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GLOBEC Target Species: Interactions with Top Trophic Levels

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July 1, 2004 through June 30, 2005

Dr. Cynthia T. Tynan
Visiting Investigator
Physical Oceanography Department
Woods Hole Oceanographic Institution
Woods Hole, MA 02543

Program Manager: Dr. Elizabeth Turner, U.S. GLOBEC Program Manager,
NOAA Center for Sponsored Coastal Ocean Research

Related NOAA Strategic Plan Goal:
Goal 1 – Protect, restore, and manage the use of coastal and ocean resources through ecosystem-based management.
Goal 2 – Understand climate variability and change to enhance society’s ability to plan and respond

PRJOJECT SUMMARY:
The goal of Global Ocean Ecosystems Dynamics (GLOBEC) is to understand and predict how marine species respond to global climate change. Among the uncertainties in a warmer global climate is the extent to which upwelling will increase or decrease in specific boundary current systems, such as the California Current System, and consequently affect the productivity and community structure and function. Our interdisciplinary research, as part of the Northeast Pacific GLOBEC (NEP GLOBEC) program, assists NOAA with Strategic Plan Goals 1 and 2 (above) to analyze top trophic levels (i.e., marine mammals and seabirds) in the northern California Current System (CCS) relative to mid-trophic levels and bio-physical coupling in the system. Among our objectives is to develop predictive bio-physical models of mammal and seabird occurrence patterns in order to improve our understanding of the mechanisms involved in ecosystem change, thus to improve predictability and management of living marine resources important to coastal communities.

Analyses of the coupled bio-physical data sets for two process cruises in the northern CCS during spring and summer 2000 have been completed (Tynan et al. 2005, Ainley et al. 2005). We have examined the correspondence between cross-shelf and along-shelf variation in physical forcing, oceanographic features, productivity, prey fields (as represented by acoustic backscatter at 4 frequencies), and cetacean and seabird occurrence patterns. Occurrence patterns of cetaceans and densities of seabirds were compared with hydrographic and ecological variables (e.g., sea surface temperature, sea surface salinity, thermocline depth, halocline depth, chlorophyll maximum, distance to the shoreward edge of the upwelling front, distance to the center of the equatorward jet, and acoustic backscatter at 38, 120, 200 and 420 kHz) derived from instruments on a towed undulating array (SeaSoar) and a four-frequency bioacoustic system. Using a multiple logistic regression model, 60.2% and 94.4% of the variation in occurrence patterns of humpback whales Megaptera novaeangliae during late spring and summer, respectively, were explained. That humpbacks occurred in regions of highest abundance of Pacific sardine Sardinops sagax, high densities of euphausiids, and the highest catch of juvenile salmon (Figure 1) suggests that whales were responding to a cascade of trophic dynamics enhanced by flow-topography interactions and the strong upwelling signature at a submarine bank and off Cape Blanco (Tynan et al. 2005). The percentage of variation in occurrence patterns explained by our logistic regression models for four species of cetacean (humpback whale, Pacific white-sided dolphin Lagenorhynchus obliquidens, Dall’s porpoise Phocoenoides dalli, and harbor porpoise Phocoena phocoena) are among the highest ever achieved, and are likely a result of the concurrent acquisition of fine-scale oceanographic data with the cetacean survey data, as well a result of predator knowledge of the system (Tynan et al. 2005). In the multiple regression models for distributions of 12 species of seabirds, the most important explanatory variables (among 14 initially included in each model) were distance to the upwelling–derived frontal features (center and edge of the coastal jet, and an abrupt, inshore temperature gradient), sea surface salinity, acoustic backscatter representing various sizes of prey, and chlorophyll maximum (Ainley et al. 2005).

Our analyses of cetacean and seabird distributions in the northern CCS show the importance of the alongshore upwelling front, position of the coastal jet, vertically integrated backscatter at specific frequencies (i.e., prey), and the chlorophyll maximum to resolve top trophic distributions (Figure 1 reproduced from Tynan et al., 2005). Processes important to top trophic levels include flow-topography interactions between the upwelling front and jet with bottom topography at a submarine bank and at a large coastal promontory on the eastern boundary current circulation (see Figure 2 reproduced from Tynan et al., 2005). Enhanced mesoscale variability (e.g. strong meanders) in the system also improved our ability to explain the occurrence patterns for some species (i.e. Dall’s porpoise). The responses of cetaceans and seabirds to biophysical processes in the northern California Current upwelling system are both seasonally and spatially specific. Results of these analyses provide the framework for further development of predictive biophysical models of top predator occurrence in the California Current System. This research therefore assists in the protection and management of coastal resources through ecosystem-based management. In addition, by examining the influence of upwelling dynamics and circulation on occurrence patterns of top predators, this research contributes to our understanding of the effects of climate variability on the northern California Current ecosystem. Continued synthesis and integration of numerous data sets collected during NEP GLOBEC will help elucidate the influence of climate on the physics and biology of the California Current marine food web.

ONLINE STATUS OF DATA
Cetacean and bird data from the two GLOBEC NEP NCC cruises of 2000 have been posted on the U.S. GLOBEC website http://globec.whoi.edu/jg/dir/globec/nep. Data for 2002 will be posted soon. Robert Groman (Woods Hole Oceanographic Institution) manages the data pages for U.S. GLOBEC. Additional information about the NEP GLOBEC and U.S. National GLOBEC programs is available at: http://globec.oce.orst.edu/groups/nep and http://www.usglobec.org

PUBLICATIONS:
Tynan, C.T., D.G. Ainley, J.A. Barth, T.J. Cowles, S.D. Pierce, L.B. Spear. 2005. Cetacean distributions relative to ocean processes in the northern California Current System. Deep-Sea Research Part II 52: 145-167. Contribution Number 483 of the U.S. GLOBEC program; WHOI Contribution Number 11035.

