Tuesday, 30 July 2013

Ash dieback: the fungal villain

Tony Leech, NWT Trustee and County Fungus Recorder

As far as trees are concerned, there are good fungi and there are bad fungi. For an ash tree, Chalara fraxinea is totally evil. This is the fungus that causes ash dieback, a disease which is killing over 90% of the ash trees throughout much of Europe. It was first detected in Poland in 1992 but the fungus responsible was only identified in 2006. It is thought that it may have spread from Japan where it appears not to attack the native species of ash.

Early signs include leaves wilting and withering, with black streaks appearing on the young twigs and branches. But where is the fungus? Chalara fraxinea grows within the tissues of the ash, never flaunting itself as a recognisable fruit body. However, to get to another ash tree, and thus spread the disease, it must shape-shift into something much more recognisable as a fungus.
Hymenoscyphus pseudoalbidus, June 2013, photo by Neil Mahler
If two mating strains of Chalara come together in the same fallen leaf, their mycelia grow together and exchange nuclei. This is fungal sex – whether they enjoy it or not we don’t know! The resulting ‘joint’ organism now produces a fruit body in which spores are produced. Although much smaller than seeds, these spores have the same potential to develop into new organisms and are the agents of dispersal. In the case of Chalara dispersal is by wind - except that the fungus is no longer Chalara fraxinea – it has become Hymenoscyphus pseudoalbidus. This dual personality of many fungi has been known for years. Different scientific names are given to the asexual stage (in this case Chalara fraxinea) and the sexual stage (Hymenoscyphus pseudoalbidus). Often it can be difficult to confirm that they are the same species.

Last October, ash dieback was found for the first time in an established woodland in Britain, at NWT Lower Wood, Ashwellthorpe, a Norfolk Wildlife Trust reserve near Wymondham. Within the next few weeks it had been found at a number of Norfolk sites and elsewhere in the east of the country.

It was almost inevitable that the sexual stage would appear this summer and on 2 June the first specimen in Britain was found by Anne Edwards at Ashwellthorpe. Anne is a member of the group at the John Innes Centre in Norwich working on the DNA of H. pseudoalbidus. They have determined its base sequence to compare with that of the very similar, but non disease-causing, Hymenscyphus albidus to get clues about the mode of attack.

Very soon after the discovery at Ashwellthorpe, ash trees at NWT Foxley Wood, another NWT reserve, were found to have the disease. On Saturday 29 June, Neil Mahler and I went there looking for H. pseudoalbidus and found a number of specimens. Neil motorcycled back up from Leiston in Suffolk to deliver them to Anne first thing on Monday morning and by evening they had sequenced enough of the DNA to confirm its identity. The hunt is now on to find specimens of the non-pathogenic H. albidus.

National Marine Week: Make the most of the coast

Nick Acheson, NWT Volunteer

So you reckon you know about wildlife in Norfolk? You can recognise the heaven-borne mutterings of the skylark; you can spot the fine footprint of a fox in a puddle of mud and the spraint of an otter on a wintry riverbank; you know the habits of the swallowtail and the haunts of the hawfinch. You know about wildlife in Norfolk.

Strandline with whelk eggs and Flustra foliacea, Tabitha Pearman
But do you? Have you thought about the sea? We don’t – think about the sea – do we? It’s there, of course, the grey-green-blue-brown background to our walks along the coast, to our days spent watching seabirds, and our gazing at sea lavender in bright bloom in sunny July. But we don’t think about it. Nor do we think about the plants and animals which live in it, just metres from our shore; plants and animals which are as much a part of Norfolk as the paintings of Cotman, the tang of Colman’s Mustard, and the peregrines nesting on the spire of Norwich Cathedral.

These plants and animals are astonishingly diverse. Scientists estimate that as many as half of all the species which inhabit the UK live in the sea. So, with a touch of extrapolation, we might say that half of all the plants, animals and other organisms which live in Norfolk live in the sea. It bears thinking about, doesn’t it? For, every time you see a greenfinch at the sunflower seeds in your garden, every time a hedgehog potters past your pond, every time you hear – with a leap of your heart – the lusty song of a nightingale from a thicket of blackthorn, another creature respires, divides its cells and procreates unseen beneath the North Sea’s waves.

So what are all these creatures? We’re only just learning about them. As recently as 2010 divers from Seasearch East discovered a unique chalk reef stretching for miles along the coast of northeast Norfolk. It’s home to innumerable species of marine life – among them anemones, crustaceans, sponges, algae, fish, cephalopods and nudibranchs – and is of international importance. In 2011 the same team discovered a new species of sponge there: not new for Norfolk, not new for the UK, but new for science. So it’s a sponge which, as far as we know, lives only in the chalk reef off the coast of Norfolk and until two years ago we knew nothing of its existence.

Cromer Shoal Chalk Beds, photo by Rob Spray
We have no idea yet what other creatures may lie undiscovered in the waters just off Norfolk’s shore. What we do know is that our marine habitats and wildlife are every bit as diverse, precious and threatened as our wildlife on land. Until now the UK has dragged its fins and flippers appallingly where marine conservation is concerned but the time for action is now. The most significant thing that members of the public can do is learn about marine habitats and their wildlife, and become informed lobbyists for their conservation. 

