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Atlantic coccoliths blog

Archive for the 'Coccolithophores' Category

Land ahoy

Jeremy, Tuesday, November 11th, 2008

Nearly over. After six weeks the cruise has ended, at least as far as we are concerned. We have got to the Falklands safely and docked at Port Stanley. The Falkland Islands invite rather mixed comments on ship but they looked beautiful in the early morning sun as we arrived, and to remind us of the naval history a frigate was anchored in the entrance to the sound.

Heading towards the Falklands

Heading towards the Falklands

HMS Iron Duke in front of Mount Tumbledown

HMS Iron Duke in front of Mount Tumbledown

The last few days have been rather dominated by weather as we have gone through a series of gales alternating with calm sunny intervals. The sunnier intervals allowed some sampling in these waters and we have been rewarded with green soupy water rich in diatoms, copepods, some rather unpleasant gelatinous gunge and a few whales.

A whale's tail

A whale’s tail

Coccolithophores have remained common and surprisingly diverse but the layers of different populations are no longer distinct – they now look pretty similar throughout the water column.

The zooplankton samples have been interestingly variable. Plankton net sampling has been cancelled several times but the samples which did come in made a very useful addition to the material I have been collecting.

However, science stopped completely a couple of days ago so that we could get packed before arriving in the Falklands. The first task was tidying up and sorting out the samples. There is a decent haul – we have collected from about 70 stations and accumulated about a thousand filter samples, four hundred microscope slides, eighty bulk organic samples for DNA analysis, two hundred filter samples prepared with a special buffer to allow labelling of cells with fluorescent markers, and hundreds of pteropods and ostracods picked from the zooplankton.

After that the main dismantling of the labs and packing up took place on Saturday afternoon, just as we hit particularly bad weather. To make things worse we were sailing south whilst the wind and waves were coming from the west, which made for rather chaotic ship motion and the occasional spectacular roll of up to 30°. So packing was sporadically interrupted by the need to grab something solid with one hand while restraining what ever one was trying to pack with the other hand. The rolling also added a certain something to the end of cruise dinner, and especially to the dancing in the crew bar.

A wash bottle serving as an inclinometer to record the ship's motion, although I did not manage to photograph it during any of the larger rolls

A wash bottle serving as an inclinometer to record the ship’s motion, although I did not manage to photograph it during any of the larger rolls

So that is about it for the cruise, although we will have a lot of work to do on the samples over the next few months. It has been a great experience, we have learnt an immense amount and had some excellent evenings. The RRS James Clark Ross is a fine ship and everyone from galley staff to the captain has made us welcome. It’s nice to see dry land but we will be sorry to say farewell to the ship.

Jeremy & Martine, Port Stanley.

Storms, albatrosses and our own CTD cast

Jeremy, Wednesday, November 5th, 2008

It’s Sunday 2nd November now, so only another week of the cruise, which is maybe just as well since we are running low on supplies for sampling, boxes to put them in, microscope bulbs, and energy. As we left the tropics we ran into a gale and a big swell, which set the ship rolling quite nicely and resulted in two of our sampling stations being cancelled – which was a bit disappointing but it did allow us to stop work and enjoy the sea. Standing on monkey island (i.e. above the bridge), as the ship rose in and out of big waves was very impressive. Then as a bit of a bonus our first albatross appeared.

Going through the gale - the James Clark Ross hitting a wave relatively firmly

Going through the gale - the James Clark Ross hitting a wave relatively firmly

The first albatross we have seen on the cruise

The first albatross we have seen on the cruise

Generally the number of birds is increasing as we leave the tropic and go into more fertile waters. The weather improved today and at lunchtime we were able to stop for our noon sampling station in relatively calm sunny waters and slowly gathered a little flock of petrels and albatrosses. Indeed albatrosses are beginning to get positively common.

Numerous birds watching the lunchtime water-sampling

Numerous birds watching the lunchtime water-sampling

Another albatross

Another albatross

Scientifically today was rather special for us. One of our prime objectives on the cruise has been to study the change in distribution of coccolithophore populations with depth. Our observations so far have suggested that, rather than there being separate near-surface and deep communities, there is a continuous succession of different assemblages with depth. Luckily for us there was also some ship-time available for additional science and the principal scientific officer, Malcolm Woodward, was able to arrange a separate CTD sampling mission for us. So, today after the regular noon sampling the ship stayed on station for another hour or so as the CTD and rosette sampler was sent back down for a special Natural History Museum sampling mission, collecting water every 12 metres from 275m to the surface. This means a late night beckons as we work our way through 260 litres of seawater.

