2015 Ocean Indicators Summary
A summary of ocean indicators of the northern California Current for 2015.
Many of the ocean ecosystem indicators in 2015 suggest this being a relatively poor year for juvenile salmon survival. The PDO was strongly positive (warm) throughout 2015, coinciding with anomalously warm ocean conditions in the NE Pacific called "The Blob" that began in the fall of 2013 and have persisted through 2015. El Niño conditions also turned positive in April 2015 and have remained strongly positive, signaling a strong El Niño at the equator. Despite the strongest upwelling observed since 1998, sea surface and deep water temperatures off Newport, Oregon, remained warmer than usual (+2°C) throughout most 2015. During the strongest upwelling period in June, shelf waters did cool and were salty but returned to positive temperature anomalies quickly from July onward. The zooplankton community remained in a lipid-deplete state throughout 2015 and was dominated by small tropical and sub-tropical copepods and gelatinous zooplankton that generally indicate poor feeding conditions for small fishes upon which juvenile salmon feed. Krill biomass was also among the lowest in 20 years.
On the other hand, the biomass of larval fish species common in salmon diets in spring was above average this year. However, there were also high concentrations of larval sardine and anchovy, generally indicators of poor salmon feeding conditions. We also observed many new copepod species that have never been seen 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. The new species were warm-water species, known to occur offshore and southwest of Oregon, suggesting a tropical/subtropical origin. However, exactly where these species came from is a topic for further study.
The Marine Heat Wave
An anomalously warm water mass began to form in the Gulf of Alaska during autumn 2013 and was named "The Blob" by Nick Bond (Bond et al. 2015). This warm water mass spread across the entire North Pacific by summer 2014. However, in the eastern North Pacific and on the Oregon shelf, offshore Ekman transport associated with coastal upwelling kept "The Blob" offshore during summer 2014. In mid-September of 2014, northerly winds ceased, and "The Blob" moved shoreward into shelf waters off southern British Columbia, Washington, and Oregon, raising coastal SSTs by six °C over 6 hours off Newport! By early November 2014, "The Blob" was firmly entrenched in coastal waters off Oregon, with an 80 m thick mixed layer with 2-3°C anomalies. Except for the strong upwelling period in June 2015, warm anomalies remained off Newport throughout most 2015.
Sea-surface temperature (SST) anomalies in the Pacific from July to December during the initial phases of El Niño events of 1982, 1997, 2015. The strongest El Niño events in recent history occurred during 1982-83 and 1997-98. The 2015-16 event is expected to be the strongest on record. What sets this year, 2015, apart from the other strong El Niño events, is that the northeast Pacific was already anomalously warm before the El Niño arrival due to "The Blob."
The decrease in the SST anomalies in the southern Gulf of Alaska and offshore of the Pacific Northwest from November through December 2015 can be attributed to a regional atmospheric circulation pattern that produced surface wind anomalies from the northwest (not shown). These atmospheric patterns were not indicative of El Niño. However, the recent bout of torrential rains off California, which began on 4 January 2016, are. Thus, while" The Blob" appears to be diminishing, it does not appear that the Northeast Pacific is necessarily returning to a near-normal state.
The ecosystem impacts of "The Blob" have not yet been fully documented, however to date, three types of responses are clear: many unusual species were found: media reports documented northward displacement of tropical and subtropical reptile and fish species on the order of several 1000 km into the northeast Pacific: moonfish (opah) and swordfish were caught off central Oregon (45°N), green and Olive Ridley turtles were found off Washington and Oregon, and two yellow-bellied sea snakes (Pelamis Pelamis) have washed up on a beach in southern California. Also, sunfish, pomfret, and pompano were commonly caught in the Gulf of Alaska. A total of 18 species of warm-water copepods occurred in 2015, 11 of which were new records for the NCC shelf/slope; an additional seven species have occurred only in waters far offshore of Oregon or during strong El Niño events (1983, 1998). Many of these copepod species had North Pacific Gyre and/or North Pacific Transition Zone affinities indicating that the source of "The Blob" was from far offshore and from the south. Copepod species richness anomalies reached a peak in August 2015, but after that, anomalies have declined and, by early November 2015, turned negative. The copepod species we are observing now are the same as those seen during any normal winter, with a dominance of subtropical neritic species transported to Oregon from coastal waters of central/southern California waters by the Davidson Current, which runs northward from October-March in most years.
In addition to unusual species, there were impacts on commercial fisheries. Sockeye and summer-run Chinook salmon migrating back to the Columbia River in the summer of 2015 experienced high mortality because river waters were anomalously warm as a result of a Blob-related drought and subsequent low flows; coho salmon returns to the Columbia River in autumn 2015 were the lowest in at least 25 years. Impacts on juvenile salmon that migrated to the sea in spring/summer 2015 will not be known for several years.
