Last week I was on holiday in Bretagne (Brittany), France. There was not a lot of opportunity for snorkelling or rock pooling activities, but the last day I checked out the pontoons of the large marina in Trinité-sur-Mer. I was not disappointed; the pontoons in Cornwall are full of life, but these ones 200 or so kilometers further south were exceptionally diverse. The most striking find was that of orange, red and purple Rosy feather stars Antedon bifida. These also occur in the UK but I had not seen these yet here so I was quite excited. I did not go into the water myself and the photos I took holding my camera under ended up being not great so I took some shots from above water as well, too bad I did not have more time!The first photo below gives a good impression of how abundant and diverse life attached to these pontoons is. Many species are the same as the ones I see in Mylor marina, including invasive species such as the Bryozoan Bugula neritina and the tunicate Styela clavata. In addition to the many sponges, anemones, mussels, oysters and colonial tunicates I even saw things such as scallops (not sure which species) and urchins (Psammechinus). The peacock worms were absolutely huge. The plumose anemones Metridium senile looked different to the ones I am used to here to with orange individuals having brown collars which sometimes were really big and wavy. It seems no one that moors their boat in a marina ever takes notice of what is attached to the pontoons, but they should, as the diversity and beauty can almost rival coral reefs. I hope I can go back one time to properly investigate but for now I will check out the local marina’s and keep an eye out for feather stars…
Sunday was a beautiful spring day and we headed out to a new spot: Sandy Acres Beach on St. Ives Bay, North Cornwall. Beautiful dunes and a vast beach with very few people on it! With the kids running amok, I had only very little time to scour the high tide strand line. However, even with only 50 meters or so covered, it was the best bit of beach combing so far. Many cuttlefish bones, bits of Horn wracka and quite large mussels covered in seaweed holdfasts. Below a quick snap. At the bottom, I am not 100% sure, two Thornback ray Raja clavata- a Spotted ray Raja montagui and just above that a tiny Small-spotted catshark Scyliorhinus canicula mermaid’s purses (egg cases, see here for a useful key). Next to the mussel Mytilus edulis, some Hornwrack Flustra foliacea (a Bryozoan), two sponges which might be Mermaids glove and Chocolate finger sponge (thanks Steve Trewhella at the Beachcombing facebook group) and a spiky piece of Sea beard Nemertesia antennina, a hydroid. At the right of that a piece of a whelk Buccinum undatum egg cluster (better pic here). Not a bad haul, looking forward for a proper walk along this beach very soon!
In the series ‘pontooning‘, I returned to Mylor a week ago Friday to have a quick look around in the marina. The water was choppy, but visibility on the sheltered side of the pontoons was OK. I noticed a brown slug-like thing flapping about next to a boat. My first thought was a sea hare (I have seen plenty but have not yet seen them swimming). Upon closer inspection, I saw that it was something else, it had a shell like Haminoea or Akera, species I had never seen, especially not swimming. It turns out that it was Akera bullata, an Ophistobranch mollusc that is rarely seen in Cornwall and generally is observed crawling on the mud, not swimming. Why they swim is not well understood, but they usually swarm in numbers and so there must be some general response to the environment or mating behaviour going on. I saw four other individuals nearby so that fits. I made a couple of movies but as I could not look through the viewfinder the footage is not great (I went back Saturday and Sunday to try and find them back but was not able to). The shell can be clearly seen hanging down (Akera is related to the Sea hare but has retained its external shell). When lifted out of the water, the animal folds its mantle around its shell.
There were some other interesting things to see. The dominant organism on the pontoons is the tunicate Cione intestinalis (I see there are some other tunicate species hiding in these pictures; I will have to take a closer look next time). Amongst it grows the purple invasive Bryozoan Bugula neritina. Next, a colonial tunicate thta could be Botrylloides violaceus, Trididemnum cereum or Didemnun maculosum (or something else again). After that, the beautiful Lightbulb sea squirt Clavelina lepadiformis.Plumose anemones Metridium senile are always common here. I for the first time noticed another species Diadumene cincta, very pretty!
On to some of the more tricky species to identify. The rock overhangs, the home of the Painted top shells, are covered in sponges, tunicates and bryozoans. These are organisms I need to spend some more time on, as they are diverse, pretty and easy to photograph (they do not scurry away or give any macro depth-of-field problems). First two pictures of the large, nicely textured sponge Ophlispongia papilla. After that, the cream-coloured sponge Dysidea fragilis and the yellow sponge Aplysilla sulfurea. Side-by-side the bryozoan Disporella hispidata and what might be the sponge Clathrina coriacea.
There were quite a lot of other sponges and bryozoans to see as well, so I’ll definitely investigate more the next low tide. Some other species: the tiny polychaete worm Euphrosine foliosa (first two pics). Next, Chaetopterus variopedatus, a quite large polychaete worm (thanks to David Fenwick for the ID), a tiny glossy bivalve Kellia suborbicularis (thanks to David again) and what is probably a Chameleon prawn Hippolyte varians.
Went back today for some more peering from the pontoons in Mylor Bridge marina. Besides the Thicklipped mullet and Two-spotted gobies, small schools of Sand smelt Atherina presbyter were out and about. A short clip of this silvery, pretty fish made using the Canon Powershot 30D and after that a clip made with a GoPro 3+ (not in HD as it was my 2nd, free upload)):
(Annoying that wordpress makes the 2nd clip smaller!) I managed to find back the single 1 cm Elegant anemone Sagartia elegans mentioned in the last post but again was unable to remove it; seems like this species knowns how to attach itself a bit better than do Plumose anemones. I noticed that besides the tunicates, sponges, bivalves (mussels and oysters), seaweeds, anemones and peacock worms, hydroids and bryozoans are also very abundant. I still have to educate myself a bit about these groups. The peacock worms would be beautiful for the aquarium. Although they would be easy to dislodge, it would be problematic to fasten them to something again. Maybe I’ll find a small object with some attached when I’m diving that I could take back some time (frozen artemia might be too big for them to eat, so I would need to look at artifical plankton products for food).
