Tuesday, 28 January 2014

Water, water everywhere

The importance of protecting fresh water habitats on the North Norfolk coast

David North, Head of People and Wildlife

Water is vital for people and wildlife but as anyone who has swallowed a mouthful of seawater will know there’s a big difference between salt water and fresh water and it will come as no big surprise that the two are not interchangeable for people or for wildlife.

Aerial photo after the floods, Mike Page

Following the storm surge in December 2013, which damaged sea walls along parts of the North Norfolk coast, flooded our nature reserves at Cley and Salthouse Marshes, and breached the shingle ridge in two places between Cley and Salthouse, there is now heated discussion as to the importance of repairing sea defences simply to protect wildlife. So what are the freshwater habitats and do they really matter? If large areas of freshwater habitats at nature reserves such as Blakeney Freshes, Cley Marshes and Salthouse were regularly flooded by the sea what difference would this really make?

The stunning diversity of wildlife found along the North Norfolk coast and recognised as internationally important in the confusing maze of designations: from SSSI to Ramsar site, from National Nature Reserve to Special Protections Areas, from AONB to SAC, clearly is pretty special. Our North Norfolk coast wildlife sites have a lot of letters after their famous place names, and places like NWT Cley Marshes and NT Blakeney Point with their unique histories, unique landscapes and stunning wildlife are truly areas Norfolk can be very proud of. They are well known across Britain and beyond, much loved and also attract many visitors from near and far.

Marsh Harrier and Avocets, photo by Steve Bond

The reason that these areas, and the whole North Norfolk coast, is so good for wildlife lies in its diversity of habitats – freshwater, brackish, salt and marine. Lose the diversity of water types and you lose some of the amazing richness of wildlife. This is why the potential permanent loss of freshwater habitats following the December storm surge matters. If you are a freshwater fish this is a matter of life and death. But people should care about this too. Local tourism benefits hugely from the visitors who come to marvel at North Norfolk’s wildlife. They come in winter for our wonderful skeins of geese. They come in in summer to watch elegant breeding avocets and the magnificent aerial displays of marsh harriers. They come in spring and autumn for a chance to spot rare migratory species. All this is also great if you are a North Norfolk business, a hotel, B&B, a pub or a food shop. Great for the local economy and the loss of any of this wildlife diversity will impact on people too.

But won’t it all be just as good without the freshwater? And what are these special habitats that rely on keeping the sea out?

Freshwater habitats

Fresh water pools and grazing marsh, photo by Barry Madden

Protected areas such as Cley and Salthouse Marshes have three habitats completely dependent on freshwater: the cattle-grazed marshes with their network of freshwater dykes; the reedbeds; and the freshwater pools (many originate as shooting pools, others scraped out on nature reserves to encourage breeding and migratory species).

Lapwing, photo by Maurice Funell
The list of wildlife dependent on these coastal freshwater habitats is extensive. Birds such as migratory wigeon and brent geese from Russia and pink-footed geese from Iceland feed during the winter extensively on grass. And grass doesn’t grow in salt-water! In summer the freshwater marshes are a stronghold for species declining elsewhere, for example the attractive black and white lapwings with their tumbling spring displays. The freshwater dykes which edge these North Norfolk grazing marshes support a host of water insects which can only survive in fresh-water: from ‘whirligig’ diving beetles to water boatmen and many species of freshwater fish, from minnows to pike and even the now endangered European eel.

Freshwater reedbeds support huge numbers of insects from showy dragon and damselflies to myriads of tiny flying insects. That why so many birds come to them in spring – swallows and swifts feed over the reedbeds and water rails, bearded tits, marsh harriers and even the rare bittern nest within them. Without the freshwater insects these reedbeds would not be alive with reed and sedge warblers each summer or the sound of the cuckoo which feeds on moth caterpillars found in the reedbeds. Our reedbeds can survive occasional floods of sea-water quite well but their ecology would be very different and much less diverse if this became permanent.

The freshwater pools on our coastal marshes attract ducks in winter – pintail, gadwall, teal, mallard, shoveler among them. In spring and autumn the muddy edges of these freshwater pools are where waders such as sandpipers, black tailed godwits and snipe come to feed along with rarer species which delight the many birders who come to the hides that over-look these pools.

Saltwater habitats

Salt water habitats are important too of course. These include tidal salt marshes, saline lagoons (saltier than the sea), and tidal mudflats and sandy foreshores.

Sea lavender, Stiffkey saltmarshes, photo by Denise Emmerson
There are species which are only found in this salty, tidal world which constantly changes with wind and tide. These include wonderfully salt adapted and highly specialised plants. The sea lavenders which turn our coastal marshes purple in July and August. A whole range of specialised salt marsh plants; sea aster, samphire, sea purslane, sea beet, colourful pink thrift, bushes of shrubby seablite, spiky cord grass forming complex and fascinating high, mid and low marsh communities, each species adapted to withstand different periods covered by the sea. In that rarest of coastal habitats, the saline lagoons, endangered species such as starlet sea anemone and rare shrimps make their precarious homes. Saltmarsh tidal creeks form valuable nursery grounds for marine fish’ including plaice, flounder and mullet, as well as a habitat for numerous shore crabs, shrimps, marine worms and snails which in turn are food for gulls, terns, egrets, and herons.

In summary the richness of our coastal nature reserves depends on both fresh and salt water habitats and the interplay between the two. Many species will use both habitat types but will be dependent at critical times on just one – geese feeding on the freshwater grasses but roosting on sands and salt marsh protected by the tides is just one example. The balance between salt and fresh water changes daily with the tides, monthly with rainfall and changing seasons, and over much longer periods is also changed by both human activity such as sea defences and natural events including storm surges. However we need both fresh and salt water habitats if we are too keep the present diversity of wildlife that we love so much. And protecting that diversity is something worth fighting for.

Species photos submitted by members of the public to NWT's online wildlife gallery.

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