It has been a while, and there is a lot to go through – so best start with some light browsing! – In Science we’ve got links to a super set of marine life photos, plus an amusing look at cnidaria from the guys at Deep Sea News. The section ends with new takes from molecular biology on the flagella and the mitochondrion – fundamental building blocks of cells.

In conservation we look at attempts to model population dynamics across a patchwork of marine reserves. This kind of understanding is essential for planning effective reserves, as if reserves are too small, or the gaps between them are too large, then they will not protect all of the species within them from over exploitation. This section ends with a look at how well displaced populations survive – as aliens in the Med or the Caribbean, or displaced benthic faunal communities.

Fisheries has an interesting couple of articles on cod fishing in the Baltic – I had full access to the PLoS 1 journal article, and that appeared to say that fisheries, seals and cod could co-habit, though there would be problems. The ScienceDaily headline is a lot more strident, in saying that seals will be the financial ruin of small fishermen. Otherwise there is a paper drawing our attention to the possibility that fisheries and climate may not be independent variables. If this is that case it will make modelling fish stock that bit more challenging…

In fact there is a second link between fisheries and climate change this issue, with news that slow growing fish in the Tasman Sea are being adversely effected by temperature rise – the Tasman Sea has increased in temperature by 2°C in the last 60 years. Thankfully the Weddel Sea has only warmed by 0.6°C, but this still represents an enormous amount of heat entering the Southern Oceans from our warming climate. To ensure there is no silver lining in this issue, we learn that bacteria are the true rain makers.

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Thanks to Gordon for organising an excellent dive weekend based at Tralee Bay (see map) near Oban last weekend (6th-9th May 2011). Eleven of us from the MCS and Preston Sub-Aqua Club enjoyed some spectacular dives.

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These including a fast run through the Creran Narrows, which Jo and I followed with a linked dive into an eddy pool by the North West shore, to get some better photos of the brittle star beds there, (it never ceases to amaze me how much colour there is in these beds, which appear from a distance to be rather unpleasant grey cob-webby places) before a rather hard swim back on the surface.

We also visited the wormery – where the serpulid reefs seem more substantial than ever – less substantial reefs are also to be found in the inner basin of Loch Creran.

Our final dive though was at Galanach, where I wanted to visit the sea-pen beds, with the intention of getting some better photos. As a rather nice bonus, however, I saw a large thorn-backed ray, which hung about long enough for me to get his mug-shot!

We also managed a small amount of microscopy, looking at a single plankton sample from Galanach. Unfortunately the phytoplankton have now disappeared (they formed a substantial component of the samples at Lochaline last month), though there is a large amount of zoo-plankton, with copepods and barnacle larvae (cyprids) as the major component.

Usually we start the science section with stories from the vertebrates, and work ‘down’, in a blatant piece of species-ism. This time the anemones float to the top, however, with reports of how the corals might have evolved, and the id of one of the chemicals that induces their free-floating larvae to settle down. We end the section with a series of parties with the world’s largest vertebrates.

Fisheries and exploitation has a report about fishermen being paid to collect plastic. Sounds environmentally beneficial? We’re not sure how the collection will work, as while there is a vast amount of plastic waste at sea, is is usually in small fragments and not very concentrated, making for a very energy intensive clean-up. A skimming exercise that would remove small fragments will also remove many of the small invertebrates and plankton that form an essential part of the food chain… It will be interesting to see if there are any benefits from this bit of horse-trading.

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A life and death issue, with a look at the short lives of copepods in our science sections, followed in exploitation by a look at how tunicates may hold the secret of a prolonged life for all of us. In conservation we ask if traditional conservation practice is the best way of protecting the marine ecosystem, and see that anoxic waters don’t stay buried!

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A very successful trip to Lochaline on the West coast of Scotland was enjoyed by ten members of our group. General weather and sea conditions over the four days was on the whole very good.  Based at the Old Post Office in Lochaline we were only a couple of  hundred yards from the access point to a spectacular dive location, the  Hotel Beach Wall. The dive starts off swimming down a very gentle slope of mainly white silica sand with occasional large boulders covered with kelp and sheltering shore crabs and sea stars etc. as the slope gets steeper tube anemones, Cerianthus lloydii  in a variety of colours are very common.  The sandy slope ends quite abruptly as we reach the top of the almost vertical wall which plunges down to a depth of more than one hundred metres.  Just a few of the very common inhabitants on the wall are Tubularia with numerous nudibranchs,  football sea squirts, squat lobsters, feather stars and sponges etc. We  are also able to add a further two animals to our Group’s list of recordings for this dive site, a lumpsucker, Cyclopterus lumpus spotted on a couple of dives and a number of Brachiopods, (lamp shells)  Terebratulina retusa.  Dives also took place at Fiunary Rocks, a typical sea loch slope  further West along the Sound of Mull and on the sea grass beds at Rubha-nan-So’rnagon  in Loch Linnhe. 

Most members of the party spent some time walking in the area, on the shores of Lochaline, to see the carved stones at Kiel and to the East side of the loch to the fossil burn where we were very lucky to see otters.

Many thanks to Jo and Barry for such a well organised trip.

Our diary has just been updated with events for this summer. This includes a series of talks on common marine ecosystems around the UK coastline, plus dive trips and walks.

