Underwater Fluorescence

It has been three months since the last blog post so high time for an update. I have not been out much as the weather has been grim. In fact, the photos in this post are one year old! I bought a blue LED light for fluorescence photography which has been gaining popularity in recent years. Many organisms and fluoresce (i.e. absorb light and emit it at a longer wavelength), although the function of this is generally not well-understood (perhaps in some cases it might not even have a function and just be a byproduct). Coral reefs can especially be spectacularly fluorescent but the cold waters of the UK harbour a variety of fluorescent organisms too, most notably anemones and corals, see here for great marine fluorescence photos from Scotland by James Lynott. Anyway, I bought my light and a yellow barrier filter (which serves to let the emitted fluorescent light through but not the blue light) to be held in front of the camera housing, as well as a headset barrier filter from a very knowledgable German chap here; his site contains a lot useful information for those interested in the background and applications of this type of photography (see also here, here and here). The photography is very tricky: the ISO needs to be bumped up in the dark which results in a lot of noise. The dark also requires long shutterspeeds which results in shaky images. A large aperture for more light is best, but since the subjects are usually small this results in suboptimal depth of field.  I have only been out twice last January, and only whilst rockpooling (I have not done a single nightdive or nightsnorkel in Cornwall and I am not overly tempted to do so!). The very shallow rockpools high up at Castle Beach in Falmouth reveal some fluorescent animals, including hermit crabs but I focused on anemones. Snakelocks are big and very fluorescent (the green ones, the grey variety is not, although it does emit red light via its symbionts) but not common high up the shore. Hardly visible normally due to their small size and inconspicous colours, red-speckled anemones, daisy anemones and gem anemones become apparent using a blue light (in fact, this method is use to study tiny coral recruits in the tropics). The top photo shows two green gem anemones Aulactinia verrucosa (with red and purple coralline algae in the background). The anemones are very small (2 cm max) and I used my CMC-1 wetlens on my Canon G16. The other two photos show Daisy anemones Cereus pedunculatus. I only later noticed the tiny anemone babies (this is a livebearing species). I hope when the rain and wind disappear and the evenings still start early to go out again and post some more photos. Also, I have bought both a new camera and a new aquarium so I have plenty more to post about!

Aquarium Update 17

I started this blog mainly to document keeping a temperate marine aquarium; browsing back I see that that was more than four years back already! (see this introduction). Over time, I became more passionate about rock pooling, snorkeling and diving, specifically about seaweeds and photography, and blogged less and less about my aquarium. The aquarium had its ups and downs, as coldwater aquariums tend to be a bit more trial and error (coldwater marine aquariums do not consist of relatively slow growing stony corals as in tropical marine aquariums and house much more (higher order) diversity than tropical or cold freshwater aquariums). Also, I am a lazy man. The last aquarium update was from last November and the aquarium did not look that great, but I have lately spend more time on it and it looks much better now, so here a quick new post.I bought an upgrade Red Sea Max pump (much better) a while back, and more recently a Tunze 9001 skimmer (MUCH better than the stock skimmer, removed¬† years ago as it was so noisy). The only problem is that the pump is so powerful that the water does not get sucked fast enough in the back compartment and it starts to run dry, I need to think how to fix that. The water is very clear though. I only have Cornish suckers as fish at the moment, and it might not be safe to add other fish as there are quite a few anemones at the moment. I have collected a bunch of Daisy anemones Cereus pedunculatus whilst diving (these are very common here in Flushing). I feed all my anemones small pieces of defrosted prawn by hand, these little ones respond very well to that and I hope they will grow much larger. I also collected some more Redspeckled anemones Anthopleura balli (below). David Fenwick kindly gave me an oyster with many Jewel anemones Corynactis viridis attached (crappy pic, sorry). These did relatively well for a while when feeding fine dry foods (sold for reef aquariums) but they were bothered by the squat lobster and cushion stars and I put the oyster back in the sea (I was also worried the oyster might die and cause a huge nitrogen spike). As an experiment I removed a few jewel anemones with a scalpel and superglued them to frag plugs but they did not survive. Ah well, that might have been a first, so worth a try. With a smaller, dedicated aquarium with better filtration (to deal with many small food particles) it must be doable to keep these. At the moment there are several species of gastropods, a cute little clam, mussels, Snakelocks- Dahlia-, Beadlet- and Strawberry anemones, a small Hairy crab, Cushion stars, green urchins and a Common starfish. The echinoderms seem easiest to keep of all. I actually put the common starfish back as it was picking of all my snails which I need to keep algae in check (and are interesting in their own right of course). I added a Cushion starfish with six legs though (‘Dave’). Hopefully I can find some more anemones when diving over the summer and who knows experiment with seaweeds again.

