Wednesday, 30 January 2008

Whales and Albatrosses

Last night we crossed over a ridge into the Georgia Basin. This means that we are now downstream of South Georgia. This has two main impacts on the biology. Firstly, iron from South Georgia and/or the shelf surrounding it fertilises the water and causes a very strong phytoplankton bloom, concentrations being several times levels found further south. This captures a large amount of carbon dioxide out of the atmosphere and probably exports it to deep waters. This takes it out of contact with the atmosphere for several hundred years. I say probably as we we will recover the sediment trap tomorrow, but we (Southampton/PhD hat on temporarily) have shown this around the Crozet Islands. The second effect is we've got Krill back. We spent all night trying to catch them, but without success - very frustrating. Also means cetacean numbers are up - 6 Humpbacks and 6 Southern Right Whales this morning, and 5 Hourglass Dolphins.

A feeding group of Southern Right Whales

Bird numbers are also up and we had a new game during the last CTD cast of reading the code on a plastic ring on the leg of one of the birds. I eventually got it through binoculars and Jose confirmed with an excellent photo. Will be interesting to hear about the bird, it is presumably from Bird Island, a BAS base on a small island at the western end of South Georgia where birds and seals are studied.

ps to Elaine (and maybe others) I am starting to get some photos of inside the ship and will post them soon.

Sunday, 27 January 2008


After 6 weeks in the Southern Ocean I guess I can't really complain about a bit of a blow, but it certainly came at a frustrating time. We had found a site of very low productivity (from satellite images of chlorophyll), which we wanted to sample as a contrast to the high productivity found around South Georgia. We did a day's work there but then the wind got up and we couldn't put the big nets in. We can deploy CTDs in rougher weather than the nets so time pressure forced us to abandon the remainder of the station and press on with the CTD transect. Then it got too bad for CTDs. We skipped one (we go much slower in rough weather so were still losing time) but then sat at the next CTD location until things improved. They did, briefly, and we got to the next station. Then it got properly windy, which is better in some ways as you know you're not going to deploy anything for at least 12 hours so can relax (or just switch concentration to the ship pitching up and down into the waves, though I'm basically immune to that now). Things are better now, we've done the survey and crucially recovered the mooring (needs calm conditions). Better still, all the instruments on the mooring have worked.

Wildlife-wise there have been occassional sightings of Hourglass Dolphins, my view lasting about a second, so no chance of photos. We've started seeing Diving Petrels - common but not very good fliers (they are quite similar to Puffins) so they don't venture far from South Georgia. Macaroni Penguins are also a new species for the trip. At 6.30am a couple of days ago the low sun picked out large numbers of Prions and Blue Petrels flying away from South Georgia (they change over at the nest at night and we are 120 miles away, they also have white underwings).

Their place, we're just fairly incompetent visitors.

Antarctic Prion, feeds on zooplankton. We're trying to show it goes to places with lots of zooplankton, would make sense, but we'll see how the data comes out.

Wandering Albatross. It's rarely possible to accept how big they are (about 11foot wingspan - that is, a sensibly sized person each way from the body.

Saturday, 19 January 2008

Settled in

We are now about three weeks into the cruise and everyone is settling into the routine of transect, survey, 2-day station.

The transects is a series of CTDs - density profiles to the bottom (well, about 10m off the bottom is the aim, and neither Mags or I have hit the bottom yet, wouldn't be good). This will be used with a series of other transects (taken at different times, oceanography is a compromise) to look at the water properties flowing into and out of the Scotia Sea to look at how the water must mix vertically and horizontally (actually along and across layers of constant density, which isn't quite the same thing) to get from what flows in to what flows out. This will be compared to direct measurements of this mixing from other cruises.

The surveys are normally 24 hours, sometimes 6 hours to characterise the area we are working in for 2 days - looking at how the point measurements relate to the larger scale and also looking for strong gradients in water properties we don't want to cross - we had a very strong gradient last station but only crossed it once and that was after we closed the net, so it was OK. We have two guys recording seabirds in a 300m box off the bridge wings during these surveys and during the transect. I'm free from the survey discipline and keep telling them what they missed behind the ship! On the last survey they recorded 50 Fin Whales and 2 Humpbacks on their side of the ship, and there were plenty more the other side and when we were turning round as well.

Fin Whales, some of many

The stations are a mix of activities to see what is in the water, from the nutrients (nitrate, silicate and iron), physiological condition of phytoplankton and associated nutrient (iron in this place) and light constraints, through small zooplankton (especially life stages Oithona similis, a copepod abundant enough to be filtered from 20l of water, collected from 12 depths during a dedicated shallow CTD cast), krill (life stages, abundance and dimensions to compare with acoustic backscatter, genetic effect on diurnal cycles), pteropods (snail-like things that are very hard to get on board without damaging them) up to fish (myctophids, one potential new species caught at the last station). Always hard to see how things are working out during the cruise (and more so before half way) but things have generally gone well, most of the kit is working and we are catching krill and fish (apparently not a given!).

