Tuesday, July 30, 2013

Natasha Christman: Along the San Juans

This week, I took part in ongoing oceanographic research based in the San Juan Islands. As a component of  the continued monitoring of the region's health and ecology, research cruises on the University of Washington's vessel the R/V Centennial occur periodically throughout the year. The cruises focuses on the waters to east of San Juan Island and to the west of Lopez and Shaw Islands.

The Centennial docked at its home port
 of Friday Harbor Labs.

The Centennial started out life as a commercial fishing boat in the Gulf of Alaska but later was converted to a research vessel. Today, when not out at sea, the 58' vessel resides at the University of Washington's Friday Harbor Labs on San Juan Island. With its formidable size, the ship can accommodate the navigation crew, the scientists, students, and the citizen-scientists that accompany the cruise. With so many different experiments and sampling going on at once, having a solid amount of space on the ship is important to keep track of it all.

The deck of the Centennial.
The picture on the left shows the deck of the Centennial as viewed from the navigation cabin. Like Shannon Point's vessel the R/V Zoea and many other oceanographic ships, the Centennial also has a CTD to take water samples at fixed depths and profiles of the water column. The long transect of water the cruise investigates is broken up into several regions. At the edge of each region, the CTD is lowered down to several meters above the seafloor bottom to record a detailed profile. This gives us better insight to the conditions and characteristics of the area's water, helping to establish the ecological makeup of the region.

Dr. Apple and the captain working to lower the net
Apart from the CTD and related data collection like nutrient and chlorophyll samples, a group of citizen-scientists also come aboard the vessel to tally the populations of birds and marine mammals they see along the transect. Additionally, water from a small plankton tow is taken to isolate and fix some of the phytoplankton from the column for later analysis. To sample and account for the important zooplankton populations, a very large plankton net is lowered into the water by a crane. There are pretty substantial differences in the phytoplankton tow size and the zooplankton tow size; while the metal rings that support the phytoplankton net are about the size of a dinner plate, the zooplankton tow rings are akin to hula-hoops in size. This difference is related to supporting the different mesh sizes that target each group of plankton. The wider meshes are great for capturing the larger zooplankton, while more fine, thin net is best for the tiny phytoplankton.

Data from this contributes to the understanding of the whole ecological chain; from the tiny phytoplankton and zooplankton to the cormorants and seals, the data gives us a pretty good idea of the current condition of the food web. With so many factors that contribute to the region's natural environment, research like this is important to understand and monitor what exactly is happening or has happened to the ecosystem. Overall, it was a fine day out on the water and contributing to this research. Next month, I will go out on the Centennial again for the next series of this experiments. Until then, I resume my research of Bellingham Bay and the environment there!

And a big thanks to the University of Washington and all the people at Friday Harbor Labs!

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