Upper Shore Pool

img_9490-copyThe last day of January I took an hour to explore a pool at the upper part of Castle Beach. The resulting shots turned out a lot better than they did the last time. As most of the pools are bare rock, there are no problems with sand/silt, but they are very shallow and on the receiving end of drainage pipes resulting in rain water mixing with the salt water, affecting visibility (this is not necessarily bad as it can make a photo more interesting). It was overcast and I did not experience problems with overexposure; I actually found that tweaking in Photoshop made the photos look worse. Below a Beadlet anemone Actinia equina, the most common anemone on rocky shores. They can be bright red or a drab brown (the green version is rare here) but have bright blue beadlets, or more technically acroraghi. These contain stinging nematocsysts used in territorial fights. After that a small Daisy anemone Cereus pedunculatus, which are usually more mottled in appearance (and not common here, or perhaps I do not know how to look for them…).img_9502img_9483Next up, a red growth which I should have investigated further, I am not even sure if it is a sponge or something else. After that, a worn Thick top shell Osilinus lineatus,¬† a young Dumont’s tubular weed Dumontia contorta, a red Banded pincer weed Ceramium sp. happily producing oxygen and finally Patella limpets covered in Brown limpet paint Ralfsia verrucosa.img_9527img_9583img_9568img_9597img_9522img_9492

Aquarium Update 7

Long time no post, just been too busy! The aquarium is doing reasonably well at the moment, especially considering the fact that I have not done any water changes since the last update and I have added a bunch of new organisms. I have added two Beadlet anemones Actinia equina. They are a dullish brown (except for a nice blue band around the base); I have not found the bright red or green individuals yet. Very similar but more striking are Strawberry anemones Actinia fragacea of which I have collected three. They are voracious, I could easily feed them a shrimp a day. The same goes for the Sea scorpion. I am afraid of sticking my hand in now as it comes after me! Time to let this buddy go. This will also give me the opportunity to add some other things such as squat lobsters.IMG_4825I have taken a break from experimenting with seaweeds and am focusing on anemones instead. I have added a bunch of small Plumose anemones Metridium senile that I scraped of the side of a pontoon. Weird fellas, they can fill up with water to be quite large, or just reduce to a crumpled little pancake. I have four white ones; I could only find very small ones of the orange variety and these were all devoured by Cushion stars (interesting). I’d like to have a large orange one as well, but I have to wait half a year until I can go diving again (they are very common in deeper water).

IMG_4812On the sheltered, silty shore of Flushing I found two small anemones attached to rock and half buried in the maerl sand. My excellent Seasearch Sea Anemones and Corals guide told me they were a Daisy anemone Cereus pedunculatus (uniform greay with many very short tentacles) and a Red speckled anemone Anthopleura balli (purplish and speckled, for a better picture of a different colour variant see this old post). Both quickly half buried/half nestled themselves under a rock so only the tentacles and the mouth are visible. They take pieces of shrimp and so hopefully they’ll be able to grow; these species should reach a decent size: IMG_4721

IMG_4729My friend marine biologist Chris gave me a snakelocks anemone that he had cured from its symbiotic algae. A very cool, bright white individual but it has returned to its original purplish colour so it must have taken up symbionts again. The snakelocks I already had, grew big, split into two and grew some more. Interestingly, one of the individuals seems to be turning from the green- to the purple colour variety:IMG_4828So six anemone species in all. I would really like to have some Dahlia anemones, they are very colourful, large, and not uncommon (old pic here). I need to go anemone hunting at a good low tide soon (I have not been out in ages).

I had the Chryseminia seaweed growing attached to the Tunze for a while and it worked OK, but it looks a bit messy and so I will remove it. However, I see that little Chryseminia plants have started to grow from the rock in many places (see top picture). I have to give the glass a weekly clean (with a tooth brush) and the rocks have turned a bit too greenish recently. I have noticed however that near the Snakelocks anemones, tufts of filamentous algae have appeared, as the grazers do not want to come too close to their tentacles (this reminds me of a work by an ecologist friend of mine who studies how seedlings can be protected from grazers when growing close to thorny shrubs, I’ll have to tell him of this observation!).

There has been some snail mortality. I mainly have Grey top shells but there are less than half of them left. I do not know why, part might be predation (which is not all bad as at least they serve as food for other inhabitants). I need to collects some more in any case. The Netted dog whelks are doing well. They are usually hidden below the sand, but as soon as they smell a defrosted shrimp, they come up like a Shai-Hulud. Their plowing through the sand is definitely good in preventing mats of diatoms to appear. Their little cousins the Thicklipped dog whelks are also doing fine. They tend to creep up the Daisy anemone to steal its food. I still have a Sting winkle Ocenebra erinacea which moves slowly but is very pretty. There are a variety of other species such as Blacklined- and Rough periwinkles. The best species however are the truly sublittoral large Turban top shells Gibbula magus (some of which have died as well, one of the shells has been taken over by a hermit crab, wich are also doing fine):

IMG_4737