Thank you to Kathy for organising, and everyone who managed to come along on Wednesday evening – thankfully the weather stayed dry for us! We collected about five kg of (mostly plastic) waste, with rather more sewage related rubbish (including wet wipes) than usual, following the heavy rains at the weekend. A summary of the finds is available in the pie-chart below, and the full report has gone on to national MCS for processing.
Above: Pie chart of litter collected 3rd July 2024. One of the more interesting finds was this discarded boat’s fender (below). It was found slightly outside our survey area, so whilst we removed it from the beach, it does not count as part of the weight of litter reported above.
The fender must have been beached on the last tide, as the attached goose barnacles were still fresh. The barnacles (Lepas anatifera) are not a local species, requiring warm tropical or sub-tropical waters to breed. The adults, however, can survive attached to flotsam, and drift with ocean currents for long periods, and it has consequently been recorded as far North as Svalbard! Here the drifting assemblage has ended up including discarded fishing line, which can be seen in the background (blue filament) of the image below.
Above: Detail of one of the goose barnacles Lepas anatifera – the distincitve jointed legs are visible. In life these form a basket that the animal sweeps through the water to catch small zooplankton that the animal feeds on.
Thanks to Kathy MacAdam for organising the beach clean, and Mark Woombs for spotting the find, and identifying the barnacles!
Disappearing diatoms and Sex in Copepods – Knott End Plankton round up, Spring 2024 Talks by Mark Woombs and Barry Kaye (Lancashire MCS) on Wednesday 8th May 2024 at 19:30 at Lancaster Maritime museum.
We are now into our third year studying the plankton at Knott End, and this year we are witness to a failure of the Spring phytoplankton bloom due to poor weather. Perhaps for the same reason, the copepod breeding season has been pushed back two months; though zooplankton numbers as a whole seem to be resilient… Join us to find out more!
If you would liek to check out some of the data from our plankton surveys at Knott End for yourself, there is a graphical interface on our website. This allows you to select plankton by groups or individual species, and follow how their populations have changed over the last eighteen months.
A talk by Alexandra and Jonathan Bujak (Azolla Foundation)
Above: Carp and ducks eating azolla in China. A fisherman is collecting azolla to feed his livestock. Image rendered by Victor Leshyk from the cover of ‘The Azolla Story’.
49 million years ago a plant called azolla covered the surface of the Arctic Ocean. The Arctic Azolla Event lasted 1.2 million years, during which time azolla sequestered enormous quantities of the greenhouse gas carbon dioxide from the Earth’s atmosphere, and moved our planet’s climate from a greenhouse world to the ice-age climate, with permanent ice and snow at both poles…
If you would like to know more, The Azolla Story: A message from the future by Jonathan Bujak and Alexandra Bujak is available from Amazon.
Alternative Zoom meeting details are available through our Newsletter – you can subscribe here.
All are welcome, we request a donation of £4 to cover costs of room hire and speaker expenses.
Wednesday 11th January 2023 at 19:30 at LancasterMaritime Museum.
Wednesday 12th October at 19:30 at the Maritime Museum Lancaster:
A talk by by Andy Richardson (Royal Society of Biology) examining the fascinating biology, sustainability challenges and innovations behind the offshore fishery for tuna and other pelagic species.
Please be aware that the meeting room is up four flights of stairs. The lift at the Maritime museum has been repaired. Alternative Zoom meeting details are available through our Newsletter – you can subscribe here.
All are welcome, we request a donation of £4 to cover costs of room hire and speaker expenses.
Above: The sea gooseberry Pleurobrachia pileus grazing on smaller zoooplankton using two long sticky tentacles that it trails behind it (to the right of the main body above) as it swims. The smaller circular organisms are ‘sea sparkle’ (Noctiluca scintilans), between 1 and 3mm in diameter.
I am not as up on zooplankton, but thought I should follow up my earlier post on phytoplankton dynamics in the earlier part of the year with something to indicate that the zooplankton are not (too) boring! For this article I have chosen the sea gooseberry Pleurobrachia pileus which, at about 2cm in diameter, is a member of the zooplankton which is large enough to be seen – though difficult to spot in the water as it is transparent… You can often find individuals stranded as the tide goes out, but their appearance on the beach as small lumps of jelly does not do justice to them underwater. In their element they are propelled by rows of modified cillia called ‘ctenes’ – you can see eight rows of ctenes, slightly inset into the otherwise oval body of the animal in the photo above. These ctenes can refract light to give bright and continuously changing coloured displays underwater…
The population of Pleurobrachia pileus reached a peak in the Wyre estuary in early June, when small examples of Beroe cucumis first appeared in the fortnightly samples. Initially the Beroe were only a few millimeters long – very much smaller than the Pleurobrachia. Despite this they latch on to their very much larger prey, and use modified ctenes to chew or rasp flesh from the sea gooseberry. Over time, and repeated attacks, the sea gooseberry is damaged, diminished, and will eventually die.
Above: A juvenile Beroe cucumis (bottom left) latched onto a sea gooseberry, which is using its ctenes to spin rapidly in the water, to try and dislodge its predator. Photograph from the Wyre river sample of the 14th June.
Over a couple of weeks feasting on sea gooseberries the Beroe increase in size, and can reach a total length in excess of eight centimeters. The adult Beroe are able to ‘unzip’ their mouths, opening them wide enough to ingest Pleurobrachia whole, as seen in the photograph below:
Above: By the 30th June the Beroe were large enough to consume smaller sea gooseberries whole, as you can see towards the left of the picture above.
Beroe itself is not without predators, however. In the photo below (same individual as above) you can see that the beroe is in turn being eaten by a ‘megalopa’ or juvenile crab.
