Thursday, 11 July 2013

Worm Takeover

The long awaited fine warm weather was bound to attract people to bathe or paddle on the north Wales beaches. At the Llanddona end of Red Wharf Bay, walking down to the sea at low tide a couple of evenings ago, we met conditions that caused some to hesitate before proceeding. The topography and texture of this normally flat sandy beach had changed with a series of hummocks and softer muddy black sediment between.

Closer inspection showed that there were astronomical numbers of small sandy tubes so packed together that the sediment was building up into hummocks. The irregular topography had encouraged fine and organic deposits, probably originating from a plankton bloom, to settle. Under a very thin surface the rate of decay was such that the soft sediment was anoxic and black.

Looking a little more closely, the worm so dominating the Llanddona beach now is the Sand Mason Worm – Lanice conchilega. These worms glue sand and shell grains together to create the long tubes in which they live. On top of the tubes they construct a characteristic fringe and feed by grasping particles from the water with tentacles. Normally you see these scattered fringe tops just protruding from the sand, but when there has been a mass recruitment there can be so many that they modify the topography of the beach or nearshore seabed. I did not have time to explore the full extent of the area covered by the unusual density of tubes, but the feature must have spread over 1.5 Km along the shore by 300 to 400 metres wide.

The muddy sand offshore area in Red Wharf Bay has been sampled on an almost annual basis for over 25 years. Experience shows that it is particularly liable to substantial changes in the species that dominate the fauna and are capable of modifying the conditions for others. Having visited Llanddona beach for many years, I do not recall seeing quite such a mass takeover of the lower shore by quite such a hugely successful recruitment of Sand Mason Worms.

Red Wharf Bay with worms - lots!
This post was written by Ivor Rees, a director of Natur Cymru amongst many other things!

Wednesday, 10 July 2013

Siskin and Turbines before AGM

Chris Wallbank was presented with a cheque for £250 donated by WWF Cymru for coming first in the Natur Cymru wildlife art competition for his painting of a Siskin. As the bird is perched amongst blossom it is likely that this will be the front cover of the spring 2014 edition of the magazine.

Left to right: Mandy Marsh, Geoff Gibbs, Andrew Oughton,
Daniel Jenkins-Jones, Chris Wallbank, Shenaz, James Robertson,
Catherine Duigan, Andrew Tuddenham, Delcie Simkin & David Parker 
Andrew Oughton from Plas Tan y Bwlch presented the cheque on behalf of WWF Cymru. The occasion coincided with the Natur Cymru AGM and board meeting which was held in the library of The Plas.

Before the presentation we enjoyed a beautiful walk through the woodland up to Llyn Mair and then down the line of the 2013 hydro scheme which replaces the one first installed in 1884. The installation was full of challenge with the need to avoid ground nesting birds, roosting bats and ant hills. To avoid root damage to particular trees, such as the Tree of Heaven and some enormous Limes, it was necessary to hand dig in parts.

The original Gilkes turbine installed in 1884 cost £48 and generated 7Kw. The 2013 turbine, also from Gilkes in Lancashire, cost £47,000 and generates 30Kw. Total cost of the project was a little over £400K and the payback is expected to be within 10 years.  

Monday, 8 July 2013

Dragons and damsels cavorting

That unproductive bogland beneath the railway is worth its weight in gold when the sun shines and the dragons and damsels come out to play.

I’m not sure how long this armour-plated naiad took to mature beneath the water before finally emerging to crawl out of its exoskeleton as an adult dragonfly.

All sorts of shenanigans as they copulate in the wheel position or territorial argy-bargy between competing males.

I would however prefer the horse flies to find somewhere else to feed.


Wednesday, 3 July 2013

Cockling on the Dee

From 1st July for six months the 53 licensed cocklers on the Dee Estuary can go cockling 5 days a week raking up to 150 kilograms per day. The cost of a licence for the season is £1,300 and an average price per kilo, depending on size and weight, is about £1.60. Doing the maths that means 150 x 5 x 26 x £1.60 = a maximum payback of £31,200.

It’s the 6th consecutive year of cockling on the Dee. Before 2008 it was boom and bust with the fishery being declared open, then ransacked by up to a thousand cocklers for 3 days or so until the fishery would be declared closed and that’s how it might stay for a few years until stocks recovered! Bad news for the cockles and all the birds, such as Oystercatchers, that depend on shellfish.

These days Natural Resources Wales assess the biomass of cockles by survey, calculate the amount needed for the birds, the amount needed for breeding and the balance that can be made available to cocklers. Again doing the maths 150 x 5 x 26 x 53 (cocklers) = 1,033,500 kilos or more than a thousand tonnes has been declared as the quota.

Based on the recent years management the fishery has been accredited by the MSC, Marine Stewardship Council, which is a great step forward.

It’s a shame that all those lovely cockles need to be exported, mainly to Spain, where they are a premium prized product. We just don’t appreciate the world class quality we produce.

Dee cockles are much larger than those from Burry Port, the other major cockling beds in Wales. But talking to a couple of cocklers at the end of the second day of the season, they say there are very few cockles the right size due to the very cold spring weather. Maybe the season’s opening should have been delayed?