Snorkeling in summer is nice because it is sunny and warm, but the seaweeds are turning a bit manky. That has its charms too though!
Above: Furbelows Saccorhiza polyschides. Middle: Thong Weed Himanthalia elongata covered in epiphytes (Ceramium?). Bottom: seaweed assemblage with Red Rags Dilsea carnosa, Irish Moss Chondrus crispus, Forkweed Dictyota dichotoma, Harpoon Weed Asparagopsis armata, Sea Lettuce Ulva lactuca and other species.
Some long overdue seaweed pics from the end of the seaweed bloom when the tides were low. I took many photos but few, if any, very good ones; sometimes you just are a bit out of luck I suppose. I have also started a Seaweed Gallery page (link also pinned at the top), gathering photos of as many different species I can find here in Cornwall. It is very much a work in progress and not a proper guide at all, but I hope it can help complement exisiting guides. Note that just a photo often is not enough to correctly identify species, so I have kept it at more easily recognisable things. On another note, I recently gave a ‘lockdown’ zoom presentation about my very niche hobby of taking photos of seaweeds for the Cornwall Wildlife Trust. If you are interested you can find it on youtube (I have not watched it back myself as if there is one thing I dislike it is seeing myself talk on video (actually, there is one thing I like even less and that is seeing myself talk on a video that is there to see for the whole world!)). I talked not so much about photography or seaweed biology as I am far from an expert in either topic, but more about how I started out with rockpooling when I moved to Cornwall in 2012, and how this slowly spiralled out of control and ended up with me lying facedown in rockpools year-round taking photos of seaweeds. Anyway, a few species below: Irish Moss Chondrus crispus, Berry Wart Cress Sphaerococcus coronopifolius, Red Rags Dilsea carnosa and Desmarest’s Flattened Weed Desmarestia ligulata. 
Last Friday I went for another very shallow dip at Castle Beach in Falmouth. Even though the weather was pretty abysmal, it was definitely worth it! Here a small selection of photos, again the quality is not top notch but many pretty species to see. The first pic below shows the Hairy sandweed Cladostephus spongiosus remnants the Slender-beaded coral weed Jania rubens featured in the last post tend to attach to. After that, some Chylocladia verticillata, Dumontia contorta with Grateloupia turutura (past its prime) in the background, Heterosiphonia plumosa under a small overhang, a thin red (Rhodophyllis irvineorum? awaiting comments on the Seaweeds of the NE Atlantic facebook group) and finally Chondrus crispus and Dictyota dichotoma. 
Above the spot where I have been snorkeling all year at Tunnel Beach, between Castle- and Gylly Beach, in Falmouth (Pendennis Castle can be seen in the background). The best time to snorkel is before low tide, as when the tide comes in the viz gets worse. I try to aim for 50-100 cm above the low tide mark which is really shallow. This area is not a real rock pool but rather a gravelly zone between the rock pools proper and the kelp forest which begins past the last row of rocks on the photo. Last week I went snorkelling three times but only last Thursday had decent viz. The photos below show the abundance of pink Harpoon weed Asparagopsis armata, green Sea lettuce Ulva lactuca and new growth of Thong weed Himanthalia elongata and older plants covered in red fuzzy epiphytes. The old wireweed Sargassum muticum plants have died off and the remnants are covered in many epiphytes such as Juicy whorl weed Chylocladia verticilata, Cock’s comb Plocamium cartilagineum and the pretty Iridescent fern weed Osmundea truncata. However, there is new growth everywhere as well so, like Himanthalia, this species seems to have a half-yearly lifecycle. 
Below some Irish moss Chondrus crispus next to Wireweed. After that, lots of little fuzzy Falkenbergia growing on top of Discoid forkweed Polyides rotundus. This combination grows in a large patch and looks interesting but I struggled to get decent photos, as the dark seaweeds on very white gravel mess up the white balance big time. Next one or two different species of fine flat reds, the last probably Nitophyllum punctatum. The Bushy rainbow wrack Cystoseira tamariscifolia is dying off (here overgrown with Asparagopsis and Dictyota) but the related Bushy berry wrack C. baccata is doing well. Among its epiphytes Spiny straggle weed Gelidium spinosum (ID thanks to Seaweeds of the Atlantic facebook page members) which is also freeliving, and finally the green Codium fragile. 
One time, when the tide came in, the water was super oxygenated, and all surfaces were covered with small silver bubbles which was beautiful (and annoying as the camera lens was also covered). The following photos show a very different looking Codium fragile, C. tamariscifolia overgrown with Sea beach Delesseria sanguinea and more Thong weed. 
Coralline algae, pink and purple, feathery or encrusting, are a conspicuous part of the local rock pools. When viewed close up, even the crusts are not boring, as they reveal little stalks and holes forming reproductive structures. The above species could be Common pale paint weed Lithophyllum incrustans or Common purple paint weed Phytamoliton purpureum; it is hard to tell species apart and there are likely more species than the few described on websites or in books. In the third photo, the thinner crusts are probably Phymatolithon lenormandii. Only when looking at close-up photos it becomes apparent that juvenile limpets (Patella spp) and White tortoise shell limpets Tectura virginea are very common.