Above: Beroe has bumped into the sea gooseberry to the right – it is still full of one of its bretheren, hoewever, so the sea gooseberry is likely to get lucky this time! You can see that the lower surface of the Beroe is distorted where it is being attacked by a megalopa, or crab larva.
I have often seen adult crabs eating jellyfish, and spider crabs will often climb kelp at the turn of the tide to catch moon jellies or lions manes that drift past, but this is certainly the most ambitious decapod I have ever seen! What goes around, comes around…
In the German Bight the appearance of Beroe results in a near total collapse of the Pleurobrachia plieus population in a matter of weeks(1). In the Wyre the population of Pleurobrachia falls significantly, but a continuous supply of larvae in the plankton ensures that the species is still present in our samples, and indeed it was Beroe that had disappeared from the sample on the 26th July 2022.
Reference
(1) Coastal Plankton 2nd Ed. by Otto Larink and Wilfried Westheide. Published 2011 Verlag Dr Friedrich Pfiel, Munchen (ISBN 978-3-89937-127-7). p74.
Early morning on Saturday 16th July 2022 we walked out, following the tide, from the Battery at Morecambe to Conger Rock, a large eratic boulder close to the Low Water Springs level between Morecambe and Heysham. The purpose of our walk was to check on the honeycomb worm reefs that had last been seen by the group in this area over thirty years ago!
Above: Lewis, Mark and Jo at Conger Rock; the Sabellaria historically the honeycomb worm reefs started just beyond this point.
Honeycomb worm reefs are built by small worms of the species Sabellaria alveolata, and can be found from close to the high water mark down to extreme low water, where the largest reefs can reach a height of 60cm. The reef is formed from sand grains stuck together to form tubes that protect the worm from predators and dessication when they are exposed at low water.
On our walk we found that while the reef is still present, much of it is in poor condition, showing signs of erosion, with no live worms. The erosion, however, allows us to see the structure of the reef in greater detail, as in the close-up photograph below.
Above: Detail of the honeycomb worm reef, showing the tubes formed from glued-together sand grains. Here the reef is dead, and the matrix between the tubes has been eroded out. It will disintegrate over time, hastened by bad weather.
Honeycomb worm reefs tend to by cyclical, and while many were in a state of decay, there were also sections of reef in relatively good condition. The reefs stretched for a distance of several hundred meters along the low water mark back towards Morecambe.
We enjoyed a super cooked breafast at the Beach Cafe on our return to the Battery!
From the start of 2022 Mark Woombs, Jean Wilson and myself have been sampling plankton every fortnight from the river Wyre estuary at Knott End. The intention of this study is to refresh our understanding of plankton diversity and dynamics in the Bay area, and contribute to studies on the health of the River Wyre. Phytoplankton – microscopic marine plants – are the base of the marine food web, and contribute approximately 50% of the oxygen we breathe, whilst quietly sequestering atmospheric carbon dioxide. Zooplankton are (generally microscopic) animals that convert phytoplankton biomass into food that is accessible to the rest of the animals in the world’s oceans.
In estuarine systems there is never really a shortage of plant neutrients. As a consequence there is the opportunity for phytoplankton to be present in high numbers from early spring, as light levels and surface water temperatures rise, through to late autumn, when grazing combined with lowered growth rates (due to reduced light and temperature) finally cut the poulations back.
Above: Preliminary analysis of phytoplankton results from the river Wyre 2022. Increased daylight triggers a massive, but very short, bloom in Odentella mobiliensis. This is followed by a smaller bloom in Coscinodiscus spp.
This does not mean, however, that the same phytoplankton species dominate our samples throughout the year. In fact, our study to date has revealed a dynamic interplay between phytoplankton species, with different species commming to dominate the total population in succession. The most likely cause of the species population collapses is disease, rather than grazing, though we only have direct evidence for this in one of our phytoplankton families, the Coscinodiscus, where the appearance of the fungal disease Lagenisma coscinodisci in late May coincided with a decline in the numbers, particularly of C. wailesii, which had been the dominant member of the Coscinodiscus to that point.
Plankton species taken during the sampling program were used to illustrate our talk to the Royal Society of Biology on 21st May, but we will have a more complete picture of plankton activity in the Wyre at the end of the year, and hope to present this work in more detail then.
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!
Two photographs of brittlestars on kelp. the main image is taken at a distance of 5m, and they appear monochrome. The inset below is taken at a distance of 30cm. To the best of my knowledge the colours displayed do not have any importance for the brittlestars concerned.
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!
Barry Kaye
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!
Man and animals are in reality vehicles and conduits of food, tombs of animals, hostels of Death, coverings that consume, deriving life by the death of others. Leonardo da Vinci
Plants are rather different – quietly converting sunlight into the food we need to survive; the shepherd with his grazing flock is the subject of a painting, the meadow, a beaucolic backdrop. In the worlds oceans, however, the plants that form the meadow are microscopic – completely invisible to the naked eye. Indeed, for most of the 20th century, the main players remained elusive even to the best optical microscopes!
Over the last decade or so satellite imagery, coupled to unmanned submersibles, have begun to reveal the true extent of marine ‘plant life’. We find a complex, dynamic pattern of blooms, and rapid disappearances keyed to the seasons, currents and climate. Alongside this, genetics has begun to unravel the complexities of the interrelationships between the different groups of marine plants – and animals…
Join us on Wednesday 13th February between⋅19:30 and 21:00 at the Gregson Centre, 33 – 35 Moor Gate, Lancaster LA1 3PY for a personal look at some of the recent research in this area. Admission £3.00, everybody welcome!
