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Wednesday, 24 January 2024

Sabellaria colonies -- our local "coral reefs"





After the winter storms, the beach level at the northern end of Traeth Mawr is at least a metre lower than the summer level.  Many thousands of tonnes of sand have been washed out into deeper water.  And the local "coral reef" is better exposed than I can ever remember.  I assume that the great cushion-like Sabellaria colonies are usually beneath the sand........

Honeycomb worms (Sabellaria spp.) are tiny worms that live around the low tide area of the beach. They build tubes, attached to the rock to live in, and the structures we see on the beach are dense colonies made up of thousands of individual worms. Fully grown, each individual worm is around 3-4cm long. The colonies however can often cover large areas of rock, forming solid reefs.  Actually they are not all that solid -- they are quite crumbly, and are easily destroyed.....






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3 comments:

Dave Maynard said...

So, if the sand is lowered, are tree trunks or peat visible?

Dave

BRIAN JOHN said...

In some places they should be -- I await reports! I have never seen the submerged forest on Traeth Mawr -- but have no doubt it is there, waiting to be discovered.........

BRIAN JOHN said...

Oops -- I should correct that. Three years ago there was a small exposure of peat beds close to the slipway, and I did see one piece of a tree. Described here: https://brian-mountainman.blogspot.com/2021/02/irish-sea-till-and-peat-bed-on-traeth.html

I'm still waiting to see something on the scale of Newgale or Amroth.......