U.S. Global Ocean Ecosystems Dynamics
July 1997
| This ENSO97 whitepaper is also available as an Adobe Acrobat PDF file [187 kb] |
Four general needs of a coordinated ENSO monitoring effort are: 1) increased sampling of subsurface observations; 2) broader sampling of ocean chemistry and biology, including nutrients and multiple trophic levels; 3) sampling at many locations along the west coast, at as high a frequency as affordable; and, 4) establishment of a more effective communication network to coordinate the many sampling and monitoring activities that occur along the west coast.
Generally, we are much better placed presently to document the physical manifestation of El Niño conditions along the west coast than we are for biological aspects of the ecosystem. The network of observation sites, including moorings, NDBC buoys off California, tide gauges and shore temperature stations at a number of locations, and survey transects and grids in place now is nearly capable of documenting the physical manifestation of an El Niño as it propagates poleward along the North American west coast. If the network is supplemented in a few sites by a) beginning programs earlier than their intended starts, b) continuing existing programs beyond their scheduled completion, or c) augmenting existing programs, physical aspects of this prospective ENSO will be recorded satisfactorily. The coastwide sampling outlook is not as favorable for nutrient and biological variables. As for the physics, some improvement in chemical and biological sampling could be obtained by beginning projects prior to their official start dates. However, some regions do not have ongoing or planned sampling of biology at all, nor are there research cruises ongoing to which additional biological sampling could be added. In other regions it might be possible to obtain additional biological sampling for minimal cost, because research cruises are already taking place for other reasons.
Given the likelihood of a major El Niño propagating to the northern Pacific extratropics in the fall 1997 to summer 1998 period, a group of researchers from the west coast met in San Francisco for a one day workshop to discuss how to develop a coordinated response to examine the propagation and impacts of this El Niño event along the Pacific coast of the U.S. and Canada. Appendix 1 list the researchers who attended the workshop. Table 2 provides the workshop agenda.
Using a computer animation, Howard Freeland provided an overview of the high-latitude ocean conditions from 1981 to the present, and used the 1983 and 1992 El Niño events as examples to demonstrate the impacts of El Niño on temperatures in the North Pacific. For both of those El Niño's, SST off of British Columbia were ca. 2-2.5°C above normal. Long-term records of nutrient concentrations along Line P, from the Strait of Juan de Fuca to Station P, show that the region of low wintertime nitrate concentration has expanded further offshore in recent decades. This has occurred independently of El Niño's and may be a response to the longer term "regime shift" that occurred in the North Pacific. The significance of the lower wintertime nitrate concentrations is that springtime primary production reduces the concentration to limiting levels over a much larger region of the North Pacific now than in earlier periods. Changes in the thermal structure and mixed layer depth associated with the El Niño at mid-to-high latitudes could reduce production even further.
Biological impacts of the 1983 El Niño were large. For instance, during non-El Niño conditions, 80% of Fraser River Sockeye salmon normally return via the southern route around Vancouver Island, BC. During the 1983 El Niño however, ca. 80% of the salmon returned by the northern route. Moreover, during the warm conditions of the early 1990s, mackerel populations were much further north than usual. Mackerel are predatory on essentially everything that they can physically consume. Mackerel sampled from Barkley Sound in the 1990's had 5-8 juvenile salmon in their guts. Survival and return of salmon from hatchery releases in western Canada declined from ca. 5% (before the warm 1990's) to ca. 0.02%--a major decline.
Ed Harrison provided an overview of the large scale temporal-spatial developments of the last four major El Niños (1977, 1983, 1988, 1992). It is clear that the different ENSO's have different temporal-spatial SST anomalies, and that there is no single "typical El Niño".
Tim Liu showed a sequence of images (and a movie) from the NASA Scatterometer that indicated two marked events of westerly winds in the western equatorial Pacific in the last few months, and showed how those anomalous winds resulted in a wave of sea level (from TOPEX) and sea surface temperature anomalies (from AVHRR) that progressed from west to east along the equator in the Pacific.
Mark Abbott noted the need for broad and expansive spatial coverage--both from satellites and in situ observations, especially subsurface)--to document the progression of El Niño conditions from the eastern tropical Pacific to the extratropics in the Northern Hemisphere.
Tom Powell described briefly the projects (PI's and titles) that were funded recently by NSF and NOAA to begin the U.S. GLOBEC NEP program. Three in particular are relevant to monitoring ocean conditions:
Tom Weingartner provided additional details about their recently funded U.S. GLOBEC monitoring project on the Gulf of Alaska shelf (the Gulf of Alaska (GAK) line off Seward). Their project will be sampling the hydrography, velocity fields, nutrients, phytoplankton, zooplankton and fish along the GAK line on six cruises per year--determined to coincide roughly with biological seasonality (e.g., spring bloom, salmon outmigration, etc.). Sampling will occur from very near shore to ca. 150 km off shore. Sampling is not scheduled to begin until March of 1998, and the question arose--Is there some way to begin the funding early to enable sampling the fall and winter conditions this year prior to the projected arrival of the peak of the El Niño conditions? According to Weingartner, shiptime is available. It was also noted that eddies are spawned off Yakutat and Sitka and propagate westward in strong El Niño years. It might be possible to use the TOPEX altimeter to track these eddies if they form this year.
Jack Helle reviewed the data collection/surveys that are being conducted by the Ocean Carrying Capacity (OCC) program. Although the abundance (catch) of salmon is at historic highs in Alaska in recent years, the individual weights of the fish in 1994 have declined (long-term trend) ca. 40% (in some species and stocks) from the sizes caught in the early 1970's. Interestingly, the size of the 1995 and 1996 fish are significantly larger than the 1994 fish, raising the question of why--perhaps there has been another "regime shift"? The OCC program will be conducting surface trawling, using a chartered trawler, from mid-July to mid-August in 1997, 1998 and 1999. Trawling is done from Dixon entrance westward to the Aleutians. Similar trawling was done last year. This year, CTD's and plankton sampling will be done in addition to the trawling. In addition to this offshore sampling, the RV John Cobb will conduct fish and plankton sampling in inshore regions of southeast Alaska.
Howard Freeland briefed the group on sampling that is ongoing in Canada. First, he noted that DFO-AES (Department of Fisheries and Oceans-Atmospheric Environment Service) has 16 buoys that have been collecting data routinely--some for as long as ten years. That data is made available in near real time via a web site (http://www.ios.bc.ca/ios/osap/dispwx.htm). The La Perouse program off Vancouver Island will continue to sample south of Barkley Sound, which includes three current meter moorings, CTD survey cruises every 6 weeks, and zooplankton sampling. Adding phytoplankton sampling to the program is being considered. The Institute of Ocean Sciences will continue its approximately quarterly monitoring of hydrography and nutrients along Line P with cruises in Aug-Sept 97 and February 98. The use of aircraft to drop AXBT's once per month along Line P is under consideration. David Welch has a cruise that will sample out to Stn Papa, then north along 145°W to Alaska. There may also be two moorings deployed along 145°W near the Alaskan shelf by the Canadians. These could be moved to offshore of the GAK (Seward) line if it were clearly advantageous to do so.
Barbara Hickey discussed a variety of programs that are conducting minimal sampling along the Washington coast. The MacArthur is conducting CTD/ADCP surveys during the summers of 1995-98 along the northern coast of Washington as part of the Olympic Sanctuary program. A single mooring was deployed in the coastal zone off Willapa Bay for a year as part of an EPA/Sea Grant project, but there are no moorings there now. There was additional sampling and moorings in the estuary. A single mooring will be deployed off Willapa Bay for the Pacific Northwest Coastal Ecosystem Research Program (PNCERS) next spring, but could be deployed sooner if additional funds became available. PNCERS will deploy moorings off Grays Harbor, WA and Coos Bay, OR in 1998 and 1999, but they will be located in fairly shallow water (ca. 50 m isobath). There will also be additional sampling conducted within the estuaries during that period. If additional funds were made available, it might be possible to deploy the coastal moorings sooner--perhaps as early as this fall--to capture the signal of the El Niño as it progresses northward.
