Colour Underwater

September 2nd, 2019

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 from 5m in natural light, and they appear monochrome. The inset is taken at a distance of 30cm with a white strobe.
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.

Posted in Marine science update, MCS talks, Science

Destroyers!

March 1st, 2019

Photographs of Orkney, sea slug and diving the High Seas Fleet.
Above top: An Orkney seascape (with defensive positions) by Lewis. Below the seaslug Coryphella by Gordon, and a diver on one of the wrecks of the German High Seas Fleet by Lewis.

Two talks about two very different types of destroyer – Lewis Bambury will talk about Orkney, including a look at how events from 100 years ago gave the islands some of the best diving in the world. Gordon Fletcher will look at the colourful world of sea slugs, giving you the chance to hear about the feeding habits of these predatory carnivores, their unusual sex lives, and the extraordinary defence mechanisms they utilise to avoid being eaten by larger predators!

These talks will be followed by the local group AGM.

Wednesday, 13 March: 19:30 – 21:00 at the Gregson Centre, 33 – 35 Moor Gate, Lancaster LA1 3PY.
Admission £3.00, everybody welcome!

Posted in MCS talks, Science

Invisible World: marine primary production

February 5th, 2019

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!

Posted in Events, Marine science update, MCS talks, Science

Dark and dull? Underwater wildlife photography in British waters

November 27th, 2018

Tunicates and worms by Barry Kaye

At our next meeting, members of the group will take personal views on the subject of photography around UK coastline. This will include a look at the photographic equipment they use, and the challenges they face in getting a ‘good’ photograph. Main speakers: Gordon Fletcher (film), Lewis Bambury (digital), Jo Kaye (macro).

Dark and dull? Underwater wildlife photography in British waters (PDF 117kB)
Wednesday, 12th December, 19:30 – 21:00 at the Gregson Centre, 33 – 35 Moor Gate, Lancaster LA1 3PY.
Admission £3.00, everybody welcome!

Please note, we do not have a meeting in January 2019, our first meeting of the New Year wil be in February, the remainder of our winter lecture programme is available in the PDF linked below:

MCS winter lectures 2018 (PDF format 82kB)

Posted in Marine science update, MCS talks

Life in Liverpool docks

April 7th, 2018

Review of ‘What’s up Dock?’, a talk presented by Wendy Northway (MCS North West England Seasearch Coordinator) on 14th March 2018.

While Liverpool’s pre-eminence as a maritime centre in the North West is undisputed today, it was only in 1751, with the construction of the world’s first commercial wet dock that she cemented her call to that title. Previously the most important port in the area was Chester, a position the city had held since Roman times.

The first wet docks allowed ships to be unloaded in a day and a half, significantly undercutting the older practice of unloading cargo to smaller boats at sea for transfer to shore – a process that could take two weeks on good weather. This gave the port a massive commercial advantage, and soon the docks were over-subscribed, leading to the rapid construction of new, larger facilities, which were also required as the expansion of trade with the industrial revolution lead to ever larger vessels…

Liverpool's Albert Dock with the Liver Building in the background. Photo B Kaye
Above: Liverpool’s Albert Dock (with the Liver Building in the background) has been cleaned up and is now a major tourist destination, housing Tate Liverpool and a number of museums. Diving in the docks is now strictly controlled. Photo B. Kaye

As each new dock was built, unseen and rather unheralded, we also built a new marine habitat, and it is these that were the subject of the talk What’s up Dock? by Wendy Northway (MCS North West England Seasearch Coordinator) to the group on 14th March 2018. The docks are no longer used commercially (having closed in 1972), but are actively managed leisure spaces. Water from the river Mersey is not used, as it is too polluted, instead the docks are topped up from the Irish sea on high water springs, giving a salinity in the range 24‰ to 28‰. The exchange of water with the Irish Sea allows for migration of marine wildlife between the Irish Sea and the docks, which have as a consequence become colonised by a fairly select group of organisms.

Mussels and algae colonising a discarded bicycle. Photo (c) BrokenDiver
Above: An old bicycle thrown into the dock has been colonised by mussels and algae. Photo © BrokenDiver.

In 1988 the docks were colonised by up to 1000 mussel spat per square meter. The absence of common starfish in the docks have allowed very large population densities of mussels to be established, and larger individuals have grown too big to have any natural predators. The mussels have been calculated to filter the entire of the docks water every four days, and are probably vital to maintaining water quality. Other filter feeders include bryozoans, sponges and tunicates, while cockles have colonised the soft, muddy bottom of the docks.

Black goby amidst mussels, bryozoans and sea squirts in Liverpool docks. Photo (c) Catherine Gras
Black goby amidst mussels, colonial hydroids and sea squirts (Ciona and Ascidiella) in Liverpool docks. © Catherine Gras

The modern docks are home to a thriving marine community, including a number of fish and crustaceans. I was, however, particularly interested to hear that the seasearch divers had confirmed the presence of an introduction from the southern hemisphere, the worm Ficopomatus enigmaticus in the Collingwood Dock. This species may have been introduced on the bottoms of ships or as larvae in bilge water. Unfortunately we do not know if this is a relatively modern introduction on pleasure craft, or a relict from the Liverpool port’s trading days.