Coralline algae are desirable in tropical reef aquariums, as they cover the brownish live rock in pretty colors. There are even special supplements for sale to promote their growth. They need low phosphates and sufficent calcium (as well as magnesium) to grow well, just as hard corals do. Good light helps, although there are also species that thrive under low light. I have a bit of coralline algae in my tank, but only in spots with high flow, so that seems important too. It might be a nice experiment to take a small tank, with a good light source and a decent pump (with rowaphos to keep phosphates down), and add some coralline algae-covered rocks to see what happens. Doing frequent 100% water changes will replenish calcium and magnesium, and not adding animals and food will keep nutrient levels minimal. With some interesting rock formations, it could develop into something pretty.
The species Titanoderma pustulatum grows on other seaweeds, such as Irish moss Chondrus crispus on the photo above. Pink plates Mesophyllum lichenoides are coralline algae that are very common on the mid- and lower shore here in Falmouth. They look a bit like a miniature version of Montipora corals. At the moment, some individuals are covered in knobbly reproductive structures housing spores. Pink plates grows epiphytically on Common coral weed Corallina officinalis, the species that makes up the bulk of the coralline algae in the rock pools (see second photo of this post, on the right). Slender-beaded coral weed Jania rubens is also quite common at the moment. Corallina and Jania can be seen growing side by side in the second-last photo. Jania here grows epiphytically on Hairy sand weed Cladostephus spongiosus (this species is normally fuzzy but in winter the branches are bare and slender). I hope to go diving soon and take more photos of the most ‘spectacular’ coralline algae: maerl.
As I noticed that the rock pools have started to look really pretty, I have gone out snorkelling four times the last week to photograph seaweeds. Bitterly cold (around 10°C) but worth it! It is my aim to post photo’s taken at the same spot every month this year, let’s see. The first three days the tide was very low, making it more of a lying on the sand rather than actual snorkelling. The sun was out and my main challenge was to get to grips with overexposure, checking histograms and decreasing image brightness. The other main challenge is to not stir the sand up and create ‘marine snow’. It makes a world of difference to actually stick your head underwater and look through the viewfinder instead of lazily only submerging the camera. For now, I have only cropped and adjusted contrast of jpegs using Picasa, but I have also shot in raw format and hope to get more out of the shots in the near future. With help from the excellent Seasearch Guide to Seaweeds of Britain and Ireland and the Seaweeds of the NE Atlantic facebook page some of the species could be identified. 
Above, Osmundea osmunda (probably), which has a very nice blueish (‘glaucus’) tinge (I need to take some close-ups of that next time). In the following photo, a whole tangle of species, mainly Hairy sand weed Cladostephus spongiosus, with Osmundea, Asparagopsis, Bonnemaisonia and Leathesia. Next, another picture of a whole variety of species, I would like to find out what the red epiphyte is. Below some photos of individual species of red seaweeds (mostly not great but it gives an idea of the diversity). First, Leafy rose weed Rhodophyllis divaricata, next Falkenbergia (which is actually not a species but a distinct phase in the life cycle of Harpoonweed Asparagopsis Armata), Berry wart cress Sphaerococcus coronopifolius, Irish moss Chondrus crispus, Beautiful fan weed Callophyllis laciniata, Under tongue weed Hypoglossum hypoglossoides, Chondrus with Falkenbergia and Hypoglossum and Plocamium on top and a small unknown species. You can see that most photos suffer from overexposure (and notice my crude upped contrasts).
The last time I went snorkelling, it was overcast and the tide was higher. I tried a bunch of shots a greater distance away to capture more of an overall impression, but with more water between the subject and the lens the shots become ‘milky’. The next shot of a whole variety of red, green and brown species (with Clawed fork weed Furcellaria lumbricalis in the middle) could have been really nice with clearer water, better framing and correct exposure! The next shot shows Cladostephus and Thong weed Himanthalia elongata on top of a rock covered with Red grape weed Gastroclonium ovatum (also on the last photo). 
Another couple of sessions trying to take seaweed photo’s. A couple of seaweed species are really thriving at the moment, one is False eyelash weed Calliblepharis jubata in the middle of the picture above. In the picture below a couple of other species, Irish moss Chondrus crispus in the foreground, Discoid forkweed Polyides rotundus on the left, Black scourweed Ahnfeltia plicata on the right, with some Red grape weed Gastroclonium ovatum at the top. Below that two ‘miscellanious’ pictures and after that some photos of individual species: the photo that turned out best was of Bonnemaison’s hook weed Bonnemaisonia hamifera, an invasive species from the Pacific. After that Juicy whorl weed Chylocladia verticilliata, a Plocamium species and my favourite, the Bushy rainbow wrack Cystoseira tamariscifolia.
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. 
An Bollenessor 