Category Archives: Conservation

Surprises in the rock pools

Rock pooling can be an emotional experience and I’ve experienced everything from happiness to horror in the last couple of weeks. The arrival of warmer weather has brought out a joyous burst of extraordinary colours in the pools and plenty of surprises too.

I’ve picked out some of the best below, but I’d suggest you put down your food before you read the last one.

Colours in the rock pools at Porth Mear - painted topshell
Colours in the rock pools at Porth Mear – painted topshell

It’s never easy to run in knee-deep water and across slippery rocks wearing wellies, but I  came close to setting a new land-speed record after hearing the cry of, ‘Octopus!’ from across the shore at Lee Bay.

The timing couldn’t have been better. I was teaching a Coastal Creatures workshop on molluscs in North Devon and here was the mollusc I’d been hoping to find for decades.

Experienced local rock pooler, Rob Durrant of Coastwise North Devon, found the Curled octopus (Eledone cirrhosa) hiding under a rock. With quick thinking, he scooped it into a transparent pot where it demonstrated its great ability to change shape and colour, blanching almost to white when we placed it in a white bucket.

Curled octopus (Eledone cirrhosa). Cephalopod molluscs have complex eyes which evolved completely separately from our own eyes and have a distinctive long pupil
Curled octopus (Eledone cirrhosa). Cephalopod molluscs have complex eyes which evolved completely separately from our own eyes and have a distinctive long pupil. Photo by Rob Durrant.
Curled octopus looking paler as we placed it in a white bucket - it also changed its skin texture.
Curled octopus looking paler as we placed it in a white bucket – it also changed its skin texture.

Octopi are natural escape artists. Because they have no bones, they can squeeze into incredibly tight spots. This one seemed to enjoy the safety of its pot and it took some effort to persuade it to swim free in the pool.

Curled octopus (Eledone cirrhosa). This species has a single line of suckers down its arms, which tend to curl at the tips.
Curled octopus (Eledone cirrhosa). This species has a single line of suckers down its arms, which tend to curl at the tips. Photo by Rob Durrant.

There were also some surprises on a recent Looe Marine Conservation Group rock pool ramble at Hannafore Beach. It’s an amazing location in a Marine Conservation Zone, so we never know what will turn up.

One of the volunteers asked me to verify what species of pipefish a participant had found. The fish did have a long snout like a pipefish, but on closer inspection I could see its body was thickened in the middle, and in front of its dorsal fin was a row of flattened spines.

15-spined Stickleback (Spinachia spinachia) in Looe
15-spined Stickleback (Spinachia spinachia) in Looe

The fifteen-spined stickleback (Spinachia spinachia) is a species I’ve only seen a couple of times before. It’s elusive and easily overlooked, but it is a remarkable fish. In addition to having the most beautiful, tiny mouth, it also has an fascinating life cycle. The male fish builds a nest, arranging fronds of seaweed just-so before the female lays her eggs in it. The female fish dies soon after laying, leaving her mate to guard the nest of eggs until they hatch.

15-spined stickleback about to be returned to its pool
15-spined stickleback about to be returned to its pool

On the same day, we had another surprise, a corkwing wrasse swam straight into Other Half’s bucket.

‘There’s something weird on it,’ he said, thrusting the bucket towards me.

Inside the bucket, a fish with bold turquoise stripes across its face was swimming at an awkward angle, looking at me through a wide orange eye. Pretty though it was, it was something just behind its eye that Other Half was pointing at. He needn’t have bothered: I was already staring at it.

I wasn’t sure I wanted to see it, but I couldn’t help looking.

No doubt, like me, you’ve heard of fish lice. They’re generally tiny copepods, a kind of swimming baked bean, that attach to a fish and suck its blood. They’re the sort of thing that can put you off your lunch, but you accept it’s part of nature.

This thing, on the other hand, was straight out of an alien movie.

Corkwing wrasse with parasitic isopods (Anilocra physodes)
Corkwing wrasse with parasitic isopods (Anilocra physodes)

Far from tiny, this parasite was at least a quarter of the length of the fish.

It was a giant, woodlouse-like animal, a marine isopod, clamped onto the fish by its jaws. On closer inspection, there were other, smaller isopods of the same sort on the fish.

