Dispatch 19: The Last Mooring     Print

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Hugo Sindelar

September 25, 2018

Location: 75° 0’ N 150° 0’ W

Weather: -0.4°C (31°F), Mostly cloudy, light snow, seas 1–2 meters by the end of the day, Southwest winds at 18 knots, seawater temperature 0.1°C (32.3°F)

Sea Ice: None

And that is a wrap!  Today the WHOI team redeployed mooring A, and in doing so finished their three mooring and three ice-tethered profiler deployments for the trip.  Though the weather was overcast and snowing, the seas were calm enough in the morning to get the mooring work done.  They did, however, build throughout the day and we are now rocking and rolling.  We just got the redeployment finished in time.  Whew!  As with the other mooring operations, things went smoothly, and we were finished by 3 p.m.  All in all, it was a great year for the WHOI team as they recovered a few ITPs (which are often lost), they deployed all three ITPs on ice (at least one ocean deployment has been common recently), and all three moorings were recovered and redeployed successfully!

After the redeployment, we immediately started steaming south to CB-3.  Now the focus of the cruise turns to finishing three more CTD stations and two CTD station “lines”.  These station lines are CTD casts, which are more closely spaced than usual.  Most of our CTD stations have been in the Canada Basin, where depths are generally around 3,800 meters.  As we sample these CTD station lines, we will be moving from the deep Canada Basin to the Beaufort Shelf, which has depths around 200 meters.  This transition zone is of great interest to the scientists on board. 

Phytoplankton, the tiny photosynthetic organisms, that make up the base of the food chain in the ocean are often nutrient-limited.  That means their populations are dependent on the amount of nutrients in the water (nitrate, orthophosphate, and silicate).  In this transition zone, when environmental conditions are right, upwelling can occur.  Upwelling brings nutrients from deeper water into depths were phytoplankton live (those depths where there is enough light for them to photosynthesize).  Phytoplankton thrive in upwelling zones and in turn form the base of a robust food chain that includes larger fish and whales. 

This is perhaps the busiest time of the cruise for the CTD watches as they will complete eight stations in only 24 hours.  Normally stations are at least 4 hours apart, giving them plenty of time to process samples.  Work will be fast and furious as we close out the cruise!