Monday, 3 February 2014

Storm surge

A tour of many of the sites affected by this winters stormy weather continued this week with a trip up to Mersehead on the Solway coast. Arriving on site just after dawn, several hundred Barnacle Geese were on the fields along the entrance track, 150 Pinkies flew over and 50+ Pintail fed on the shallow floods.  The task was to look at the impact of the surge tides in early January; this was abundantly clear from the 10 m of dune system washed away, the four breaches in the seawall and the piles of rubbish dumped across the fields by the receding tides. The pools of water across the fields were strangely variously saline or fresh, but the Natterjack Toad pools were unfortunately strongly saline.

The surge tide that hit eastern England in early December led to some dramatic headlines and has certainly had some profound effects on coastal habitats.  There was extensive flooding of more than 40 conservation sites behind seawalls and shingle/dune ridges from the Tees estuary south to Essex. These were mainly coastal grazing marshes and reedbed habitats but included some of our best-known east coast nature reserves.  Seawalls protecting at least seven conservation sites have been breached in East Anglia.  In some locations, mainly Norfolk, there are multiple breaches to seawalls.  The damage to infrastructure on some sites (birdwatching hides, footpaths, fencing etc.) has been extensive.  At Snettisham for example, as well as extensive ‘re-shaping’ of the wader roost banks, almost all of the reserve infrastructure has been destroyed.

Almost inevitably, the words ‘ecological disaster’ have been used in various accounts, but was it really such a disaster?   The impression after looking at these sites is one of both winners and losers. Although some wildlife sites at or close to the coast are sensitive to flooding by saltwater, many are remarkably resilient. It is their ability to recover and the frequency of significant flood events that matters.  Furthermore, many coastal sites are evolving in response to coastal processes; this changes the mosaic of habitats and species, but not necessarily the value of the sites. These processes can also result in the natural ‘repair’ of coastal features such as breached barrier beaches. The storms have created some exciting new habitat in many cases and it will be interesting to see what develops this coming summer.  Some coastal grasslands, designated sites but with dull and unimaginative management and trapped behind artificial sea walls, have been opened up to coastal dynamics. How will the Red Hemp Nettle and Ringed Plovers fare at Snettisham now that acres of their favoured bare shingle habitat have now been opened up.

There are extensive repairs that need to be done but they should be in the form of adaptive management. For example, at Havergate island the breached sea walls will be rebuilt but with reprofiled spillways so that floodwaters can more easily enter the site without damage but then quickly be let out through sluices. These events will happen again and we need to be prepared.

Photos: from top - Barnacles at Mersehead, Natterjack, surge re-shaping at Snettisham, Red Hemp Nettle.


Paul Tout said...

Like it. Been waiting for a GJW comment on the recent 'catastrophes' even if it doesn't include owt on the Levels' debacle. I too will be fascinated with what shakes down and agree with you re. tired habitats ... "dull and unimaginative management and trapped behind artificial sea walls". I suspect this is behind a lot of the problems faced by Kentish Plovers in Europe. I think we could see an excellent breeding season for a lot of coastal species as I think the repeated storm surges may well have knocked back a lot of terrestrial mesopredators such as brown rats and hibernating hedgehogs. Awww!!

Grumpy Ecologist said...

Let's say that I'm not in the "dredge'em" camp. I'm expecting more spoonbill activity this year. Yes, we did have a rat problem on havergate but they seem to have vanished!