Few habitats are quite as spectacular for the diver as that of an old mooring line. The line provides prime real-estate for a range of filter feeders, which are suspended in the water column, catching the best possible food carrying currents.
Over time the line can become so encrusted with marine life that the weight of it drags the buoy underwater, leaving no trace on the surface, so the appearance of the life encrusted lines on a dive is quite magical! Evantually, however, the submerged buoy collapses, leaving a tangle of line on the seabed. Sadly the habitat degrades from a good place to ‘hang out’, to that of discarded plastic rubbish…
A couple of years ago, on a dive in Loch Sunart, we found quite an extensive network of lines, layed from 16m to the 3m depth, and making for a very interesting dive. Lewis has written up the dives, with a description of some of the organisms found:
Many thanks to everyone who turned up on this rainy Sunday morning to clean the beach at Half Moon Bay. It was certainly not a promising start and we were all wet before the beach clean began. However, the rain eventually stopped and 37 volunteers cleaned the beach and carried out a survey of the litter we collected.
In total we collected just under 14kg of which there was a high percentage of small plastic pieces, bits of glass (still sharp) and some bagged dog poo! Also a variety of other items including fishing line, rope and food packaging.
The autumn magazine from MCS has an article about 25 years of beach cleaning and surveying. It seems that marine litter is still going up and we know that small, broken down bits of plastic are highly toxic to marine life as they can be ingested and travel up the food chain.
Some of our recent beach cleans at Half Moon Bay have yielded low weights and volumes of collected litter. However, if we are removing these dangerous pieces of plastic then we must be protecting some of our local marine life and the creatures further up the food chain, including ourselves!
So, please keep joining us on our beach cleans and surveys. The next one is Sunday 1st December at 10:00 am.
Nurdles are pre-production plastic pellets (about the size of a lentil) and of many different colours. These are shipped around the world by the plastics industry and turned into plastic products. Unfortunately these, along with our general plastic waste, are often lost or dumped at sea, and being less dense than water they get washed up on our beaches. Due of their low density they tend to work their way to the surface of the sand, and are caught by the wind and blown anywhere they can lodge anbove the high tide point, such as above a storm tide shingle ridge, or the vegetation behind the beach.
The scale of the pollution at The Cove, Silverdale is so great that it’s looking likely that that nothing can be done. Indeed the problem has been reported all over the world, with logging programs in the US and Scotland:
Fidra – tackling nurdle pollution at source the ‘Great Nurdle Hunt’ was set up in 2014 to track pellet pollution around the local beaches of the Firth of Forth, but has since spread to become a global citizen science project.
As a means of measuring how many are involved I took a sample with a garden auger took it home and 3 hrs of washing the woody bits out resulted in the photo below!
A Morecambe Bay survey would give an indication of how common that situation is locally – so if you have a few hours to spare after your walk on the beach, why not take a sample, as I have done above, and report your findings back?
During our beach clean on Sunday (22nd September) litterpickers found a number of rather strange cord-like objects in the strand line. The objects were generally translucent white, and resembled silicone rubber beading, of the type you might use to seal around the bath or kitchen sink. I brought a sample back home for closer investigation; it was 2.5mm in diameter, and held between tweezers, could be readily stretched by 20 of its resting length (a test section extended readily from 10 to 12cm), and recover apparently undamaged – so, rubber?
The mystery was quickly solved under the microscope, where the cellular structure of the material was evident. The samples were of Chorda filum (I call it sea-whip when I see it diving – for obvious reasons, see the photo below- but I think its common name is actually ‘sea lace’). I couldn’t find any reports of the histology of Chorda filum on the web, so I present a quick report into what might be the rubberiest plant on the planet below the photo!
Histology of Chorda filum
Generally seaweeds have very simple internal structures. Microscopy might reveal a gelatinous/slimy outer layer secreted by an organised skin or dermis, but there is rarely much internal structure to speak of. Seaweeds don’t need to transport water and salts from roots to leaves, as they are continually bathed in seawater, they can rely on diffusion for most transport requirements, so generally they lack the complex vasculature we see in higher plants.
