It’s a cloudy afternoon in early July, and the sea is as grey and still as the sky. The subdued atmosphere mirrors the stillness of Cedar Coast Field Station–it’s a quiet summer without volunteers, school groups, and summer camps. The perceptible lack of buzz isn’t unique during the rising and falling waves of COVID-19; we’re taking the moment of reprieve to dial in our educational programs and today, we’re collecting plankton.
It’s a joint effort to tow the net once submerged: it takes two of us to navigate the net’s long steel pole around the ramp railing as we walk the length of the dock. We’re doing a shallow surface tow, aiming only to sample the uppermost metre of the water column, but you couldn’t tell based on weight alone. Our focus today isn’t on data collection, though. We’re following a set of step-by-step instructions created by other CCFS educators, honing the process. What materials did we need that weren’t included on the list? Is the experience still valuable if not conducted at high tide? How long can larger groups expect the exercise to take? It’s not the same experience without the kids, of course, and our work today is motivated by a desire to give them the best experience possible when we can once again welcome visitors to the Station.
After a few more pulls of the net, we bottle up our samples and take them back to the lab. I trial a mini-lecture on plankton, discussing different types of phytoplankton (plants, mostly) and zooplankton (animals), their distributions and functions throughout the water column, and their vulnerabilities to anthropogenic disturbances in Clayoquot Sound. My listeners are curious, but their urge to check out the critters outweighs their interest in my spiel–we agree to shorten the preamble for future participants, and head straight to the microscopes.
And we are certainly not disappointed! We find and identify a number of plankton in our sample. The majority of phytoplankton observed are segmented and needle-like–Skeletonema, Melosira, and Pseudonitzschia. Zooplankton are mostly meroplankton (a larval precursor to marine invertebrates); we find sea urchin larva, nauplius larva of barnacles, and a few other unidentified animals. We’re surprised to find this many zooplankton close to the surface–zooplankton generally adhere to a diel vertical migration in the water column, spending daytime near-bottom and night at the surface. We tentatively attribute the high numbers to strong tidal and wind mixing observed nearshore, and plan to investigate further in future plankton tows!
By Sarah Rosen, Canada Summer Jobs Student & Education Program Coordinator