Wednesday, 14 March 2012

When the tide goes out - zostera!

Zostera marina
An equinoctial spring tide is a great time for exploring Porth Dinllaen and Ivor Rees had agreed to meet me there to explain the zostera beds for Country Focus (broadcast on 25th March). Lying flat on the sands were thin green blades about 30cm long which in summer will be between 100cm and possibly 200cm. This is Zostera marina, a flowering seagrass, the larger of three species. 

It’s neither threatened nor rare but this is the only (unless anyone knows differently?) place in Wales where you can see it without diving. The beds at Porth Dinllaen cover an area of about twelve hectares and it spreads either by rhizome or by seed. If I return in September I will find seeds stuck in the stems of the zostera.

On a nearby outcrop of rock there was a profusion of all sorts of seaweeds and I naïvely asked Ivor how these differed from zostera – they’re algae whilst zostera is a plant with a totally different reproductive system. 

Zostera beds are important fish nurseries for many species and off the south coast of England this is where sea horses will be found; but for the moment our waters are too cool for them.

We were not the only explorers on the beach, Chris Richardson, head of Bangor University’s School of Ocean Sciences, was there with a group of students. As well as looking at the zostera beds, and identifying goodness knows how many species and organisms, they were hunting razorfish. First identify a likely looking entrance to a razorfish burrow then pour on some salt and a few minutes later out pops a razorfish.  

As we walked over the normally sea covered sands other tasty fruits of the sea were wondering where the water had gone. King scallops were perfectly camouflaged, the bright shell buried on the underside and a plantation of seaweeds on top – then they would blow their cover by squirting water if you came too close. A sad looking lobster was trapped in a pot, other lobsters were seen lurking in puddles beneath rocks. Plaice, wrasse and prawns briefly marooned in puddles until the turn of the tide.   

What a beautiful beach. I must return with snorkel.   

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