Ha the last stretch of science. Today the wind calmed down considerably and by the evening the weather could be considered quite nice. However the stormy weather of the last days has created considerable swell. This swell is a series of long wavelength surface waves that can still attain a considerable wave height. However they generally have quite a constant frequency and direction. Since the wind had dropped the wind waves hardly affected us any more. Still the swell could make the deployment of the RMT 25 difficult enough. Not only in terms of the RMT 25 swinging about on the deck, but also in terms of the changes an peaks on the wire en the RMT25. Nevertheless we went out and gave it a try. While deploying the first net we almost got our feet wet when a wave almost reach the deck. As the net went down Sophie and Peter kept a close eye on the tension on the wire. Although the tension was high the peaks did not exceed the safe. So it became a night filled with fishing. Two stratified deployment and on Target deployment. The catch we got was quite diverse with fish and zooplankton including several strange species. So after a day of delay due to bad weather we finally got a good day of sampling. This is already more successful than the previous two attempts they had in this area on previous similar cruises. Let’s hope the weather stay on our side for another good day of sampling.
Since yesterday the main transect has been done and finished with and we are setting forth again. Now it’s towards the Polar Front. The Polar Front is the boundary between the Cold Southern Ocean and the warmer subantarctic waters. Like other areas in seas were two different water bodies collide this forms a productive and diverse area. Copepods can be found in many forms and shapes and high numbers. Feeding on these copepods is an array of mesopelagic fish such as myctophids. It is also interesting that a lot of the enigmatic wildlife such as penguins and seals will often forage in this area, despite the distance they have to travel. At the Polar front we hope to do plenty of fishing in order to investigate the diversity of these fish and their role in the ecosystem. However, going there is not without trouble. So far the weather has been quite good, grey and dull at occasion but not to rough. As we’re approaching the Polar Front we’re faced with the roughest weather so far. So we have some rest, although this is relative since we often have to hang on to our stuff or inform people that their work area has been transformed from a tidy electricity workshop to, well euh a mess.
A special bonus for this occasion: an English nursery rhyme
Whether the weather be fine,
Or whether the weather be not,
Whether the weather be cold,
Or whether the weather be hot,
We’ll weather the weather
Whatever the weather,
Whether we like it or not!
Well this morning we were passing by South Georgia. We’re nearing the end of the main transect and will soon travel to the Polar Front for a special station. When we visited the bridge just before going to bed we got some nice surprises. First of all these icebergs, despite their nearness to South Georgia, are actual Antarctic icebergs. The detached from the continental ice in the Weddell Sea and have been transported Northwards by the Weddell Sea current. On top of that we got the visit of a couple of hourglass dolphin a fairly common but rarely observed species. The contradiction lies in the fact that they occur in the Southern Ocean were not many people come. However if you get here you have a reasonable chance of spotting them.
Ha Sunday, not a day of rest on the ship, not day for watching cycling races, much rather a day for cleaning. Not for scrubbing the decks but time to change those sheets to sort out the trash and to do laundry. For those people with pondering expressions on their faces: Who on earth (or on sea) will be doing such affairs? Not Anton, he who notoriously hides behind Phd-thesis in order to escape these tedious chores one has to do in every household. He who was publicly reminded to make good his word on promises made in the foreword of that same PhD manuscript. He, who always forgets to turn inside out his clothing before laundry. To those people I say be prepared to be amazed by these graphic images: their mere nature might shock you to the core. Beds made up, clothing being turned inside out, laundry successfully washed….So I’m officially ready for these household chores, no more hiding. Except maybe ironing, I actually don’t do that on the ship….
Firstly the method takes advantage of the acoustics on-board the ship. To put is in the most simple of terms a sound (acoustic signal) that is sent straight down the water-column will hit object in the water-column and part of this signal will return to the ship. This idea is similar to that of radar that the ship uses to detect iceberg and other objects around us. But instead of making a sweeping movement round the ship the acoustic signal remains directed downward and follows the movement of the ship.
With these acoustic signals three different wavelengths are used. This allows discriminating between various types of objects. Anyhow that the scientific part of it. At the beginning of a target fishing period the RMT 8 has been put on the deck at the beginning of the target fishing both nets cocked (like a gun) and ready to go.
