Friday, August 22, 2014

Sampling the Deep Blue Sea

Kathryn draws water from
 the Niskin bottle to
measure nutrients
Photo credit: H. Rivera 
Winch used to lower and
raise Niskin for
deeper sample sites
Photo credit: H. Rivera 
One of our aims for this current expedition is to characterize and understand the water chemistry and nutrient profiles of the water around the Palauan archipelago. Water samples are taken using a Niskin bottle, a large bottle that can be lowered to a particular depth and then triggered to closed, by sending a messenger weight to trip the latch. This seals the bottle collecting the water of that depth. We can then bring the bottle back up and process the collected water for our analysis of interest. 

Max sends the messenger
weight to trip the bottle
Photo credit: H. Rivera
During our cruise we've collected water samples over each of our coral reef sites as well as several off shore sites. This allows us to see how the water changes as it comes from the open ocean over Palau's lagoon and into the reef's closer to land. We can track declines in pH, changes in salinity, temperature, and nutrient levels as the water flows over the reefs and is changed by metabolic activity, wave actions and other perturbations. 

For our deep offshore sites we had a handy winch to help up raise and lower the bottle. Our sampling went very smoothing and we had gorgeous weather, during our very last deployment though we had a minor malfunction and ended up hauling up 150 meters of line with ~30 lbs weight by hand... that gave Pat and Max quite the morning workout! They recovered our bottled though and we had our last samples :)

-Hanny Rivera

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