Trophic declines and decadal-scale foraging segregation in three pelagic seabirds

Morra, Kaycee E.; Chikaraishi, Yoshito; Gandhi, Hasand; James, Helen F.; Rossman, Sam; Wiley, Anne E.; Raine, André F.; Beck, Jessie; Ostrom, Peggy H.

doi:10.1007/s00442-018-04330-8

Cited by 6 publications

(16 citation statements)

References 53 publications

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“…Previous boatbased surveys also recorded Newell's shearwaters in the eastern portion of the area identified by our tracking study (Joyce et al 2013). Assessing potential threats within this region, including marine pollution (Sileo et al 1990, Derraik 2002, Kain et al 2016), overfishing (Ainley et al 2014, Morra et al 2019, effects of climate change (Bell et al 2013), and bycatch (Gilman et al 2008, Rodríguez et al 2019, are important to consider for the conservation of this species.…”

Section: Discussionmentioning

confidence: 99%

Post-release survival of fallout Newell’s shearwater fledglings from a rescue and rehabilitation program on Kaua‘i, Hawai‘i

Raine

Anderson

Vynne

et al. 2020

Endang. Species. Res.

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Light attraction impacts nocturnally active fledgling seabirds worldwide and is a particularly acute problem on Kaua‘i (the northern-most island in the main Hawaiian Island archipelago) for the Critically Endangered Newell’s shearwater Puffinus newelli. The Save Our Shearwaters (SOS) program was created in 1979 to address this issue and to date has recovered and released to sea more than 30500 fledglings. Although the value of the program for animal welfare is clear, as birds cannot simply be left to die, no evaluation exists to inform post-release survival. We used satellite transmitters to track 38 fledglings released by SOS and compared their survival rates (assessed by tag transmission duration) to those of 12 chicks that fledged naturally from the mountains of Kaua‘i. Wild fledglings transmitted longer than SOS birds, and SOS birds with longer rehabilitation periods transmitted for a shorter duration than birds released immediately or rehabilitated for only 1 d. Although transmitter durations from grounded fledglings were shorter (indicating impacts to survivorship), some SOS birds did survive and dispersed out to sea. All surviving birds (wild and SOS) traveled more than 2000 km to the southwest of Kaua‘i, where they concentrated mostly in the North Pacific Equatorial Countercurrent Province, revealing a large-scale annual post-breeding aggregation zone for fledgling Newell’s shearwaters. While there was reduced survival among birds undergoing rehabilitation, SOS remains an important contribution toward the conservation of Newell’s shearwater because a proportion of released birds do indeed survive. However, light attraction, the root cause of fallout, remains a serious unresolved issue on Kaua’i.

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Section: Discussionmentioning

confidence: 99%

Post-release survival of fallout Newell’s shearwater fledglings from a rescue and rehabilitation program on Kaua‘i, Hawai‘i

Raine

Anderson

Vynne

et al. 2020

Endang. Species. Res.

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“…These two groups of amino acids are frequently called "trophic" and "source" amino acids, respectively (e.g., Popp et al 2007;reviewed in Ohkouchi et al 2017). Using this framework, the δ 15 N analysis of amino acids has rapidly evolved into a unified approach: the δ 15 N values of the source amino acids in organisms directly provide the δ 15 N values of primary producers at bases of food webs, whereas difference in the Δδ 15 N AA value between trophic and source amino acids within a single organism correlates with its position in the trophic hierarchy (e.g., Chikaraishi et al 2009;Steffan et al 2013;Chikaraishi et al 2014;Broek and McCarthy 2015;Choy et al 2015;Lorrain et al 2015;Blanke et al 2017;Choi et al 2017;Dharampal and Findlay 2017;Steffan et al 2017;Ostrom et al 2017;Blanke et al 2018;Morra et al 2019).…”

Section: Introductionmentioning

confidence: 99%

A new insight into isotopic fractionation associated with decarboxylation in organisms: implications for amino acid isotope approaches in biogeoscience