Up it comes again, the sampler, this time with water just for us

Up it comes again, the sampler, this time with water just for us

Jeremy and Martine – 33°S 31°W

Sunday news

Martine, Tuesday, October 21st, 2008

Sunday 19th October, 10 pm
I’m outside by a nice clear night, writing from the hammock set up out of my cabin. It is the end of the weekend and there are not many people awake onboard… apart from Alex (the third mate) and Kevin (watchman) at the bridge to check there is nothing in our way and everything is working fine.

It’s Sunday evening, however there is no real weekend onboard as we are sampling everyday. This weekend was especially busy with a deep sampling, down to 5150m on top of the normal 2 stations. We even ran out of containers to collect the extra samples and had to use the collapsed carboys.

Still just usable, one of the carboys we collapsed through vacuum pressure

Still just usable, one of the carboys we collapsed through vacuum pressure

This supplementary collection means for Jeremy and I about 290 litres of seawater filtered instead of the usual 160 litres per day, and about 20 extra slides to look at during the day… But it also means souvenirs as we sent down a team of expanded polystyrene cups attached at the top of the rosette sampler in socks (special thanks to Glen and Jeremy who provided the socks).

Preparing the important scientific experiment – cup-filled socks are attached to the rosette-sampler frame

Preparing the important scientific experiment – cup-filled socks are attached to the rosette-sampler frame

At 5000m the pressure is about 600 times that at the surface and our valiant team was shrunk to a fraction of their previous size – this also meant that our swift marker-pen cartoons were rendered into finely detailed pieces of art.

Our cup team before and after meeting the AMT-Abyssal Challenge

Our cup team before and after meeting the AMT-Abyssal Challenge

Busy and fertile because most of the samples we collected over the weekend were really nice, and quite distinctive and thus worth having! We also had a nice barbecue-style party on the deck in the evening to relax and enjoy.

After dinner in the very dark night (no moon) some of us had the chance to observe bioluminescence (pictures to come later if we remember a camera next time) around the ship, the best observation spot was at the bow on the forecastle. The galley telegraph subsequently carried rumours of nocturnal entertainments near the kitchen (I’ve no idea what that was about, honest)…

Martine 11.13°N 32.06°W

360 degrees of nothing

Jeremy, Wednesday, October 15th, 2008

120 degrees of nothing, part of the view from Monkey Island

120 degrees of nothing, part of the view from Monkey Island

I am writing this from Monkey Island – the open space on top of the bridge where we can watch the world go by. And right now I am surrounded on all sides by absolutely nothing. There are no islands, no ships, no dolphins, no birds, just gently rolling dark blue water in all directions, except up. The complete absence of everything is because we have now got near to the centre of the North Atlantic gyre, which is one of the biggest marine deserts on earth.

Middle of the desert

Middle of the desert – this satellite derived map shows the amount of plant pigment in the surface waters with maximum values shown in reds and minimum in dark blue. We are right in the middle of the North Atlantic desert.

Of course, unlike the Sahara desert, which is 2000 miles due east of us, there is no shortage of water here. But that water contains very very little of certain key elements that life needs to grow, especially nitrogen and phosphorus (the same nutrient elements as I should be adding to my lawn back home to get the grass to grow a bit better next summer). Any trace of these elements in the water gets hoovered up by plant plankton.

Discosphaera tubifera

Discosphaera tubifera – on the left is one of our favourite surface low productivity species, in the middle is the light micrographs taken today, and on the right is a scanning electron microscopy (SEM) image, taken several years ago.

Now, you would expect that the nice marine ecosystem would sensibly recycle these elements. However, the ecosystem is in fact hopelessly inefficient and when they die the plankton sink out of the water column taking the nutrients with them. So, the sunny wind-mixed top 60m or so of the ocean is almost lifeless.

Gladiolithus flabellatus

Gladiolithus flabellatus – a very different coccolithophore specialised for low light conditions, this specimen was collected yesterday from 200m below the sea surface. The SEM image is of a specimen from similar conditions in the North Pacific.

Almost but not quite - some specialist plant-plankton have adapted to this harsh environment including particularly many of our friends the coccolithophores, the cacti of the oceanic deserts.

So, Martine’s filtering is yielding a wonderful array of exotic specimens for the microscope. From the surface layers we need to pump several litres of sea-water to get enough to find on our filters. Deeper down, where the water is more nutrient-rich, different specialist forms adapted to low light levels occur at slightly higher abundances, although down there they have a range of things to compete with including cheerily-named cyanobacteria which several other people are studying on the cruise (more on them, the people not the cyanobacteria, another time).

My friend the microscope

My friend the microscope – an old one this, but a trusty travelling companion.

As we sail south each station has a slightly different water column structure and ecology. Observing the changing coccolithophore communities in the field is both a great way to ensure we get the possible results and extremely rewarding – coccolith heaven, I am back to the microscope.