Biological Sciences Seminar: 'Long-term Diet Patterns of Black Oystercatchers in the Gulf of Alaska' - Oct. 18, 2013

by Michelle Saport  |   

Friday, Oct. 18, 12-1 p.m. ConocoPhillips Integrated Science Building, Room 120

Brooke Carney, master's candidate in biological sciences, will publicly defend her thesis, "Long-term Diet Patterns of Black Oystercatchers (Haematopus bachmani) in the Gulf of Alaska."

Abstract: Black oystercatchers (Haematopus bachmani) are a species of concern throughout their range because of their specialized habitat and small population size. The prey base of black oystercatchers, which consists of animals found in the intertidal zone, may shift in unknown ways as a result of climate change. The objectives of this study were to use stable isotopes of carbon (13C) and nitrogen (15N) to determine the proportional contributions of various prey groups to black oystercatcher diets, the diet-to-tissue fractionation values for black oystercatchers for blood and feathers and whether modern samples can be used to evaluate long-term diet patterns using archived tissues. Whole blood and feather samples, as well as potential prey items, were collected from several field locations in the northern Gulf of Alaska in 2012 and 2013. Diet-to-tissue fractionation values were informed by a small, controlled diet study of captive black oystercatchers at the Alaska SeaLife Center. Mixing models suggest that the diet of individuals sampled in 2012 and 2013 is approximately 52 percent mussels or other filter feeders, 41 percent limpets or other grazers and approximately 5 percent dogwinkles or other secondary consumers, which is consistent with previous assessments of diet. There was little variation in the intra-season 13C and 15N signatures of feathers and of blood among individuals, suggesting the sampled individuals share a similar, specialized diet throughout the spring and summer seasons. The results indicate that black oystercatchers may be susceptible to changes in the species composition of the intertidal zone.

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