Chorda filum, however, shows a very clever internal architecture; a central lumen stretches up the centre of the entire filament that constitutes the plant’s body. The lumen is surrounded by four or five layers of large box-like cells. These cells are at an angle to the axis of the filament – so they coil like a spring down the plant. This almost certainly contributes to the plants amazing elasticity, though I would not be surprised if there were not further mechanisms at the molecular level.
The box-like cells showed no internal structure in the sample I had from the strand line, but in places there was evidence of a further layer of cone-like cells attached by their apex to the outside of the tube of box-cells. These cells had clear chloroplasts in the wider end, suggesting that photosynthetic activity had been an important role in these cells while the plant was alive. I confess that I don’t understand why these cells are only attached at their apices, but this again might be to allow movement required as the plant is stretched and relaxes as each wave passes over it.
In conclusion; many seaweeds live in extreme environments. Chorda filum seems to have evolved a particularly interesting way of coping with the mechanical stresses of wave motion, and this may be one of the factors that permit it to colonise seabeds that lack good points of anchorage.
The current storms indicate that summer is passing into autumn, and at Lancashire MCS we are starting to think about our winter lectures; which we hope will bring some interest into the darker months for you! Each year those of us on the committee dive deep into our store of knowledge to bring some element of the underwater world to life…
A number of years ago the subject of underwater colour was brought up, and I had thought this would be an interesting subject (though I did not know enough about it to present a talk;-) Over the years since then I have been gathering some relevant publications, and thought that perhaps this year I would try to bring them together.
The subject rather quickly expanded, as considerations of physics (transmission of light underwater), incidental colour (plants cannot help but be green – though seaweeds often are not!) and behaviour (how animals manipulate colour for communication and camouflage) all have an important part to play. When we look at how organisms produce colour, we get a glimpse into deep-time; the genes for green fluorescent protein (or their analogues) are present in all metazoans, suggesting colour may have been important to the Ediacaran biota 540 MYA.
Is red a colour?
Our eyes have adapted to life above water, but reds and oranges are strongly absorbed in seawater, leaving a monochromatic green-blue world. A lot of sea life is red, however, and some deep sea fish generate red light. We might, therefore, suggest that the colour red is significant even if it is only visible up close: At distance red light is absorbed, so anything red appears grey or black. If you only want to advertise locally, and don’t want to attract the attention of the big fish lurking in the gloom, red might be the most important colour!
A comparison with other land animals suggests that colour perception in different species is likely to be very different to our own. Indeed, when age, visual defects, ill-health and genetics are taken into account, I might argue that colour is a personal experience, with even crude descriptions of ‘blue’ or ‘yellow’ meaning quite different things to each of us. (Web design in my day job, and it is quite important to ensure that text/background colour combinations are likely to be legible to readers!)
When we look at marine life, we see species with true colour perception ‘superpowers’. The most studied of these is that of the mantis shrimp – with twenty visual receptor types – twelve for colour (we have three), six for polarisation (we cannot detect this at all) and two for luminance (we have one). This suggests that the oceans are far from monochromatic, and there is hope for my talk…
See Unconventional colour vision by Justin Marshall and Kentaro Arikawa in Current Biology 24.24 (2014), R1150-R1154, for a primer in colour vision, and animal superpowers!
We are currently finalising our winter programme of lectures, and hope to have some external speakers this year alongside the ‘old guard’. please join us if you can – our Newsletter will keep you up-to-date.
The drive up to Roa on Saturday was not very promising, with periods of torrential rain it was no surprise that only a few made the effort… In the event, however, other than a strong wind, the evening was very pleasant. We spent the first little while, however, spelling one of the lifeboat crew watching some kayakers to make sure they reached Piel Island safely!
Due to the wind we spent a little more time than usual to the West of the lifeboat jetty. The mud flats here are the home of a large number of sand mason worms (pictured above), and scattered with common starfish, which have been stranded by the tide as they hunt for cockles in the mud. Starfish have a hydrostatic skeleton, so are completely incapacitated in the absence of water. It is clear from the sad, deflated bodies, that a few do not survive exposure, but for many the chance of a meal must be worth the risk…
The visit also allowed me to take a plankton sample, which looks very different to the one I took on the dive in July, when there were no phytoplankton, and few zooplankton. The rougher weather recently may have helped spur some activity, as the sample from Saturday had high concentrations of phytoplankton, and lots of zooplankton and larvae, to recolonise the Bay. A few weeks can make a massive difference!