Enough to put you off your food - Anilocra physodes parasitic isopods feeding on the wrasse.
Enough to put you off your food – Anilocra physodes parasitic isopods feeding on the wrasse.

I’d never seen anything like it – and would be happy not to again. I’ve come across many grim feeding habits on the shore, but never imagined that I’d see a parasite this large.

It was the find of the day, even if it did make me feel a touch nauseous.

Several people at the ramble asked if we should remove the parasite. However horrific it looks to us, all these animals are part of the ecosystem and they have to feed, so it’s best not to interfere.

It turns out that there are a couple of species of isopod that target wrasse. This one is Anilocra physodes, confirmed by David Fenwick of Aphotomarine. David suggests looking out for another isopod that replaces the tongue in weever fish. Yes, you read that right! I have no idea how to go about looking in the mouths of weever fish.

It goes to show that there’s no end of surprises on the shore.

To allow you to get back to your food, here are some less alarming rock pool finds from the recent spring tides.

Happy rock pooling!

A green shore urchin with purple-tipped spines
A green shore urchin with purple-tipped spines
Xantho hydrophilus - the furrowed crab - with brown claws
Xantho hydrophilus crab –  with brown claws
Scorpion fish eggs
Scorpion fish eggs

Spring arrives early in the rock pools

There’s no better way to explore the shore than with a group of experienced rock poolers. During this month’s big spring tides, I was privileged to join a small, dedicated team to survey Hannafore Beach in Looe. Best of all, David Fenwick who runs the brilliant Aphotomarine website brought along his newly-converted marine laboratory camper van for a test run.

A few weeks on and I’m still downing hot chocolate to recover from the cold (any excuse!), but this was a priceless opportunity to expand my knowledge and encounter new species. Over the week we recorded over 230 species, some of which I never knew existed and I finally found my first Snake pipefish.

Glamorous beach wear for the new season - me wearing every piece of clothing I own under my waders! Photo by Cornish Rock Pools Junior.
Glamorous beach wear for the new season – I’m wearing every piece of clothing I own under my waders! Photo by Cornish Rock Pools Junior.

Day one got off to an inauspicious start. David’s marine lab van broke down on its way to the beach, meaning he missed the best of the tide that day. Those of us who did make it had to leap back into our cars to take refuge from the hail before we’d even got our boots on.  Despite the wind chill, we were soon in full swing. Incredibly, the pools were full of signs of spring.

Scorpion fish lay their clusters of yellow glitter-ball shaped eggs earlier than most other species. In some, the baby fish were already taking shape and hundreds of eyes gazed into my camera lens.

Scorpion fish eggs with eyes looking out.
Scorpion fish eggs with eyes looking out.
A Scorpion fish (Taurus bubalis) - perhaps one of the proud parents - relying on camouflage not to be seen.
A Scorpion fish (Taurus bubalis) – perhaps one of the proud parents – relying on camouflage not to be seen.

Along the grooved bellies of some of the worm pipefish, there were also lines of eggs. Like seahorses, it is the male pipefish that carries the eggs until they hatch.

It’s hard to think of slugs as migratory animals, but several sea slug species have made their annual journey onto the shore to breed. We saw lots of the rarely-recorded slug Aeolidella alderi. My friend Jan from Coastwise North Devon found one that had been chomping on a dark anemone. The colour had passed into the cerrata on its back so that instead of the normal bright white, this one looked almost red.

Aeolidella alderi sea slug - with pigment in its cerrata, probably from eating an anemone.
Aeolidella alderi sea slug – with pigment in its cerrata, probably from eating an anemone.

Another had distinct yellow tips to its antenna and cerrata. This species always has a ring of short white cerrata below the head, making them look like they’re wearing a white ruff.

Another Aeolidella alderi - this time with yellow tips to its cerrata and antennae.
Another Aeolidella alderi – this time with yellow tips to its cerrata and antennae.
An unusual yellow Daisy anemone - perhaps what the sea slug had been eating.
An unusual yellow Daisy anemone – perhaps what the sea slug had been eating.