Takizawa

Takano

Choi

et al. 2020

Prog Earth Planet Sci

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Stable nitrogen (15N/14N) and carbon (13C/12C) isotopic compositions of amino acids in organisms have widely been employed as a powerful tool to evaluate resource utilization and trophic connection among organisms in diverse ecosystems. However, little is known about the physiological factors or mechanisms responsible for determining the isotopic discrimination (particularly for carbon) within amino acids of organisms. In the present study, we investigated the inter-trophic discrimination of nitrogen and carbon isotopes within amino acids (Δδ15NAA and Δδ13CAA, respectively) using four consumer–diet pairs. Each pairing illustrates a metabolic perspective of isotopic fractionation of amino acids. The Δδ15NAA values in these combinations reveal a trend consistent with those observed in many other combinations in previous studies. This further validates a standard scenario: the deamination preferentially removes 14N amino group from diet-derived amino acids, leaving behind the 15N-enriched amino acids in consumer biomass. The Δδ15NAA values thus mirror the activity of amino acid deamination in consumers. In contrast, the trends in the Δδ13CAA value suggest a different metabolic fate for the amino acid carbon isotope. Based on our results, we predict the following scenario: decarboxylation preferentially removes 12C α-carbon (i.e., carbonyl-carbon) from pyruvic acid in glycolysis, and from α-ketoglutaric acid in the tricarboxylic acid cycle, leaving behind the 13C-enriched both pyruvic and α-ketoglutaric acids. The 13C is then transferred to amino acids that are synthesized from the 13C-enriched precursor molecules within consumers. The Δδ13CAA values therefore mirror the pathways of de novo amino acid synthesis in consumers. The proposed link between nitrogen and carbon isotopes can refine our knowledge of the potential processes affecting the isotopic fractionation within diet and consumer compartments, as well as environmental samples. Graphical abstract

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“…These problems affect marine ecosystems in many ways, including alterations of the food webs (e.g. Ostrom et al 2017, Morra et al 2019.…”

Section: Introductionmentioning

confidence: 99%

Trophic hierarchy of coastal marine fish communities viewed via compound-specific isotope analysis of amino acids

Xing

Choi

Takizawa

et al. 2020

Mar. Ecol. Prog. Ser.

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Coastal marine ecosystems are very complex and composed of myriad organisms, including offshore, coastal, and migratory fish occupying diverse trophic positions (TPs) in food webs. The illustration of trophic hierarchy based on the TP and resource utilization of individual organisms remains challenging. In this study, we applied compound-specific isotope analysis of amino acids to estimate the TP and isotopic baseline (i.e. δ15N values of primary resources at the base of food webs) for 13 fish and 1 squid species in a coastal area of Sagami Bay, Japan, where a large diversity in the isotopic baseline is caused by an admixture of ocean currents and artificial nitrogen inputs. Our results indicate that the TP of fish and squid varies between 2.9 and 3.9 (i.e. omnivorous, carnivorous, and tertiary consumers), with low variation within individual species. Moreover, the δ15N values of phenylalanine revealed the diversity of isotopic baselines between and within species. Low values (7.8-10.3‰) and high values (18.6-19.2‰), with a small variation (1σ < 1.0‰), were found in 2 offshore species and 3 coastal species, respectively. In contrast, highly variable values (9.8-19.7‰), with large variation within species (1σ > 1.0‰), were found for the remaining 9 migratory species. These results represent evidence of differential trophic exploitation of habitats between offshore and coastal species, particularly among individuals of migratory species, that were all collected in a single area of Sagami Bay.

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Trophic declines and decadal-scale foraging segregation in three pelagic seabirds

Cited by 6 publications

References 53 publications

Post-release survival of fallout Newell’s shearwater fledglings from a rescue and rehabilitation program on Kaua‘i, Hawai‘i

Post-release survival of fallout Newell’s shearwater fledglings from a rescue and rehabilitation program on Kaua‘i, Hawai‘i

A new insight into isotopic fractionation associated with decarboxylation in organisms: implications for amino acid isotope approaches in biogeoscience

Trophic hierarchy of coastal marine fish communities viewed via compound-specific isotope analysis of amino acids

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