Differential responses of seabirds to inter-annual environmental change in the continental shelf and oceanic habitats of southeastern Bering Sea

Yamamoto, Takashi; Kokubun, Nobuo; Kikuchi, Dale M.; Sato, N.; Takahashi, Akinori; Will, Alexis; Kitaysky, Alexander S.; Watanuki, Yutaka

doi:10.5194/bgd-12-17693-2015

Cited by 3 publications

References 85 publications

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Identifying key marine habitat sites for seabirds and sea ducks in the Canadian Arctic

et al. 2019

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The Canadian Arctic hosts millions of marine birds annually, many of which aggregate in large numbers at well-defined sites at predictable times of the year. Marine habitats in this region will be under increasing threats from anthropogenic activities, largely facilitated by climate change and long-term trends of reduced sea ice extent and thickness. In this review, we update previous efforts to delineate the most important habitats for marine birds in Arctic Canada, using the most current population estimates for Canada, as well as recent information from shipboard surveys and telemetry studies. We identify 349 160 km2 of key habitat, more than doubling earlier suggestions for key habitat extent. As of 2018, 1% of these habitats fall within the boundaries of legislated protected areas. New marine conservation areas currently being finalized in the Canadian Arctic will only increase the proportion protected to 13%.

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Identifying key marine habitat sites for seabirds and sea ducks in the Canadian Arctic

et al. 2019

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Inter-annual climate variability affects foraging behavior and nutritional state of thick-billed murres breeding in the southeastern Bering Sea

Kokubun

Takahashi

Paredes

et al. 2018

Mar. Ecol. Prog. Ser.

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Sustainability within the fisheries of the commercially important European whelk Buccinum undatum has become a major concern because of over-exploitation and increased landings in many European coastal shelf seas due to the expansion of export markets to East Asian countries. Current management of B. undatum populations is difficult to achieve as several life history traits are problematic to accurately monitor. The current method of age determination for stock assessment has a low success rate and focuses on the use of putative annual rings on the surface of the organic operculum. Here, we validate an annual periodicity of growth ring formation in B. undatum statoliths that provides an alternative, reliable and accurate method for determining a whelk's age. Laboratory-reared juvenile B. undatum of known provenance and age deposited a hatching ring at the time of emergence from their egg capsule and a clearly defined growth ring during February of their first and second years. Stable oxygen isotope profiles from the shells of 2 adult whelks confirmed annual growth ring deposition by demonstrating seasonal cycles of δ 18O in the shell that matched the relative position and number of visible growth rings in the statolith. Validation of annually resolved statolith growth rings will, for the first time, provide fisheries scientists with a tool to determine the age structure of B. undatum populations and allow analytical stock assessments that will enable informed decisions for future management practices of whelk fisheries.

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Foraging segregation of two congeneric diving seabird species (common and thick-billed murres) breeding on St. George Island, Bering Sea

Kokubun¹,

Yamamoto²,

Sato³

et al. 2015

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Abstract. Sub-arctic environmental changes are expected to affect the ecology of marine top predators. We examined the characteristics of foraging behavior of two sympatric congeneric diving seabirds, common (Uria aalge: hereafter COMU) and thick-billed (U. lomvia: hereafter TBMU) murres breeding on St. George Island located in the seasonal sea-ice region of the Bering Sea. We investigated their flight duration, diel patterns of dive depth, and underwater wing strokes, along with morphology and blood stable isotopes. Acceleration-temperature-depth data loggers were attached to chick-guarding birds, and behavioral data were obtained from 7 COMU and 12 TBMU. Both species showed similar trip duration (13.21 ± 4.79 h for COMU and 10.45 ± 7.09 h for TBMU) and similar diurnal patterns of diving (frequent dives to various depths in the daytime and less frequent dives to shallow depths in the nighttime). During the daytime, dive depths of COMU had two peaks in shallow (18.1 ± 6.0 m) and deep (74.2 ± 8.7 m) depths, while those of TBMU were 20.2 ± 7.4 m and 59.7 ± 7.9 m. COMU showed more frequent wing strokes during the bottom phase of dives (1.90 ± 0.11 s−1) than TBMU (1.66 ± 0.15 s−1). Fishes occurred with higher proportion in the bill-loads brought back to chicks in COMU (85 %) than in TBMU (56 %). δ15N value of blood was significantly higher in COMU (14.47 ± 0.27 ‰) than in TBMU (13.14 ± 0.36 ‰). Relatively small wing area (0.053 ± 0.007 m2) of COMU compared to TBMU (0.067 ± 0.007 m2) may make them more agile underwater and thus enable them to target more mobile prey including larger fishes that inhabit deeper depths. These differences in foraging behavior between COMU and TBMU might explain the differences in their responses to long-term marine environmental changes.

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Differential responses of seabirds to inter-annual environmental change in the continental shelf and oceanic habitats of southeastern Bering Sea

Cited by 3 publications

References 85 publications

Identifying key marine habitat sites for seabirds and sea ducks in the Canadian Arctic

Identifying key marine habitat sites for seabirds and sea ducks in the Canadian Arctic

Inter-annual climate variability affects foraging behavior and nutritional state of thick-billed murres breeding in the southeastern Bering Sea

Foraging segregation of two congeneric diving seabird species (common and thick-billed murres) breeding on St. George Island, Bering Sea

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