a shallow Maerl dive

The weather was not great last weekend and we were too late at the diveshop on Saturday to be back in time to get the tanks refilled for a dive on Sunday but the one dive was (as always) worth the effort! We took dive buddy Chris’s boat from Loe Beach in Feock over to the other side of the Fal Estuary (between St. Just and St. Mawes) to explore the Maerl beds. See an earlier post on a snorkel trip to see this bed of ‘Cornish coral’ for some more background information. After the usual faffing about with equipment on board we plunged in the water. I took a single photo of the boat which turned out quite dramatic:IMG_1869Although we were diving 1-2 hours before high water (the best time, as clear seawater is pushed in the estuary), the visibility was quite bad. After going just a couple of meters down, fields of maerl loomed into view (the dive was really shallow, 5.9 meters max I think!). There were quite a lot of Thornback ray Raya clavata egg cases (foreground first picture) but we did not see the rays themselves. There are two main Maerl genera around here, Phymatolithon and Lithothamnion but their growth forms are varied and there are other encrusting Pink paint weeds that could look similar. We saw a number of golf balls that were completely covered in coralline algae, quite cool.IMG_1946IMG_1871IMG_1945IMG_1989We saw a couple of *very well* camouflaged crabs sitting about. They were completely covered by sponges, coralline algae and seaweeds. There are a number of crab species shaped like this but most of them seem too small. Best guess is the Toad crab Hyas coarctatus the Europan spidercrab Maja squinado in a particular extravagant mood. There are lots of little things hiding in the Maerl; gobies (rock gobies I think), squat lobsters, swimming crabs, hooded prawns and things that hide faster than I can identify them. I noticed a dainty little prawn sitting about which is probably Thoralus cranchii, although it could also be Eualus occultus (second picture is cropped).IMG_1969IMG_1971 IMG_1887IMG_1957 IMG_1957 - CopySwimming crabs were common and probably mostly were the Harbour crab Liocarcinus depurator. The first picture was the only one with flash and shows the Maerl colours a bit better. The second photo shows a Velvet swimming crab Necora puber under a snakelocks anemone sitting on top of a bottle. This species can be very commonly seen rockpooling. Lastly an empty shell of the largest European sting winkle Ocenebra erinaceus I have seen so far and probably the largest sponge I have seen so far too (with a human head for scale).IMG_1927 IMG_1982 IMG_1898 IMG_1995

diving

Having a diving certificate, being passionate about marine life and having lived in Cornwall for the past few years, it was a bit of a crime to not have been diving (bar a single dive last year). Last week I had the opportunity to join some experienced divers and went for two dives. The first dive was at local spot Silver Steps in Falmouth. We did not go deep (8 meters or so) and could stay in for over an hour. We spotted some cuttlefish (too shy to be photographed), a Greater pipefish Syngnathus acus and two Snake pipefish Entelurus aequoreus. A picture (made with my recent Canon Powershot purchase) of me (looking rather angrily) holding the latter species:IMG_0131For the second dive, we went to Porthleven, west of the Lizard peninsula and sheltered from the easterly winds. It was hard to figure out where to best enter the water; east of the village the cliffs seemed a bit high. In the harbour itself we still had to clamber of some rocks and then had to swim out a bit first to stay out of the way of any passing boats:IMG_0150This dive site was prettier than the first one: there was a larger rock face covered by seaweeds (notably the large Desmarestia ligulata that was completely absent from Silver Steps) with a clean sandy bed beneath (loads of Two-spotted gobies around as always). Lobsters Homarus vulgaris seemed to be relatively common, as we did not particularly look hard but found two individuals (as well as a Spidercrab Maja squinado):IMG_0168

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IMG_0191One of my dive buddies pointed out a fish, I enthusiastically but mistakenly chased a small Bib Trisopterus luscus; much to their bemusement they were actually pointing at a Red gurnard Aspitrigla cuculus. It was not shy at all:IMG_0176

IMG_0178Finally, when getting out of the water, amongst the Shannies I noticed a beautiful Montagu’s blenny Coryphoblennius galerita:IMG_0203

Bretagne: Pleneuf-Val-Andre – part 1

The second good rock pooling session in Bretagne was in the little port of Pleneuf-Val-Andre. The rock pools themselves were very similar to those in Erquy. The only interesting find there was a pretty gastropod I had not seen before (a white snail with a dark brown/black shell about 1,5 cm in length). It looks like a Trophon muricatus, although I am not 100% sure Raphitoma purpurea:

IMG_4640 The number of Slipper limpet Crepidula fornicata (live and dead) was quite amazing, there were whole banks of them:

IMG_4625The little channel from the port to the sea, a mix of sand and rocks, was more interesting than the actual rock pools:

IMG_4655with a variety of organisms washing up, for instance this large (dead) Common spider crab Maja squinado (European shoe size 45 in the background…):

IMG_4604A Dog cockle Glycymeris glycymeris shell:

IMG_4605Egg cases (‘a sea wash ball’) of the edible Common whelk Buccinum undatum:

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Cuttlebones were scattered everywhere along the shore and we even found a clump of Common cuttlefish Sepia officinalis eggs:

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IMG_4670The eggs were quite big and had a weird texture. I don’t know if these egg clumps can survive hours on the beach at low tide, probably not. It would have been cool to take them to an aquarium to see if they would hatch. It is extremely difficult to keep cuttlefish though, they need live food and large aquariums which usually are still too small still to prevent ‘butt burn’ when they jet backwards into the tank wall and their cuttlebone gets exposed right through the mantle. In the next post I will get to the washed up seaweeds.

Bretagne: Erquy

Last week we crossed the channel to attend a friend’s wedding in Bretagne (Brittany). This of course also called for some rock pooling action, first at the village of Erquy. It was interesting to compare the shores of Bretagne to Cornwall (or at least Falmouth and this small stretch of coast in northern Bretagne). Immediately noticeable was the large amount of oysters on the rocks (with some locals busy collecting them, quelle surprise); these are pretty much absent in Falmouth:

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Similar to the Cornish coast, wireweed Sargassum muticum was abundant. This Pacific invader surely must have a large effect on the native flora and fauna:

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Invertebrate diversity was strikingly low compared to my local rock pools. For example,  the only fish to be found were Shannies (and not a lot of them), there were no Cushion stars and no large crustaceans except for the shore crab. However, we did find a Common spider crab Maja squinado:

IMG_4495As there was not that much to see, I turned my attention to some of the less spectacular life forms, such as Pink paint weeds, red algae forming a calcified crust. The particular species pictured below forms a patchwork of individuals, crinkling up at the edges where they meet. This could be Litophyllum incrustans, but species are hard to identify by non-specialists such as myself. The little spots on the surface are the openings of reproductive structures called conceptacles.

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IMG_4486The European sting winkle Ocenebra erinacea was quite abundant and distinctive vase-shaped egg cases could also be found:

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