Mike Kosro described the sampling that Bill Peterson has been conducting along the Newport, OR line since May 1996. Using a small vessel (daytrips only) zooplankton (vertical and surface horizontal tows) and hydrography have been sampled ca. every other week. The stations are located 1, 3, 5, 10, and 15 miles from shore. According to Peterson, the spring transition in 1997 occurred early, upwelling was strong, the spring bloom was large, and zooplankton populations were abundant--until May. In May, there were strong and consistent anomalous southwesterly winds, and upwelling shut down (and hasn't resumed in any significant way). By mid-June, zooplankton populations were extremely low. Local populations of the common murre have crashed; few chicks fledged this spring, and adults are starving and washing up on beaches. This happened also last year, when upwelling was also poor. The lack of zooplankton in the nearshore will certainly provide for hard times and poor survival of Oregon coastal coho salmon this year. It is important to note that none of this is directly caused by the El Niño, the effects of which are unlikely to have been felt yet at Oregon latitudes, but rather are caused by locally-driven phenomena (e.g., anomalous winds; no upwelling). The cumulative impacts from an El Niño superimposed on the already poor conditions could be disastrous for nearshore marine species.
Kosro (and later Jeff Paduan) showed surface velocity data sets from high-frequency (HF) shore-based radars, which could provide surface current data at 1-2 km resolution out to 40-50 km from shore. It was noted that there are now three HF radar systems that will (or could be) sampling the nearshore current fields from just north of Point Conception (Libe Washburn), Monterey Bay (Paduan), and Newport, OR (Kosro). Both Kosro and Paduan showed how the HF radar data agreed reasonably well with satellite observations of ocean features collected simultaneously, and with time series observations obtained from moorings located within the field-of-view of the radar.
Jane Huyer and Bob Smith described the monitoring transects that U.S. GLOBEC has recently funded. Transect lines will be sampled quarterly (January, March, August and November) for hydrography, currents, chlorophyll and zooplankton. Sampling could begin as early as September/November 1997 if shiptime could be funded (the ship is available). Current plans are for multiple transect lines--a northern line at Newport, OR and a southern line off Coos Bay, OR. This GLOBEC project has arranged with NSF for two days of ship time in September to do the line off Newport. Ship time would be available in November to do the Newport, Coos Bay, and an additional northern California transect, if funds were available.
Francisco Chavez briefed the group on the sampling that is being conducted at three stations every three weeks by MBARI in Monterey Bay and slightly further offshore. In addition, there are two permanent moorings; one is at the mouth of the bay in 1000 m of water, and the second 20 km further offshore (in 1800 m of water). The hydrography, ADCP, nutrients and chlorophyll from the Monterey Bay dataset, which encompass the period from 1989 to present, indicate that nearshore data from within the Bay are not sufficient to document and describe the impacts of El Niño's (a point noted also by Mark Abbott from satellite observation analysis) because the nearshore zone can remain relatively unaffected while regions further from shore are altered dramatically. To adequately document El Niño impacts, additional data from further offshore are needed. Toward that end, MBARI is supporting three large-scale monitoring cruises in 1997. The MBARI survey grid is centered on CalCOFI transect line 67, and extends 400 km offshore. Three cruises will occur next year as well. The MBARI large-scale cruises contain little physical oceanography, and that aspect of central California monitoring needs additional resources. Moreover, this MBARI effort lacks a higher trophic level component (zooplankton, etc.), other than presently unfunded efforts "piggy-backed" on cruises in the region. Jeff Paduan also noted that there are a number of other research cruises in the region that could complement the seasonal coverage, including a Naval Post-Graduate School education/teaching cruise (July 1997), a Monterey Bay Marine Sanctuary cruise (August 1997), and a NAVOCEANO cruise (September 1997), if they were coordinated properly.
