Buoy Biodiversity

A while ago I played around with taking pics of the underside of a buoy, which was fun, and so i wanted to practice this some more. My mistake the first time (see here) was to use a fast shutterspeed (the buoy was bobbing about after all) which made the water look unnaturally dark. I tried again this weekend and it went a bit better, although I already know I can improve things. This time I thought it would be nice to put some names to the amazing fouling biodiversity (I did this before for some seaweed images, see here). Crustaceans (tube-dwelling Jassa), Sponges, Bryozoans, Seaweeds but especially a lot of Tunicates (seasquirts; both solitary and colonial species). David Fenwick (of AphotoMarine fame) had a quick look to help with some IDs; there is a more there but this was not meant to be exhaustive. I have underlined species that are invasive. Anyway, I am sure I will post more of these types of images: the buoys are always there and these organisms do not swim off when you try to take a photo!

Buoy

A rare sunny interval on Saturday meant I grabbed my gear for one last snorkel this year before returning to The Netherlands for Christmas. The visibility seemed good the last couple of days (judged by peering down the quay) and there was no wind, but I was quickly disappointed when sticking my head underwater at Flushing beach (also had major brain freeze!). I headed to the nearest buoy to practice some close focus wide able shots with my two strobes (one just arrive back from Japan for repairs). This proved difficult but fun. Lots of adjusting positions; outward when they created back scatter and inwards when the middle of the photo was not lit up. As the buoy was bobbing about I used a fast shutterspeed which resulted in dark water but that too has its charms. Lots of diversity, including the solitary seasquirt Cione intestinalis, colonial seasquirts Botryllus schlosseri, Diplosoma listerianum, Didemnum (maculosum?), bryozoans Watersipora subatra and Bugula and/or Bugulina species, the purse sponge Sycon ciliatum as well as tufts of red seaweeds and green Ulva. There are an enormous amount of tiny critters such as worms and snails hidden between all these species as well. It will be a nice project for next year to take a better wide able pic and complement these with macro pics of individual species.

St. Cuthbert’s Cave

Holywell Beach on the North Coast of Cornwall is known for a small sea cave which houses a ‘holy well’. According to Mabel Quiller-Couch, in her 1894 book “Ancient Holy Wells of Cornwall” in 995 AD the bishop of Lindisfarne, Aldhun, was bringing the remains of saint Cuthbert back to Ireland. Blown off course in a gale, he was left stranded in Cornwall where he settled and built a church dedicated to St Cuthbert. After some years however, an oracle instructed Aldhun to return the relics of St Cuthbert to Durham. As he was leaving from Holywell Bay, the saint’s bones touched the side of the well, giving the spring its magical healing powers. In medieval times, many people flocked to this cave to seek out the healing powers of the spring.

I was in the area this week when the tide was low (at high tide the cave is completely flooded, so you have to check the tides!) and decided to bring out the fisheye lens and a tripod to take some long exposure pics. They came out all right. There are more colourful photos available online, but my suspicion is that these use artificial light and sometimes also some enthusiastic post-processing. By using the longest possible exposure time on my camera (Olympus OMD E-M1markII), a full minute, I was able to let enough light into the camera. This enabled me to use f/18, allowing great depth of field, and ISO200, meaning little noise.

The formations result from a rare (in Cornwall) limestone deposit in the roof of the cave. Slightly acidic rainwater percolates through this limestone, dissolving calcite and becoming enriched in calcium bicarbonate. When the water drips down the rocks, the process is reversed and calcite precipitates, especially in areas where the water moves a little, causing CO2 to gas off. This results in the dam-like rimstone (or gours) formations. The tiny ‘rice terrace’-like formations on the dams are called microgours. I’d like to go back one time to experiment more and also to take some macro photos of the microgours and colourful microbes.

Snorkel Adventures

The sun is shining (most days) and the water has warmed up, so ideal conditions for a bit of snorkeling. I have been out at my usual spot in Falmouth (rockpools and kelp forest) and my local beach in Flushing (seagrass) (and yes, I really count myself lucky every time that l live here!). The last couple of times I have brought my son along, as he is now old enough (nine). He is a nature freak just like his dad, actually probably more so! I need to get him fins and a weight belt soon, but he has been doing fine in the water already.

The photos above and below illustrate the state of the rock pools at the moment: quite brownish with the Sargassum and Himanthalia growing everywhere. The red, pink and purple species have largely disappeared (apart from Harpoon weed) and there is quite a bit of green Ulva growing. The water teems with juvenile pollack in the rock pools and schools of sand eels a bit further out. Diving over sandy patches, you can see the latter species shooting out of the sand en masse. It is crazy how such a silvery pelagic fish can also burrow in the sand. I guess it does take its toll, as there are quite some dead ones to be seen too.

The Flushing snorkel site is very different, no (deep) rockpools, only a little bit of kelp but with a very healthy patch of seagrass. No catsharks or thornback rays when we went in, just the odd small sea bass. There are many small Snakelocks anemones on the seagrass. I used to think that it was mostly the purple form that did this but I now noticed that most were the green variety, so the morphs do not seem to differ in this respect after all. One anemone had ‘caught’ a crystal jellyfish (an Aequorea medusa). Not sure if it was in the process of being digested or just ‘stuck’.

I have played around with my new INON strobe, which works a lot better than my old strobe. I have ordered a second one for Wide Angle photos too….(as you can see there is quite some backscatter in the pic of the Shore Crab above). I will need to get back to some shore diving to make optimal use of two strobes, as I am too lousy a freediver to get the lighting and exposure right in one breath!

An Bollenessor is Back

It has been a wile since I last posted. This winter was long and dreary, the sea choppy and grey. I managed to do some rock pooling, and took a bunch of pictures, which I probably should have posted… The good news is that a mishap with my camera housing last year resulted in Olympus giving me a new model housing + a new model camera to fit (OMD EM1 mark 2) AND a new dome, lucky me! Regular readers of this blog know I get very excited in March, as this is when the seaweeds look at their best. This week the tides were low and the wind conditions favourable (the sun was not always out unfortunately), so I made sure to go in the water every day. The water is cold (9C), especially after being in for 2 hours, but it is all worth it. The seaweed growth was lush, with species literally growing on top of each other. I tried to shoot with strobes, but this proved too difficult and switched to natural light. Keeping ISO at 200, I aimed to lower shutter speed to 1/30, managing an F stop of between 5 and 8, depending on cloud cover. I now get the hang of that, but it is difficult to keep photos well-exposed, with enough depth of field and maintain sharpness. Below some examples. I am lazy and will not add seaweed names (but see the Seaweed Gallery page at the top if you are interested). When the tides are low again at the end of next week I hope to go out again!

some good’uns

l have not made much progress sorting through recent seaweed pics but it is easy to post two recent photos that came out well. Above the Spiny starfish Marthasterias glacialis. This seastar can grow up to 70 cm across, but on the shore you generally do not find them much larger than 20 cm. It occurs from Northern Norway down to West Africa. Below a patch of Snakelocks anemones Anemonia viridis, probably originating via binary fission. The most common anemone in the rockpools here, around half are this tan colour, the other half is green with purple tips. No one knows why. (And interestingly, it is not the only anemone species that shows two colour variants, beadlets are red or green, plumose anemones white or orange). Although the water was 9C, with the sun on the white sand it looks pretty tropical to me, a clownfish would not have been out of place! (I took a photo of this same patch in March but that one was not nearly as good.)

Mermaid’s Purse

Just three pics of the same shark egg case (‘mermaid’s purse) laid by a Nursehound (Scyliorhinus stellaris), also known as Large-spotted dogfish, Greater spotted dogfish or Bull huss. My camera was only five centimetres away from it (this technique is called ‘close focus wide angle‘). Mostly attached to perennial and tough Bushy rainbow wrack (Cystoseira tamariscifolia). 

March Seaweeds I

Last week it was time to check the state of the seaweeds and as expected they looked glorious. Unfortunately it was a bit windy and choppy and so the viz left something to be desired, argh! These are some of the better pics. I am in the process of creating a gallery of seaweed species (just reds to begin with), see the link at the very top of the blog. This is by no means a proper guide, as for that you often need more detail than just underwater impressions, but extra images might help in conjuction with a proper guide such as  the “Seaweeds of Britain and Ireland” Seasearch book. Anyway, I have started gathering old pics and hope to add more soon. The common flat red species in the photos above and below is very pretty but it is one of these species you need to look at under the microscope so I will not attempt to label it with a name (yet). Other species can be identified more easily, such as Under tngue weed Hypoglossum hypoglossoides (two photos below). Below, Thong Weed Himanthalia elongata, Little Fat Sausage Weed Champia parvula and Juicy Whorl Weed Chylocladia verticillata and a bit of Bushy rainbow wrack Cystoseira tamariscifolia covered in red epiphytes.