ACCESS - Applied California Current Ecosystem Studies
- Jaime Jahncke
Point Blue Conservation Science
- Jan Roletto
Greater Farallones National Marine Sanctuary
- Dani Lipski
Cordell Bank National Marine Sanctuary
- Resources Legacy Fund Foundation
- National Fish and Wildlife Foundation
- California Sea Grant
- Faucett Family Foundation
- Hellman Family Foundation
- Cordell Bank National Marine Sanctuary
- Gulf of the Farallones National Marine Sanctuary
- Farallones Marine Sanctuary Association
ACCESS partners have been investigating the spatial and temporal relationships between oceanographic processes, zooplankton, and marine birds and mammals in the region surrounding Cordell Bank and Greater Farallones National Marine Sanctuaries (Figure 1 under the Figs and Images tab).
Ongoing surveys started in May 2004. Three to four cruises are conducted annually between April and October. Forty-three (43) cruises have been completed to date and 3 more cruises have been planned for 2016.
ACCESS was formed in 2004 as a multi-disciplanry collaborative between Point Blue and NOAA’s Cordell Bank and Greater Farallones National Marine Sanctuaries. It supports marine wildlife conservation and healthy marine ecosystems in northern and central California through scientific research that informs resource managers, policy makers and conservation partners. ACCESS also works to coordinate private and governmental marine research at an ecosystem scale to addresses urgent local management needs.
Summary to DateAlongshore winds are responsible for driving upwelling. Winds were moderate to strong in in the first few months of 2015, then relaxed and remained weak for the summer. Other years with average to warm water temperatures also showed weak alongshore winds (e.g. 2004-06, 2010, 2014), while most other years of our study period experienced strong winds in the early months (Figure 2; note all figures can be viewed under the Figures and Images tab).
The spring transition that marks the beginning of the upwelling season in each year occurred at the long-term average in 2015. Spring transition dates have varied, with early dates observed in most years (2006-09, 2012-13), while some of the warmer years had late transition dates (e.g. 2005 and 2010).
Sea surface temperature measured by the NOAA buoy (46013) near Bodega Bay showed warm temperatures for all but one month in 2015. 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 known as “the blob” manifested along the central California coast in mid-2014, and surface waters have remained unusually high ever since (Figure 3).
Pacific-scale climate indices have shown great variability in ocean conditions since the start of our research in 2004. Overall, results from 2015 showed a warm ocean state. From 2005 to 2009, Pacific Decadal Oscillation (PDO) and North Pacific Gyre Oscillation (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 mid-2013, the indices had converged and were indicating warm conditions (Figure 4).
Zooplankton community composition results are not yet available for late 2012 and all of 2013-15, but results to date illustrate the effects of improved ocean conditions on overall zooplankton abundance, with low abundances in poor ocean condition years (2004-06, late 2009, early 2010) and increased zooplankton abundance (particularly for copepods and euphausiids [also known as krill]) in colder ocean periods (2007-08, late 2010, 2011-12) (Figure 5).
We caught mostly adult krill in Tucker trawl samples during June and September cruises in 2015, but these adults were smaller than adult krill sampled in the cold water years (e.g. 2007-13). The 2014-15 adult sizes were similar to the other warm water years (2005-06) in our time series.
Copepod community composition results are not yet available for late 2012 and all of 2013-15. Results to date indicate a large increase in the abundance of boreal (northern) copepods in 2007-08, spring of 2009, summer/fall of 2010, and 2011; these were times of cold, productive ocean conditions in our region. Species common to mid-latitudes (transition zone copepods) also became more abundant in 2007, although not as dramatically. Equatorial copepods (i.e., copepods from southern latitudes) increased in abundance in the September cruises of 2007 and 2008, likely when the equatorward California Current flow relaxed (Figure 6).
The Cassin’s auklet, a zooplanktivorous seabird, mainly ate euphausiids (krill) in most years, including 2015. Mysids were the dominant prey in 2005-06 (poor ocean condition years), and the Cassin’s auklet experienced unprecedented breeding failure. Increasing amounts of krill in the diet since those years has coincided with increasing productivity on the Farallon Islands since 2007 (Figure 7).
The common murre, an omnivorous seabird species, fed almost entirely on juvenile rockfish in 2015. Common murre diet shows predominantly rockfish in the 1970s and 1980s, then mostly pelagic anchovy and sardine in the 1990s and mid-2000s, and back to rockfish under recent improved ocean conditions (2008-13). In general, poor ocean conditions correspond to a lower percentage of rockfish in the diet and reduced productivity for murres on the Farallones, although 2014-15 could be considered an exception to this trend.
Acoustic measurements on krill in the upper 200 m of the water column were slightly higher in 2015; they have remained at low densities since 2013, but there are signs of a slight increase since then. Results to date indicate an increase in krill biomass through 2011, followed by a decline in 2012-13. Krill biomass showed high variation in the first four years of our time series (2004-07). 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) 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 they appear to be increasing in the region since then (Figure 8).
- See summary above.
- All Figures referenced above are under the Figures and Images tab.
- Chl A
- Trophic association
- Habitat association
Study MethodsSurveys have been conducted from the R/V John H. Martin NOAA Ship McArthur II, and R/V Fulmar from 2004 to the present. Surveys are conducted during spring, summer and early fall, generally four times per year: May, June, July and September.
At predetermined stations, water column data (salinity, temperature, fluorescence, dissolved oxygen) are collected using a Sea-Bird Electronics SBE 19Plus SEACAT CTD Profiler, equipped with a WET Labs WETStar fluorometer and a Sea-Bird Electronics dissolved oxygen sensor. Continuous underway data on surface temperature, salinity and fluorescence of chlorophyll-a are also collected. Phytoplankton community composition is assessed with vertical plankton net hauls; data are processed by California Department of Health as part of their state-wide program designed to detect toxin producing species of phytoplankton in ocean water before they form a potential toxic bloom and impact the public.
The overall zooplankton community is sampled in the upper 50 m using a hoop net, while the krill community from the ocean’s surface down to 200 meters is assessed with targeted-sampling using a Tucker trawl. The hoop net data provide densities of zooplankton taxa, while the Tucker trawl data provide information on the species and age class composition of the krill population. In addition, acoustic backscatter data are collected at three different frequencies (38 kHz, 120 kHz, and 200 kHz) using the ship’s SIMRAD EK60 echosounder to determine general abundance of krill.
Observations of marine birds and mammals are counted along predetermined transect lines. Data are binned into 3 km intervals to look at spatial relationships; seabird densities are estimated per unit area surveyed (birds/km2), and mammals densities are estimated per distance surveyed (mammals/km).
Figures and Images
Figure 1. Map of study area indicating survey lines, oceanographic and zooplankton sampling stations.
Figure 2: Monthly anomalies of alongshore winds (strong = blue, weak = red), 2004 –2015. Black lines represent ±99% confidence intervals around long-term monthly means.
Figure 3. Monthly anomalies of sea surface temperatures (cold = blue, warm = red), Bodega buoy, 2004–2015. Black lines represent ±99% confidence intervals around the long-term monthly means.
Figure 4. Pacific-scale climate indices (PDO and NPGO) from 2004-2015.
Figure 5. Zooplankton composition in the upper 50 m of the water column determined from hoop net samples, 2004-2012.
Figure 6. Average monthly abundances of the three categories of copepods, 2004-2012.
Figure 7. Cassin’s auklet breeding success anomalies on South East Farallon Island, 1971-2015. Solid black line represents 45-year mean, and dotted red lines represent ±80% confidence intervals.
Figure 8: Humpback whale abundances, 2004-2015.