Welcome to this week’s marine science briefing, which starts with a sad tail of fickle fishes, before the main course on getting about underwater. In this we see three adaptations by marine vertebrates to propulsion, including how whale design can improve underwater turbines, and what the fastest sharks would be wearing at the 2012 Olympics in London!
Archive for November, 2010
I was in Cleveleys this Sunday (21/11) and a on short diversion down to the beach I counted 20 dead sea mice Aphrodita aculeata on a 2 or 3 metre stretch of the hight tide strand. The tide was in so there wasn’t much beach to look at and I couldn’t tell if this was a localised collection or if it was typical of the whole shore. Got to admit that there was a bit too much dog muck on the beach for me to want to look much further!
miceThis was striking to me as a diver because sea mice are creatures that we rarely see. I would guess that I’ve done something of the order of 300 dives in British seas and in that time I’ve seen 3 sea mice. That’s a 1 in 100 dive ratio of sightings. So 20 – admittedly dead – in one smal area is unusual. It also has some interesting similarites to a sighting of a large number of sea mice made by Lancashire MCS members on a dive in Loch Fyne in November. Follow up dives were arranged in subsequent years to see if this was a regular occurence (I saw 2 of my total count on one of these dives) but nothing conclusive was found again. Maybe we should have been looking a bit closer to home?
What else was there on the beach? You can see a mermaid’s purse – probably a dogfish’s – in the debris behind the sea mice. I was also quite surprised to find jellyfish stranded. It’s not a time of year that I would have thought of for strandings. Didn’t see any leatherbacks though.
Leatherback turtles are popular this issue, with scientists tracking them across the Atlantic, how they thermo-regulate, and how to stop them ending up in the soup… Otherwise there is a nice bit of experimental work ‘proving’ that faster flow = more life (this doesn’t mean that low-flow = no life, however!). We are also, perhaps, getting closer to understanding why coral bleaching occurs at a molecular level.
On November 10th at our monthly meeting Barry Kaye gave an excellent illustrated talk on the Gulf Oil Spill. He explained in the most clear and concise way the complexity not only of the problem, but also of the solutions.
It quickly became clear that the human thirst for petrol and diesel driven mobility drives the demand for oil, and that if the economics are right, it will be extracted from the most inaccessible or environmentally sensitive places. The great depth of the Gulf of Mexico site produced it’s own problems, but BP was using ‘state of the art’ technology at the time. There are clearly questions about the quality of some of the technology, but we also learned that this was far from a unique case, instead it is just the latest of a series of accidents in the gulf, involving more than just the BP company.
It would seem that any idea of the Gulf spill having been ‘cleaned up’ is just a cosmetic illusion. The shores and wetlands are a very visible indication of what has been achieved there, and dispersants have removed the oil from the surface waters, but this is just a fraction of the larger impact of the spill. The less obvious but greater impact is out of sight in the mid-depth waters of the Gulf, and on the deeper sea bed. Only time will tell what the longer term impacts are on the ecology of these waters, which in turn will have an impact on surface and inshore marine life.
We’ve just added our events diary for January to May 2011 – some good talks to look forward to plus lots of things to get involved with: beach cleans, our annual photo comp., coastal walks and dive/walking/survey trips up to the West Coast of Scotland.
This issue we look at the behaviour of seals and jellyfish – choose the ideal holiday destination for starfish – then dive into a microbial ocean. How to manage fisheries, this time on a Chilean archipelago (there are some mitigating circumstances here, but best of luck guys), and catch up on more news from the Gulf of Mexico. One factor that we need to take on board is that the Gulf was in bad shape before the spill, and that the $20B oil spill response isn’t going to start managing the Gulf ecology properly.
The Lune Deeps are not known for crystal clear visibility. To dive here you have to have the right weather, the right tides, and these have to coincide with time that you can spare to go diving. I have to admit that it would be a first for me. So I was very lucky to get a phone call from Ian at Darwen SAC inviting me on a survey dive in the Deeps. This did mean getting up at 4:00 am a couple of days later on an October Sunday morning, in order to get to Knott End in time to launch for the high tide slack water, but these opportunities don’t come up very often and I grabbed it while I could.
Setting up gear in the car park, it had the feeling of a night dive in the dark. Boats launched, we set off for the chosen site with the sun rising above Blackpool, turning the sky over the bay shades of pink. Fantastic – as a diver what more can you ask for?
Well there’s the dive. The plan was to drop to the sea bed at about 10m just out of the deeps, and to swim over the edge and down the slope; each buddy pair to have a surface marker buoy visible. Things went pretty much to plan for us, we found the sea bed and managed to work down the slope to 30m. We could have gone deeper but my – borrowed – computer had run out of no-stop time and I was wary of running it into decompression.
So, what was it like? Where we started the sea bed had quite a few fist sized pebbles and was silty enough that any misplaced fin kick would reduce visibility to zero; this wasn’t too much of a problem as the tide was running fast enough to move us smartly along and clear the silt away. At the end of the dive we got a glimpse of a clearer, more gravelly sea bed. Throughout one of the most striking things was that the dominant species was bryzoan Hornwrack Flustra foliacea, which is quite an unusual habitat to find yourself diving. The silt covering meant that much of the benthic fauna was difficult to discern, but there was still plenty to see, with numerous Coryphella nudibranchs and even a large Triton Sea Slug Tritonia hombergi. As well as some butterfish and a greater pipefish we did find an area with quite a few goldsinny wrasse, which was a bit of a surprise; several people reported seeing large dogfish.
An interesting dive, but considering the size of the area that we covered there is still plenty of the deeps undived and waiting to be explored. Would I do it again – certainly.
A real mixed-bag this week, our marine science highlights consider techniques for identifying viruses (or molecular quasi-species) and nanotech trackers to follow zooplankton. In conservation, we see progress on a new generation of bioreactors that promise to remove nitrogen from land runoff. In fisheries, even the best environmental practices at fish farms need improvement. In pollution, science of the gulf oil spill in the service of the law.
For those of you who worry about climate change, but feel they can’t do anything about it right now, we finish with the opportunity to transcribe the logs of British warships from the turn of the last century. The transcriptions will extend our baseline data about climate back in time over a wide area of the Earth’s surface, and so improve the qualty of our climatic forecasts.