SEAPLEX Day 18 Part 1

All sampling on the SEAPLEX cruise has stopped.  They are experiencing some rougher weather (6 feet swells).  This means that the ship can’t travel quite as quickly, so they don’t have time to slow down even more to sample if they want to make it to Newport on time.  So now, they are packing and anxiously awaiting the time when they will be near enough to shore to have internet access again!

Our first post today is from Darcy Taniguchi.

Darcy writes:

Hello yet again outside world! This is Darcy Taniguchi, writing to you from the R/V New Horizon as our cruise winds down and we head closer to port. After all these blogs, I’m sure you have seen mentioned several times our various standard sampling instruments—the manta net, Matsuda-Oozeki-Hu trawl (aka Oozeki trawl), bongo net, and CTD. I am sure that you have read some of the other information about these pieces of equipment. However, I will use this blog
entry tell you what data we obtained from each one.

First, the manta net. Oh the manta net. This piece of equipment has become sort of the bread and butter for several people on this cruise.   It samples at the surface,  so it is used to catch particles and organisms which are floating at or very near the surface. In it, we have managed to capture such things as numerous types of crustaceans, gelatinous salps, glowing lantern fish, and, of course, multi-colored plastic pieces.

Next, the bongo net. This instrument is also used to collect zooplankton, just like the manta net. However, it is used to catch organisms deeper in the water. On this trip, the bongo net has been able to catch many little crustaceans, such as the often abundant copepods and krill, as well as glistening comb jellies and perhaps the occasional piece of plastic.

Now, the Oozeki trawl. This is another kind of net, but it is bigger than a bongo or a manta, with a frame about the size of a Smart Car. The target depths to which this equipment is deployed is between 150 and 800 meters (492 to 2625 feet). At these different depths, the net has come up with various types of interesting, sometimes rarely observed, fish, although, there are other (unlucky) organisms which have also been pulled on deck—pyrosomes that exhibit bioluminescence, jellies that you have to squint to see, and squid with googly eyes, to name a few.

Last, but most certainly not least, is the CTD, which stands for conductivity-temperature-depth. The CTD is a real workhorse in oceanography, being used in the realms of marine chemistry and geology, physical and biological oceanography to look at the structure of various properties of the water with depth. Besides the sensors for temperature and conductivity (used to determine salinity), the CTD can also be outfitted with equipment to measure oxygen, light from the surface, fluorescence (from things like phytoplankton), nitrate, and water clarity. These sensors are on a large, cylindrical frame that is also outfitted with special bottles called Niskin bottles. These bottles have caps on either end that are closed with a click of a button at whatever depth the scientists on board wish to snap them shut, thus collecting water from that chosen depth, which is later sampled. Thus, the CTD can provide immediateinformation about the different regions in the ocean described by these variables as well as for the collection of water within regions of interest.

With these different pieces of equipment, we are cooperatively trying to collect various types of organisms at different depths within the ocean, as well as put them in the context of the structure of the water column with depth. These instruments are by no means unique to our expedition but instead are tools which can be and have been used in a wide variety of studies. Nevertheless, we hope that they have done well on this particular cruise in collecting enough information to begin to help us determine what effects, if any, plastic may be having on organisms of the north Pacific gyre.

Captain Wes Hill on the bridge of the R/V New Horizon during the SEAPLEX research cruise.