Regular beach cleaners with our local group at Half Moon Bay, Heysham will know that we always take a survey of the litter collected and this information is put into a database held by MCS. We thought it would be interesting for people to see the attached graphs which show some of the changes in litter at HMB since 1998.
Although this data may not be very exact it does show some encouraging changes for example items described under “sanitary” have reduced. Perhaps the “don’t flush” campaigns are working?
Plastic bag numbers have come down, though the amount of plastic in general has increased although oddly, glass has increased from 72% to 76% of the total rubbish on the beach.
The local MCS group doubled the survey area at HMB in April 2018 but the amount of litter collected has not increased which is very encouraging. Although sometimes our volunteers are a bit disappointed that there isn’t as much to do!
MCS value the data we submit and believe it to be important for their monitoring purposes. They have asked us to continue to beach clean and survey at HMB.
So, we still need your support and really appreciate everyone giving their time and efforts. Of course you can beach clean/litter pick anytime, anywhere so why not carry out a 2 minute litter pick nearer home?
After a string of possible dates this year that we were unable to get in at Roa Island we finally managed a dive on Friday (we had to bring it forward a day to miss the worst of the weather). It was well worth the effort. Visibility was only 2 to 3 metres at best but that is plenty to search the reef for interesting macro life. Our species list – which for invertebrate species goes back to 1968 – grew by at least 2 new species. First to be found were several Goldsinny (Ctenolabrus rupestris), unusual not just as a first for that species, but the first species of wrasse to appear on the list.
The next was a nudibranch (that’s a fancy name for a sea slug) called Jorunna tomentosa (pictured below) – it doesn’t have an English name. Both are common species around the coasts of the UK, so of course may have been here all the time, but this is the first time we have them on record here.
There are many predators in the marine ecosystem and animals have a variety of strategies to help them find food, and avoid being eaten. The Long-spined Scorpionfish is a master of disguise – hiding in plain site by blending its skin colour in with its background; if a crab or small fish comes too close they will be grabbed at lightening speed, predators large enough to tackle it will need sharp eyes to see it, and if they do this fish has a back-up plan – the eponymous long spine on its gill cover, just visible in this picture.
Perhaps the most suprising thing about the dive was the water temperature – depending in depth it ranged from 18ºC to 20ºC. I don’t think that I’ve dived in water that warm either at Roa Island or anywhere else around the Irish Sea. Unfortunately I can’t check my dive logs after a computer glitch trashed them a couple of years ago.
Thanks to Philip and Rebecca for providing shore cover!
After a year’s absence, it was good to be able to attend the Kite Festival at Morecambe again this year. Our ‘new’ gazebo had its first outing – and proved to be very successful, bringing us a bit closer to the people moving along the prom viewing the kites!
There was quite a lot of interest in our stand, and we are greteful to everyone who came to chat to us, as well as a number of donations. The local area group made £26.80 from donations, and sales of pin badges raised £42 for National MCS.
Saturday, coincided with Armed Forces Day, so we were treated to a Dakota fly over and parachutists! Sunday was more difficult, with high winds causing us to close down a little early for fear of loosing our gazebo!
While the amounts of money raised are small, as long as we can break even, events like these allow us to ‘spread the word’ about quite how special the marine life around the UK is, and how much it deserves our protection. On this score, it was great to see how many younger visitors were interested in our marine life, and clued up as to some of the threats it faces…
A big thank you to everyone who turned out for the beach clean at Half Moon bay on the 5th June – a decidedly un-summery evening. The photo is by Ian Croucher, having his first taste of a beach clean, and looking to set up or join similar events with colleagues from work on the railways, so we wish him all the best!
Again the beach was relatively clean – which is good news, though we are seeing more wet-wipes than has been the case in the past. Again a quick reminder to anyone who has not got the message – don’t flush wet wipes. Despite what it says on the packet, they don’t belong down the loo.