Ainley, D.G., L. B. Spear, C.T. Tynan, J.A. Barth, S.D. Pierce, R.G. Ford, T.J. Cowles. 2005. Physical and biological variables affecting seabird distributions during the upwelling season of the northern California Current. Deep-Sea Research Part II 52: 123-143. Contribution Number 438 of the U.S. GLOBEC program.

PRESENTATIONS OF RESEARCH:
During 2003 – 2005, more than 14 presentations of the research were given at national and international conferences, US GLOBEC meetings, and universities.

Tynan, C.T., Ainley, D.G., Spear, L.B., Barth, J.A., Cowles, T.J., Pierce, S.D., Peterson, W.T., Brodeur, R., Batchelder, H., Strub, T., Thomas, A., 2003. ‘Mesoscale distributions of cetaceans and seabirds relative to oceanographic processes in the northern California Current: A GLOBEC study, 2000 and 2002.’ ONR International Field Office, Joint Planning Meeting US, UK, NATO, London, January 21, 2003

Tynan, C.T., Ainley, D.G., Spear, L.B., Barth, J.A., Cowles, T.J., Pierce, S.D., ‘Cetacean distributions relative to ocean processes in the northern California Current System: A GLOBEC study.’ Eastern Pacific Ocean Conference (EPOC), Sept. 24-27, 2003. Ainley, D.G., Spear, L.B., Tynan, C.T., Barth, J.A., Cowles, T.J., Pierce, S.D., ‘Factors affecting the spatial patterns of occurrence of seabirds in the northern California Current waters, spring and summer, 2000’. Eastern Pacific Ocean Conference (EPOC), Sept. 24-27, 2003, poster

Tynan, C.T., Ainley, D.G., Spear, L.B., Barth, J.A., Cowles, T.J., Pierce, S.D., ‘Cetacean distributions relative to ocean processes in the northern California Current System: A GLOBEC study.’ Invited seminar: WHOI Biology Department Seminar, October 2, 2003 Tynan, C.T., Ainley, D.G., Spear, L.B., Barth, J.A., Cowles, T.J., Pierce, S.D., ‘Toward predictive biophysical models of cetacean occurrence patterns in the California Current System, an upwelling boundary current system.’ Invited talk: ONR – Effects of Sound on the Marine Environment (ESME), Woods Hole, October 21, 2003

Tynan, C.T., ‘Developing predictive biophysical models of cetacean distribution in the California Current System.’ Invited seminar: Old Dominion University, Center for Coastal Physical Oceanography, November 3, 2003 Tynan, C.T., Ainley, D.G., Spear, L.B., Barth, J.A., Cowles, T.J., Pierce, S.D., ‘Toward predictive biophysical models of  cetacean occurrence patterns in the California Current System.’ Invited Science Talk, US GLOBEC SSC, National Academy of Sciences, Woods Hole, November 6, 2003

Ainley, D.G., L.B. Spear, C.T. Tynan. ‘Occurrence patterns of seabirds in the California Current’. Pacific Seabird Group, Cabo San Jose, Mexico, January 2004.

Tynan, C.T. and R. D. Brodeur, Session Chairs for OS21J, ‘Understanding the Physical and Biological Coupling of Marine Population Dynamics: Higher Trophic Levels in the Northeastern Pacific, January 26-30, 2004 AGU Ocean Sciences, Portland, Oregon.

Tynan, C.T., D.G. Ainley, L.B. Spear, J.A. Barth, T.J. Cowles, S.D. Pierce, ‘Toward predictive biophysical models of cetacean occurrence patterns in the California Current System’, January 26-30, 2004 AGU Ocean Sciences, Portland, Oregon; participation in GLOBEC SI meeting and synthesis planning workshop following AGU.

Ainley, D.G., L.B. Spear, C.T. Tynan. ‘Occurrence patterns of seabirds in the California Current’. ASLO, Honolulu HI, February 16-20, 2004.

Tynan, C.T. ‘Toward predictive biophysical models of cetacean occurrence patterns in the California Current System, an upwelling boundary current system’. Requested presentation for Mr. Donald Schregardus, Deputy Assistant of the Navy (Environment) (DASNE) and CDR Karen Kohanowich, Ocean Resources Advisor, during visit to WHOI, March 9, 2004.

Tynan, C.T., Ainley, D.G., Spear, L.B., Barth, J.A., Cowles, T.J., Pierce, S.D., ‘Biotic and abiotic cross-shelf transport: comparing carbon transport by humpback whales with carbon transport in offshore jets of the California Current System’, Eastern Pacific Ocean Conference (EPOC), Sept. 22-26, 2004, poster.

Tynan, C.T., Ainley, D.G., Spear, L.B., Barth, J.A., Cowles, T.J., Pierce, S.D., ‘Biotic and abiotic cross-shelf transport: comparing carbon transport by humpback whales with carbon transport in offshore jets of the California Current System’, GLOBEC SI Meeting, Corvallis, Oregon, November 15-16, 2004, poster.

Last updated: August 19, 2008
 


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