Unfortunately, the weather turned before I had another opportunity to go diving (or snorkeling). The wind and rain have reduced visibility too much and so I’ll have to wait half a year or so before conditions improve….too bad! I missed the low tides recently as well. However, today there was time for a bit of ‘pontooning’, i.e. lying flat on a pontoon and staring at the creatures attached to it. It is quite convenient as it is not dependent on tides and the communities are very different from that of rock pools. There is a very large marina at nearby Mylor Bridge that I had visited before in summer. There was a bit more life then (schools of mysid shrimp, more seaweeds, more tunicates) but it is still looking nice now. I used my iPhone to take pictures before, but holding it above the water was tricky and did not produce good results so I brought my new Canon Powershot instead (still not easy to take pictures as at the same time I had to prevent my two-year old son falling in the water). The bulk of the biomass hanging from the pontoons consists of tunicates (mainly Ciona intestinalis). Small Plumose anemones Metridium senile are common (more about those in the next aquarium update), as well as the sponge Sycon ciliatum. I even found a small Elegant anemone Sagartia elegans (var. venusta). The invasive Bryozoan Bugula neritina is very common; it looks a bit like seaweed even though it is an animal (see here for a description). Finally, the Peacock worm Sabella pavonina is common (and very striking). Just two pictures below as the rest was subpar; I have to go back on my own sometime soon maybe.
A lot of different creatures live among and on seaweeds. One abundant and species-rich group are the Bryozoans or Moss animals, which are not the easiest of critters to make sense of (then again, which are!?). Here are three species common on seaweeds, identified with the help of David Fenwicks excellent Aphotomarine site. A Sea chervil Alcyonidium diaphanum, Flustrellidra hispida and a close-up of Tubulipora plumosa:
As in Falmouth, the rock pools in Flushing are not looking that great at the moment. Lots of the Corallina has turned white/died (although the clumps in my tank are still their normal purple!). Of course, many species were still thriving, Grape pip weed Mastocarpus stellatus (top), Bunny ears Lomentaria articulata (bottom), new Thong weed Himanthalia elongata ‘buttons’ and a young blade of kelp along with some green Ulva:Among the seaweeds that were thriving was Slimy whip weed Chordaria flagelliformis (I am by no means a seaweed expert and I might be wrong about this, please comment if I am!) and also the beautiful Harpoon weed Asparagospis armata growing as an epiphyte on some darker coloured False eyelash weed. Harpoon weed is invasive and so a good candidate to do well int he aquarium (as most invasive species are quite opportunistic and not too finnicky). It died off in the tank before, but I decided to bring some home to try again now I have a chiller.
Another tangling invasive species: Bonnemaison’s hook weed Bonnemaisonia hamifera (a characteristic curved hook can be seen in the top-middle):Loads more seaweeds to be found but I will save those for another time. All kinds of tunicates pop up in spring, some of them pretty (see for instance here), some of them less so. For instance the invasive species, the Leathery sea squirt Styela clava and an out-of-focus photo of a second, large (>10 cm) species that did not get a lot of response on the NE Atlantic Tunicata FaceBook group. Aplidium nordmanni was offered, see here for a much smaller version of that species. Not a looker either in any case!
I brought my little aquarium net and found many juvenile (<1 cm) fish as well as Mysis shrimp. The fish look like gobies but it is hard to see. They were completely translucent and so you can see what this one just ate. I should take some bits of seaweed home to see what comes crawling and swimming out under a little USB microscope (quite easy to make little videos). It is hard to come up with decent images squatting and squinting on a slippery rock with a salt-encrusted mobile phone!
Last Sunday I ventured to the north coast for a rock pool ramble with Matt Slater of the Cornwall Wildlife Trust (see this great blog) and the local marine conservation group (who also have a nice blog). I actually had never rock pooled at the north coast before (shame on me) and so it was nice to see this exposed habitat, quite different from my main haunts at Castle Beach in Falmouth and Trefusis Point in Flushing:
The rocks were much more bare and the number of animals a lot lower. However, there were quite some seaweeds. I finally saw (the edible) Laver Porphyra spp (probably Black laver Porphyra dioica):
Another edible species, Dulse Palmaria palmata, was incredibly common here:
I won’t add too many seaweed pics in this post, but I liked this shot of Serrated wrack Fucus serratus:
Brown and yellow Flat periwinkles Littorina obtusata (or possibly Littorina mariae, I did not bother to check) where common:
We found a Shore cling fish Lepadogaster lepadogaster and a Five-bearded rockling Ciliata mustela:
I found a couple of pieces of a branched seaweed covered in the bryozoan Electra pilosa:
All in all a good session. I hope to go back soon to take better pictures of the seaweeds!
A close-up of the Sea mat Membranipora membranacea taken with my olloclip macrolens for the iPhone. This Bryozoan forms colonies on flat seaweeds. Each rectangular chamber (cuticle) houses an individual zooid. Each zoid feeds on plankton using a lophophore, a group of ciliated tentacles. Zoids differentiate into specialized types, for feeding, cleaning the colony surface or as brood chambers for embryos.
A close-up of the Hairy sea mat Electra pilosa, a species very common under rocks: