USC Dana and David Dornsife College of Letters, Arts & Sciences

What are the elusive and mystical ANACONDAS??!!

Sorry, the answer is not a swarm of mythological creatures that grant wishes to anyone able to find them deep beneath the Amazon River plume, though that would be pretty sweet.  Maybe next cruise. ANACONDAS is actually the name of the project we are working on here.  It is an interesting acronym that stands for: Amazon iNfluence on the Atlantic: CarbOn export from Nitrogen fixation by DiAtom Symbioses (ANACONDAS).  One or two liberties may or may not have been taken with that acronym but cut us some slack, we’re scientists not word…people.

The very broad goal of the ANACONDAS project is to try to understand the influence the Amazon River has on the ocean.  The Amazon River is very different from the Tropical Atlantic Ocean it feeds into.  Other than the most obvious difference: the river, unlike the ocean, is fresh water, the river is loaded with nutrients (e.g., nitrogen and phosphorous) and organisms that differ from those found in the open ocean.  The “open ocean” refers to parts of the ocean where there is no land around, go figure.  Land is a source for nutrients, so the open ocean is usually low on nutrients and therefore life, which is a stark contrast to the water flowing out of the river.  When these waters mix it allows organisms that can take advantage of this increase in nutrients to grow and outcompete the organisms that are normally found in the open ocean.  We want to get a first hand look at this.

Now, getting a little more sciencey, the cruise aims to understand how nitrogen is cycling and in turn, use this information to better understand how the carbon cycle is working.  This can give us an idea of the balance between how much carbon is being taken up by photosynthesizing organisms and how much is being respired by organisms.  We can then determine whether the Amazon River plume is a source or a sink for CO2 from the atmosphere.  By “sink” I mean taking CO2 out of the atmosphere.  This is where the DAS of ANACONDAS comes in and DAS ist gut.  Sorry about that, just could not resist. DiAtom Symbioses is referring to an interesting relationship between a photosynthetic plankton and nitrogen-fixing bacteria.  Though we do not completely understand the complexities of their relationship, we believe that they have some sort of symbiotic association where the bacteria fixes nitrogen and supplies it to the diatom (a small plankton) while the large diatom possibly provides protection from smaller predators that could graze on the tiny bacteria.   Isn’t nature just amazing?  Sometimes I just can’t believe how beautifully evolution works.  Anyway, these larger–now I feel I should qualify the use of this word here.  When I use the word “larger” here, I mean that relatively; these diatoms are on the order of micrometers, which are about a million times smaller than a meter.  Again something that is so bewildering; such complexity at such a small scale.–Anyway, these “larger” diatoms are made of silica (pretty much like glass), which is somewhat dense, and so with their size and makeup they sink faster than some other plankton.  If they pull CO2 from the surface water and use that to fix carbon (something like fixing nitrogen as I discussed in an earlier post) into their biomass and grow, they can then sink out of the surface, bringing that carbon with them where it can be stored for thousands of years.  This makes less total carbon in the surface so more must diffuse in from the atmosphere to replace it.  This removes CO2 from the atmosphere and makes the area a CO2 sink, which can help mitigate the effects of climate change.  Less CO2 in the air, less heat gets trapped, a slight decrease in temperature can occur over time.  We will try and collect more data on this area to determine if the Amazon River plume is a source or a sink of carbon.

How do you do all this?  You get in a boat and ride down to the mouth of the river.  We can than use parameters like salinity (how much salt is in the water) to orient ourselves in and around the plume and roughly determine at a given point how much water is coming from the river and how much is from the ocean in a given area.  This gradient can allow us to navigate through the plume and measure what things are like in the more saline low nutrient open ocean and how they change along a gradient as the two water masses mix until you get into the eventual low saline high nutrient river water.

You can get more information about the project if you go to this website:
http://amazoncontinuum.org
I do not believe it has been updated in awhile but there is still a lot of background information on the science and some of the people along for the ride.  Check it out if you have some time.  However, I do not think I am on there so don’t get your hopes up.

Lastly some of the detail about the cruise. It leaves shortly, July 13 out of Barbados and returns to the same port on July 30.  So that makes the cruise 17 days.  The past two cruises I have been on have been double that, 35 days, so I think this one should be a breeze. Cruises are normally very hectic at first, as you’re trying to set everything up and make sure it all works.  That first week usually goes by quickly, then you settle in and just hit a rhythm, and things continue to go by swiftly.  But by the end of week 3, I usually hit a wall, realizing that I pretty much have to repeat the same amount of time and work before it is all over and I can step on dry land.  Time starts to slow to a halt.  On this cruise though, at that point we will already be sitting on the beach in Barbados.  17 days should go by relatively quickly…

Back to work!