This Sunday we went on a lovely walk from Helford Village to St. Anthony in Meneage on the south coast of the Helford river. The tide was very low, so we decided to follow the mud flats for a bit before heading to the woodlands. The mud flats are a brown-grey and strewn with shells, pebbels and, unfortunately, litter. Not as pretty as the rock pools, but still interesting. There were small banks with mussels, cockels, slipper limpets and oysters, both the native oyster Ostrea edulis (quite some juveniles) as well as the invasive Pacific (or Portuguese) oyster Magallana gigas. Of course also the abundant, barnacle-covered periwinkles Littorina litorea. I saw my first Auger shell Turritella communis (which does not reflect rarity at all, just the fact that I usually stick to rocky shores); the small shells around it are Needle whelks Bittium reticulatum. Finally a Chinaman’s hat (probably no longer the prefered nomenclature!?) Calyptraea chinensis.We met up with David Fenwick and partner-in-crime Carol who were busy sampling around Treath. David’s interest was caught by a mooring rope covered in seasquirts, and a boxful was collected for careful examination under the microscope later. The clump I am holding below shows the Compass seasquirt Asterocarpa humilis (red, middle) (invasive), Morchellium argus (orange, top) (native), the Dirty seasquirt Ascidiella aspersa (three grey ones) (native) and the Creeping seasquirt Perophora japonica (tiny yellow zoids connected by stolons growing over the Ascidiella) (invasive). Astonishingly, by the next day, in a single tupperware box filled with muddy seasquirts, David had found 70 species! (With 142 species recorded in total on the day.) To finish this post full of grey blobs and brownish molluscs, I am adding photos David made of four out of nine species of Heterobranchs (Nudibranchs ‘proper’ as well as Ophistobranchs) present in the sample. Stunning images and proof that there is tremendous biodiversity to be found on a muddy bank if you know how to look for it. More of David’s nudibranch work is featured in this old post. See for his continously expanding collection of images, from seaweeds to fish and from tiny marine fungi to stranded seaturtles, aphotomarine.com.
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…
Finally, time for a (solo)dive last Saturday, at probably the most accessible local site: Silver Steps in Falmouth (you can just make out the steps in the photo above). The sun and high tide had attracted quite a lot of other divers too, including University of Exeter and Falmouth University students learning the ropes. I was very keen to get in the water and take photos but my approach is probably not the best: I just shoot whatever happens to be in front of me. Better results could be obtained to specifically look for macro subjects, to stay in the water column and search for jellies, befriend the Ballan wrasse or stay put in front of a Leopard-spotted goby hide-out (or check out seaweeds of course). I’ll do one of these things next time, for now, some random shots. I spotted several Spider crabs; these are always shy and try to quickly retreat, except for one. This big crab came after me as soon as we spotted each other. I should have tried more shots, as unfortunately he did not fit the frame. You can see in the short movie why I didn’t!
The viz was not great (I find it hard to estimate it in meters though). In the water I noticed a small hydrozoan Leuckartia octona. The underside of some wreckage harboured Light bulb sea squirts (see previous post) and some were predated on by Candy striped flatworm Prostheceraeus vittatus. (I brought my new LED light with me to help bring some colour out but I just ended up with combinations of glare and shadows so stuck to my normal natural light pics.) Next, a curious Ballan wrasse Labrus bergylta. Finally, some not so clear shots that nevertheless give a good impression of how tall the invasive Wireweed Sargassum muticum are growing. Hopefully more dive posts 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!
