Winter plankton update

It has been an interesting Winter 2021-2022: large amounts of rain, dramatic temperature swings from winter snowy cold to unusual January high temperatures. While the large amounts of rain are typical for a La Niña (as opposed to El Niño) winter weather pattern, high temperatures are not. I happened to be out collecting zooplankton for my Marine Environments students to observe during this brief mid-month warm spell at Boston Harbor, the north end of Budd Inlet. This location has a much more marine influence than the downtown Olympia, Deschutes River-Capital Lake southern end of the Inlet, where the week before, we saw very high turbidity from the high river (and local storm drain) outflow. I was trying to keep my zooplankton expectations low based on some of the observations from previous years, so I was very pleasantly surprised that my students did indeed get to see several varieties of invertebrate larvae from my 80μm plankton samples. (I didn’t see any bivalve larvae, but I’m hoping to be able to stage some bivalve gonads in lab next month as a student exercise.) As I was towing right off of a dock with a healthy encrustation of fouling organisms, I was able to observe:

  • cnidarian planulae (probably sea anemone)
  • 3 varieties of (and definitely two different species) of polychaete larvae (one trocophore and two setigers, one probably a spionid)
  • 3 varieties of crustacean larvae (barnacle and one other nauplius, brachyuran crab zoea possibly Hemigrapsis sp.)
  • 2 varieties of gastropod mollusc veligers (one with a slightly larger whorled shell, the other smaller and emerging from an egg capsule containing 6 embryos)
  • bryozoan cyphonautes

An excellent reference:

Shanks, A. L. 2002. An Identification Guide to the Larval Marine Invertebrates of the Pacific Northwest. OSU Press, Corvallis. 320 p.