National Marine Week - The round up

National marine week has long been a highlight of the Cornwall Wildlife Trust calendar. It’s a national celebration of the seas that, over the years, has morphed into a fortnight of marine activities. In fact, it’s two weeks long to accommodate for tidelines and all allow every coastal Wildlife Trust across the UK to enjoy activities from sea to shore!

This year was a little different due to the coronavirus pandemic.  Government guidelines meant that we were unable to run large public events as we have in past years, so we decided to ask the public to take part in our first ever Cornwall Marine BioBlitz and record and report all the marine life they saw from the 25th July to the 9th August.

Fortunately, we have an amazing recording system; the ORKS app which is becoming increasingly popular. ORKS, which stands for Online Recording, Kernow and Scilly, was developed to make sending in wildlife records as easy as possible. It works on smart phones and you can also access it through the ERCCIS website on your computer at home. I downloaded the app during lockdown and have discovered that recording wildlife using it is not only easy, but surprisingly fun! I have a great collection at my fingertips to remind me of all the wildlife I have encountered since I downloaded it and it is great to know that the data collected is now available for anyone who needs it, including for Cornwall Wildlife Trust’s vital conservation work.

the silhouette of a snorkeler signing "ok" as they swim through crystal clear water

We kicked off National Marine week or (weeks!) with a fabulous day out snorkeling in a giant rockpool in a secret location in West Cornwall. Joined by BBC Spotlight’s Johnny Rutherford, we were able to find some really cool stuff, including a fantastic view of a tiny but very unique sea slug, the solar powered sea slug. This creature is unusual because it doesn’t digest all its food! Instead, some of the seaweed eaten is kept just beneath its skin where it continues to photosynthesize producing sugars that feed the slug!

This glittering slug slides across some green seaweed and shimmers with irridescent light. It had translucent frills running along it back, a cream stripe along its body and a fawn or pinky hue to its body. It shimmers with tiny green and blue dots across its body

Elysia virids Matt Slater (spotted by Abby C)

The solar powered sea slug. This creature is unusual because it doesn’t digest all its food! Instead, some of the seaweed eaten is kept just beneath its skin where it continues to photosynthesize producing sugars that feed the slug!

Week two of National marine week saw Our Your Shore Beach Rangers team out snorkeling (again with small hand-picked teams) and our Shoresearch Cornwall team out running shore surveys. There were some amazing discoveries including brightly coloured cup corals in gullies on Cornwall’s north coast, and stunning anemones on the South coast. The snorkelers witnessed corkwing wrasse building their nests out of seaweed, stunning compass jellies and beautiful fifteen spined sticklebacks!

across a jet black rock, hundres of tiny, peach coloured dots cling onto the rock. Soft white tentacle-like things flail in the current and give a fuzzy appearance to the coral

scarlet and gold cup corals porthmear 2020 matt slater

The week was finished off with a marine team outing to Durgan on the Helford where we snorkeled and dived through the beautiful seagrass meadows there. At this time of year the seagrass plants are producing seeds which was fascinating to see. The meadows are rich in life and are vitally important as carbon sinks, drawing down carbon that is dissolved in the seawater and storing it very efficiently!

Find of the day was a pair of tiny sea slugs on a strand of sea grass that looked absolutely tropical!

On a thin blade of sea grass, two incredible sea slugs cling together.They have bright white bodies with light orange tentacles the cover it's body, its cute little 'horns' have orange tips and the slug looks like a cute and amazing alien!

Polycera quadralineata

During the two weeks we succeeded in encouraging lots of people to go out and to record marine life;

At the last count we had received 468 records from a total of 56 contributors. Kayaker Rupert Kirkwood reported bluefin tuna off Fowey, Diver David Morgan swam with blue sharks off Falmouth, angler Chris Gill reported short fined Pilot whales off Mevagissey,  beautiful bright orange seaslugs were found in a rockpool on the lizard.

 Detailed shore surveys were sent in by Patricia Farrel of Mylor and Bude Marine Group’s Martin Dancey.  6 very detailed seasearch forms were submitted. Our deepest data came from Seasearch diver James Gregory who visited a wreck off the North coast, bristling with life, at a depth of 57.5 meters down! Our most unusual record was a tiny baby common dolphin which live stranded at Holywell bay beach, sadly dying shortly after.

Our shallowest dive was made by filmmaker Tom Daguerre, who lay in a rockpool for a whole day at a depth of a couple of centimeters and got some stunning time-lapse videos of abundant life in the pools there!

A close up of an unusual sea slug with peachy pink/orange colouration. Two light pink 'horns' poke out from one end of the slug whilst the  other end has skirt of tiny peach tentacles. The body of the slug is covered in white and black micro-flecks

Rostanga rubra 1 Lorian hartgroves found by Arwenna

One thing that was noted was how full of life our seas are.

One thing that was noted was how full of life our seas are. In some cases, there is a little too much life. For example; Devils tongue weed Grateloupia turuturu, a non-native seaweed species from Asia was recorded for the first time in large quantities in the pools at Porthmear on the North coast near Porthcothan. This is worrying sign, as no one can predict what potential impact new species colonizing can have.

a pale yelllowy brown seaweed is held between two fingers. The rockpool beneath is full of the same seaweed

Devils tounge weed 

Overall, we were reminded during this National marine Week, how wonderful Cornwall’s marine life is and how lucky we all are to be able to get out and to enjoy and study it! It is an incredible asset not just for Cornwall but the whole of the UK and we need to protect our marine life for future generations. We have several Marine Protected Areas in Cornwall but within these areas damaging activities often are able to continue. 

A cuttlefish glides along purple seaweed and a rocky seabed. Its brown mottled pattern means it is almost invisible against the rocks whilst it's trailing cream 'horns' and textured face give this cuttlefish the appearance of a mythical dragon

Cuttlefish Janet Dallimore

Cornwall still lacks any highly protected marine areas (what used to be called no take zones) a recent report by the government concluded that we should establish a network of these around the UK coast and we strongly feel that unless we can study areas of our coast that are left completely untouched by damaging activities we will never know the true potential for productivity and revival that is possible. Please visit this page to register your support for Highly Protected Marine Areas.

Massive thanks to all who have contributed by sending in their records and pictures.

Well done all, please keep up the great work!

Don't forget to check out:



Seaquest South West

Your Shore Beach Rangers