When a mark indicating a swarm of krill, is spotted (see the red blob in the picture) the bridge is phoned and a marker is put at the time when the swarm is detected. This allows the ship to find this spot again on the cruise track of the ship. Then the fun starts. A “battleship” turn is initiated. This is basically a turn for emergency situations, such as an iceberg in front of the ship or a man overboard. The direction of this turn is specific for each ship, or rather the rotational direction of the propellers. When turning to one side the prop will actually help in making the turn, turning to the other side only the rudder will give the force needed for turning. After these manoeuvrings the ship will return in its own tracks.
This is the time for action: we need to get on our weather gear, our safety boots, work helmet and safety harness. Some at such times feel like firemen swept up b the alarm, other like fighter pilots getting ready for a scramble, the more down to earth ones among us…. Just like fishermen… Then the net is put over board and lowered to the depth were the swarm has been seen before. When it then comes back on the screen the net is guided through the swarm opening right in front of it and closing just behind it. Then the net is brought back in with a catch that hopefully allows people to do some work.
Oh no, more than a week since my last post…… Well things have been busy around here. I’ll put in extra pics to compensate. Putting in the nets, sorting out the catches and when there is time trying to get some exercise or work on that paper that needs revision.
The JCR has a tiny gym, never the less it is well equipped. But each time I get in there I wonder how they managed to fit everything in there: Was it all measured out in advance or was it a case of trail and error (or bump?). Additionally there’s also an extra workout at 16.30 on Mondays, Wednesdays and Fridays: Circuits. This takes place in the fore hold and is lead by the ships doctor Nerys (This is a welsh name with no etymological link with Nereis diversicolour). Basically it’s about seven stations where you have to do a set of exercises (for instance ten press ups, ten sit ups and ten military star jumps).
First time round you have to repeat these exercises for 3 minutes, the next round 2 and finally 1 minute. There is a small group of hardcore participants (Picture: Ruth, me, Garaint, José, Alex and Nerys) and the occasional influx of other people depending on their work. Anyhow it is all great fun and a great way to start the day unless of course you get called out to start working on the nets…..
Traveling across any part of the Southern Ocean gives you the chance to see unique seascapes, magically sculpted icebergs and a unique wildlife. These things might sometimes make you forget what a harsh environment this is. Here the struggle for life and survival of the fittest can be equally harsh. In the last few days we’ve seen a perfect example of what survival of the fittest means and how relative this is. There is a small white heron called the Cattle Egret. This species is originally native to parts of Asia, Africa and Europe. It is found most in dry grassy habitats often accompanying large mammals such as cattle or even rhinoceroses and feeds on invertebrates and small vertebrates.
With the expansion of man this species has undergone a rapid expansion and successfully colonized much of the rest of the world. So in a global context this species is really successful and can be considered being quite “fit”. However this is quite relative and we’re seeing the brute example. Yes a long bill and a hunched posture is great for picking at those insect and little vertebrates hiding in the grass. Those long stalky legs are also perfect for walking through small shrubs. And that dispersive nature is great for getting you around and to find new pastures, but what if you end up in the Southern Ocean. Well then all of this gets you nowhere. Without salt glands drinking seawater is out of the question, so there’s no drink around for miles. Without waterproof plumage resting on the sea is a dangerous endeavour, especially without webbed feet to help paddling around.
With luck it is possible to eat some invertebrates but that’s hard to do without getting more saltwater into your body. So the only thing left is trying to rest upon a research vessel passing by, trying to get those feathers dry and to survive another day. The first day we saw the Egrets they were about 22 a day later their numbers were already greatly reduced, by now they are gone..
One knows sampling has properly started when the most you get to see is either the inside of your eyelids or the contents of a sampling bucket. As we seem to be arriving at a new station almost every day our days are packed. Our schedule should be one long night every three nights but so far we’ve had three long nights in a row. This is actually the first night that is a tad bit more relaxed and allows me to write another contribution to the blog.
