Tracking Ocean Climate

ACCESS partners have been tracking ocean climate to examine seasonal patterns through the oceanographic year and assess how the ecosystem is responding to large, basin-scale climate shifts among years.  Ongoing cruises started in 2004, and take place from April to October on the NOAA National Marine Sanctuary Research Vessel Fulmar.  Fifty-one (58) cruises have been completed to date and no cruises were possible during 2020 due to the COVID19 pandemic.

We summarize and produce an annual ‘Ocean Climate Indicators Report’ that provides information about the status and trends of physical and biological climate change indicators selected with input from 50 regional scientists and resource managers during a 2-year process led by NOAA’s National Marine Sanctuaries.

Ocean Climate Indicator Status Report: 2021

Follow this link to download our Ocean Climate Indicators Status Report for 2019 or read our synopsis below.

El Niño / Warm ocean year in 2019

Alongshore winds (strong = blue, weak = red) are responsible for driving upwelling. Overall, weak winds were observed with short periods of stronger winds in July and the fall in 2019. Other average to warm water years showed weak alongshore winds (e.g. 2004-06, 2010, 2014-16), while most other years of our study period experienced strong winds in the early months.

The spring transition that marks the beginning of the upwelling season in each year occurred about 10 days later than the average transition date (March 31st) in 2019. Spring transition dates have varied, with earlier dates observed in most years (2006-09, 2012-13), while some of the warmer years had later transition dates (e.g. 2005, 2010, 2016).

Sea surface temperature (cold = blue, warm = red) measured by the NOAA buoy near Bodega Bay showed mostly warm temperatures in 2019, with a period of cooler waters later in the year (July-November). In 2004, sea surface temperatures were relatively warm but close to the long-term averages. Warm temperatures were observed in 2005-06, followed by cold surface temperatures in 2007-09. Sea surface temperatures in 2010 were warm early in the year and cold for all other months, and temperatures have remained relatively cold until mid-2014. The anomalous warm water mass was part of the broader North Pacific marine heatwave, which started in the Gulf of Alaska and manifested along the central California coast in mid-2014; only in the latter half of 2016 have these warm waters started to cool.

Pacific-scale climate indices have shown great variability in ocean conditions since the start of our research in 2004. Overall, NPGO results from 2019 showed a warm, low ocean productivity state. PDO data are not yet available for 2019; however, neutral PDO values during 2018 indicate a cooling trend. From 2005 to 2009, PDO and NPGO were following opposite trends; a positive PDO and negative NPGO values indicated poor ocean conditions in 2005-06, while a negative PDO and positive NPGO indicated productive ocean conditions in 2007-08. Beginning in mid-2009, both PDO and NPGO have been following relatively parallel trends; a positive PDO and NPGO indicated productive ocean conditions during 2010, despite the year being deemed an El Niño year. These indices showed signs of diverging in mid-2012, but by late 2013, the indices had converged and were indicating warm conditions. In general, warm conditions have persisted in the area since late 2013.

Strong upwelling = more zooplankton

Zooplankton community composition results are not yet available for 2016-19, but results to date illustrate the effects of improved ocean conditions on overall zooplankton abundance, with low abundances in periods of warmer ocean conditions (2004-06; late 2009; early 2010 and 2012) and increased zooplankton abundance (particularly for copepods and euphausiids [also known as krill]) in colder ocean periods (2007-08; late 2010, 2011-13). While overall zooplankton abundance was high in 2014-15, most of this abundance is represented by gelatinous species (represented in the “Other” category), which are good indicators of a warm ocean state.

Strong upwelling = more adult krill and fatty copepods

Zooplankton communities were different between poor and productive years. Gelatinous zooplankton dominated under poor ocean conditions (2004-06; late-2009 to mid-2010). Northern copepod species (i.e., large, fatty copepods) reappeared in the study region starting in 2007 and tend to be found in higher abundances during colder, productive ocean conditions. The zooplankton community in 2014-15 (during the marine heatwave) appear to be different than other warm water years, which may be due to higher abundances of gelatinous species compared to other warm years.

We caught mostly adult krill in Tucker trawl samples during 2019. The adult krill caught in 2019 were larger than krill caught in 2018, similar to the adult krill sampled in the colder water years (2007-13). Adult krill in 2017 were smaller and resembled the size classes observed in warm water years (e.g. 2005-06, 2014-16) in our time series.

Copepod community composition results are not yet available for 2016-19. Results to date indicate a large increase in the abundance of boreal (northern) copepods during times of cold, productive ocean conditions in our region (e.g. 2007-08; spring/summer of 2009, 2011, and 2013; summer/fall of 2010; early 2014). Species common to mid-latitudes (transition zone copepods) also became more abundant in 2007, although not as dramatically; more noticeable increases were seen in 2011 and 2014-15. Equatorial copepods (i.e., copepods from southern latitudes) increased in abundance in the September cruises of most years, likely when the equatorward California Current flow relaxed.

Bad times for the Cassin’s auklet (the krill-eater)

The Cassin’s auklet, a zooplanktivorous seabird, mainly ate euphausiids (krill) in most years. Mysids were the dominant prey in 2005-06 (poor ocean condition years), and the Cassin’s auklet experienced unprecedented breeding failure (see figure below). Increasing amounts of krill in the diet since those years has coincided with increasing productivity on the Farallon Islands since 2007. While krill comprised the majority of diet items identified in 2013 samples, most of these krill were juveniles; the prevalence of these smaller krill (which contain fewer calories than the adult krill) is thought to be the cause of a large young-of-the-year Cassin’s auklet die-off event that occurred in 2013. Diet data are not yet available for 2019, but productivity data for 2019 show extremely low reproductive success that may suggest a low amount of krill in the diet in this year.

Bad times for the common murre (the fish-eater)

The common murre, an omnivorous seabird species, fed mostly on anchovy and sardine in 2019. Common murre diet shows predominantly rockfish in the 1970s and 1980s, then mostly pelagic anchovy and sardine in the 1990s and mid-2000s. Rockfish became the dominate prey under improved ocean conditions (2008-13), although murres are now consuming more anchovy/sardine in recent warm water years. In general, poor ocean conditions correspond to a lower percentage of rockfish in the diet and reduced productivity for murres on the Farallones (see figure below), which includes 2016. Results from 2014-16 (marine heatwave years) could be considered an exception to this trend.

High abundances of krill and Humpback Whales

While we do not yet have the krill density results yet for 2019, the densities of Humpback Whales and their krill prey in 2018 were high compared to most other years in our time series. Results to date show krill in the upper 200 m of the water column varied, with higher abundances in 2004-06, 2008-11, and 2017-18, and lower abundances in 2007 and 2012-16. The apparent high abundance in spring 2006 is due to high abundance of highly reflective gelatinous zooplankton in the water at that time. High krill biomass was observed in 2009 and 2010, despite the later year being deemed an El Niño year.

The Humpback Whale, a main predator of krill, follows very similar patterns to the krill abundance. Years of lower krill abundance (2004-08, 2012-15) have corresponded to low abundance of Humpback Whales in the region. Signs of increasing Humpback Whale abundance began in late 2009, and almost five times as many whales were sighted in the summer and fall of 2010 compared to the first four years of the study. This rise in whale abundance coincided with the great krill biomass observed in 2010. Since then, Humpback Whale abundances declined through 2013, but then increased to their record high abundance in 2016.

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