The anomalously warm ocean conditions (nick-named the “Warm Blob”) that have persisted in the northeast Pacific since early 2014, brought warm ocean water to the California Current. During a ‘normal’ year northern (boreal) copepods are delivered to Oregon via alongshore currents and they dominate our coastal zooplankton community. These northern copepods are rich with lipids (fatty deposits) needed to overwinter. The northern copepods are eaten by forage fish, which are eaten by larger fish (e.g., salmon), which are eaten by seabirds and marine mammals. Therefore, these lipid-rich copepods fuel a very energy rich food chain.
However, this year the lipid rich zooplankton community was replaced with tropical and subtropical lipid-deplete zooplankton as well as gelatinous zooplankton. You might have observed some of these gelatinous organisms such as the water jelly (Aequeora spp.) and the purple Doliolid washed up on the beaches in large numbers.
We also observed many new copepod species that have never been observed off Newport since sampling began in 1969. Copepods are drifters, they go where the water goes, and therefore they are good indicators of water transport. Exactly where these new copepods are coming from, however, is a topic of further study. What we do know is that these species are not arriving from coastal and southern origins, as occurs during El Niño events, rather they are likely coming from an offshore source.
Krill (Euphausiids) are also an important food source for many fish, seabirds, and marine mammals. This year, krill density was very low, and the krill that we did collect were much smaller than average.
The diatom Pseudo-nitzschia that produces the neurotoxin domoic acid was in high abundance in spring and summer, and was responsible for one of the most persistent and widespread harmful algal blooms that spanned from British Columbia to southern California. High levels of domoic acid is responsible for the closure of the harvest of razor clams and has delayed the opening of the Dungeness crab fishery off Washington, Oregon and California.
What’s next on the horizon? The sea-surface temperature at the equator is anomalously warm, signaling that a strong El Niño is occurring. The past strong El Niño events have occurred during 1982-83 and 1997-98. A striking difference between those past El Niños events and this current event, is that the northeast Pacific is already anomalously warm due to the Warm Blob.
So, how will we know if the El Niño arrives and how will that affect the ecosystem?
Stay tuned as we continue to monitor the zooplankton and ocean conditions off Oregon.