Marlene Noble described the USGS moorings in northern/central California. Currently, there are efforts in two regions: a transect extending across the shelf from Santa Cruz (3 moorings with current meters, thermistors, and sediment traps), and a planned deployment of three moorings on the slope off San Francisco (near Farallon Islands). The former are scheduled to be pulled in August 1997, but if there is a strong desire, could be redeployed at the same location (or nearby) to provide current records prior to and during the El Niño.
Figure 1 shows a summary of some of the observation programs in place now or that will be implemented in the near future to monitor ocean conditions along the Pacific coast of North America. Each observational program is depicted by letter; the observations being made at each site are summarized in Table 1.
Figure 1. Locations of selected observation programs along the Pacific coast of North America. A-K identify specific programs (see Table 1 and text for additional details). Stars indicate locations with moorings. Shaded lines indicate offshore extending transects. Shaded regions indicate locations with survey grid sampling.
Table 1. Selected observational programs along the Pacific coast of North America.
| Identifier in Figure 1 |
Program/PI's | Frequency of Sampling | Observations | Missing Obs./Needs |
|---|---|---|---|---|
| A | OCC/Helle et al. | annual survey in mid-July to mid-August | juvenile salmon trawling, zooplankton, CTD, diet composition | chlorophyll, nutrients, ADCP, hi-freq. acoustics |
| B | EVOS SEA/Cooney et al. | productive season cruises; one mooring? | CTD, zooplankton, juvenile salmon, chlorophyll | |
| C | GLOBEC/Weingartner et al. | 6X/year along GAK line | hydrography, ADCP, nutrients, chlorophyll, zooplankton, hi-freq. acoustics, trawling | doesn't begin till March 1998; need earlier start, preferably November 97 |
| D | Line P/Freeland | quarterly cruises | CTD, ADCP, nutrients, chlorophyll, zooplankton? | |
| E | La Perouse/Canada | CTD survey every 6 weeks; several moorings | CTD, zooplankton | nutrients, chlorophyll |
| F | PNCERS/Hickey | nearshore moorings off Gray's Harbor, Willapa Bay (and maybe Coos Bay, OR) | temperature, currents | phytoplankton, zooplankton; needs to begin before scheduled 1998 start |
| G(1) | GLOBEC/Smith et al. | 5X/year, Newport and Coos Bay; moorings | CTD, nutrients, ADCP, chlorophyll, zooplankton | juvenile salmon trawling; need earlier start |
| G(2) | NMFS/Peterson | biweekly cruises nearshore at Newport | CTD, zooplankton, chlorophyll, nutrients | fish |
| H | USGS/Noble | 3 moorings on shelf off Santa Cruz | currents, temperature, ADCP, sediment traps | scheduled to end in August 1997; need turnaround and redeployment for another year |
| I | MBARI/Chavez et al. | quarterly cruises to 400 km offshore; nearshore moorings | CTD, ADCP, nutrients, chlorophyll | zooplankton; offshore mooring; additional fall 1997 cruises; better physical observations |
| J(1) | MMS/Winant | 12 moorings N and S of Pt. Conception | currents at several depths; temperature, salinity | scheduled to end in October 97; need some turned around and redeployed for another year |
| J(2) | MMS/Washburn | HF coastal radar; hourly | surface water velocities out to 40-50 km off Pt. Conception | |
| K | CalCOFI/Hayward et al. | quarterly survey cruise | CTD, nutrients, chlorophyll, ADCP, zooplankton |
The coastwide sampling outlook is not as favorable for nutrient and biological variables. As for the physics, some improvement in chemical and biological sampling could be obtained by beginning projects prior to their official start dates (e.g., C, G). Some regions do not have ongoing or planned sampling of biology (e.g., F, H, J), nor are there research cruises ongoing which could accommodate additional biological sampling. However, in other regions it might be possible to obtain additional biological sampling (esp. zooplankton) for minimal cost, because research cruises are already taking place (e.g., I).
