I joined a seaweed identification get-together at the Cornwall Wildlife Trust organised by Matt Slater last week. It was fun to chat with likeminded people and also made me want to stick my head underwater again! The weather has been horrible for over half a year now and I have been in only a few times, with little chance to take decent photos, hence the blog inactivity. This has been especially frustrating as March is the best month for seaweeds (see the 2017 Falmouth Seaweeds tag) and I am missing my window. I therefore jumped in the next day. The tides were at their very lowest, actually too low for most of my usual rockpool spot! The viz was not great due to the 20+ mph winds but just about good enough for the fisheye lens. I really hope for some good weather in the next 2-3 weeks to be able to make the seaweed photos I really have in mind.The very top photo is Berry wart cress Sphaerococcus coronopifolius shot with a very shallow depth of field. The single stone above hosts a whole variety of species. The largest is Slender wart weed Graciliaria gracilis and just as the Berry wart cress it is covered in mucus threads, which must come from the tiny gastropods Rissoa parva that can be seen on it when you zoom in. To the left the wiry Black scour weed Ahnfeltia plicata. To the back the invasive Devils tongue weed Grateloupia turuturu. Green Ulva and young kelp can also be seen. Below some Harpoonweed Asparagopsis armata. The snakelocks anemones Anemonia viridis were also out in force. I hope the weather settles soon!
Last weekend it was THE BEST weekend in the year for seaweeds here in Falmouth: the short window where most species peak (just before the bluebells are flowering on land), with a low tide, flat seas and sun. Unfortunately I was still waiting for my my new camera to come back from repair, which was very frustrating…. I took some pics with the Canon Powershot instead, but they are not really worth posting. I finally got my camera back last Tuesday: no damage to the lens but some replaced camera parts; with a bill under £150 it could have been a whole lot worse. As soon as I received the camera, I drove to Castle Beach and went for a 2.5 hour snorkel. The weather was not great, and the viz was neither. I took my strobe but that ended up in a big scatterfest so I quickly proceeded without it. First some general impressions of the rock pools with lots of Sargassum, Jania and Ulva. I also noticed quite a bit of Desmarestia ligulata (3d pic down):
I went fully Manual, varying ISO, shutterspeed and aperture which went surprisingly smoothly. The bad visibility and overcast skies however made it tricky to get good results and most photos were underexposed (of course still with some blown highlights). Also, I noticed the 8mm fisheye results in quite a bit of distorsion around the edges, more so than the wetlens I am used too even, which is slightly disappointing (but partially solvable by cropping). I tried a quick over-under shot which will I will practice more using a strobe (as the above water part is much brighter), but the main challenge will be to find a background that is more interesting than a bit of rock! Having a camera+ lens in a housing rather than a wetlens stuck on a housing is a huge improvement but I stilll have issues with having lots of bubbles on the dome. The seaweeds are happy at the moment and photosynthesising lots. The pic below of Harpoonweed Asparagopsis armata shows all the oxygen bubbles on the plant. Next, two photos of False eyelashweed Calliblepharis jubata and of Beautiful fan weed Callophyllis laciniata (I think!). Finally some animals. I discovered a small (3 inch or so) and exquisetly camouflaged Longspined scorpionfish Taurulus bubalis under the Thong weed, can you spot it? This is a shot that really needed a strobe but alas….Snakelocks anemones Anemonia viridis are common here. Again this pic is a bit underexposed and the vibrant colours do not come out but it shows the beautiful shape of this animal at least. What I need to do the coming months is too practice (especially with the strobe) so I will be well-prepared for the second seaweed season in autumn! (See the ‘2017 Falmouth Seaweed’ tag at the bottom of the webpage for posts showing how seaweed species wax and wane over the year.)
During my ‘seaweed sessions’ I of course keep my eyes open for animals too. Most prominent are the beautiful Snakelocks anemones Anemonia viridis (see also here). Other anemone species seem much more rare, such as the Dahlia anemone Urticina felina. Little schools of Mysis shrimp are very common (and very hard to photograph) but fish seem less common than a few months back. The common dragonet Callionymus lyra is (as the name suggests) not uncommon but hard to approach, the third photo was the best I could do and demonstrates how masterfully it is camouflaged (but see here what fullblooded males can look like!). Next a very pretty pink sea squirt species and a Broad-clawed porcelain crab Porcellana platycheles, completely flat so, very-well adapted to living under rocks. Finally, a tiny stalked jellyfish Calvadosia campanulata. Stalked jellies seemed to have disappeared over summer, but like the seaweeds are making a little comeback during autumn. There are not many around though, I have seen less than one per hour snorkelling (see this post for better stalked jellyfish photos; I need to work on the depth of field!).
I have been snorkelling a few times in recent days and it has been generally fantastic. The pools are probably at their peak now when it comes to seaweeds, I hope it lasts a little while longer (in June it will most definitely be over, see this old post, actually, they are in decline in May already). It is the plan to get in the water again this week to take some more seaweed photos, but in the meantime some photos on one of the more common anemone species: the Snakelocks anemone Anemonia viridis. There are two colour morphs: the greys and the purple-tipped greens. In Falmouth, they seem equally common, no matter if it is high on the shore or subtidally. I recently learned that in Scotland there are almost only greys, perhaps in the Med there are mainly the other type and it has something to do with temperature tolerance, if you know please let me know in the comments! I really like thuis species, in fact, the very first blog post back in 2013 consisted of a photo of these anemones in my aquarium. I have two of these in my aquarium at the moment, they are very easy to keep. This might be because in addition to being voracious predators, they are also capable of living on sunlight, as they harbour photosynthesizing algae. In any case they grow rapidly (and very occasionally split into two).I took these photos in very shallow water. When scuba diving you can commonly observe the commensal Leach’s spider crab Inachus phalangum sitting under the anemones (see here in the aquarium and here in the wild). (In Dorset there is a beautiful little prawn that lives as a commensal, and in the Mediterranean there is a goby that is associated with this species.) Only very occasionally do Snakelocks attempt to retract their tentacles (see here); tentacles can be quite long and slender or more stout (see here), probably a response to the strength of the currents. I have tweaked some of the photos a tiny bit (but not the nicest one on top for instance). Below two photos taken on different days of the same three anemones with different light conditions and different camera settings (most importantly probably the white balance, which I use to tone down the reds caused by the seaweeds).
Last Wednesday I went for a sneaky worktime dive across the Fal estuary on the Maerl beds between St Just in Roseland and St Mawes. Maerl is a slow growing, calcified type of seaweed (looks more like coral) which forms a unique and quite rare habitat, see these older posts. The water was 17°C so nice and comfortable and it was probably the shallowest dive I’ve ever done, no deeper than 3 meters. I took my new Canon G16 in a Fantasea housing and went all semi-pro by adjusting the white balance first (not that I had a go at any other settings…). I was really pleased with the results, a world of difference to the Canon D30. The beds are an expanse of maerl nodules with very little to break it up, no rocks, no sand, just the occasional old bottle and so it is hard to get any exciting angles. Still there is always something to see. In order: a baby Smallspotted catshark Scyliorhinus canicula, a Spiny starfish Marthasterias glacialis, a (breadcrumb?) sponge, a closed-up Snakelocks anemone Anemonia viridis (a rare sight), a Parasitic anemone Calliactis parasitica, a Fan worm Myxicola infundibulum, a Harbour crab Liocarcinus depurator, a Velvet swimming crab Necora puber and a very well-camouflaged Spider crab Maja squinado.
I have been a bit busy and so the photos below are some weeks old. The seaweeds are in decline already it seems. Actually, that is not true, there are plenty of seaweeds growing, but some of the prettier ones are dying off and some of the uglier ones are taking over. The window to take the nicest rock pool shots is quite short, pretty much early spring only. The ubiquitous False eyelash weed Calliblepharis jubata is yellowing, the green Sea lettuce Ulva lactuca is starting to cover everything and the Red grape weed is getting ‘fluffy’. Not the best session photo quality-wise and probably the last of the year. The Bushy rainbow wrack Cystoseira tamariscifolia is abundant and looking good (on the photo with Discoid forkweed Polyides rotundus) and I managed I nice shot of young Thong (or Spaghetti) weed Himanthalia elongata. I have done some more research into ‘proper’ underwater cameras and was tipped of about the Canon G16 (thanks Thomas from HydroMotion Media), maybe something for next year….The past couple of times when focusing on the seaweeds I also encountered some animals (it is hard not to). Many Snakelocks anemones Anemonia viridis, with some having very short tentacles. Next, a Decorator crab Macropodia rostrata covered in Banded pincer weed Ceramium. Mermaid’s purses (egg cases) of the Bull huss/Greater-spotted Dogfish/Large-spotted Catshark/Nursehound Scyliorhinus stellaris seem to be exclusively attached to Bushy rainbow wrack. Finally, a Stalked jellyfish Haliclystus octoradiatus on Wireweed Sargassum muticum.
The 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:
This 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:
The 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!
Last weekend I went for a bit of snorkeling off Pendennis Point to catch some new inhabitants of my tank: some Snakelocks anemones and a Leach’s spider crab (just one for a start). Although it was overcast and late, it was nice to be in the water. I was lucky to straight away find a diving knife, this helped me to cut of some kelp housing snakelocks. I took a perforated plastic Lidl bag with me in the water to serve as a net for the crab, low tech but it worked fine. The tricky thing was to get the snakelocks from the kelp afterwards (I did not want a load of rotting kelp pieces in the tank):
With some finicking I could get the anemones off the kelp and on the rocks or gravel. The Leach’s spider crab (decorated with small pieces of red seaweed) quickly hid behind a rock. However, after two days it was accustomed to its new surroundings and found a place underneath one of the anemones right in the front of the tank:
The sun was shining this weekend and the sea water is currently at its warmest so we went out for a bit of snorkeling off Pendennis Point in Falmouth. My experience with the iPhone waterproof case was not that good, so I took my Panasonic Lumix (DMC-FT10) along (which is not too great either!). The seaweeds are dying off mostly; the kelp is covered by bryozoans and hydroids to the point that they are completely fuzzy:
I mentioned in the previous post that the Spiny starfish Marthasterias glacialis was common in rock pools; bigger ones can be found when snorkeling:
Big Snakelocks anemones Anemonia viridis were everywhere and perhaps half of them had a little Leach’s spider crab Inachus phalangium associated with them. Wikipedia tells me that these crabs eat the anemones’ leftover food and also their mucus:
This hour of snorkeling gave me some inspiration for a new aquarium set-up: less seaweeds (specifically less dying seaweeds clogging up the filter and releasing nutrients) and more rocks. On top of these a couple of big snakelocks with spider crabs and some Two-spotted gobies Gobiusculus flavescens. The latter are very common and pretty. I will have to catch them underwater with a net though, which will probably be difficult…
OK, part two of my list of fun and easy species to keep in an unchilled native marine aquarium (see here for numbers 10-6). I will later post about species to avoid, and of course also about easy seaweeds to keep.
5: juvenile crabs
Crabs are active and interesting to watch, however, in a community tank they should not be too large as they can be quite destructive as well. Juvenile Shore crabs Carcinus maenas are an option, or a variety of crab species that stay small, such as Pirimela denticulata (I am not too sure what species the above pictured crab is, but it is still doing well four months after collecting it).
4: Squat Lobster Galathea squamifera
Squat lobsters Galathea squamifera can be a bit shy but are entertaining to watch as they scuttle about. Very common under rocks in silty areas.
3: Snakelocks Anemone Anemonia viridis
Very pretty and common anemones that are easy to keep. Beadlet anemones Actinia equina and Strawberry anemones Actinia fragacea survived in my aquarium as well but they seemed to shrink a bit over time rather than grow and these species can retract their tentacles which looks less nice. I did not specifically feed my anemones by dropping artemia or food pellets on them. The photosynthetic capabilities of Snakelocks anemones due to their algal symbionts probably makes it easier for them to thrive when food is relatively scarce. Beware for the tentacles of larger individuals though, as they can sting!
2: Common prawn Palaemon serratus
Prawns* have been a rage in tropical freshwater aquariums for years but people forget that there are very pretty ones right in our seas. I must admit I have not got round to checking rostrum (the ‘nose’) structures to differentiate between several closely related Palaemon species, but I think I have the Common prawn. They are always foraging and flock to any new object in the aquarium to check for edible bits. If the pumps are switched off they will swim and compete with the fish for food.
* or shrimp, these two names can mean different things in different English-speaking countries. In other languages ,like my native language Dutch, we only have a single word (garnaal) for these critters
1: Cushion star Asterina gibbosa
My numbers 2, 3 and 4 could have been number 1 as well, but I ended up picking the very common Cushion Star. Although grey and just an inch in size, these quintessential rock pool inhabitants are active, hardy and just plain cool!