Stacey Jambura: Sargassum, Sargassum, Sargassum! July 15, 2012

Stacey Jambura
July 6 – 17, 2012
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Geographical Area of Cruise: Gulf of Mexico
(You can view the NOAA ShipTracker here: http://shiptracker.noaa.gov/shiptracker.html)
Date: July 15, 2012
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Weather Details from Bridge: (at 18:45 GMT)
Air Temperature:  28.6◦C
Water Temperature: 28.5◦C
Relative Humidity: 73%
Wind Speed: 9.28 kts
Barometric Pressure: 1,017.65 mb
 

Science and Technology Log

The Neuston Net

Nueston Net
Neuston Net

The Neuston net is the first net to be deployed at sampling stations. This net has a wide rectangular opening that skims the surface of the water to collect surface dwelling organisms. Before the net is deployed, a cylindrical cod end is attached to the bottom of the net. The cod end has many holes that are covered by a screen. The screen allows water to flow through, but the organisms to get caught. We usually deploy the neuston net for 10 minutes, but sometimes we only deploy it for 5 minutes, depending on the amount of sargassum that is collected inside the net.

Filefish
Filefish collected from sargassum.

Sargassum is a type of seaweed that floats at the surface of the water, almost like little islands. Sargassum provides an important habitat for many marine animals in the open ocean. We frequently find small filefish, jacks, and flying fish, as well as juvenile puffer fish, crabs, and shrimp. Young sea turtles also use the sargassum as a hiding place from larger predators, though we have not found any during this trip.

Sargassum
Sargassum
(image from www.bigelow.org)
Emptying the Neuston net
Emptying the Neuston net.

When sargassum makes its way into our Neuston net, we collect all of it into large buckets. We have to rinse all of the sargassum off into large buckets to make sure that we collect all of the creatures living inside of it. We do this because we want to get the most accurate sampling of the population of living organisms in the sampling area. Depending on how much sargassum is collected in the Neuston net, the collection process can anywhere from 10 minutes to an hour!

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Rinsing a sample into a sieve.
Rinsing a sample into a sieve.

Once the sample has been rinsed into buckets, the buckets are poured into sieves. The sieves have screens that allow the water to flow through, but not the organisms we want to save. Once the buckets have been poured into the sieves, rinsed, and poured out again (to make sure nothing stuck to the inside of the bucket), we use alcohol to rinse the sieves into funnels that channel the sample into quart-sized jars. Once the entire sample has been rinsed into a jar, we fill the jar with alcohol, place a label inside the jar to record the location the sample came from, stick a similar label on the lid, and place the jar in a box back in our chem lab. The samples are analyzed later at a lab once the survey is over.

 

The Bongo Nets

Bongo Nets
Bongo nets being deployed.

Bongo nets are similar to the neuston net, but there are some differences. The bongo nets have cod ends like the neuston, but they have two cod ends because there are two separate nets, where the neuston has only one. The holes of the bongo cod ends are covered by screens that have smaller openings than the neuston cod ends so that they can collect smaller organisms. The main purpose of the bongo nets is to collect plankton samples. We cannot collect plankton easily using the neuston net because the openings in the screen on the cod end are larger.

Bongo Nets and Cod Ends
Bongo Nets and Cod Ends
Relaying Flow Meter Numbers to the Lab
Relaying Flow Meter Numbers to the Lab

Before the bongo nets are deployed, we have to report the numbers on the flow meters from the left bongo net and the right bongo net. The numbers on the flow meters are used to determine the amount of water that passed through the nets during deployment. Depending on how deep the water is determines how much water passes through the nets. After the nets are deployed, a sensor sends a message back to the lab to determine their depth. The person back in the lab monitors the depth and makes sure that the nets go as far down as possible, but do not make contact with the ocean floor. If the nets were to make contact with the ocean floor there is a good possibility that they could be damaged, which is why it’s so important to closely monitor the depth of the bongo nets. After the nets are brought back up on deck, the numbers are reported back to the lab where they subtract the first number of each flow meter (left bongo net and right bongo net) from the final number from each bongo. The difference is then divided by the length of time the net was deployed in the water.

Flow Meter Numbers
Flow Meter Numbers
Bongo Net Sample
Bongo Net Sample

Personal Log

Day 8 – July 12th

Sunset
Calm waters as the sun sets over the Gulf of Mexico.

Today was a VERY slow day. We only had four sampling stations, and of those only one was a trawl station. I was able to work a bit more on my blogs today, and start working on some cool lesson plans to bring back to school with me this fall. We also managed to watch a couple movies and raid the ice cream freezer during our down time. The seas were exceptionally calm tonight, almost as smooth as glass. It was very calming and serene, almost surreal! I made sure to take several pictures before the sun had set. The waters were smooth for the rest of the night which made for easy sleeping..

Day 9 – July 13th

Trawling was the focus of today. We had 4 trawls plus a couple neuston and bongo net sampling stations, so it was quite the busy day! We saw quite a number of new species that we hadn’t seen in previous trawls so I made sure to photograph those to share with my students later. At one of our sampling stations, we collected almost 6 5-gallon buckets worth of sargassum in our neuston net. It took us quite a bit of time to rinse it all down and collect the samples into preservation jars. It took three, quart-sized jars to hold all of the sample we collected!

Day 10 – July 14th

I found out this was our last day of sampling before we make our way back to Pascagoula. We mostly had trawls today, so we got to examine lots of critters. We had lots of down time because one of our runs to a sampling station was almost four and a half hours long! I spent that time working on my blog, and taking a much needed nap to catch up on my sleep! We had a really pretty sunset right before a thunderstorm that delayed one of our trawls. We worked right up until the next team came onto their shift and took over cleaning up from our trawl.

Day 11 – July 15th

All of our sampling was completed over the night, but I was able to work on the last neuston/bongo sampling when I went onto my shift. After all of the sampling was done, it was time to start scrubbing everything down to get it back into ship shape! The wet lab, dry lab, neuston net, bongo nets, and the stern were all hosed down, power-washed, scrubbed, bleached, and Windex-ed until everything smelled clean again. It took us most of the afternoon, but when it was done, we were done! The rest of our time on the Oregon II was left for unwinding and relaxing. After a lunch of king crab legs and a Thanksgiving-like dinner, my stomach was happy and satisfied (but not until after an ice cream sandwich of course!) Movies filled the remainder of the afternoon and evening, until I was ready for bed.

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