Usually a sampling night starts with some target fishing for krill. For this the RMT 8 is used to sample specific location were the acoustics have indicated the presence of krill. However it has proven astronomically difficult to find krill patches and to successively sample them in large enough numbers for the different studies that are going on. So we often use al if not more than our dedicate time in order to find these ever elusive krill. To make things more fun salps seem to be quite abundant. (Some scientists will say this is only logical but we’re not going to discuss the contents of Nature papers here). Salps are jelly like things, often referred to as the vacuum cleaners of the oceans. For us however they are quite annoying, and beyond the fact that they protect the catch from being damaged by the net there is few positive things to be said. They weigh quite a lot and seem to be blocking anything. Furthermore as the whole catch needs to be processed we need to go through them as well. As soon as everybody is happy with the amount of krill that have been caught, we can move on to other things. This can either be an array of sampling devices with exotic names as the GoFlo, the FRRF, the HPLR, the bongo, the other bongo, the MOCNESS and CTD’s (you cant do oceanography without deploying plenty of CTD’s). Generally these devices require little help from our behalf. So when these are scheduled it’s a slow night for us and we can occupy ourselves with other things. But as told we haven’t had many of those yet. It’s when we deploy the RMT 25 that things get serious.
The RMT 25 is probably the larges net on board and like the RMT 8 is composed of two rectangular net that can be opened and closed from the ship. During a night we deploy it twice. First to sample the upper water masses (400 to 200 and 200 to surface) followed by the deeper water masses (1000 to 700 and 700 to 400). The reason for doing it in this order is twofold: first it allows us the most time to sort out the first catch and as these deployments often get delayed, it is better to sample the deeper layers closer to dawn as the behavior of animals will be less affected by the increase in sunlight. As we are all quite keen on fish and other creatures from the depths of the Southern Ocean it seems we al get an extra jolt of energy once the catch is on deck. Because of the large amount of salps this can be a quite difficult job. The first step in the main lab is sorting out all the fish and invertebrates from the salps. Once this first step is done Gabi generally takes control in writing down the different species and quantities. Usually Yves dives into the invertebrates, identifying a wide range of specimen at sight. Meanwhile José and I attack the fish, we sort them by species and when in doubt Yves has a look at the otoliths often to confirm our suspicions. After that it’s measuring time for José and writing time for me. By the time we work ourselves through all of the catches it is often getting light or it is well beyond that point. So while other people are getting up for their shift and a breakfast we get ready for some good shuteye.
Anyhow working the late shift often gives unique experiences. When we were bringing back the LHPR, a group op chinstrap penguins was feeding next to and behind the ship. From the deck we could see their little bodies darting through the water and occasionally jumping out. Anyhow time to go to bed, before we get blinded by the morninglight……
As we were just of the shelf of the South Orkneys we had quite a mass of water below the ship, over 5000 m of depth to be sorts of exactly. As the first night at this station didn’t involve deploying the RMT 25 we only had to help deploying the other gear. Just at the end of our shift a deep CTD would be deployed.
So it was time for a physics experiment. The duty mess was raided in search of polystyrene cups, the disposable cups you get hot beverages in. These cups were den clearly labeled and put into a bag. This bag was then attached to the CTD to make the trip below 5000 m. The results of the experiment were astounding.
As the depth increases by ten meters the pressure increases by one bar. This means that at about 5000 meters you have a pressure of 501 bar. While such an increase in pressure doesn’t affect solid materials (The CTD looked pretty much the same coming up) it does affect more compressible materials such as polystyrene cups. Anyhow, the before and after pictures should speak for themselves.
On this campaign there are four people working on fish: José, Gabi, Yves and me. We form quite a heterogeneous group in terms of nationalities and interests. José is a highly energetic Portuguese squid and top predator specialist. Gabi is a German scientist working at BAS that analyzes the foodweb structure of the Scotia Sea using isotopes and fatty acids. Yves is a French household name in the study of penguins and other predators. This group is completed by a Belgian guy doing ecology and genetics.
Our main task on board are helping putting the RMT 25 nets out as well as sorting out the catch an preserving everything so it can go back to Cambridge. Their the samples will be set to use for various purposes to suit our needs. As most of the fishing with the RMT 25 will take place during nighttime, when it is easier to catch the fishes, we’re all on a night shift (18.00 to 6.00 Falkland time). So last night we finally got the chance to get started with the proper work. And getting the Big RMT 25 in and out of the water is indeed a proper job. It takes at least four persons to haul in the nets, especially if they are well filled. And after that it’s sorting time: looking at the various specimen net only fish but also jellies, decapods and amphipods. Once in a while an exclamation is heard in the lab when a new curious specimen is discovered. All in all the first catch wasn’t that big, but there was a considerable variety and it was just he right size to keep us occupied until the end of our shift an curious for more discoveries.