July 7, 2009
62° 11.99 N
Yesterday was a normal sampling day. I was up well before the morning CTD cast at 07:30 because I had gone to bed so early last night. At station 122-ML3 we sampled five depths for thorium, two for POC, the normal seven for pigments, and ran the accompanying filtrations.
We were heading towards the mainland into shallower waters that were frozen over only weeks ago. Hoping the fresh water layer created by the ice melt had not yet mixed with the saltier water below, Pat told me after lunch to keep an eye on the salinity level. I was to take surface samples if the salinity dropped below 30.5 ‰. Unfortunately it never did (31.4 was the lowest I observed) and no samples were taken. I used my time to finish off Lake Wobegon, Summer 1956 and went to bed soon after dinner.
No sampling today for me so I spent part of this morning trying to finalize the girls' soccer schedule for this fall. This would be a much easier task if I was not 4000 miles away from my school and had my calendar in front of me. I'm sure my athletic director's patience will soon wear thin with my e-mailed questions and requests and I will get what I get. I probably plan too much anyway.
We are closing in on the end of the SL line, which runs in an east/west direction about 60 miles south of St. Lawrence Island. The Thompson is roughly one day ahead of schedule at this point so a science meeting was convened at 12:30 in the main lab to discuss our options. We are at the northernmost point in our cruise and the yet to be completed 70-meter line will bring us southeast along the continental shelf back towards the Aleutian Island chain and closer to Dutch Harbor. With this in mind, three options existed. We can delay the start of the 70-meter line by one day and sail farther north to sample, take a quick detour in the middle of the 70-meter line to sample someplace new, or add a sampling station or two at the end of the 70-meter line on our way back to Dutch.
The last suggestion of sampling in closer to Dutch was quickly dismissed. This would not allow the scientists ample time to run their experiments after they sampled and before they disembarked in Dutch. The second reason was also dismissed for an equally practical reason. There is a fairly large storm (with 20-ft seas and 50 kt. winds) skirting the Southern Bering Sea and the longer we put off going South, the less likely we were to be affected by it. So by default we will head north.
At the end of the SL line, we were only two nautical miles from Russian waters. The ship turned Northeast on a heading of 43°, skirting the international border, and beginning the newly created BN line. The BN line stands for "Benthic Nirvana" and is comprised of 8 stations along a 120-mile tract in the area of the Bering just southwest of Saint Lawrence Island. This region has a historically high concentration of benthic organisms due its proximity to the St. Lawrence Polynya.
A polynya is a region of polar water that is ice-free year round and can result from one of two things, ocean currents and/or wind patterns or an upwelling of warmer water from below. The St. Lawrence Polynya is the latter type. Ice piles up on the northern side if the island but on the southern side the winds prevent the sea ice from accumulating by driving any ice that forms away from the island. As a result, the area around the polynya experiences an ice melt much earlier in the year than the rest of the Northern Bering Sea. Colder waters mean no zooplankton to graze on the blooming phytoplankton. Thus, when the phytoplankton die they fall to the bottom feeding the benthic community.
As soon as I finish typing this entry I am going to head back to my stateroom for the night. It is now 21:00 and we are scheduled to sample at 145-BN3 early tomorrow morning. I will set the alarm for 05:30.