Nearby, a relative of Aeolidella alderi, the more common ‘Great grey sea slug’ (Aeolidia sp. probably filomenae) is feasting on an anemone. This hungry slug isn’t holding back and has dived headfirst into its feast.

Headfirst into its lunch - a Great grey sea slug (Aeolidia sp.) eating a snakelocks anemone.
Headfirst into its lunch – a Great grey sea slug (Aeolidia sp.) eating a snakelocks anemone.

Yellow-clubbed sea slugs (Limacia clavigera) were also out looking for mates. They’re not easy to spot when the tide’s out, as they look like minute splodges of white jelly on the rocks. Once in the water, they are transformed, with spiral rhinophores sprouting from their heads and robust yellow-tipped cerrata sticking out from their heads and bodies.

Limacia clavigera - the yellow-clubbed sea slug exploring my petri dish.
Limacia clavigera – the yellow-clubbed sea slug exploring my petri dish.

When, towards the end of day 2, I glimpsed a shape gliding through the seaweed my heart leapt. I’ve been looking out for this fish for years to no avail, but this one was hovering above my foot. Snake pipefish, like other pipefish, freezes and relies on its fabulous camouflage to escape predators.

Snake pipefish showing off its distinctive trumpet nose and pale striped pattern.
Snake pipefish showing off its distinctive trumpet nose and pale striped pattern.

I was able to reach into the water and lift it out for a quick photo. It wasn’t slippery to hold, but it wound its body around my arm so I had to overcome the powerful urge to squeal and drop it.

Snake pipefish can grow to 60cm and have pale vertical lines down their bodies so are easily recognised. They like to live among sea grass beds so are not commonly seen on the shore.

Snake pipefish (Entelurus aequoreus) on a brief visit to my bucket before release.
Snake pipefish (Entelurus aequoreus) on a brief visit to my bucket before release.

Inevitably, other fish were more evasive. David saw a Conger eel among the kelp, but it slipped away.

Among many amazing and less-common species, David Fenwick showed me this rare prawn, Caridion steveni, which appeared to have an especially short, blunt ‘nose’ (rostrum) compared to some other species. Its bright red pigmentation helps it blend in to the seaweeds.

Caridion steveni - A rare prawn species (Hippolytidae family)
Caridion steveni – A rare prawn species (Hippolytidae family)

Among the weeds on the rocks, tiny spider crabs were everywhere, only visible when they moved their spindly legs. Even when I take close-up photos it can be hard to make out the shape of the crabs.

A small spider crab - Macropodia deflexa (identified by its downcurving rostrum)
A small spider crab – Macropodia deflexa (identified by its downcurving rostrum)

Junior spotted a crab with an even more amazing disguise. We were looking under a boulder when he gasped and pointed at a seaweed-covered stone.

What I thought was a seaweed-covered stone.
What I thought was a seaweed-covered stone.

‘It’s a crab, I saw it move,’ he whispered, as though it might hear him and realise the game was up.

Whichever way I looked at the stone that Junior was waving his finger at, it still looked inanimate. It was only when I picked it up that I felt the sharp spines of the Common spider crab (Maja bracchydactyla) lurking below the seaweed camouflage. We turned it over to see the crab’s legs neatly tucked under its carapace. Junior delighted in placing the ‘stone’ back in the water to watch it sprout legs and scuttle away into the safety of the seaweed.

Even up close it was hard to tell this is a crab - but I could feel the sharp spines on its shell and the legs began to move.
Even up close it was hard to tell this is a crab – but I could feel the sharp spines on its shell and the legs began to move.

On day one I reached, or frankly surpassed, my cold tolerance limit. By the end of the week I  was only able to function by keeping my hands thrust deep inside my scarf to warm them against my neck. I must have ressembled a trussed chicken, but there was no point caring. As always, the rewards outstripped the pain.

Next weekend we’re expecting some huge spring tides in Cornwall, and yet more freezing winds, so you know where I’ll be.

I’m excited to be leading a couple of fabulous training events on Friday 2 March in Falmouth and Sunday 4 March in Looe. Maybe I’ll see you there? Wrap up warm!

