Monthly Archives: March 2015

a superlow tide at Flushing

Posted on by under anemones, eelgrass, eggs, fish, seaweeds, sponges

IMG_6840The tide this Sunday in Flushing was as low as it was the day before in Mount’s Bay and the weather was just as great too. We could walk among the Eelgrass and Golden kelp Laminaria ochroleuca. There were lots of Snakelocks anemones Anemonia viridis around; especially striking were patches of what must be clones. The tentacles are much shorter than the ones in my aquarium or those found deeper on kelp, must be due to being less exposed to the waves. Loads of fish as is usual here, a single overturned rock yielded five species alone! Again pictures of the Connemara clingfish Lepadogaster candollei, a Butterfish Pholis gunnellus (very wriggly, hard to get a good shot) and Tompot blenny Parablennius gattorugine eggs:IMG_6880

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IMG_6865This site is sheltered and silty and some species are more characteristic for this habitat and much less common in Castle Beach in Falmouth. Examples include the Keyhole limpet Diodora graeca, the Elephant hide sponge Pachymatisma johnstonia and the Yellow-plumed seaslug Berthella plumula:IMG_6869

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IMG_6885The diversity of seaweeds was very high and I think the pictures below give a good impression of that. Very low on the shore Bushy noduled wrack Cystoseira nodicaulis can be found; in this case almost as iridescent as is Bushy rainbow wrack Cystoseira tamariscifolia. We found some Beautiful kidney weed Kallymenia reniformis, here David Fenwick is taking a photo of it on his first visit to my local haunt. All in all one of the best rock pooling weekends so far!

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A superlow tide at St. Michael’s Mount

Posted on by under crustaceans, fish, invasive species, molluscs, rock pooling, seaweeds, worms

IMG_6745The 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. IMG_6720

IMG_6774I 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….IMG_6778

IMG_6760Some invertebrates: the large scale worm Alentia gelatinosa, a Strawberry worm Eupolymnia nebulosa larger still, a tiny hermit crab Anapagurus hyndmanni and the Arctic cowrie Trivia arctica:IMG_6782

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IMG_6793The 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.IMG_6786

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beach combing on the Roseland

Posted on by under cnidarians, crustaceans, molluscs, seaweeds

Back at Carne Beach on the Roseland Peninsula. No time for a good rock pooling session, but a nice walk along the beach revealed some nice surprises. Amongst the Laver and Furbellows lay Common starfish, Pod razorshells, Striped venus, Banded wedge shells and Rayed trough shells. A first: the Masked crab Corystes cassivelaunus (a female): common offshore buried in the sand, and usually only seen when washed up dead on the shore as is the case here (next to it a Sea apple). Also a beautiful piece of Sea beach (or Sea oak? the margins seem not ruffled enough though…). Finally, a Barrel jellyfish Rhizostoma pulmo, remarkably firm and heavy. This is a small one, about 20 cm across; 40 cm is normal and occasionally they grow to more than a meter in diameter, making it the largest jellyfish species in British waters.IMG_6407

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Trying out the OpenROV!

Posted on by under OpenROV

IMG_6303Last week saw the arrival of an OpenROV (an open source Remotely Operated underwater Vehicle, see for a little bit more background my work blog). An older version is still in the process of being built so the second, newer version, was ordered pre-assembled so we are ready to go. The goal of these machines is to help in community outreach events, to use for student projects (eg surveying local eelgrass beds or quantifying the extent of marine litter), to hopefully do some science with (see here for Chris, the marine biologist in charge) and also to just have a peek at what lives a good deal deeper than we can scuba dive! Fortunately, the ROV was easy to set up: load with six  batteries and plug in to a laptop running Chrome. This makes the HD webcam come on, and propellors, LEDs and lasers (to measure distance) can be operated using the keyboard (a game controller is on the way).IMG_6308

IMG_6310After greasing the O-rings, sealing the main- and battery compartments and tightening some straps we were confident that we could dunk it in the water. Fortunately a large flume tank in use by wave energy engineers can be found on campus: perfect for a first try.  Navigation is still a bit tricky. This little clip does not show how fast it can go (pretty fast). The video shows the ROV in action filmed with my iPhone and my GoPro placed underwater (the water is very cloudy because it is seeded by tiny glass beads used to visualize waterflow). We had a quick try in the Fal Estuary afterwards but cut it short because of the bad weather. Use in open water proved a lot more difficult. It was tricky to go under and so we’ll have to adjust buoyancy (i.e. tie-rap more nuts and bolts to it).  Also, the ROV was operated from the car (out of the rain) and so there was no direct visual contact making it difficult to find your bearing (of course there won’t be either when the ROV is deployed in deeper water). Hopefully some ‘real’ footage here very soon!