Wednesday 14th September at 19:30 at the Maritime Museum:
Above: The squat lobster Galathea strigosa stares back at me from his crevice between rocks. Due to the optical properties of seawater the blue patterns on his face will stand out to other animals, but reds fade quickly over distance, and will appear grey – providing camouflage until you are very close! Photo: Barry Kaye.
How crustacea sense their environment, and how an understanding of thesir senses might give us insights into their life. Crustaceans have been adapting to life at sea for 500 million years, and possess a suite of sensory capabilities that are astounding in their sensitivity and complexity. Some can see in the ultraviolet and infrared spectrum, and detect plane and circularly polarised light, extending their perception of colour far beyond that of the most accomplished painter! They smell with their legs, and while they are covered in armour, their sense of touch is the most sensitive in the animal kingdom…
We are pleased to announce our program of talks for 2022-23. Talks are usually on the second Wednesday of the month, and will be held at the Maritime Museum on the Quay in Lancaster starting at 19:30. Please subscribe to our Newsletter for further details and any changes to our program!
14th SeptMy Life as a Crustacean by Barry Kaye (Lancashire MCS) 12th OctFisheries for large pelagics by Andy Richardson, Royal Society of Biology 16th NovThe “Little Cucumber” Fish of Wyre, Osmerus Eperlanus by Tom Myerscough, Wyre Rivers Trust. 14th DecIt’s Not Christmas Yet – Christmas Quiz with Lewis Bambury, Lancashire MCS 11th JanThe Azolla story: How an amazing plant changed our climate 49 million years ago by Alexandra and Jonathan Bujak, The Azolla Foundation. 8th FebSeagrass – experience at Knoydart and Gigha, and discussion of its potential for carbon capture in the Bay by Mark Woombs and Barry Kaye, Lancashire MCS 8th MarThe ‘Tabarka’ and other blockships of Scapa Flow by Gordon Fletcher and Lewis Bambury, Lancashire MCS 12th AprPhytoplankton in the river Wyre 2022 by Barry Kaye, Lancashire MCS 10th MayMark’s Mini Monsters of Morecambe Bay by Mark Woombs, Lancashire MCS 14th JuneExposed shores by Gordon Fletcher, Lancashire MCS plusFighting phytoplankton (short talk) by Barry Kaye, Lancashire MCS
ALL WELCOME!
Talks will start at 19:30 at the Maritime Museum, the Quay, Lancaster (Facebook link). Please join us in person if you can, but note there are four flights of stairs up to the meeting room. Funding permitting we hope to broadcast meetings over Zoom for the benefit of those unable to negotiate the stairs – or who live ouside of the Lancaster area.
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.
On the 23rd July 2022, Mark and Caitlin Woombs, Jean Wilson, Lewis and myself dived deep into our collections to present a course on Crustacea to the Royal Society of Biology as guests of the Wyre Estuary Country Park. The course started with a general introduction to marine crustacea – one of the most diverse groups of animals on the planet – by Mark. This was followed by a maze building experiment, overseen by Caitlin, to show how simple experiments demonstrate that shore crabs can learn quite complex tasks.
Above: Carapace widths of Carcinas maenas, showing the cut-off at 35mm, indicating the current maximum size of this year’s young shore crabs.
Jean had gathered large numbers of shore crab moults from the beach at Knott End, which were used to see how the population is developing through the early part of the year. The rough graph of carapace widths, produced during the practical session, is reproduced above.
I updated an old presentation on ‘Colour underwater’ to look more specifically at sensory perception in crustacea – a fascinating field that I think went down OK, and I hope I can revisit in our winter lecture series later this year. Finally, Lewis tied the afternoon off with a review of all things crustacean in the form of a quiz. How many legs has it got?
Above: The light hearted crustaceans quiz, presented by Lewis (right) with Mark dressed as a lobster!
Thanks to Jean for organising, and to Alison Boden and the staff at the Wyre Estuary Country Park for making us very welcome!
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.
Two of our quarterly beach cleans/surveys took place on April 24th and June 15th with 12 volunteers each, so thank you again to those who took part. The June one was particularly enjoyable with the warm, late sun. A great way to spend an evening.
As we have found in beach cleans over the last few years, Half Moon Bay continues to be cleaner than in the past. The litter we find is mainly in the form of small, plastic pieces which often is found in the strand line seaweed. We don’t take away heavy bags filled with rubbish but, we are taking away the dangerous fragments of plastic which can be so toxic to marine life. Define worth the effort!
You can view our survey data on the website which includes pie charts so you can see the results of our survey data. They provide a colourful reference and it’s a visual way to see the percentages of litter collected.
The next beach clean at Half Moon Bay will be the annual national Great British Beach Clean which takes place between the 16th and the 26th September 2022.
We will meet on Saturday 24th September at 3:00 pm. Please register on the National MCS website in the usual way.
Views along the Morecambe Bay Cycle Path. Photos by Lewis Bambury
The Bay Cycle Way will take you on a 130km (80 mile) journey from Glasson Dock, around Morecambe Bay, as far as Barrow in Furness. The route along one of the most beautiful stretches of coastline in Britain, gives the cyclist the opportunity to explore its natural history, transport, industry, landscape and art.
Over the last year Lewis Bambury has cycled the length of the Morecambe Bay Cycle Path in stages, as part of his recuperation from long COVID. His talk to the group in February opened a great deal of interested discussion from those present.
Our next talk is at the George and Dragon, Lancaster, on 9th March 2022. Presented by Mark Woombs (Lancashire MCS/CAOLAS), it will look at the marine life in Loch Tarbert (Isle of Jura). Subscribe to our Newsletter to keep up to date with what is going on at Lancashire MCS!
Photo of Rita with her husband Ron at St Abbs in 2005 (photo by Gordon/Chrissie Fletcher)
It is with great sadness that we have heard about the death of Rita Crosby. Rita was the group treasurer for many years, helping Ron, and ensuring the group stayed on a sound financial footing! Our thoughts are with the family.
Many thanks to all of you who took part in our beach clean on December 12th. On each side of the beach we took 3.5 kg rubbish, although the weight isn’t always the important part. We removed over 300 pieces of plastic of various sizes. This is so important for the protection of marine life and birds. Other items included 55 cotton bud sticks and several other sanitary items including a PPE mask. This is more than usual and may have something to do with the recent storms. I will put the full surveys on the MCS database.
Whatever we remove helps protect wildlife and make the beaches more pleasant to use, so thanks again and hope to see you on another beach clean.
