Peter Sheesley – Weeks 3 & 4. Data Days, the Art of Plankton Counting, a Dead Whale, and a Pre-digital Oceanography Machine

In weeks three and four, I am now past the introductory and training phases of my summer and into the activity of data collection. This means both collecting water samples and counting the phytoplankton content of the samples. We have established our 15 sampling sites along the coast between Horsefall and South Cove, spread over a range of about 10 km of coast near Charleston, OR. The goal is to collect three samples at each site, within a 2-3 day period. These will make up a data set, and will probably be repeated two or three more times in the next four weeks. We’ll then be looking at how having a different surf-zone width (due to the angle of the ocean floor) impacts the presence of plankton.

Myself and Leyia collecting samples at Pack Trails. We have switched to casting the sampling tube with a fishing pole.

There are two phases of the project, going out to collect the samples, and analyzing the samples under the microscope. My estimate is that for each one day of collecting there are about four days of analysis. For each approximately 250 mL sample, I strain the sample to create a more dense sample, usually of about 25 mL. I then count the amount of five different types of plankton in a one-mL subsample. I can then extrapolate the amount of each type of plankton per one-Liter of the sampled water. To find the amount of plankton in the one mL on the Sedgewick-Rafter slide, I count circular frame-by frame in rows and columns. If one of the counts reaches 200 before making it through the slide, the frame number is noted and the amount per one-mL slide is extrapolated.

The types of phytoplankton I’m counting are Pseudonitszchia, Chaetoceros, Dinoflagellates, Navicula, and Asterionellopsis. Pseudonitszchia are of particular interest because they are toxic and cause some shellfish to be toxic to humans. Chaetoceros are generally the most abundant. Dinoflagellates have two flagella, one like a tail and another like a belt, and have been generally more rare. Navicula are boat shaped and also fairly rare. Asterionellopsis are a surf-zone species that are able to secrete a substance that moves them toward the beach during the day and then release the substance, moving them back down and out at night.

Straining a sample to make the plankton more dense per volume.

A stack of samples ready to be counted.  And a stack of containers from already counted samples behind those.

A page from my lab book. Each hash mark represents a single viewing frame counted under the microscope. There are five different samples/1 mL slides on this page.

A data sheet showing four samples, raw counts, and extrapolated per-Liter amounts.

During one of my days spent counting plankton at the microscope I began reflecting on just how accurate my counting method is, how much skill it takes (if any), and how often I’m making informed inferences about what I’m seeing. After all, the numbers of plankton per Liter can be over a million in some samples—and there’s no way my counting is so accurate that I’m getting the exact number over one-million in a one-Liter sample. In essence I’m arriving at an estimate of the amount. There are several other factors, besides sheer quantity, adding to the inaccuracy of my count. To begin with, I’m counting circular frames in a grid pattern, so there are areas in the corners being left out. To compound that problem the frame is advanced by hand-and-eye, leading to inevitable overlaps or jumps. Also the plankton are often in varying states of decay. I have an ideal form I’m looking for, and then I have to decide whether the organism is close enough to be considered for counting. Additionally I am looking from one angle at three-dimensional shapes. Sometimes chains are spiraling in ways that make counting an exact number of cells at that particular angle impossible. Then there is the factor of basic human error and fatigue. I’m counting many frames over periods of hours and trying to maintain focus regarding the presence of five different shapes and forms. Surely there will be errors. 

. . . and at this point in my reflections on the accuracy, skill, and decision making in counting, I begin to think that counting is in some ways an Art (that is Art with a capital “A” because it is the name of a specific type of discipline). I’m basing my thinking about Art in my years of being a professional Fine Artist, MFA in painting, and in several years of training in the martial arts. I think counting plankton is an Art because it involves pursuing an ideal (the perfect count) knowing full well you’ll not achieve that ideal. This is much like doing a form, or kata, in the martial arts. You do the same form over and over, each time striving to perfect it, knowing that perfection is impossible. Or it is like making a series of paintings, striving to communicate an idea, knowing that idea will never be perfectly communicated. And just as painting and the martial arts require discipline and endurance—so too does counting plankton. There are ups and downs in all of these practices; moments when the plankton is enchanting and wonderful to look at, and moments when it becomes boring and tiring. The practice of the Art means working through the lulls and cherishing the peaks. It means keeping in mind the big picture of what is being accomplished through the daily work.

In another way, I also began seeing each circle of light in the eyepiece as a work of art. The plankton made an unending variety of successful compositions. Some of them even reminded me of circular Chinese woodblock prints on parchment paper.

This one looks like a dragon fly landing on a tree branch in front of the moon.

This is "Plum Blossom Branch in Circular Fan Shape," an Illustration from the Ten Bamboo Studio Manual of Calligraphy and Painting (Shizhuzhai shuhua pu), after 1633 - before 1703, in the Harvard Museum.

Also, in week four, a juvenile humpback whale was found dead at Bastendorff Beach. I didn’t ever hear conclusively about why it died, but it did have many abrasions around one of its fins. Some of the local researchers cut samples from the animal. It was impressive to walk around the whale on the beach. Even just a young, small whale seemed huge. The skin was thick and rubbery. I was able to pry the eye open slightly and see how large the iris was. I can only imagine how different it would be to encounter this magnificent creature alive in the ocean. My imagination wanders, contemplating the depths it saw and the distances traveled.

Me and underside of whale's head.

View from the tail end.

One of the sample sections was removed here.

A view of the whale from the water.

Lastly, I’ve begun reading Sir Alister Hardy’s, The Open Sea, 1965. In some ways it is like an introductory manual to Oceanography. Although it is now outdated, it also provides an account of the science at a time when scientific instruments were more often hand-made, rather than purchased from a supply store. One of the instruments and its description was particularly interesting to me. In a time before digital electronic instruments, the ingenious contraption used marbles released at regular intervals into a compartmentalized disc, to determine the direction and prevalence of currents. The drawing and description of the Ekman Current Meter is below. (This is the same Ekman that Ekman Transport--a spiral pattern of movement in the water--is named after.)

Two consecutive pages from Hardy's book The Open Sea