Saturday, June 28, 2014

Peter Sheesley - A week of introductory reading and plankton counting practice.

Hello everyone. My name is Peter Sheesley and I've just finished a year of general biology and general chemistry at Centralia Community College, in Centralia, Washington. Centralia is half-way between Portland and Seattle on I-5. In the fall I'll be a full-time student at Evergreen State College, Olympia, WA. This is my second time through college; in my previous career I was a fine-art painter. I've also done some theoretical-science illustration and that was what initially sparked my interest in studying biological science. Marine science is particularly interesting to me because of the variety of life in the ocean and the mysteriousness of life in a habitat so foreign to us. I applied to PRIME because it was recommended by my community college professor, Dr. Steven Norton. In the spring I assisted in a research project of his, dealing with DNA analysis of freshwater sculpin. I'm located at the Oregon Institute of Marine Biology in Charleston, OR. My mentor is Dr. Alan Shanks. Here are a few photos to introduce you to my location at OIMB.

A view of Coos Bay from above OIMB.
A view from nearby Cape Arago State Park.
A view from nearby Cape Arago State Park.
The sign in front of campus.
A view of campus.
The dining hall and some of the dorm rooms.
Our project with the Shanks lab involves analysis of larval recruitment, when individuals are added to populations as they settle from planktonic phase to early juvenile phase. The lab studies the impact of shelf and surf topography and hydrodynamics on larval recruitment. Another PRIME intern, Leyia Johnson, and I are working side-by-side in the Shanks lab. Our first task was to read several previous papers of Dr. Shanks' in order to understand the purpose and mechanisms of the lab. The papers were a valuable introduction to the concepts. Next we were given a net and a jar and instructed to collect phytoplankton samples. These samples were then viewed using compound light microscopes. 

We then spent several days learning to view and identify plankton, and count them. The plankton were transferred to sedgewick-rafter slides and viewed mostly at 100x. One of our main tasks is learning to identify plankton from the genus Pseudonitzschia. Our sampling will quantify these plankton because they contain some toxic elements. They are particularly difficult to identify because they vary in size and are easily mistaken for several other types of plankton. The long pointed Pseudonitzschia cells link together forming even longer chains. Each individual cell is between 50 - 150 micrometers long. Despite a sometimes weary neck and back, I enjoyed getting lost in the minute yet geometrically fascinating world of plankton. Here is an illustration showing some of the first things I learned. 

In addition to looking at plankton in the microscope, we also practiced casting our sampling tube. It is an approximately two-foot-long, three-inch-diameter, clear plastic tube with a stopper at one end and a moveable plastic ball in the interior of the other end. This ball allows water to enter but not exit, mostly. There is an approximately fifty-foot-long rope attached to the tube. The tube is twirled and released towards to ocean in one hand while a spool of rope is held in the other hand. Casting took some practice, but we found success. We also towed a larger net (six-feet-long, three-feet-diameter at the wider end of the cone), to catch zooplankton. We looked at the zooplankton in a dissecting microscope. The dissecting scope is nice because objects appear very three dimensional. Both the compound light-microscope and the dissecting scope bring out different aspects of plankton. The light-microscope emphasizes linear and two-dimensional aspects, and the way light passes through objects. The dissecting scope, with its stereoscopic vision, emphasizes the 3-D and the way light reflects off things. I've just started learning to differentiate and identify various larval forms. 

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