09 April 2004

Friday, 9 April 2004

Sifting the seas

Today is our penultimate day of patch occupation! The SF6 shows that the patch is holding together fairly well, and the phytoplankton are still healthy. I measured the chlorophyll a concentration this morning in the patch and it hasn’t really changed significantly in two days. We are all still a little perplexed by why there hasn’t been a much larger increase in plankton, but it has certainly been interesting to follow and try to figure out. Late last night we received some results from a light experiment and it appears as if the phytoplankton, if given enough light, will accumulate in biomass. It is significant that throughout most of this voyage, the sky has been heavily clouded. There is still much more work to do to fully understand this experiment, but it may be that light is a part of this puzzle.

It’s not uncommon to reflect on your workload towards the end of an oceanographic cruise. At teatime yesterday a couple of us were pondering the magnitude of seawater volume being filtered on this cruise. I was inspired to share the results of this conversation with you and highlight some fun facts on our top filterers. Consider this a tribute to the unsung hero: the resolute, the persevering, a.k.a. the filtering fool. They are those of us that handle great amounts of water in order to make their measurements. Two filtering scientists that came to mind were Scott Nodder (NIWA) and Karl Safi (NIWA). Scott focuses on making biogeochemical measurements in the water column. He is interested in how much the particulate pool is changing in terms of its nitrogen, phosphorus, chlorophyll and silica concentration. Karl Safi is interesting in rates of microzooplankton grazing. Microzooplankton are the small (< 200 um) zooplankton that live in the water column. Although Scott and Karl are interested in different aspects of the water column, they both filter the water to obtain their sample of interest. Sometimes we put seawater through a filter and collect what goes through and other times we are actually interested in what gets caught on the filter. In a head-to-head competition, Karl actually wins for volume with 2200 liters!!! Scott’s efforts resulted in impressive total of 650 liters. Scott uses a liter of water for each of his measurements; this means that he’s used a graduated cylinder 650 times this cruise. Whew, I’m getting tired just thinking about it.

Another big event today was when the computer on the flow cytometer, an instrument that counts phytoplankton and bacteria cells, had some problems. In the photo Julie Hall is showing it who’s boss. The flow cytometer is a critical instrument for our biology group. Since it is able to count cells, we can understand what is happening in the patch and in our experiments quickly and react appropriately. Through a multi-approach group effort, the team on board was able to get it up and running again by the afternoon. Incidentally, in the same photo, you’ll see a bear. This is no ordinary bear supervising Julie. Meet Bryan the Teddy Bear. He’s jumped in the photo in order to send a friendly message home.

I am Bryan the Teddy Bear. I am a GeoBear and belong to Mrs. Abbotts’s 1st and 2nd Grade class from Meadow Vista California. I joined the research cruise with one of the scientists. I would like to say Hi to all the students in the class. I will be home soon!!!

And so will we!

Jill Peloquin (VIMS)

Julie tackles the flow cytometer.

Karl Safi filtering water samples.

The other filtering legend: Scott Nodder.

Jill Peloquin at work in her lab.

Research subject: Oceans