Tag: codend

NOAA Teacher at Sea
Julia West
Aboard NOAA ship Gordon Gunter
March 17 – April 2, 2015

Mission: Winter Plankton Survey
Geographic area of cruise: Gulf of Mexico
Date: March 22, 2015

Weather Data from the Bridge

Time 1700; clouds 100%, stratus; wind 325° (NNW), 9 knots; air temperature 22°C, sea temperature 25°C

Science and Technology Log

Here’s what we have covered as of Sunday evening, 3/22. I’m getting quite the tour of the Gulf! Notice we are going back and forth across the shelf break (the edge of the continental shelf), as that is our area of interest.

Again, thanks to all of you who are reading and asking questions. One recent question had to do with whether we are bringing specimens back. So let me explain what we do with them. Most plankton are so small that you see them best through a microscope. So the “specimens” that we are bringing back are all in jars – thousands of organisms per jar! Every time we collect samples, we get at least three jars – two from the bongo nets and one (or more) from the neuston net. That’s not including the CUFES samples described earlier, which are only big enough for a tiny bottle. Here are some pictures:

These samples get brought back to shore for analysis in the NOAA lab. Oddly, many of the samples get sent to Poland to be analyzed! Why Poland, you ask? Well, for a few decades we have had a cooperative agreement with the Polish sorting and identification center. They remove the fish and eggs from all samples, as well as select invertebrates. These specimens and the data get sent back to US for analysis. We double check some of the IDs, and plug the data into models. (If you are a biology student, this is an example of how models get used!) The information then goes to fisheries managers to use to help form fishing regulations. This division of NOAA is called the National Marine Fisheries Service (NMFS), which manages stocks of fish populations.

NOAA has been doing spring and fall plankton sampling for 30 years now. Winter sampling is newer; it started in 2007. SEAMAP (SouthEast Area Monitoring and Assessment Program) is cooperative agreement between the Gulf states, federal (NOAA), and university programs. The samples from the states and universities get sent to Poland with our samples. The the timing of the surveys is to target specific species when they are spawning. This winter survey is targeting grouper, tilefish, and other winter spawning species. The other surveys target bluefin tuna, red drum, red snapper, and mackerels, which spawn at other times of the year. The invertebrate data is used to build an understanding of invertebrate community structure throughout the Gulf.

In science, research is cumulative. We know, from past research, what the mortality rate of some fish species is. So if we get a fish larva or fry that is a certain size, we can estimate the percentage of that size larvae that will reach adulthood, and back calculate to see how much mortality has already happened to get fish of that size. All this allows us to get a peek into the size of adult population.

The first piece of equipment that we use when we get to each station is the bongo nets. You can see how they got their name!

Here are the bongos ready to be deployed:

The flow meter is inside each bongo net, near the top. We read the numbers on it before the net goes out, and after it comes back. Using this information – the rate of flow, together with the area of the opening, we can calculate the volume of water filtered. The SeaCAT is a nifty unit that measures conductivity (salinity), temperature, and depth. Since we have a much fancier unit to measure these factors, we use this primarily for depth, so we know when we are getting to 200 meters (or the bottom, whichever comes first). We go to 200 meters because that is the lowest effective light penetration. Phytoplankton need light, and zooplankton need phytoplankton! What’s more, larval fish have not yet developed their lateral line (the organ that many fish use to sense vibrations in the water around them), so they feed visually. Even if they want to eat something below the photic zone, they wouldn’t be able to “see” it yet.

I, of course, am full of questions, and knowing that I’m supposed to identify every acronym I write, I asked what SeaCAT stands for. The unit is made by a company called SBE (Sea Bird Enterprises), so is the CAT just a fun name that they came up with? Nobody knew the answer! But everyone was curious, and Tony and Steve (both electronics technicians) did some emailing and got the answer straight from SBE. CAT stands for “Conductivity And Temperature” (seems we could have figured that out). And the Sea? Could be for Seabird, Seattle, or just the plain ol’ sea!

Once we get the nets in the water, the crane operator monitors the speed that it is lowered. Our job is to communicate the “wire angle” constantly to the bridge and the lab. Here’s how this is done:

The angle of the cable is important because it allows the nets to sweep the desired amount of water as they are pulled up. If the wire angle is too high (above 55°), the crew on the bridge slows the ship down just a bit. The perfect angle is 45°. Many other factors can mess this up, most notably current. The ship has to be facing the right direction, for example, so the current isn’t coming toward the ship (have you ever been fishing and had your line swept under the boat?). It’s tricky business, requiring constant communication between bridge, lab, and deck! Oh, and by the way, the cable is a “smart wire,” meaning it has electrical flow through it, which is how the depth gets communicated to the computers. Fascinating technology, both on the micro and macro scale!

Once we pull in the bongos, we hose them off very thoroughly, to get any of the little plankton that are stuck to the net. They are all funneled into the codend, which is a PVC cylinder. From there, we dump the sample into a sieve, and transfer it into a jar, and get read to do it again in 3 hours or so.

Did I tell you that sampling goes on 24/7? Perhaps you figured that out when you heard the shift times. It costs a lot to run a ship; operations continue whether it’s night or day.

Personal Log

Now, to keep people happy when they are living in close quarters, far from home, and working strange shifts, what’s the most important thing of all? FOOD! The Gunter is well known among NOAA circles for having fantastic food for people of all diet types and adding ethnic flavor to her meals. The person responsible for our good and abundant food is Margaret, our Chief Steward. She has worked for NOAA for ten years, and says it’s the best job she has ever had. Her husband is now retired from the Coast Guard, so they moved around a lot. Margaret worked for the Coast Guard for four years, then went back to cooking school, and had various other jobs before signing on with NOAA. She has a few years left before she retires, and when she does, what will she do? She wants to do subsistence farming! This is right up my alley – Margaret and I have a lot to talk about! Not to mention the fact that Margaret makes her own juices, some amazing homemade hummus, AND dries her own fruit (dried cherries -yum!).

Margaret also has a helper, Mike, who was reluctant to have his picture taken. He’s not the usual assistant steward, but sure seems highly capable! It always sounds like a lot of fun is being had in the galley.

That’s it for this post – I’m getting hungry. Time to eat!

Challenge Yourself

What executive branch of the U.S. government does NOAA belong to? Is it the same branch that oversees our national parks? How about our national forests?

Did You Know?

There are nearly 4000 active oil and gas platforms in the U.S. Gulf of Mexico (NOAA), and more than 27,000 abandoned oil and gas wells (Assoc. Press, 2010)