground, resting site as well as a hiding spot from predators. Often the highest ground on the shore, saltmarsh islands and ridges are used by many birds at while they wait for surrounding mudflats to appear again after each high tide. Birds can be hard to spot in the saltmarsh as many blend into this yellow, brown and green landscape and are often sitting still, even sleeping, while they spend time here. But the mudflats beneath the saltmarsh are also a fantastic feeding ground at low tide so no matter when you find yourself alongside a saltmarsh you have a great chance to spot waders, ducks and geese.

Saltmarshes

What are they? 

This special habitat is found on the upper part of the shore, an area that the sea reaches only when the tide is high. It is covered in plants that can cope with salt and with being regularly underwater.

Saltmarsh can look quite plain and non-descript but if investigated more closely, it is not so much what you see on the surface (although plants like samphire/glasswort and sea purslane are fascinating) but what lies beneath in the mud that makes it so incredible.

In fact, saltmarshes are incredibly intricate, dynamic habitats, they are highly productive ecosystems, rich in birds, plants and insects. Their ecological value is so diverse from nutrient regeneration, to shoreline stability and they even act as carbon sinks, drawing down CO2 from the atmosphere into their carbon rich soils.  So, as the saying goes, don’t judge a book by its cover.

The Solent has many fantastic examples of saltmarsh: along the creeks in Chichester Harbour; on the banks of the Hamble and the Beulieu rivers; and at Lymington and Keyhaven Nature Reserve and Newtown Nature Reserve on the Isle of Wight.

However, this habitat is under great threat and suffering serious declines due to sea level rise and coastal development. There are subsequently multiple projects around the Solent region working to generate new areas for this vital habitat to have it’s come-back.

How is it formed? 

Saltmarshes start life as mudflats.

In areas of sheltered water, like a harbour, the sediment held in the water settles out and builds up. The structure of saltmarsh is created by the way that water moves, as waves dissipate their energy and deposit silt during higher spring and storm tides and the water then runs back off the marsh. The latter process creates branching creeks that drain the marsh, from small meandering ditches, to waist-deep, fast-flowing channels with slippery, muddy sides.

When the accumulating mud rises above the water surface on average tides (halfway between spring and neap tides), saltmarsh plants can colonise. These capture more sediment and allow the marsh to keep building for as long as it is still low enough to be flooded by the higher tides.

As the mudflats build up, different types of plants can grow and live there creating a salt marsh habitat made up of blocks of flat low growing vegetation with narrow channels between. The development of mudflats and saltmarsh over time is known as ‘succession’.