Lancashire MCS summer diary

No limit to growth? – This is the surprising conclusion from studies on reef ecosystems, where it is found that total productivity continues increasing as the biological diversity on the reef increases. The broader implication for marine conservation management is that it is important to maintain balance across the widest possible diversity of life in the ecosystem.

Otherwise in this issue we see reasons not to be popular – if your a Weddell seal, and your popularity is as a snack for orcas. Also we get a glimpse of the slow lives of deep corals – which have led blameless, if rather uneventful, lives since the times of the Roman emperors, only to be killed by the recent oil spill in the Gulf of Mexico. There are no places left on the planet that can claim to being untouched by human activity. We must understand our impact better, and take responsibility for our actions – our ancestors will be able to read the records of our crimes in the sediments of the deep seas…
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This issue’s worrying news is of an oil spill that has devastated two islands in the Tristan da Cunha archipelago. Otherwise we have cutbacks, and separated populations, watching sharks get spruced up, and an indication that water fleas do have a history…

In our final article you are warned to slap on sun block now if you live in the Northern Hemisphere, due to a hole in the ozone layer. This problem is set to disappear by the end of the century, however, so it is one climatic problem we won’t be handing over to our grandchildren to solve.
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Sea Cucumbers in the Indian Ocean – Mandy Knott

March’s meeting was a talk by Mandy based on her work with Shoals Rodrigues (http://www.shoalsrodrigues.net/), surveying sea cucumbers in the lagoon of the island of Rodrigues.

Rodrigues is the furthest east of the three Islands of Mauritius and, from a marine biology view, is interesting because it is effectively isolated from lands to the west by the trade winds and ocean currents that sweep in from the south east, from which direction the nearest landfall is Australia. Politcally it is an autonomous region of Mauritius. Much of the land is mountainous and many people turn to the sea to provide their living. To this end Rodrigues does possess the largest coral lagoon in the world.

There’s always a ‘but’ and for Rodrigues there are several when it comes to taking advantage of this resource. What all the ‘buts’ come back to is overfishing; the large predatory fish have all gone from the lagoon, the fishermen have no boats capable of fishing beyond the safety of the lagoon, and the sea cucumber has become the main stay of the fishery.

Sea cucumbers are not vegetables, or even plants, but animals – Echinoderms – closely related to urchins and starfish. Their basic form is a sausage shaped animal with a mouth at one end that has tentacles that pass food to the mouth. Food for these animals usually being detritus or some other microscopic source or protein. Reproduction can be sexual or asexual – either male and female animals communicate by and respond to chemical signals in the water to synchronise the release of sperm and eggs into the water, or some species can also multiply by splitting into two parts. Overfishing therefore can be a big problem for sexual reproduction in these animals – as they need to be close enough to one another in order to be able to use their chemical communications effectively; the population could drop to a point where the animals are present but unable to breed.

That they could be thought of as food may seem an unlikely direction, as to western eyes they don’t appear all that apetising and the processing they go through after being caught doesn’t improve this viewpoint at all. However sea cucumbers are valued in China and South East Asia for both cuisine and traditional medicine – the general rule being the uglier the better.

Signs that the sea cucumbers were following the fish have been there for some years, and four reserves were set up around the lagoon to give areas where there was no fishing. Unfortunately it seems these are not being managed or enforced. An earlier Shoals Rodrigues survey had estimated the sea cucumber population of the lagoon at @48 million. The 2010 survey looked at many of the same sites and used the same statistical model to estimate the population again – and found a significant reduction in the overall population.

Prior to restrictions of fishing being imposed a official study found that 55000 animals were taken in 15 days (these were just the fishermen they knew about – there were probably more people fishing unregistered).

One glimmer of light on the horizon is the possibility of ‘ranching’ sea cucmbers. This would be a bit like farming them. Even this has its problems though; the Rodrigues government is understandably very keen to to get it going and wants use a species – Holothuria Scabra – that is native to Mauritius and has been successfully ranched elsewhere. One of the key criteria is that the species used should be one that is native to the Rodrigues lagoon and Holothuria Scabra has only ever been recorded on one survey there – one commissioned by the government; it has never been recorded by any of the other surveys, which have taken many days and many sites into account. Naturally there is some scepticism about that one survey and some concern of the effects the introduction of a non-native species could have on the endemic species resident in the lagoon.

Another glimmer is that a fisherman’s cooperative has been set up and is in the process of obtaining and fitting out boats fishing beyond the reef, which would hopefully reduce pressure on the lagoon species. To what degree that is successful remains to be seen.

See also –

http://www.sos.bangor.ac.uk/research/php/theme.php?project=445 for some information on Bangor University’s work in Rodrigues

http://www.sempa-rodrigues.com/images/3rd%20Ecology%20and%20GIS%20Interim%20Report.pdf – a report on SEMPA (the South East Marine Protected Area) including survey data

In marine science this issue, most of our articles relate to how phisico-chemical environment influences the distribution of species. I particularly liked the way the bio-geographical history of the North Atlantic has been revealed through the mDNA of the rough periwinkle. Conservation issues cover cetaceans, coral and cod. Our first article in fisheries raises some questions about the sustainability of invertebrate fisheries. Finally, new estimates suggest that ocean currents (rather than biological activity) are more important in removing carbon from surface waters in the North Atlantic.

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