Ophiocomia nigra brittle star
Ophiocomia nigra brittle star
Humpback scallop
Humpback scallop
Jewel anemones
Jewel anemones

Chilly autumn rockpooling

I’m not a fan of winter. Even though I go rock pooling all year round and love the way the wildlife varies with the seasons, the November to February period is a challenge for me. The thought of sticking my hands in icy-cold water makes me want to hibernate. Right on cue, a fierce northerly wind blows in for the spring tides. I layer up and wear my fluffiest, most comforting jumper to bring you this week’s blog post.

Obelia geniculata - a hydroid known as 'sea fir'.
Obelia geniculata – a hydroid known as ‘Kelp fir’. Recognisable by its zig-zag ‘stems’.

I’m trying to photograph hydroids at the moment. These relatives of the jellyfish and anemones are generally translucent and no more than a few centimetres long, making them hard to spot. At this time of year when the seaweeds die back and the waves roll in, it’s especially tricky. My camera doesn’t like focussing on them and they won’t stay still in the current, but their nodding tentacles and curious structures are mesmerising.

Another hydroid - Coryne pusilla. This one can't retract its tentacles into little cups. It has a ringed stem (visible in the bottom-left of the photo).
Another hydroid – Coryne pusilla. This one can’t retract its tentacles into little cups. It has a ringed stem (visible in the bottom-left of the photo).

As always there are strange creatures galore. This Sea gherkin is unusually large and gnarled.

A Sea gherkin (Pawsonia saxicola) - this is a type of sea cucumber and clings onto the rock with its tentacle feet.
A Sea gherkin (Pawsonia saxicola) – this is a type of sea cucumber and clings onto the rock with its tentacle feet.

Among the sponges and brittle stars I come across this invasive species from the South Pacific, the Orange-tipped sea squirt, Corella eumyota.

The invasive Orange-tipped sea squirt
The invasive Orange-tipped sea squirt

The twisted gut is very prominent in this species and you can see the orange colouration at the top. It’s thought this species may compete with native squirts and other invertebrates, but we will only find out by monitoring its spread. This is the first one I’ve recorded here.

Nearby I find the native sea squirt Ascidia mentula with lovely red flecks in its almost transparent test.

Ascidia mentula - a tunicate sea squirt. The red streaks reminded me of fireworks.
Ascidia mentula – a tunicate sea squirt. The red streaks reminded me of fireworks.

This sponge also catches my eye. It’s hard to identify many sponges with any certainty without examining their spicules under a microscope, but this one has the appearance of Myxilla rosacea.

A striking sponge with its fine structures and deep pores. Possibly Myxilla rosacea.
A striking pink sponge with fine structures and deep pores. Possibly Myxilla rosacea.

On the next tide we make a successful return visit to the beach where Cornish Rock Pools Junior achieved finding a world record haul of stalked jellyfish last year. We come close to matching the numbers we found last time. I lose count at 25 because Junior makes it clear he doesn’t want his record broken.

Many of the stalked jellyfish are juveniles, only a few millimetres long and it tests my eyes to pick them out among the swirling seaweed. Then I spot this 1mm pinprick of a jelly blob and take a photo in case it turns out to be a stalked jelly.

My eyes must still be good - a 1mm baby stalked jellyfish. It's not possible to say for sure what species.
My eyes must still be good – a 1mm baby stalked jellyfish. It’s not possible to say for sure what species.

On my screen at home its column is clearly visible although the tentacles are either retracted or haven’t yet grown. Little is known about the very early stages of development of these creatures and how to separate the species by sight, but David Fenwick who runs the amazing Stauromedusae UK website confirms that it is definitely a stalked jelly.

It’s great to be able to show a friend from Natural England how abundant these species are in the Looe and Whitsand Bay Marine Conservation Zone, which aims to give them protection from developments and disturbance.

Haliclystus octoradiatus - the blobs between the arms are primary tentacles, which easily identify this species from most others we see.
Haliclystus octoradiatus – the blobs between the arms are primary tentacles, which easily identify this species from most others we see.

One of her sons does an impressive job of finding stalked jellies and even finds one that is in the middle of eating an amphipod. The current is too strong to get a great photo, but you can clearly see the unfortunate creature’s head sticking out of the stalked jellyfish’s mouth here.

