WHAT LIES BENEATH THE ROCKPOOLS AT MIDNIGHT

PUBLISHED: 19:52 03 August 2014 | UPDATED: 13:17 30 August 2017

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Cornwall Wildlife Trust holds midnight rockpooling event at St Michael's Mount

Cornwall Wildlife Trust, is giving dedicated Shoresearch volunteers a fantastic otherworldly experience with a night rockpooling survey of the shoreline beneath St Michael's Mount.

Matt Slater, Marine Awareness Officer for the Trust lead the volunteers out on a damp drizzly evening with no great expectations as to what would be found. “We had surveyed this site many times before during the day and the marine life here is astounding but with the poor weather and no light we weren’t expecting to see much.," he says. "However we were amazed to find the shore even more teeming with life than usual as nocturnal animals were out and about en masse!”.

We were amazed to find the shore even more teeming with life than usual as nocturnal animals were out and about en masse!

Dressed in high-vis reflective jackets, wetsuits and wearing head torches 15 people headed down the causeway towards St Michaels mount. It was a bizzare sight to witness. “We hope no one on the island saw us and were alarmed, as they may have thought they were being invaded!” said Matt.

“Walking down towards the water we were amazed to see large numbers of shore crabs out and about, foraging under the cover of darkness. They were presumably enjoying the warm moist air which stops them getting dried out. The marauding crabs were extremely active and looked indignant to find crazy humans shining torches at them. We actually interrupted a crab fight in which one crab was eating another ones claw, evidence that life is harsh on our shores."

“It was surprising how many small mysid shrimps and prawns were teaming in the shallows and we soon realised that they were being attracted to our torch light! Following their shrimp prey, tiny Atlantic cuttlefish (Sepiola atlantica) were also attracted to our lights. These little creatures only grow to a maximum size of 3cm unlike their larger cousins the common cuttlefish. These alien-looking, colour-changing cephalopods seemed inquisitive and were fascinating to watch, often producing little puffs of black ink if startled!”

Looking under rocks and amongst sea weed yielded bizarre sea spiders, tube worms, beautiful nudibranchs and a candy striped flat worm, a primitive but stunning creature. We also found a small, delicate, spider crab called a decorator crab that was entirely festooned with fluffy seaweed which it attaches to itself using Velcro-like hairs on its legs. A large sea scorpion fish was found sleeping in a clump of seaweed and a foot long greater pipefish was seen gliding through the eel grass.

“There were juvenile Pollack and small wrasse darting around everywhere, the place really was teaming with life," saysJake Meyers, a volunteer for Shoresearch. "It was awesome!”

Matt Slater went on to say: “The excitement of the volunteers was unprecedented! We were constantly seeing amazing things. So many of our intertidal species are more active at night it allowed us to get a far better idea of the extent of marine animals present

“It is important to stress that although exciting, night rockpooling is potentially very dangerous. Never go night rockpooling without knowing the area well and having explored it in the daytime first. Like when diving, it is important to always go with a night rockpooling buddy’ and stick together so you can keep a look out for each other. Carry at least two torches each and check the tide times so you don’t get caught out by the tide. Slippery rocks covered in seaweed are a particular risk and when rockpooling at night it is really easy to fall over so it is best to choose a site without steep gullies or deep pools which you could fall into.”

Modern LED torches often have a blue tinge – this is great as the blue light will cause many marine species, particularly anemones to fluoresce and glow strange colours. One of the most beautiful seaweeds we find on Cornish shores is Rainbow wrack (Cystoceira tamariskifolia) which actually glows blue under torch light!

Data collected at the night rockpool will be submitted to Natural England in support of the establishment of a Marine Conservation Zone within Mounts Bay. Through the PANACHE project we have been engaging with local people with an interest in marine wildlife and have trained a team of Shoresearch surveyors who carry out user friendly surveys to monitor the health of our shores. We have also trained a team of divers who carry out surveys further out to sea. As well as recording rare and threatened species the volunteers also record climate change indicator species and look out for non-native species which shouldn’t be found in our waters but have been introduced by us humans and are now colonising our shores”.

shoresearchcornwall.blogspot.org.uk

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