NOAA Teacher at Sea
Wes Struble
Onboard NOAA Ship Ka’imimoana
July 8 – August 10, 2010
Mission: Tropical Atmosphere Ocean (TAO) cruise
Geographical area of cruise: Equatorial Pacific from 110 degrees W Longitude to 95 degrees W Longitude
Date: 3 August 2010
Weather Data from the Bridge
Position: 7 degrees north latitude & 95 degrees west longitude
Cloud Cover: 5/8
Cloud Type: Cumulus, Stratocumulus, & Cirrus
Visibility: 10 nautical miles
Wind Speed: 14 knots; Wind Direction: 240 degrees
Wave Height: 1 foot; Swell Height: 3 – 4 feet
Atmospheric Pressure: 1010.5 mb
Temperature: 27.2 degrees C (81 degrees F)
Science and Technology Log
As I have mentioned before many of the buoys in this part of the Pacific Ocean are badly vandalized and some are completely missing. Buoys that have been deployed for 6 months or more often sit low in the water. This is not because the flotation toroid loses buoyancy (although when damaged they can take on large volumes of water), rather it is usually due to the massive amounts of marine life that tends to cling to the buoy and its underwater substructure.
When the buoy is slowly lifted onto the fantail work area at the stern of the ship it will be encrusted with barnacles that can add up to an additional 500 to 1000 lbs to the buoy’s weight. Many are attached directly to the float’s surface while others have extended themselves and hang down several inches. Sometimes they have completely covered the substructure. These barnacles create a lot of extra work for the science crew – scraping, cleaning, and repainting of the buoy toroid.
In addition to the barnacles one often finds small crabs. Most of these are no bigger than a half dollar coin (although we did find one larger specimen – see the included photo). One of the most odd and dangerous creatures often present hidden in and around the barnacles are Fireworms (see photos). These particular polychaeta organisms can reach up to 20 inches in length and have a diameter about the same size as an average adult human finger. They are covered with a very impressive set of spines and/or hairs that carry a potent toxin that stings and burnstouched. I have been told that the sting is particularly painful. These organisms can get relatively large and at times there can be quite a few on one buoy. The science team has to be wary when they are handling and cleaning a buoy so as to avoid touching these creatures. On the previous buoy we found a total of six.
In addition, we even found one small fish that got caught in the substructure and brought in with the buoy. It is not difficult to understand barnacles attaching to the buoy substructure because we know that ships often will have problems with barnacles on their hulls. But it is more difficult to understand how Fireworms and crabs (which usually inhabit the sea floor) could be living on the buoys where the water is over 10,000 feet deep!
We have also had more aerial visitors the last several days (probably due to our relative proximity to the Galapagos Islands – which are currently about 200 nautical miles to the east). Earlier today some members of the crew sighted a Boobie and we are now being followed by a small flock of frigate birds. In fact, one of the frigate birds was hiding inside the central cavity of the buoy. It escaped when we began retrieving the buoy line.
We just released an Argo buoy yesterday afternoon. There are a number of differences between the Argo buoys and any of the other floats or buoys we work with here on the KA. First of all they are much smaller and lighter (they weigh about 60 pounds, but are precision weighted in order to maximize buoyancy ability. Nothing extra can be put on them without buoyancy compensation being taken into consideration) than the large TAO buoys (which weigh in the neighborhood of 1500 lbs.). Most buoys are anchored to the ocean floor in order to get a constant data return from a particular location. The Argo buoy, on the other hand, is a drifting buoy, like a disposable/portable CTD – it is not tethered to the sea bed but drifts with the currents collecting temperature, salinity, and density readings.
The other main difference is the way that Argo buoys collect data. These buoys are semi-autonomous being programmed to follow a particular sequence of data collection events and motions. When released the buoy begins floating at the surface in a horizontal position. There is a small hole in a compartment at the base of the buoy. This cavity slowly fills with water causing the buoy to flip to an upright position. When in this position the buoy’s antenna is out of the water and is able to transmit data to the data collection center. After a time it slowly sinks to a depth of 2000 meters (over 6000 feet or over 1 mile) where it remains for 10 days. After this period the buoy then rises to the surface to expose its antenna and transmit data, which it does for a period of hours depending on how long it takes to transmit the data. There are many Argo buoys drifting in the Pacific and you can see their current positions and review the collected data on this web site http://www.argo.ucsd.ed
Personal Log
I have been at sea now for just about four weeks and I am starting to get a bit anxious to get back home. Assuming there are no problems or difficulties we should be pulling into Manzanillo, Mexico on the morning of the 10th of August. After being out of sight of land for over a month it will be a welcome sight. It has been a very interesting experience to get up in the morning day after day, week after week, and see nothing but water in every direction for as far as one can see. It took me a while to adjust to the constant motion of the ship – now I take it for granted and don’t really think about it that much. I am curious how I will react and how it will feel when I step back on land and have a completely stable surface on which to walk. The ship seemed very large when I first came on board but as you can imagine as the days and weeks have gone by the vessel has gotten smaller and smaller.
Animals Seen
We had a rare treat during one of our recent buoy operations. While recovering the buoy at 5 degrees north latitude we noticed many fish in the water around the ship – especially off the stern. All of a sudden off the starboard side a small school (10 – 20) of large Mahi mahi started jumping out of the water in arcs as they swam. They did this for several hundred meters, first moving parallel to the ship and then off the starboard stern. A number of them were very large (4 – 5 feet) and a beautiful blue color. It makes one wonder if they are enjoying themselves.
We also have had quite a few birds, mostly gulls and frigate birds, beginning to follow the ship, although I did see a smaller bird darting around the fantail that I could not identify (but it reminded me of an oversized starling).