Ficopomatus enigmaticus, an Austrolian introduction. Photo Wendy Northway (c) PhoebeSparke
Above: The characteristic pagoda shape of the tubes created by the worm Ficopomatus enigmaticus, an Australian introduction. Photo Wendy Northway © PhoebeSparke

NOTES: Ficopomatus has become a nuicance in many areas it has colonised, producing dense aggregations that can interfere with dock gates and other marine/estuarine structures, though at high densities in docks may help clear the water of particulates, and improve bottom biodiversity (JNCC report linked below). In some places it forms large reef structures in shallow brackish water. Needing a temperature above 18°C to breed, it may not be as invasive in our local open waters, but has been recorded in the docks at Barrow, so we should be looking out for it in the Bay! More information on Ficopomatus enigmaticus at ‘The Exotics Guide‘ and JNCC.

Posted in Marine science update, MCS talks

Sea Level Rise – the hidden coastal process?

January 3rd, 2018


Above: Simulation of sea level rise on the Fylde coastline.

Our next talk, by Trevor Lund of Blackpool and Fylde College, will examine the evidence from around the Bay for sea level change in the past, look at the processes involved and consider how this will affect us all in the future. The process of sea level rise is one of the most important in shaping our coasts and shallow seas, but what exactly is it and can we see any evidence for it in the environment around us?

Wed. 10th January 2018 at 19:30 ‘Sea Level Rise – the hidden coastal process?’ by Trevor Lund (Blackpool and Fylde College)
Meeting in the cinema upstairs at the Gregson Community Centre, Lancaster, LA1 3PY. Admission £2 – all are welcome!

Sea Level Rise (PDF 294kB) Poster with more information.

Posted in MCS talks

Marine Jellies

December 3rd, 2017

Photograph of the jellyfish Aequorea vitrina, by Gordon Fletcher

Contributing to the festive season, we have an illustrated talk on ‘Marine Jellies’ by Gordon Fletcher on the 13th December. Gordon is a good story teller, and an excellent marine life photographer. I cannot think of a more able person to bring some of the strangest and most beautiful creatures in our seas to life for us!

Wed. 13th December 1t 19:30 ‘Marine Jellies’ by Gordon Fletcher (Lancashire MCS)
Meeting in the cinema upstairs at the Gregson Community Centre, Lancaster, LA1 3PY. Admission £2 – all are welcome!

Posted in Events, MCS talks, Science

Sealochs and Kelp Forests

February 2nd, 2017

Loch Creran by Gordon Fletcher.
Above: Loch Creran offers a wide variety of interesting, and often colourful, marine habitats to explore. Photo: Gordon Fletcher.

On Wednesday 8th February, we have two illustrated talks about some of the most interesting and accessible dive sites around the British Isles. Gordon Fletcher (MCS Lancashire) will look at Sealochs, characteristic features of the West Coast of Scotland, that offer sheltered diving on a diverse range of marine habitats. Barry Kaye (MCS Lancashire) will look at Kelp forests – interesting and diverse ecosystems, that are often avoided by divers, as looking a bit too much like Tolkien’s Mirkwood

The talks are aimed at a general audience, and an admission fee of £2 is charged to cover costs.

WHERE: The cinema at the Gregson Community Centre, Lancaster, LA1 3PY
WHEN: Wednesday 8th February at 19:30
ADMISSION: £2.00 Admission
Everybody Welcome!

Sea lochs and kelp forests poster (PDF 672kB).

Posted in MCS talks

The rough and the smooth

January 4th, 2017

Wednesday 11th January 2017 at 7:30PM Two talks looking at how life has adapted to conquer marine environments at opposite extremes of the energy spectrum. Still Waters (and muddy bottoms) by Barry Kaye and Exposed Shores by Gordon Fletcher.
Upstairs in the Cinema at the Gregson Centre, Lancaster, LA1 3PY.
£2.00 admission, all welcome!

Please note we have added a beach clean to our calendar for Sunday, 5th March. This will be at Half Moon Bay, meeting at the Cafe car park at 11AM. Please bring suitable clothing/footwear and tough gloves to protect your hands while picking.

Posted in Events, MCS talks

Man made habitats

December 2nd, 2016

Blackpool pier by Lewis Bambury.

On Wednesday 14th December we have our last public meeting of the year, with two talks from the local group looking at how some marine organisms have adapted to the ‘built environment’. Lewis Bambury will look at static objects, under the title Piers and Jetties, whilst Barry Kaye will take a look at Bilges and Bottoms

The meeting is at 19:30 in the Cinema, upstairs at the Gregson (click for website with address and venue details).
Admission is £2. Everyone is welcome.

You can download a copy of the poster below:

Man made habitats poster (116kB PDF)

Photo: Blackpool pier by Lewis Bambury.

Posted in MCS talks, Science