Ross Sea currents

Scientist Stu Hanchet uses a computer simulation that shows how the eggs and larvae of the Antarctic toothfish are distributed by the Ross Sea currents.

Points of interest for teachers:

• Students could discuss the factors that these models have to take into account, i.e. annual ice cover.

Transcript

STU HANCHET

In the Antarctic waters there’s two main currents. You’ve got the ACC, the Antarctic Circumpolar Current, flows in an Easterly direction, here in the black arrows and close to the Antarctic continent you’ve got the Antarctic coastal current which flows in the opposite direction around to the West. Now where these two currents meet you’ve got a very strong area of upwelling called the Antarctic divergence and this is shown by this, by this complex area of gyres and circulation patterns.

Now over the first two or three weeks of the survey, we’ve been surveying this area down here in the Ross sea shelf itself which is bathed in very cold water. Over the last week or so we’ve now moved up into this area of complex seamounts to the, to the North, in this area of very rich upwelling, around the Balleny Islands and around Scott Island here. There’s lots of krill here, humpback whales, Baleen whales feeding on the krill and also take toothfish for example.

This is a computer simulation of toothfish eggs and larvae and how they’ve been taken by the prevailing ocean currents. You can see the current taking the eggs across here in the ACC, coming down to the South, being entrained in the Ross Sea jar. Moving down towards the Antarctic coastline and then running back to the West in the Antarctic coastal counter current and this brings those eggs and larvae back into this cold water where they will grow as juveniles and grow up into adults.