Wednesday, 16 July 2008

'A whiff of a porpoise'

Every time the camera lander is deposited on the seabed to take photos, a C-POD is attached to listen for and record the clicks of porpoises and dolphins. So I’ve had a few deployments of the CPOD and each time I have sent the files we collected to Nick Tregenza who built the C-PODs (Chelonia Ltd.), and within hours he’d reply… ‘no animals’. Until yesterday! When Nick reported a ‘whiff of a porpoise’: three minutes of porpoise clicks – wooohooo! Meanwhile, Inigo found few fish in his photographs and wondered whether the porpoise had scared all the fish away.

So that was yesterday’s excitement (thanks Nick!)… that and a ‘muster drill’ – every so often we have to practice the emergency drill – what happens when the emergency alarm goes off. We all gather on the deck complete with warm clothes, woolly hats, and lifejackets. If we have to abandon ship we have assigned life rafts complete with immersion suits – like big waterproof duvets – that we have to don. Yesterday Claire & Chris had to demonstrate the donning of the immersion suits – see the photo to the left! More like a space suit than a sea outfit!!!

Meanwhile, the box circuit over the bank was repeated this time at neap tides – so round and round we go around the oval looking for birds and fish while the scanfish zig-zags up and down the water column measuring temperature and salinity. It looks like more fish, more widely distributed feeding gannets, but fewer feeding storm petrels from a first glance at the data. And certainly much smaller undulations of internal waves – nothing so dramatic as the spring tide internal waves. Not sure what all this means yet, but looking forward to finding out as we do the analysis.

We’ve just finished the neap box circuit, and taking more zooplankton samples, more measurements of the water column with the CTD, and more sediment cores. Talking of which, it’s very clay-like here at the bottom of the bank (we’re at MS3 at the moment), unlike the top which is loose sand. Morten (pictured on the right with his sediment cores) & Susan are collecting these samples – Morten is using the samples to look at the nitrogen cycle within the sediment. What is the nitrogen cycle? Well, nitrogen is an essential element in life – amongst others it is found in DNA and proteins, and luckily there is a lot of nitrogen around since the air we breathe is 78% nitrogen. However the nitrogen in the air is not in a readily usable form, so organisms (especially bacteria – they do have their uses!) have to process it (‘fix’) the nitrogen into a form that can be used by other living organisms. Some bacteria (especially in the ocean) reconvert the nitrogen compounds back into nitrogen gas & so complete the cycle. It’s a bit more complicated than that – I’d recommend reading the Wikipedia guide if you’re interested.

So, anyway, Morten is measuring the nitrogen cycle within the sediment by taking chunks of sediment and ‘incubating’ them (keeping the sediment with all its bacteria in a nice cold room at a similar temperature at which it would have been on the bottom of the sea, and measuring the nitrogen & nitrogen compounds released). He’s also measuring the oxygen in the sediment – since many bacteria need oxygen to live. Apparently here in this offshore turbulent water the oxygen layer depth is only 1cm (so only 1cm has significant levels of oxygen), whereas productive coastal areas have a much deeper oxygen layer – especially undisturbed areas. I think this means there isn’t much activity going on in the sediments here – the sediment bacteria process all the dead animals that should fall to the bottom - so maybe the dead organisms are being swept off elsewhere to settle & feed bacteria elsewhere… science is full of many mysteries… (which is what makes it fun!).

So, is it all work and no play on the ship? Not at all! There’s a library, a video room, a bar (which is well frequented), a gym and a sauna! Now I’ve not tried out the sauna yet, but yesterday I did finally venture to the gym, which isn’t badly equipped for a ship (see photo below)! But for now, I’m off to the bar ;o)

Inigo & Linda 'relaxing' in the gym

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