St. Agnes

I did a little ‘recon’ last Sunday in beautiful St. Agnes on the north coast but my timing was a bit off (the tide came in, with sediment getting suspended and the water becoming super-oxygenated, resulting in lots of bubbles on the wetlens). Luckily, this Thursday with no wind, the sun out and low tide, I had the opportunity to nip out again: awesome! Trevaunance Cove has a small beach, with rock pools on either side, I chose the Trevellas Cove side. Coincidentally, Shoresearch Cornwall (facebook here and here) had a survey and so caught up with Matt and Adele as well as Thomas from HydroMotion Media who I had not seen in a while. The north coast is quite different from the south coast I am used too: more exposed and this site for instance had none of the long Thong weed and Wireweed which dominate Castle Beach. The pools are also wider and in parts have a rocky, gravelly or sandy bottom. One spot had a considerable rock overhang, and I probably spent a full hour alone just at these six meters or so as there was so much to see. With the tide out, it was only about half a meter deep, with rocks encrusted in purple corraline algae, pink and orange sponges, bryozoans, tunicates and red seaweeds. The over-under shot is not particularly great but gives a rough impression, as do the two underwater shots (note the mysis shrimp in the last photo): There is a great diversity in red seaweeds, but I find these species quite hard to ID. The red rags Dilsea carnosa look pretty ‘ragged’ in Falmouth at the moment, but in this shaded, high wave energy spot they looked very fresh (first photo). I made a lot more photos but I was really struggling, as the bright sun reflected on the sand, with the seaweeds sticking out from the shaded overhang, such as Sea beach Delesseria sanguinea. The third photo give a good impression of the beauty of this habitat. Black scour weed and Discoid fork weed manage to scrape around in the shifting sands. Serrated wrack hangs and drips from the rocks into the pools below.Apart from the mysis shrimp in the water column, very large prawns patrol the rock surfaces and Edible crabs, Velvet crabs and Spiny squat lobsters hide in crevices. The prawns are curious and really beautiful. Most spectacularly, I found a large lobster in a cavity and at one point had a small lobster walking over to me: Many fish could be spotted as well: Topknots are common (you can just about see one glued to the rocks behind the lobster in the photo above) and there were a couple of big fat Tompot blennies around as well. Dragonets patrol the sand and are very well camouflaged (and hard to approach). A juvenile fish was hiding on and in a sponge; I first thought it was a juvenile Black-faced blenny Tripterygion delaisi, but in subsequent facebook correspondence thought of a Montagu’s blenny Coryphoblennius galerita (very common here) but then settled on a little Tompot blenny Parablennius gattorugine. This would have been a very good subject for a proper macro-shot if only I could get to grips with my strobe! In general this was a great place and time for fish. Apart from the topknots, tompots and Montagu’s blennies (juveniles were abundant, present even in the tiniest pools), I saw sand eels, corkwing wrasse, a pollack and horse mackerel (both a bit lost in these shallow pools), corkwing wrasse, shannies, sand gobies and rock gobies. I thought I spotted a Giant goby, but this turned out to be a very large rock goby Gobius paganellus (thanks Matt Slater). After the large goby photo, a tiny Rock goby (I think), a Shanny, a Cushion star and Snakelocks anemones. I cannot wait to get back to this beautiful site, but will need to wait a bit for the next good tide…

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