Wednesday, February 22, 2012

my brain is full!

I’m at the Ocean Science Meeting in Salt Lake City Utah. After the end of day two, I can officially say my brain is full.

Monday, 20 February 2012 - Day 1

I got up early to attend one of the first sessions of talks titled ‘Integrating Oceanography and Animal Tracking - the Ocean Tracking Network’ as my work is part of this project. An interesting point was raised: “results will not reflect the properties of fish ‘untouched’ by the hand of man.” Putting a tag inside the fish will alter its behavior, at worst the surgery could kill it at best it might swim away after a really bad day.

Tagging fish can answer questions like: how long a fish remains in an area, if they make daily migrations or movement related to tides, or how many of a population stays put compared to numbers that go wandering.Tracking projects were discussed from South Africa to Australia to Canada.

The migrations of the American eel made an interesting tracking example. These eels spend most their lives in fresh water ranging from Greenland to the north coast of South America. At the end of their lives, all of these eels migrate to the Sargasso Sea to spawn. We know close to nothing about this migration, but we do know their population dropped dramatically in the last 30 years.

To learn more and potentially take preservation measures, eels were tagged in the St Lawrence River. 145 eels were tagged in 2010 and 2011. From the acoustic signals recorded we learned that they don’t migrate as a group, and they take advantage of tides and darkness to move. Temperature data showed that unlucky eels were eaten by Tuna and shark as their stomachs are warmer than the surrounding waters.

A twist on finding tagged animals is in testing off the coast of Nova Scotia. Receivers are put on a big enough animal. Since, grey seals range over large areas, they are ideal predators to lead us to feeding hotspots while recording signals of other tagged fish.

Other talks I went to delved into how energy is dissipated from surface waves, decay rates of white cap foam and temperature fronts in the ocean. I found the images of currents that form jets in the southern oceans fascinating as I had no idea it was so complex - the pictures looked like a chaotic mass of snakes.

Tuesday, 21 February 2012 - Day 2

I started with attending Arctic talks in a session titled ‘The Arctic and subpolar North Atlantic as the pacemakers for climate change.’ I’m aware that there is a sea surface height difference between the Pacific, which is higher, and the Atlantic, this results in flow across the Arctic to the Atlantic. What I didn’t know is that fresh water is accumulating in the Arctic, specifically in the Beaufort Sea as a gyre. This gyre as increased in fresh water content significantly since 2003 by 5400 square kilometers. What happens when this fresh water is released? This and other fresh water anomalies could potentially impact our climate if they stop or slow down the Meridional Overturning Circulation - this is a basin wide process in the Atlantic that includes the warm water from the Gulf Stream the keep Europe warm.

I also found it interesting that Arctic observations peaked in the 1980s - cold war related?

My afternoon was filled with talks on flow/topography interactions, an area I looked at in detail for my masters work. The room was packed, meaning this area is very much the focus of active research.

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