NOAA Teacher at Sea
Kevin C. Sullivan
Aboard NOAA Ship Oscar Dyson
August 17 — September 2, 2011
Mission: Bering-Aleutian Salmon International Survey (BASIS)
Geographical Area: Bering Sea
Date: August 28 – September 2, 2011
Weather Data from the Bridge
Longitude: 162.93 W
Wind Speed: 10 Knots
Surface Water Temperature: 10.5 C
Air Temperature: 55F
Relative Humidity: 97%
Science and Technology Log:
Well, at this time tomorrow, the Oscar Dyson will be tied up in port at Dutch Harbor. This is our end destination for Leg I of the BASIS survey. I will write-up a summary/conclusion either at that time or shortly after getting back into town. For now, I will fill you in on some material that I promised. As noted in earlier blogs…I have been intentionally writing in a trophic bottom up approach. That is, I started my first blog entries with descriptions of the primary producers, the Phytoplankton. I covered this extensively and correlated it to the oceanographic work that has been going on aboard this ship. It seemed logical to work from the base of the food chain and work my way up the trophic levels to the more complex consumers.
However, before I close the chapter on Phytoplankton take a look at the picture I took below. When I stepped outside and saw this, I thought I had been transported to the Caribbean. Clear skies, calm seas, tropical blue waters are not typical descriptions for the Bering Sea. If you look closely enough, you can even see the shadow of the clouds on the surface of the sea. Science is the field of making observations, forming hypothesis, designing and conducting experiments and drawing conclusions about the natural world we live in. So…what would you make of this observation? What has caused this temporary “mirage” of tropics? Clearly something is going on here.
Well, although not 100% certain, the most likely explanation is what would be called a Coccolithophore bloom. These are single-celled algae which are characterised by special calcium carbonate plates as seen in photo below under magnification.
Under certain conditions, (some speculate that wind pattern changes fail to mix the water column favoring cocolithophore blooms as opposed to other plankton) coccolithophores can create large blooms turning the water brilliant shades of blue pending on the species of coccolithophore blooming at the time. Ed (Chief Scientist) was telling me of a major bloom that had occurred back in the late 90′s. I researched it a bit and the following picture is of this bloom in the same general vicinity where we are now. Amazing to think of how microscopic plants can influence a region on the scale of an entire sea and be seen from space. *Note: this is not a false colored Image
There is also some speculation that these types of blooms may be linked to sub-average runs of salmon (and even impact seabirds negatively in the area). Some hypothesize that this may be due to the idea that salmon prey heavily upon euphausiids (see picture I took below on 08-28-11 and the one centered beneath for a closer look taken from NOAA) and the euphausiids have difficulty subsiding on the extremely small coccolithophores. Remember what I was saying about visualizing the flow of energy as a pyramid and the effects of taking out a few or many blocks that make up the base of the food chain.
Ok, to make this easier for the reader, I am going to stop this blog here and start a new one dedicated to the zooplankton…..I got a little sidetracked with the whole coccolithophore bloom event…….
Earlier this morning we were greeted with some higher winds and consequently some larger seas. As my friend back East says conditions got “Sporty.” Here is a picture from where we launch the CTD. Winds were out of the SW gusting to 30 knots and seas were in the 10′ range with some larger swells thrown into the mix to keep things interesting.