The aquarium was in desperate need of a make-over (again…). I hauled a ton of rocks over from the beach and stacked them up. (I thought at first that I would need something to stick the rocks together (epoxy, superglue or waterfall foam) but that wasn’t really necessary). I also removed most of the gravel and replaced it with sand. So quite a big change but it really looks a lot better. However, my nice burrowing Red-speckled anemones suffered a bit when putting the sand in, and even after siphoning it off again I could not really find them anymore….hopefully they turn up again! The aquarium is still a bit bare and I have to go out and collect things that will live on the rocks, such as anemones and seaweeds. However, there is some progress on the seaweed front. There is a bit of Irish moss Chondrus crispus growing spontaneosly from the back wall. There are also some patches of pink corraline algae; which must be Coral weed Corralina officinalis judging from one outgrowing patch. Having this species grow would be great, but they do not seem like fast growers. Chrysymenia wrighti is still thriving on the circulation pump; I remove a bit every now and then, so it acts as an ‘algae scrubber’, removing nutrients from the water. I have placed a couple of other seaweeds in the aquarium, a bit risky as they can die off and start trouble, but I can’t help it. The red Soliera chordalis below has done well before but unfortunately has started to die off a little already (first pic). I have a big piece of a flat red species that has started to grow from nowhere as well (second pic).One day, the aquarium was full of strings of Painted topshell eggs. I noticed when feeding a day later that the water was not very cold: I had forgotten to switch the pump/chiller back on two days previously! So the trick to breed this species is to increase the temperature, although I am not expecting much to happen with the eggs. Either the Thick-lipped or Netted dogwhelks are also occasionally sticking their egg masses to the glass. I placed a chunk of orange Estuarine sponge in the aquarium; this was devoured by Painted topshells and Cushion stars, so it is a good bit of live food to add. I had planted a little washed-up eelgrass plant to see if it would survive and indeed it has grown more roots. (If you want to try this yourself, please always use washed up plants and don’t dig out any, as eelgrass beds are vulnerable habitats.) It would be great to have a second tank dedicated to eelgrass….The little scallop is still happy (see close-up). I have added another filter feeder: a Leathery sea squirt Styela clavata. Butt-ugly, but that is actually fun too. I am trying it out as they are an invasive species and so probably pretty hardy. A Sting winkle seems to like it (but not eat it). I have never seen my two Sting winkles eat anything actually. They move about very slowly, but they have grown.Now the snakelocks anemones are gone, I have added some more fish. I have caught some juvenile Pollack Pollachius pollachius with my net. At first I caught ones that were less than an inch, but they did not survive. Of the six two-inch or so ones I caught, three dissappeared after one day, but the remaining three are going strong. Very nice looking fish! I also caught a little Tompot blenny Parablennius gattorugine (by hand at low tide). It is quite shy, but is increasingly showing itself. A beautiful little fish! I have one remaining Two-spotted goby. The Common goby is doing very well and eats from my hand. I think I’ll go for another little tompot, more Pollack and Two-spotted gobies. Ideally I would catch some Leopard-spotted gobies with a trap when diving, let’s see….The other fish I would like to have again is the Goldsinny wrasse: very pretty and not as nervous as Corkwing wrasse.
The lowest tide of the century so far, on a Saturday, with beautiful weather and on a stunning location: what could go wrong? Very little! St. Michael’s Mount, Marazion, Mount’s Bay is one of the most beautiful spots in Cornwall and an excellent site for rock pooling with a mixture of eelgrass beds, rocks and sandy expanses. I felt like a kid in a candy shop: wanting to turn every stone, photograph every seaweed and inspect every gully before the tide would come back in. I needed to collect some more Clawed fork weed Furcellaria lumbricalis for a cool student project. That was abundant so easy to sort. Chock full of Pheasant shells Tricolia pullus. One other amazing thing was that the place was littered with Bull huss Scyliorhinus stellaris (a.k.a. Nursehound, a.k.a. Large-spotted dogfish) mermaids purses. Mount’s bay is an important breeding ground for these sharks. The yolk was easy to spot, but the embryo’s still to small to be seen. There were loads of pretty seaweeds gently waving among the eelgrass in the crystal clear water. I saw a bright green Chameleon prawn swimming about, but the picture I took was a bit underwhelming.
I had met up with David Fenwick, so could get all species identified on the spot. Very striking was a great amount of small, fuzzy pink seaweed balls: Falkenbergia, the tetrasporophyte stage of the Harpoon weed Asparagopsis armata (it looks so different from the gametophyte stage, see some old posts, that it was long considered a separate species). Also, a picture of Bushy rainbow wrack Cystoseira tamariscifolia, simply because one cannot post too many pictures of Bushy rainbow wrack….
The find of the day (the month probably) was a Little cuttlefish Sepiola atlantica. This picture is crap, but David has made some stunning photos back in his lab and they will appear sometime soon on his aphotomarine site I am sure.
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.