Southern Ocean Iron Experiment (SOFeX) Cruise
January 5 - February 26, 2002
Skip to Log Entry from the R/V Melville
February 9, 2002: Day 36
Position @ 2/9/02 0511Z, -54 10.5562, -169 17.9274
R/V Revelle Log Entry: Hi world. Were sitting right in the middle of the North Patch, conducting a sampling station.The MLVS pumping system is operating right now for about 7 hours, which is giving us a slight break. Weve been going non-stop since we entered the North Patch yesterday at 1315. The SeaSoar group towed all night and finished operations just after breakfast.
Our initial survey with the ship shows that the patch (shown here as chlorophyll fluorescence contoured in the odd and arbitrary units used by the ships data computer) is strung out in a long filament oriented to the NE. The SeaSoar group managed a very nice tow up its long axis (and defined its northern limit), as well as several sections across the patch. A weak, but nicely coherent, SF6 signal shows that this is our patch. That first turn along the ships track from the south at 54.4 is the initial way point that we set 700 miles back as we left the South Patch. Pretty good aim, thank you! This patch finding business is a piece of cake.
The weather has been cooperating beautifully. Wind has been less than 10 knots all day and the sky is clear right now. Were hoping for another SeaWIFS image. All the imagery, daily updates, e-mails etc. are delivered courtesy of Dan Jacobson the shipboard computer tech.Dan is the ships raconteur and, most importantly, fixer of broken e-mail servers. Also takes all the heat when the chief scientist delays e-mail to complete the daily update and complaints come pouring in. Says he only came for the bird watching! Careful with the XBT launcher, Dan, you might bonk an albatross!Another Shackleton contestant. Thats all for now.Time for a rest.
- Ken J.
Position: 66 degrees, 10 minutes South, 171 degrees, 58 minutes West
R/V Melville Log Entry: A very productive In Station yesterday culminated in Mike Landry and Cecilia Sheridans "zooplankton tow'." The funny thing is that even though this is a 200 micron net, through which most phytoplankton should pass, they catch very few zooplankton. But they sure catch a lot of phytoplankton!Maybe this is a joke only appreciated among ship-bound oceanographers.
It has been reported that shipwrecked sailors in lifeboats used pillowcases as sea anchors to keep their bow into the wind and keep them from drifting too far.They would then pull in the pillowcases, harvest the plankton caught on the fabric and eat it. In this way they could sustain themselves for quite some time on this vegetable stew. A short vertical 5 minute tow nearly clogged Cecilias 1 meter net. One could certainly last a while eating vegetable stew from this station. But where are all the zooplankton to eat such a feast?Mike hand examined and picked an entire tow (representing many hundreds of cubic meters of water) and came up with only about 50 (about 1 per 10 cubic meters of water). This is a small number for such a bloom, like one cow in all of Petaluma - not really enough to have a big impact on all the grass. This may also be the reason why the bloom seems to be gaining in momentum and biomass: lack of zooplankton grazers to mow this crop of phytoplankton. I see a big fire season coming on.
Cecilia has been taking the zooplankton she does find and incubating them with water from the patch. Later she analyzes their gut contents to see what species they are preferentially grazing. Like cows, copepods are selective and wont or cant eat some kinds of phytoplankton. Unlike cows, the products of zooplankton grazing can export the system at the rate of hundreds of meters per day. These are real steamers and the term "fecal pellet express", coined by sleep deprived and overcrowded oceanographers, was derived from this efficient and rapid transport of surface water derived materials to the deep sea. Who says cows cant fly?
Saturdays stations also revealed some of the highest chlorophyll we have seen yet at this station - this is about 20 times above background (Outside Patch) stations. The condition is visible to the naked eye and would be readily detectable from space if we had a clear day. A muted coastal green is the color from the side of the ship.
Sundays activities involve a linear transect through the patch from inside to outside, turning around and completing the transect inside to out in the other direction. This makes for fast and furious turn-arounds of the CTD Rosette sampler and a busy water brigade in the aft hanger. My water budget shows samples being taken for 33 different analyses. The rosette is essentially being sucked dry as water thirsty scientists (David Cooper, Eva Bailey, Atma Roberts) fill their tubes, flasks, pressure vessels and bottles.
Oops, the CTD Rosette just tried to go through the shiv on the A-frame. It is going to be a long day. Gotta go.