Considering the sampling that is occurring already, we see the following immediate needs (letter identifiers refer to sites in Figure 1 and Table 1):
Mark Abbott Oregon State University mark@oce.orst.edu Hal Batchelder Univ. California, Berkeley halbatch@socrates.berkeley.edu Steve Bollens San Francisco State Univ. sbollens@sfsu.edu Mary-Elena Carr Jet Propulsion Lab. mec@pacific.jpl.nasa.gov Francisco Chavez Monterey Bay Aquarium Research Inst. chfr@mbari.org Kendra Daly National Science Foundation kdaly@nsf.gov Elizabeth Dobbins Univ. California, Berkeley ldobbins@zanclopus.biol.berkeley.edu Howard Freeland Institute of Ocean Sciences hjfree@ios.bc.ca Judith Gray NOAA Coastal Ocean Program jgray@cop.noaa.gov Ed Harrison Pacific Marine Environmental Lab. harrison@pmel.noaa.gov John Helle Alaska Fisheries Science Center jhelle@abl.afsc.noaa.gov Barbara Hickey Univ. of Washington bhickey@u.washington.edu Jane Huyer Oregon State University ahuyer@oce.orst.edu David Johnson NOAA Coastal Ocean Program djohnson@cop.noaa.gov Mike Kosro Oregon State University kosro@oce.orst.edu Tim Liu Jet Propulsion Lab. liu@pacific.jpl.nasa.gov Marlene Noble U.S. Geological Survey marlene@octopus.wr.usgs.gov Jeff Paduan Naval Post-Graduate School paje@mbari.org Thomas Powell Univ. California, Berkeley zackp@socrates.berkeley.edu Robert Smith Oregon State University rsmith@oce.orst.edu Mark Stacey Univ. California, Berkeley mstacey@sagitta.biol.berkeley.edu Tom Weingartner Univ. of Alaska, Fairbanks weingart@ims.alaska.edu
Informal ENSO response meeting.
11 July 1997. Westin Airport Hotel, San Francisco, CA
8:30 Welcome. Review agenda. Introduction. Aims. T. Powell
8:45 Overview. H. Freeland
9:05 Overview continued. E. Harrison
Individual presentations. Interest and capabilities.
Each presentation should be 10 minutes, with 5 minutes for questions.
9:15 GLOBEC Northeast Pacific monitoring. T. Powell
9:30 NASA satellite observations. T. Liu
9:45 West coast satellite observations. M. Abbott
10:00 BREAK
10:30 Gulf of Alaska. T. Weingartner
10:45 Southern Alaska region J. Helle
11:00 Queen Charlotte Is., Vancouver Is. coasts H. Freeland
11:15 Washington coast. B. Hickey
11:30 Oregon coast. I. M. Kosro
11:45 Oregon coast. II./N. Calif. A. Huyer/R. Smith
12:00 LUNCH
Individual presentations (continued).
1:00 Central Calif./Monterey Bay S. Bollens/F. Chavez/J. Paduan
1:15 USGS Work in Northern/Central California M. Noble
1:30 Comments on Individ. presentations. Other regions, e.g.,
comparisons to open ocean regimes, etc.
"Open Mike".
Agency perspectives. Facilities and resources.
1:45 NSF K. Daly
NOAA J. Gray/D. Johnson
NASA M-E. Carr
2:15 Discussion. Focus: what is needed for coordination?
2:45 BREAK
3:15 Discussion. Coordination needs (continued).
4:00 Assignments. An incomplete list might include (but is not limited to) the following.
Writing tasks, if any? Individual written items?
Collective written materials?
Ship, facilities coordination?
Inter-calibration, -comparison of collected data?
Communication: e-mail, web-site(s?), other?
Additional People and groups to be included in future activities?
Future meetings?
Other?
5:00 ADJOURN