Incubators - water is collected and put in bottles, incubated in pumped seawater to keep it cool and shaded (a known amount, different between the boxes) from the sun, to simulate being under a certain depth of water. Some bottles have iron added to see what difference that makes.

LHPR (someone-someone Plankton Recorder) catches small zooplankton against a gauze that rotates every 2 minutes, to give a profile through the water column. A specialist in flat zooplankton then picks the animals off the gauze.

MOCNESS (Multiple Opening/ Closing Net and Environmental Sampling System), opens and closes at different depths (via someone sat at a computer) so sample relatively small things at known depths between 1000m and the surface.

RMT25 (25 metre squared net opening) coming back on deck. The winches are run by crew, but scientists pull the net on (the four guys with harnesses on). Used to sample large things (up to myctophid fish) down to 1000m. A smaller version (RMT8) is used to catch Krill near the surface and bring them back alive.

Geraint and Jose recording the non-fish part of a catch

Some of the fish, from between 1000m and 700m deep.

We have also pushed southwards into the ice to repeat a line of CTDs to look for changes in water mass properties associated with changes in sea ice or land-ice inflow. We are taking samples of water to analyse (well, for someone else to analyse) for oxygen 18 isotope ratio (to the common oxygen 16). Being heavy, O18 fractionates during evaporation (it preferentially doesn't) so land-ice is low in O18 compared to sea-ice so it can be used to distinguish between fresh water from land-ice melt (via icebergs) and sea-ice melt. We had a couple of hours at Signy research station as well, long enough to roll some empty oil drums past some Elephant Seals and walk out to a stream to collect fresh water running down from an icecap, as an end-member for the O18 ratios (no sea ice at all). Was fun to get out for a short walk (through fresh snow, up to 2 feet deep) and talk to the base assistant (professional cameraman, mostly video). No Emperor Penguins despite lots of searching, one very southerly King Penguin got me excited though (and was a good record in it's own right). One Minke Whale amongst the ice, missed a Killer Whale by about a minute and saw what must have been a Leopard Seal - only saw a grey thing roll very quickly, but the 50 penguins radiating out from that spot at full speed was something of a clue.

Pushing through the broken ice floes.

Crabeater Seals - seen fairly frequently through the ice.

Snow Petrel - typical species of the ice, only rarely seen over open water

The ice edge, as we left.

Yes, we did do some work down there, exact locations of CTDs varied from planned locations as we needed to find a large enough hole in the ice.

The ship, from Signy (apparently the area was free of snow the previous evening)

The cargo tender that brought us, some empty oil drums and some fresh veg in. We didn't have to stop, but it was clearly much appreciated by the guys on base, and everyone enjoyed having a bit of a walk.

One of the locals

There is running water here, honest (we had to dig down to it)

One of the many small islands around the South Orkneys.

Some stunning sights, helped by the sun being out on the northern side of the islands.

Saturday, 5 January 2008

Settling down

We're coming to the end of the first of 9 process stations we'll be occupying during this cruise and things are beginning to settle down. There have been the inevitable problems with kit but they are mostly sorted by the tech guys now. We spend about two days on a station, mostly using a variety of nets and fishing methods to get plankton of different sizes from different depths for different reasons - some want live krill to test their daily rhythms, some just want to know how much is down there and don't mind how it comes back so long as they can identify and count it. There are three CTD casts per station - one full depth for physics and deep water, which doubles as a shallow cast for phytoplankton (the whole package goes to the bottom, but most bottles are closed near the surface; the other two are for collecting large volumes of water for a couple of people's work, but we will use the data from the casts for a couple of things.

Between stations there will be a series of full depth CTDs for physics so we (Mags and myself) will be much busier between stations than on them - out of sync with everyone else. Most of the initial rush to set up processing programs to deal with the exact details of the cruise and kit is done now so things are getting calmer. I have also been editing some of the processing scripts to make them easier to use.

This station has been the 'ice edge' but due to restrictions of using nets and towing things we have had to stay about 6 miles off from the main areas of ice so it doesn't really feel like it. There are a few icebergs around, but there were several hours to the north as well.

The first iceberg and the best bit of ice so far

A few icebergs around - not really what many of us had in mind for an 'ice-edge' station!

Bird/cetacean-wise we (there are some other keen birders amongst the biologists, and two dedicated seabird observers) haven't seen any ice-edge specialists. There have been some photogenic Chinstrap Penguins around and a few birds around the ship. A Minke Whale investigated the ship briefly at the beginning of the station but that has been the only cetacean, except for some that the seabird guys have seen.

Chinstrap Penguins have been hanging around the ship today. The calm water is because it is in the lee of the ship. The sea is calming down now after a relatively strong blow at 4am made everyone stop to consider what work we could do, luckily it didn't continue.

Wilson's Petrel - about the size of a Blackbird, but quite at home in the open sea.