We've been seeing some friendly faces in our bi-weekly plankton samples. A dramatic shift occurred in the last few months; our samples have been full of Pseudocalanus, Acartia longiremis and Calanus marshallae. These are copepod species that have boreal water mass affinities, indicating that we have our biological transition!
Seeing large abundances of these species marks the arrival of a cold-water copepod community off our coast. These cold water copepods are lipid-rich and represent a productive food chain for higher trophic levels. This is especially exciting because in recent years (2015 and 2016) we never saw the copepod community transition from a warm winter community to a cold summer upwelling community, and in 2017 the transition occurred very late in the season.
We've also been seeing a healthy abundances of adult krill in our recent offshore samples.
These are all good indications that the zooplankton community is transitioning back to a more 'normal' state.
Last week, I returned from a cruise aboard one of America's newest oceanographic research vessels, the R/V Sally Ride.
Scientists aboard the Sally Ride were taking part in a multi-year project studying mesozooplankton food webs in the northern California Current. Transects off Newport, OR and Trinidad Head, CA were sampled with a high-resolution imaging system and coupled MOCNESS tows to examine plankton abundance and distribution and gather net samples for diet and biomarker analysis. The science crew included marine scientists from institutions all over Oregon, including OSU, UO, PSU, and NOAA. So many knowledgeable people on one boat!
At Trinidad Head, near-shore waters were green and cold with max fluorescence at 15.5 mg/m3 and SST at 10°C. Plankton nets and the ISIIS imaging system were also capturing a large amount of adult krill. This contrasted with sampling at the Newport Line with steeper clines and SST near 17°C! Pyrosomes were clogging up the nets and adult krill were not as abundant.
Now that the samples have been collected, the real work begins. I look forward to following the plankton teams progress and future sampling trips.