A stalked jellyfish (Haliclystus octoradiatus) eating an amphipod.
A stalked jellyfish (Haliclystus octoradiatus) eating an amphipod.

I’ll be submitting all my stalked jellyfish records to help reinforce the evidence that will hopefully keep these protected species from harm.

A juvenile Calvadosia cruxmelitensis stalked jellyfish. We found 3 species of stalked jellyfish on the site.
A juvenile Calvadosia cruxmelitensis stalked jellyfish. We found 3 species of stalked jellyfish on the site.

I can’t help taking a look at some other things while I’m here. But before long the cold is hurting my fingers and chilling my insides in the sort of way that can only be fixed by a steaming mug of hot chocolate.

That’s the bit of winter I look forward to!

Rayed trough shell
Rayed trough shell
Aslia lefevrei - the brown sea cucumber. This sea cucumber lives in crevices in the rock with just its tip poking out.
Aslia lefevrei – the brown sea cucumber. This sea cucumber lives in crevices in the rock with just its dark tip poking out.
Dysidea fragilis - or the hedgehog sponge as I call it.
Dysidea fragilis – or the hedgehog sponge as I call it.
3-spot cowrie hanging on an overhang
3-spot cowrie hanging on an overhang

 

Happy rockpooling!

Citizen Science in action with Shoresearch

Every year, the Cornwall Wildlife Trust’s Shoresearch project undertakes the ultimate rockpooling challenge with a week of beach surveys. I’d love to survey all five locations, but Junior has other plans, including a midnight rockpooling session. Watching hermit crabs bombing about the pools at 1am is great fun, but isn’t conducive to being the other side of the county bright and early.

Night-pooling at Hannafore. Many rock pool animals are more active at night.
Night-pooling at Hannafore. Many rock pool animals are more active at night.

We catch up with the indefatigable Matt and Adele from the Cornwall Wildlife Trust on days three and four of their Shoresearch survey marathon. Together with a team of enthusiastic volunteers, we complete a randomised quadrant transect and a general search at Readymoney Cove in Fowey and Hannafore beach in Looe.

Shoresearch crew in action at Readymoney
Shoresearch crew in action at Readymoney

It’s lovely to hang out with like-minded people and whether you’re experienced or completely new to rockpooling, there are always new things to find and learn by exploring the shore in a group.

At Readymoney Cove, we soon discover that there are lots of Common starfish about. These are the classic orange five-armed sea stars that are always represented on children’s seaside books, but are more common in deeper water than on the shore.

Common starfish are less common on the shore than Spiny starfish and Cushion stars.
Common starfish are less common on the shore than Spiny starfish and Cushion stars.

In fact, it’s an echinoderm-rich sort of day, with loads of representatives of this family of animals on the shore. There’s a whole collection of echinoderms together on one rock: a green shore urchin; sea gherkin (a type of sea cucumber); brittle stars and cushion stars.

Sea gherkin - these small sea cucumbers are often found on rocks on the shore. They're related to starfish and urchins.
Sea gherkin – these small sea cucumbers are often found on rocks on the shore. They’re related to starfish and urchins.
A spiny starfish
A spiny starfish

It feels like interrupting a family meeting so I replace the stone and leave them to it.

Later in the day we find another echinoderm, the Kaleidoscope starfish (Asterina phylactica) which is very small and lives among the pink coral weeds in sheltered pools. Its back is covered in colourful circles of orange and white, forming a dark star in its centre. The dots are made by the little pincers (pedicillerae) which the starfish uses to keep its back clean, as you can see in the photo.

Asterina phylactica - the kaleidoscope starfish in a rock pool at Readymoney, Fowey.
Asterina phylactica – the kaleidoscope starfish in a rock pool at Readymoney, Fowey.

Other great finds were numerous Devonshire cup corals.

Devonshire cup coral at Readymoney. This species has a squashed oval shape to the cup and is a pale creamy-yellow colour.
Devonshire cup coral at Readymoney. This species has a squashed oval shape to the cup and is a pale creamy-yellow colour.

When these are underwater they extend their translucent tentacles, but on the shore you tend to only see the calcerous cup shapes.

