This is a resumé of a short talk I gave at Bowness-on-Solway on Saturday 22nd January, as part of the event that launched the ‘Hadrian’s Wall 1900’ celebrations. I’m posting it here because some of the audience wanted to know more – and I appreciate that it’s not always easy to remember animals’ names!
I shall be starting my low-tide guided walks again in the Spring, when it will be possible to see honeycomb worms and perhaps, if we’re lucky, piddocks. Dates, times, booking arrangements will soon be on the ‘events’ section of my website The Fresh and the Salt, www.thefreshandthesalt.co.uk
The honeycomb worm reefs, Allonby Bay
Allonby Bay was designated as one of the Solway’s all-important Marine Conservation Zones (MCZ) because of the honeycomb worm reefs and the variety of animals they support.
The worms – Sabellaria alveolata – each build a protective tube around themselves, using their tentacles and sticky mucus (they have no eyes!) to select sand grains of the right size and stick them edge-to-edge. Aggregations of the tubes form dramatic and sculptural blocks of reef that trap sea-water in lagoons and small pools as the tide goes out.
You can see them at their best below Dubmill Point on a low Spring tide. It’s worth heading down there as the tide is still ebbing, so you can spend time looking for the greenish-yellow mats of breadcrumb sponge, the variety of algae (seaweeds) in the lagoons, including large broad fronds of oar-weed and crinkly sugar-kelp, and burrowing anemones (which may have ‘hidden’ themselves by tucking in their tentacles and covering their exposed surface with bits of shell and sand). Shrimps, hermit crabs, small fish like blennies or baby flatfish, young starfish, beadlet sea-anemones and other more unusual creatures may be there too.
But keep an eye out for when the tide turns (look for scum on the edge of the water).
There’s more about the honeycomb worms and other invertebrate animals in Chapter 1, Invertebrates on the Edge, in The Fresh and the Salt.
Piddocks in the peat
Piddocks are bivalve molluscs (like mussels), but the outside of the valves (shells) is heavily-ridged and has tooth-like projections. The animals ‘shuggle’ their shells to bore into hard substrates like rock and clay – they arrive as tiny larvae, attach to the surface, and set to work. Once the tunnel is made the animal feeds and grows by filtering food from the water; it doesn’t leave the tunnel again.
Occasionally the banks of peat formed after the last glaciers retreated are uncovered by the sea, and some lucky piddock larvae found them and bored into this rather softer substratum. This might have been as long as about 5-6000 years ago. The peat has been covered by sand and sea and then uncovered again, perhaps several times. The piddocks we can find in the exposed peat (if we are very lucky) are long-dead. .
Why is the peat there on the shore? Why can we sometimes find the preserved remains of a ‘submerged forest’ on the shore? Have a look at this blog-post, The long-lost piddocks and the peat, and also the chapter on ‘Changeable Depths’ in The Fresh and the Salt.
If you live along the edges of the Upper Solway, you have to love mud! From the eastern side of Grune Point, past Calvo and Newton Arlosh saltmarshes, Moricambe Bay, Campfield and Bowness and Rockcliffe – ‘mud, mud, glorious mud’ dominates . And of course on the Scottish side too – I’ve spent many hours in the mud and merse along the River Nith.
Mud might look lifeless, but step out onto it and press with your boot – small spurts of water might shoot out from the surface, from the openings of the tiny U-shaped burrows of mudshrimps, Corophium.
There may be as many as 10,000 burrows of these tiny animals per square metre. The shrimp is about 1cm long with two very long antennae, and it is a beautifully-adapted and very important animal of the mudflats. By beating its legs it oxygenates the water in its burrow (and the surrounding mud), and it eats microscopic algae on the surface of sandgrains – so it acts as a ‘bioengineer’, affecting the stability of the mudflats’ surface, and keeps the upper layers oxygenated for other small invertebrates and the millions of bacteria and algae that live there.
Mudshrimps also provide food for wading birds! The Upper Solway’s mudflats and marshes are highly-protected for birds and other wildlife, with local, national and international protections (for more about those conservation acronyms, and why you should love them, read this blogpost too!).
There is much more about my favourite animals in this blogpost, The charisma of Corophium, and in Chapter 7, Mud-life, in The Fresh and the Salt. (There is also a section in that chapter about how artists – including Alison Critchlow from Bowness – ‘see’ and interpret the Upper Solway and mud.)