The year 2015 also witnessed perhaps the largest and most wide-spread harmful algal bloom in recorded history: a bloom of the diatom Pseudonitzschia, began in April 2015 and extended from southern California to the coastal Gulf of Alaska. The bloom became extraordinarily toxic such that in May 2015, the State management agencies ordered a closure of the razor clam (Siliqua patula) fishery off Washington and Oregon. Subsequent blooms in June and August resulted in toxicity remaining high throughout the remainder of the year leading to a ban on the harvest of Dungeness Crabs off California, Oregon, and Washington in November 2015.
"The Blob" has resulted in ocean conditions that might be a precursor of future climate scenarios and provides a natural experiment to monitor its effects on the pelagic ecosystem and associated fisheries of the California Current (and perhaps across the entire North Pacific). Given that global climate models were (and continue to be) unable to anticipate "warm events" such as" The Blob" with much lead time, it is imperative we maintain existing marine observation programs and begin others so that ecosystem impacts can be more closely tracked. Finally, given that the strong 2015 El Niño event has begun to arrive, we expect that abnormally warm conditions will continue along the west coast of North America well into 2016, and so there may well be another chapter (or more) to this story.
PDO and ONI
Following several years of being consistently negative, the PDO turned positive (warm phase) in January 2014, and has remained strongly positive throughout 2015, reaching values similar to what was observed during the 1997-1998 El Niño. In April, the equatorial temperature anomalies crossed the threshold into El Niño conditions, and the Ocean Niño Index (ONI) has remained strongly positive, indicating strong El Niño conditions at the equator.
Upwelling Index at 45°N
The upwelling season began (spring transition) on 13 April and ended on 5 October, which is both in line with the 40-year climatology. Despite the on-time beginning and end to the upwelling season, the total amount of upwelling in 2015 was the highest we've observed since 1998. Upwelling began strongly in mid-April, was moderate in May but was then strong and sustained throughout June. From July onward, upwelling was generally weak with a few moderate pulses.
Sea Surface Temperatures (SST) at NOAA Buoy 46050
The anomalous warm ocean conditions in the NE Pacific called "The Blob" arrived on the Oregon shelf in Sept 2014, with temperature anomalies of +4°C, and dominated the surface ocean temperatures for much of 2015. Sea surface temperatures off Newport remained warmer than usual (+2°C) throughout most of 2015, apart from the month of June, the strongest upwelling period, during which shelf waters cooled and were salty. However, with the weakening of upwelling in July, positive temperature anomalies returned from July onward.
Temperature and Salinity
The upper 40 to 60 m of the water column on the shelf was dominated by "The Blob" water and was anomalously warm and fresh throughout the winter before the onset of upwelling. In slope and oceanic waters, the warm and fresh Blob water occupied the upper 80-100 m. Since the water that upwells onto the shelf usually originates from deep waters just offshore of the shelf from a depth of ~150 m, the deep temperature and salinity during the upwelling season (May-Sept) were quite average), being cold and salty. After the strong upwelling in June subsided, the deepwater became warm and fresh, resembling the water characteristics that occurred during the strong El Niño in 1997.
In 2015, this shift from a warm copepod community to a cold summer community did not happen, which is the first time in our 18 year time series that this biological spring transition did not occur. The zooplankton community remained in a lipid-deplete state throughout 2015, and was dominated by small tropical and sub-tropical copepods and gelatinous zooplankton that generally indicate poor feeding conditions for juvenile salmon. The biomass of southern ("warm water") copepods remained higher than average. Except for June, when upwelling was the strongest, the biomass of northern ("cold water") copepods remained lower than average throughout 2015. We also observed many new copepod species that have never been observed off Newport since sampling began in 1969, and the species richness was the highest we have observed since 1998. Copepods are drifters, they go where the water goes, and therefore they are good indicators of water transport. We know that these new species did not arrive from coastal and southern origins, as occurs during El Niño events. Rather they are likely coming from an offshore source. Exactly where the source is, though, is a topic of further study. Finally, although not a topic of this web-page, it is noteworthy that krill biomass was among the lowest in our 18-year time series. Large adult Euphausia pacifica (18-20 mm) were conspicuously absent.
The winter-time (Jan-March) abundance of larval stages of fish species common in salmon diets was above average this year, ranking fourth highest over the 18 years of data. However, high concentrations of larval sardine and anchovy were found, which are generally indicators of poor feeding conditions for salmon.