There were several Devonshire cup corals in this dark overhang
There are several Devonshire cup corals in this dark overhang
This coral was submerged and you can just see some of its tentacles coming out at the bottom. As is often the case it was in an awkward position so I couldn't see to focus!
This coral is submerged and you can just see some of its tentacles coming out at the bottom. As is often the case it is in an awkward position so I can’t focus!

There are several Calvadosia campanulata stalked jellyfish in the pools. They seem to grow large this time of year and are easier to spot as the seaweed begins to die back.

Trying to take a photo of a Calvadosia campanulata stalked jelly, but being photo-bombed by a common prawn!
Trying to take a photo of a Calvadosia campanulata stalked jelly, but being photo-bombed by a common prawn!

After a lot of looking, I finally turn up some sea slugs too. There are several Sea lemons under one rock and next to a coil of spawn I also find a Jorunna tomentosa slug.

Jorunna tomentosa sea slug
Jorunna tomentosa sea slug

On the next day we survey Hannafore, which has a vast are of rocky shore. We spread out looking for interesting creatures and have no problem finding them.

The bizarre-looking echiuran worm Thalassema thalassemum
The bizarre-looking echiuran worm Thalassema thalassemum
Exterminate! Junior loved the shape of this Lamellaria perspicua mollusc - the hollow syphon does look like a gun!
Exterminate! Junior loves the shape of this Lamellaria perspicua mollusc – the hollow syphon does look like a gun!

We spend a lot of time failing to re-find the very rare Lucernaria quadricornis stalked jellyfish which was recorded on this beach a few months back. We do, however, find many other fabulous creatures while we are looking.

Close-up of a Sea lemon sea slug
Close-up of a Sea lemon sea slug
An interesting creature congregation: A Scyon ciliatum sponge (left) and a Candelabrum cocksii (right), which is a hyrozoan animal related to jellyfish and anemones.
An interesting creature congregation: A Scyon ciliatum sponge (left) and a Candelabrum cocksii (right), which is a hyrozoan animal related to jellyfish and anemones.

Junior and I decide to leave a bit early as he’s been wading in deep water and is completely sodden, so we miss the find of the day, a Giant goby.

Shoresearch has been going for a good few years now and is a perfect opportunity to learn about wildlife, contribute to conservation and connect with others. I’m hoping I’ll get to do all five days of Shoresearch Week next year as well as other surveys and events during the year. Perhaps I’ll see you there?

In the meantime here are some more of the week’s finds…

A tortoiseshell limpet (Tectura virginea) living on kelp, Hannafore
A tortoiseshell limpet (Tectura virginea) living on kelp, Hannafore
Tethya aurantium - a 'golf ball' sponge at Hannafore
Tethya aurantium – a ‘golf ball’ sponge at Hannafore
A white Painted top shell (Calliostoma zizyphinum) - usually pink
A white Painted top shell (Calliostoma zizyphinum) – usually pink
Scorpion fish (Taurulus bubalis) - the white barbel at the corner of the mouth is a good way to identify this species.
Scorpion fish (Taurulus bubalis) – the white barbel at the corner of the mouth is a good way to identify this species.

Giants of the Cornish rock pools

Last week I shared with you the miniature world of the sea slugs, so this week I’ll super-size things and bring you some big fish. Silly-season reports of Great-white sharks often hit the headlines in Cornwall, but I prefer rock-pool giants; they’re not made up, and you can get close to them without having your leg bitten off!

Cornwall is brilliant in all sorts of ways, our network of local, grassroots marine conservation groups being just one of them. The public launch, last week, of the new Three Bays Wildlife Group brought experts and volunteers together and gave me a chance to explore some new beaches in the St Austell area.

Judging by the squeals of excitement from the children and adults alike, the crabs, pipefish, prawns and anemones we found at the main rockpool ramble on Portmellon beach near Mevagissey went down well. By the end of the day, the local group had recruited lots of potential new volunteers.

Green shore urchin at Portmellon beach - adorned in seaweed
Green shore urchin adorned in seaweed. Portmellon beach.