Holding an edible crab, photo by John Hurst
The good news is that in July each year The Wildlife Trusts hold a festival called National Marine Week, aimed at spreading the word about our seas, and one of the most active players is Norfolk Wildlife Trust. Again this year there will be host of events in Norfolk, for experienced naturalists, for families, for members of the public, and again this year many of them will be free.

To find out more, and to take become involved in marine conservation in Norfolk, visit the events pages of the Norfolk Wildlife Trust website.

Wherever you are along the coast, happy marine wildlife-watching to you this month.

Sunday, 28 July 2013

Work starts again at Hilgay wetland creation site

Nick Carter, Conservation Officer (Fens)
The badger gate and fencing, photo by NIck Carter   
 The recent spell of dry weather has meant that Fen Group has been able to resume work on the site. Two of the major tasks left to do are finishing the installation the abstraction system from the River Wissey and to install the pump chamber and pump next to the storage lagoon. An outlying badger sett has held up the former but as this is no longer being used, digging the trench from the river to the storage lagoon can be finished off at the end of July. We have erected a badger gate and fencing to ensure no badgers are present in the sett when we started to dig the abstraction trench nearby. The nesting sand martins, close to where the hole for the pump chamber will be dug, have finished breeding so work can proceed there too.

The predated sand martin burrow, photo Nick Carter
With no ability to abstract water onto the site yet, levels have dropped in the ditches and patches of water in the storage lagoon have shrunk. Breeding lapwing and little ringed plover, as a consequence, have not had a very successful year. No young of the latter have been seen, although several nests were located, and only a few singletons of the former have been observed. The sand martins had more success with about 30 juveniles ringed on one visit but a predator (probably badger) located the burrows and dug out several of the nests. The birds did not hang around for a second brood. It is hoped that with better control of water levels next year the burrows should be less accessible.

Reeds growing in the storage lagoon, photo by Nick Carter
Plans are well under way for reed planting to be carried out from mid-August onwards. Adam Pimble, from NWT’s Hickling Team, will be supervising the planting. We are aiming to plant 40,000 plugs over one hectare of the site. The reed rhizomes planted in April have grown well and will help to protect the storage lagoon banks once it starts to be filled. Reed planting will then move to Hickling to do another 40,000 plugs at a wetland creation site there. The plugs are grown by British Wildlfower Plants, based locally at North Burlingham.

Friday, 26 July 2013

The Weeting Warden’s Diary: July

Simon Thompson: Summer Warden Weeting Heath NNR

Inside the Weeting Heath moth trap, photo by Simon Thompson
I’ve been getting quite excited about moths this month. I’d been to a trapping session or two before but had never run a trap of my own. 10 traps in and I’m well and truly hooked. Being a beginner is great, with in excess of 800 species of macro-moth, generally speaking the big ones, and an additional 1,600 or so micro-moths there’s almost always something new in the trap. The learning curve is steep but it’s amazing how quickly you begin to pick things up and become familiar with the different families of moths and the more regular species.

Tawny Wave, Scopula rubiginata, photo by 
2011 Weeting Summer Warden, Amy Green
The list is building steadily each week and we’re now up to 150 macro-moth species for the year. The full Weeting Heath species list has been compiled by various trappers over the last few years including previous Summer Wardens, Amy Green and Ellie Rickman and it is now at 290 macro- and 80 micro-moth species. 

The list includes a few rarities; Tawny Wave - a Red Data Book species trapped both this year and in 2011; False Mocha – a Biodiversity Action Plan priority species recorded in 2010; and Lunar Yellow Underwing – a nationally scarce species which is in decline, recorded regularly this year and also in 2008 and 2011. 

Small Elephant Hawkmoth, Deilephila 
porcellus, photo by Simon Thompson
It is obviously a real buzz to be recording rarities however some of the more common moths are some of the most popular with visitors here at Weeting, particularly the large, flamboyant hawkmoths. We have Privet-, Pine- Eyed-, Poplar-, Elephant- and Small Elephant- hawkmoths visiting the trap regularly. One trap produced 34 of the bright fuchsia and mustard coloured Small Elephant Hawkmoths which really was a sight to see!

Rosy Footman, Miltochrista miniata,  
photo by Simon Thompson
If you and your family are interested in seeing how a trap works then we are holding an event in August called Fantastic Nightfall Fliers. We’ll be having a look at the moth trap and some of the moths that it catches, heading out for a short walk in the forest, hopefully hearing stone curlews call and finding some creatures that hunt moths in the night, before heading back to the visitor centre for a hot chocolate. The event will be held here at Weeting Heath on Saturday 24 August from 8 – 10pm. Tickets cost £2 per person or £6 for a family ticket (2 adults and 2 children). If you just can’t wait that long then feel free to contact me at the NWT Weeting Heath Visitor Centre (Tel. 01842 827615) and I’ll be happy to let you know when I’m planning the next trapping session.

Eyed Hawkmoth, Smerinthus ocellata, photo by Simon Thompson

Lobster Moth, Stauropus fagi, photo by Simon Thompson
For more great moth pictures from the Weeting Moth Trap, have a look in our Facebook album.