2017 Ocean Indicators Summary
A summary of ocean indicators of the northern California Current for 2017.
The anomalous warm ocean conditions that have persisted since September of 2014 might be dissipating. While ocean ecosystem indicators in 2015 and 2016 suggested some of the poorest outmigration years for juvenile salmon survival in the 20-year time series, some of the indicators in 2017 were fair, indicating that the ecosystem might be returning to normal. The PDO was strongly positive (warm) throughout the first half of 2017. However, the index declined to more neutral levels from July through November 2017. Strong La Niña conditions at the equator persisted from August through December of 2016 and then became neutral throughout most of 2017. Before the onset of upwelling in 2017, ocean conditions off Newport, Oregon, remained warm and fresh. However, after the onset of upwelling, sea surface temperatures were cooler than average, and the near-bottom water on the shelf was salty. In 2015 and 2016, the seasonal shift from a warm winter copepod community to a cold summer community did not occur because of the extended period of warm ocean conditions. However, in June 2017, the copepod community transitioned to a cold water community, signaling that the marine ecosystem might be transitioning back to normal.
PDO and ONI
The PDO turned positive (warm phase) in January 2014 and has remained strongly positive through June 2017. From July 2017 through November 2017, the PDO values declined to more neutral conditions. La Niña conditions (negative Ocean Niño Index values less than or equal to -0.5) persisted during the fall/winter of 2016 from August through December, then became neutral throughout most of 2017.
Upwelling Index at 45°N
The winter downwelling period was close to the climatological mean. Following the winter downwelling period, the onset of upwelling began slightly later than average on April 26, 2017, compared to the 40-year climatological mean of April 13. Upwelling was weak in May and June, with some strong periods of downwelling. Beginning mid-June, upwelling was persistent until mid-Sept. While the length of the upwelling season in 2017 was average, the overall cumulative upwelling was slightly higher than the mean, and the sum of the May-September upwelling index was above average.
Sea Surface Temperatures (SST)
The anomalous warm ocean conditions in the NE Pacific from the Blob arrived on the Oregon shelf in Sept 2014 with temperature anomalies of +4°C and continued to dominate the surface ocean temperatures for most 2015 and 2016. However, beginning in Jan of 2017, sea surface temperature anomalies off Newport remained positive, but they were not as warm as the previous two years. At the onset of upwelling in mid-April 2017, SST anomalies were negative but then fluctuated from positive to negative in response to the intermittent downwelling that occurred until mid-June. In mid-June, upwelling was persistent, and SST anomalies remained negative until the fall transition in mid-Sept.
Temperature and Salinity
The upper 20 m of the water column on the shelf and the deep water on the shelf and slope were dominated by water anomalously warm and fresh throughout the winter before the onset of upwelling. However, after the onset of upwelling, the deep water on the shelf remained warmer than average but was saltier than average.
Hypoxic oxygen concentrations below 1.4 ml/L were observed on the shelf from July through mid-September, with the lowest value in the 12-year time series recorded in September of 2017. These low oxygen conditions have been linked to die-offs of benthic organisms. Fortunately, an early winter storm mixed the waters in mid-September, dispersing the hypoxic water.
In 2015 and 2016, the seasonal shift from a warm winter copepod community to a cold summer community did not occur because of the extended period of warm ocean conditions. However, in late June 2017, the copepod community transitioned to a cold water community, signaling that the marine ecosystem is transitioning back to normal. Before this transition, the zooplankton community remained in a lipid-deplete state with a continuation of negative anomalies of lipid-rich northern copepods and high biomass anomalies of small southern copepods. While the species richness was lower than the peaks during the summers of 2015 and 2016, richness remained higher than average throughout 2017 until September, when species richness was neutral.
Colonial tunicates called pyrosomes were a common occurrence in our plankton nets throughout 2017. We started seeing these rare organisms in the Fall of 2016, and they increased in density and size in the spring of 2017. After the onset of upwelling, these organisms were rarely collected on the shelf off Newport. However, the weekend after Thanksgiving, they washed up on Oregon beaches by the millions. During a research cruise the following week, we collected them from 10-85 miles offshore. We know very little about these organisms that are native to tropical and subtropical water, and we are uncertain why they have flourished in the Northern California Current at this time. Research is underway to understand their distribution and habitat and what they feed on.
Harmful Algal Blooms
In April 2017, cells of the domoic acid-producing diatom Pseudo- nitzschia were observed in continental shelf waters off Newport. Densities increased to moderate levels following the onset of the spring transition in late April. Domoic acid concentrations from water samples collected simultaneously as the phytoplankton samples indicated that the Pseudo-nitzschia cells were toxic. Pseudo-nitzschia blooms persisted at moderate to high levels from late June through early September. A fall Pseudo-nitzschia bloom also occurred in late October through early November.
The winter biomass of larval stages of fish species common in salmon diets was above average this year, ranking the highest over the 20 years of data. While this suggests a high abundance of food for juvenile salmon, the species composition of the wintertime larval fish community included high proportions of larval rockfish. During years when juvenile salmon consume higher amounts of rockfish, survival is lower.