Continue reading Giants of the Cornish rock pools

My First Fox Club Expedition To Porth Mear

It’s the middle of the night and I’m convinced there’s something wrong with my eyes. I’ve unplugged my phone, tried blinking several times but I’m still seeing flickering lights and flashes. Finally I twig what’s going on and open the curtains to reveal incessant sheet lightning.

My first thought is that it had better stop by the morning, else no-one will turn up to my first rock pooling event at Porth Mear with Fox Club, the junior branch of the Cornwall Wildlife Trust. As a child, I was a keen member myself so I’ve been looking forward to this for months.

By the morning the lightning storm has given way to wind and rain, but conditions are less than inspiring. It’s amazing anyone shows up for rock pooling, but a few hardy well-wrapped-up folk do, as does a lovely volunteer assistant. Continue reading My First Fox Club Expedition To Porth Mear

50 Years on from the Torrey Canyon – A fragile recovery

Next month, 50 years will have passed since the Torrey Canyon tanker ran aground off the Isles of Scilly, releasing a 700 square km oil slick. On the last day of 2016, I visited Porth Mear to learn how a long-term survey has revealed the secrets of the beach’s fragile recovery, and to see if the St Piran’s hermit crab (Clibanarius erythropus)has managed to make more than a temporary comeback.

Clibanarius erythropus - A red legged hermit crab making a comeback in the Cornish rock pools this year.
Clibanarius erythropus – A red legged hermit crab making a comeback in the Cornish rock pools this year.

When the Torrey Canyon hit rocks in February 1967, its cargo of oil ended up on the Cornish, Breton and nearby coasts. The oil, along with huge quantities of solvent emulsifying chemicals used in an attempt to disperse it, decimated seabird populations and marine wildlife.

Concerned by the impact on his local beach, biology teacher, Richard Pearce, decided to monitor the wildlife on the shore three times a year. He’s been doing his survey without fail ever since.

I wasn’t born when Richard first marked out his quadrats on Porth Mear beach, but I grew up hearing stories of the horror people felt at the sight of the thick black tide, the pervasive smell of the oil, and the woefully unprepared volunteers attempting to shift the cloying oil with garden tools. Decades later, lumps of tar were still washing onto our beaches after every storm.

I’ve always wondered what the process of recovery looked like, so I jumped at the chance to join Richard at Porth Mear for survey number 150.

Survey 150…

It’s clear, after many surveys, that Richard knows the beach well. So well, in fact, that even when the gouged crosses and splodges of green paint that mark the survey quadrats have worn away or been covered up by seaweed, he still knows exactly where they are.

Richard examines a quadrat while Chris notes the data
Richard examines a quadrat while Chris notes the data

As he shows me his method, calling out the presence and coverage of seaweeds, barnacles and molluscs to his partner, Richard tells me how after the Torrey Canyon disaster the green seaweeds were the first to flourish. With many of the grazing molluscs wiped out by the oil and the chemicals used to disperse it, the seaweeds soon took over. After this other animals gradually returned.

Crosses in the rock and paint marks show the quadrat boundaries - now on his 150th survey Richard knows just where they all are!
Crosses in the rock and paint marks show the quadrat boundaries – now on his 150th survey Richard knows just where they all are!

Over the years, Richard has seen many changes. Some are seasonal or weather related, others are harder to explain but may be due to warming seas. Why one pool that was once crammed with mussels now has almost none and why limpets are doing particularly well this season is hard to say, but the data he is collecting reveals changes that would otherwise go unnoticed.

 

Not for the faint-hearted - Richard has to scrabble down steep rocks and wade knee-deep to reach some of his quadrats.
Not for the faint-hearted – Richard has to scrabble down steep rocks and wade knee-deep to reach some of his quadrats.

The tide drops and, while Richard is knee-deep examining a quadrat alongside a long deep pool, I explore the lower shore pools, determined to find out whether the St Piran’s crab is still here. After an absence of more than 30 years, this equal-clawed hermit crab started to reappear around Cornwall in 2016 and we had one record on this beach in the spring. Although past records are too patchy to be sure, it’s thought that pollution from the Torrey Canyon played a role in the loss of this species, so 50 years on it would be lovely to find it re-establishing.

