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Seasonal and inter-annual oceanographic changes induce diet switching in a piscivorous seabird

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Title: Seasonal and inter-annual oceanographic changes induce diet switching in a piscivorous seabird
Authors: Ito, Motohiro Browse this author
Minami, Hiroshi Browse this author
Tanaka, Yuzan Browse this author
Watanuki, Yutaka Browse this author →KAKEN DB
Keywords: Prey switching
Stable isotope signatures
Rhinoceros auklets
Tsushima Current
Issue Date: 30-Oct-2009
Publisher: Inter-Research
Journal Title: Marine Ecology Progress Series
Volume: 393
Start Page: 273
End Page: 284
Publisher DOI: 10.3354/meps08192
Abstract: The structure of a marine food web can change quickly within seasons as well as interannually in response to physical oceanographic changes. In this study, we examined the relationship between temporal changes in the marine ecosystem of northern Hokkaido, Japan, and diets of rhinoceros auklets Cerorhinca monocerata breeding in this region. To obtain an integrated measure of changes in diet composition on short (days) and inter-annual (2004 and 2005) time scales, we used a 2-pronged approach. We examined (1) the diets of adults using stomach contents and stable isotope signatures in tissues, and (2) chick diets using the composition of bill-loads delivered to chicks. During the incubation period, the diet of adults comprised euphausiids (Thysanoessa longipes and T inermis). During the chick-rearing period, the diet of adults was age 0 Japanese sandlance Ammodytes personatus and age 0 Japan Sea greenling Pleurogrammus azonus in the early period, but switched quickly (<10 d) to warm-water-preferring Japanese anchovy Engraulis japonicus when the warm Tsushima Current intruded into their foraging range. Adult blood plasma stable isotope ratios reflected these seasonal changes in stomach content. Diets did not differ between age categories. Furthermore, the timing of diet switching to anchovy differed inter-annually, and was about 10 d later in 2005 than 2004, reflecting a difference in the timing of the intrusion of warm water. We conclude that rhinoceros auklets respond sensitively to current-related rapid marine food web changes.
Rights: © 2009 Inter-Research
Type: article
Appears in Collections:水産科学院・水産科学研究院 (Graduate School of Fisheries Sciences / Faculty of Fisheries Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 綿貫 豊

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