Olszewski, Susin D.

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University of Puget SoundSound IdeasSummer Research2010Determining Pacific Northwest Seabird Diet UsingStable IsotopesSusin D. OlszewskiUniversity of Puget SoundFollow this and additional works at: http://soundideas.pugetsound.edu/summer_researchThis Presentation is brought to you for free and open access by Sound Ideas. It has been accepted for inclusion in Summer Research by an authorizedadministrator of Sound Ideas. For more information, please contact soundideas@pugetsound.edu.Recommended CitationOlszewski, Susin D., "Determining Pacific Northwest Seabird Diet Using Stable Isotopes" (2010). Summer Research. Paper 19.http://soundideas.pugetsound.edu/summer_research/19Determining Pacific Northwest Seabird Diet Using Stable Isotopes Susin Olszewski*, Kena Fox-Dobbs, & Peter Hodum University of Puget Sound, Tacoma, WA 98416 INTRODUCTION Seabirds have often been used as gauges of conditions in marine environments, as changes in their breeding and health can indicate the state of marine ecosystems with regard to pollution and prey population sizes.1 Northern fulmars are one such indicator species. These generalists—feeding on whatever is near the surface— are particularly susceptible to ingesting and retaining marine debris. This study investigated diets of 15 fulmars, 6 western grebes, and 6 common murres found dead on the outer coast of Washington during the fall of 2009 using stable isotope analysis. This technique allowed us to determine diet at an individual level and gain insight into the trophic structure of Washington seabirds.         METHODS I. Collection of muscle tissue and bone from fulmars (n=15), western grebes (n=6), and murres (n=6) II. Chemical preparation of tissues and weighing of samples III. Analysis of samples at stable isotope lab at UC Santa Cruz             PART III. WASHINGTON FULMAR COMMUNITY          ACKNOWLEDGEMENTS & LITERATURE CITED I would like to thank my faculty advisors, Kena Fox-Dobbs and Peter Hodum for their support and guidance, funding provided by the University of Puget Sound, the University of California Santa Cruz, Dr. Shugart, and the Slater Museum.  1. Furness R. W., K. J.. Camphuysen. 1997. Seabirds as monitors of the marine environment. ICES Journal of Marine Science: Journal du Conseil 54:726-737. 2. Provencher J. F., A. J. Gaston, and M. L. Mallory. 2009. Evidence for increased ingestion of plastics by northern fulmars (Fulmarus glacialis) in the Canadian Arctic.   Marine pollution bulletin 58:1092-1095.   PART I. SEABIRD COMMUNITY FOOD WEB                    Future Work •Explore the ingested plastics in fulmars with increased sample size looking for trends in age, fragment size, and color. •Gain isotopic data from prey items specifically from the outer coast of Washington. •Utilize isotopic mixing models to determine the contribution of movement verses diet to the isotopic signal, using    murres as a proxy.     PART II. FULMARS & PLASTICS      Many seabirds mistake plastic for food and end up consuming a great deal of it. Fulmars are unable to regurgitate plastics and thus, retain these indigestible objects in their stomachs.1 For example, in one study, between 62-84% of fulmars sampled contained plastic in their guts.2  Of five birds we dissected, all contained plastics. It was observed that fragments tended to be red or white. 18 Figure 2. Average isotopic bone collagen values from various studies and locations. δ13C and δ15N values decrease with increases in altitude. Locations were Monterey, CA (Fox-Dobbs, 2006; Schoeninger, 1984), the Gulf of Farallones (Sydeman, 1997), and the Aleutian archipelago (Ricca, 2007).                 Northern Fulmar (above right), Western Grebe (bottom right), Common Murre (above). Photographs courtesy of Paul Higgins, Earl Orf, and Kate Sutherland  Summary •Isotopic data affirms that fulmars are generalists and off shore feeders. •Grebes (fresh water breeders) show mixed fresh water & marine signature. •Murres appear to feed more discriminately on prey items of similar size. •Isotopes show significantly different feeding ecologies between 3 species. Figure 1. Isotopic data from seabird bone collagen. Ellipses indicate a 95% confidence interval. Trophic level and prey size increase with increased δ15N. Lower δ13C values indicate open ocean feeding whereas higher δ13C indicates near shore feeding. δ13C values of western grebes suggest fresh water feeding. Fulmars show a wide spread in the trophic level at which they are feeding. Paired post hoc species comparisons showed all species significantly different feeding ecologies (approxF4,44= 6.64, p= 0.0003).   Trophic Level Open Ocean  or Fresh Water Near shore Figure 3. Count of plastic fragments and rocks found in five Washington fulmar stomachs. The most impacted stomach contained 42 plastic fragments. Fulmar stomach full of plastics (Top), fulmar dissection in (Below). Photos by Susin Olszewski. (a) (b) Figure 4. Regressions between muscle and bone for 13C (a) and 15N (b). The dotted red line indicates the theoretical regression. There was no correlation at the individual level for 13C (r2= 0.0134, p= 0.71). 15N also lacked correlation between muscle and bone (r2= 0.0148, p=0.69). Figure 5. Washington fulmars compared with the muscle of potential prey. Isotopic data gathered from the Aleutian Islands are shown in pink and data from the California coast are shown in orange. Error bars indicate standard deviation. List of reference literature available upon request.  Summary • Lack of correlation at the individual level in Figure 4 (a & b) reflects several possible factors impacting muscle:      1. Migration     2. Starvation    3. Variation in time spent in WA       before death  • Isotopic data agrees with biological knowledge of diet, such that components of the fulmar diet are:  1. Amphipods                  2. Squid                 3. Small Fish                           4. Krill     

Determining Pacific Northwest Seabird Diet Using Stable Isotopes

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Determining Pacific Northwest Seabird Diet Using Stable Isotopes

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