Every time I see a shell move, I leap on it, looking for the red legs and spotty eyes, but every one is a common hermit crab (Pagurus bernhardus).

The disappointment mounts... I find lots of common hermit crabs (Pagurus bernhardus) - the right claw is much chunkier than the left with lots of raised bumps on it.
The disappointment mounts… I find lots of common hermit crabs (Pagurus bernhardus) – the right claw is much chunkier than the left with lots of raised bumps on top.

Rooting around in the pools always reveals some unexpected treasures. I make my first record of a stalked jellyfish (Calvadosia cruxmelitensis) at this site.

Stalked jellyfish - Calvadosia cruxmelitensis - at Porth Mear
Stalked jellyfish – Calvadosia cruxmelitensis – at Porth Mear

This is always a good beach for finding Cornish clingfish, and the rocks of the lower shores don’t disappoint. In one small area I find a dozen of these stunning little duck-faced fish, some with iridescent blue spots on their heads.

Cornish clingfish at Porth Mear
Cornish clingfish at Porth Mear

 

And another Cornish clingfish...
And another Cornish clingfish…

As I follow a gully across the shore I find several scorpion fish lurking among the rocks. Brittle stars lurch away into the seaweed and Xantho pilipes crabs close up, pretending to be pebbles.

My other half and Junior join me, hunting for crabs and fish. Every thirty seconds I remind them that we need to look for little hermit crabs and they ignore me as they should. They’re used to me and my missions.

Not a hermit crab... a feisty male edible crab at Porth Mear.
Not a hermit crab… a feisty male edible crab at Porth Mear.

Junior at least keeps pointing out suitable pools. He knows they like the ones with pink coralline seaweed and there are lots here. I barely have time to glance at one before he’s trying to drag me to the next.

And then it happens. A shell moves and as soon as I pick it up I know. The legs are red, the shape’s wrong for the common hermit crab.  When the crab extends its claws there can be no doubt, they’re hairy and pretty much equal sized. This is a St Piran’s crab.

When I see the red legs and equal-sized claws I know - a St Piran's hermit crab at Porth Mear
When I see the red legs and equal-sized claws I know – a St Piran’s hermit crab at Porth Mear

I yell like I’ve won a golden ticket. Under my camera it’s easy to see the black and white spotty eyes of the crab. We all gather to look and as I take an underwater photo, I see other shells moving.

The long eye-stalks with black and white-spotted eyes are distinctive too - a St Piran's crab at Porth Mear
The long eye-stalks with black and white-spotted eyes are distinctive too – a St Piran’s crab at Porth Mear

Sure enough, this next shell has a St Piran’s crab in it, and the next, and the next. While I’m taking photos in the pool, Richard is examining shells on the rock by a small overhang. “There are nine more here,” he says. Soon we’ve counted at least fourteen. They’re all larger than the one found here earlier in 2016.

A St Piran's hermit crab in the pool at Porth Mear
A St Piran’s hermit crab in the pool at Porth Mear

Whether there are other groups of St Piran’s crabs on this beach is hard to say. The tide is surging in now so we’ve run out of time to search.

A St Piran's crab foraging in the pool at Porth Mear
A St Piran’s crab foraging in the pool at Porth Mear

The existence of the St Piran’s crab is a fragile one; storms, temperature change, pollution and disturbance threaten our shore wildlife now more than ever. Richard’s survey provides an incredible conservation tool with its wealth of data about what’s here and how it changes.

50 years on from the Torrey Canyon disaster, the confirmation of the St Piran’s crab’s comeback is an uplifting way to complete this survey (and the year).

A Scorpion fish at Porth Mear
A Scorpion fish at Porth Mear
A rock goby
A rock goby
A brittle star on the move at Porth Mear.
A brittle star on the move at Porth Mear.
Xantho pilipes crab pretending to be a pebble at Porth Mear
Xantho pilipes crab pretending to be a pebble at Porth Mear
As the last tide of 2016 rushed in, I had to say aurevoir to this little St Piran's hermit crab. Hopefully they'll be sticking around in 2017.
As the last tide of 2016 rushed in, I had to say au revoir to this little St Piran’s hermit crab. Hopefully they’ll be sticking around in 2017. Happy New Year!