Dimensions of diet segregation in grey seals Halichoerus grypus revealed through stable isotopes of carbon (δ13C) and nitrogen (δ15N)

Tucker, Strahan; Bowen, W. Don; Iverson, Sara J.

doi:10.3354/meps339271

Cited by 47 publications

(49 citation statements)

References 51 publications

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“…Hall-Aspland et al 2005b, Drago et al 2009b, Hanson et al 2009). In addition, in conjunction with data on prey values, estimates of the relative contribution of various prey species to biomass consumption have been obtained (Hall-Aspland et al 2005a, Hammill et al 2005, Huckstadt et al 2007, as well as evidence of ontogenetic and inter-individual variation in niche breadth (Tucker et al 2007, Drago et al 2009a, Newsome et al 2009). …”

Section: Abstract: Australian Fur Seal · Otariid · Stable Isotopes ·mentioning

confidence: 99%

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Stable isotopes reveal inter-annual and inter-individual variation in the diet of female Australian fur seals

Arnould¹,

Cherel²,

Gibbens³

et al. 2011

Mar. Ecol. Prog. Ser.

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Section: Abstract: Australian Fur Seal · Otariid · Stable Isotopes ·mentioning

confidence: 99%

“…Tucker et al 2007). Few studies have documented age-related differences in the trophic niches of adult pinnipeds.…”

Section: Inter-annual and Inter-individual Variationmentioning

confidence: 99%

Stable isotopes reveal inter-annual and inter-individual variation in the diet of female Australian fur seals

Arnould¹,

Cherel²,

Gibbens³

et al. 2011

Mar. Ecol. Prog. Ser.

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“…YOY up to 6 mo old had a wide dietary breadth, while adults, especially females, were often highly individually specialised on just 1 or 2 prey species (Beck et al 2007, Tucker et al 2007. Generalist strategies are usually less efficient than specialist strategies, particularly in competitive environments or where different prey items require different capture and handling strategies (Stephens & Krebs 1986, Estes et al 2003.…”

Section: Foraging Effort and Agementioning

confidence: 99%

Development of foraging strategies with age in a long-lived marine predator

Breed¹,

Bowen²,

Leonard³

2011

Mar. Ecol. Prog. Ser.

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The development of foraging strategies as animals mature depends upon experience, stage-specific physiology, the onset of reproductive maturity and the reproductive costs incurred by each sex. To understand the ontogeny of foraging behaviour, we compared movement behaviour of 24 young-of-year (YOY) juveniles (12 male, 12 female) with 6 subadult (4 male, 2 female) and 81 adult (43 male, 38 female) grey seals Halichoerus grypus. We used a behaviour discriminating state-space model followed by a series of mixed-effects models to examine trip structure and habitat use in these age classes. In foraging trips, tortuosity and speed of outbound travel were not different in YOY, subadults and adults, suggesting that YOY navigate as well as older animals. On average, however, YOY trips lasted 1.2 to 3.5 d longer and required up to twice as much transit time to reach foraging areas that were 1.5 to 3 times farther from haul-out sites than those of subadults and adults. This suggests an overall apparent higher foraging effort for YOY. Differences, however, were highly seasonally dependent. In all groups, apparent foraging effort decreased in the summer and increased in the winter, which is consistent with seasonal changes in prey distribution and energy content. Adult foraging patterns showed complex seasonal patterns influenced by both reproductive cycles and seasonal environmental variation, whereas annual foraging patterns of YOY and subadults, neither of which invest in reproduction, were simpler and appeared more closely tied to seasonal changes in prey availability and condition. Although foraging in the same habitats, male and female YOY showed small but significant differences in movement behaviour and trip structure. These differences are unlikely to be due to size difference, which is minimal at this age, and suggest that sex-related differences in foraging develop early before sexual size dimorphism is significantly expressed.

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“…The effect of animal size on contaminant loads is difficult to assess accurately in mature birds and mammals because after they reach maturity they do not continue to grow (as fish typically do). Changes in feeding behaviour and energy requirements, inferred from stable C and N isotopic composition of tissues, [220] can influence a population's Hg accumulation. [144,146] For example, d 13 C and d 15 N values revealed a switch of polar bear (Ursus maritimus) diet from sympagic to pelagic food webs, which resulted in an increase in Hg concentrations in polar bears.…”

Section: Freshwater Food Websmentioning

confidence: 99%

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

123

147

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Environmental context. Mercury, in its methylated form, is a neurotoxin that biomagnifies in marine and terrestrial foodwebs leading to elevated levels in fish and fish-eating mammals worldwide, including at numerous Arctic locations. Elevated mercury concentrations in Arctic country foods present a significant exposure risk to Arctic people. We present a detailed review of the fate of mercury in Arctic terrestrial and marine ecosystems, taking into account the extreme seasonality of Arctic ecosystems and the unique processes associated with sea ice and Arctic hydrology.Abstract. This review is the result of a series of multidisciplinary meetings organised by the Arctic Monitoring and Assessment Programme as part of their 2011 Assessment 'Mercury in the Arctic'. This paper presents the state-of-the-art knowledge on the environmental fate of mercury following its entry into the Arctic by oceanic, atmospheric and terrestrial pathways. Our focus is on the movement, transformation and bioaccumulation of Hg in aquatic (marine and fresh water) and terrestrial ecosystems. The processes most relevant to biological Hg uptake and the potential risk associated with Hg exposure in wildlife are emphasised. We present discussions of the chemical transformations of newly deposited or transported Hg in marine, fresh water and terrestrial environments and of the movement of Hg from air, soil and water environmental compartments into food webs. Methylation, a key process controlling the fate of Hg in most ecosystems, and the role of trophic processes in controlling Hg in higher order animals are also included. Case studies on Eastern Beaufort Sea beluga (Delphinapterus leucas) and landlocked Arctic char (Salvelinus alpinus) are presented as examples of the relationship between ecosystem trophic processes and biologic Hg levels. We examine whether atmospheric mercury depletion events (AMDEs) contribute to increased Hg levels in Arctic biota and provide information on the links between organic carbon and Hg speciation, dynamics and bioavailability. Long-term sequestration of Hg into non-biological archives is also addressed. The review concludes by identifying major knowledge gaps in our understanding, including:(1) the rates of Hg entry into marine and terrestrial ecosystems and the rates of inorganic and MeHg uptake by Arctic microbial and algal communities; (2) the bioavailable fraction of AMDE-related Hg and its rate of accumulation by biota and (3) the fresh water and marine MeHg cycle in the Arctic, especially the marine MeHg cycle.

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Dimensions of diet segregation in grey seals Halichoerus grypus revealed through stable isotopes of carbon (δ13C) and nitrogen (δ15N)

Abstract: Dimensions of diet segregation in grey seals

Cited by 47 publications

References 51 publications

Stable isotopes reveal inter-annual and inter-individual variation in the diet of female Australian fur seals

Stable isotopes reveal inter-annual and inter-individual variation in the diet of female Australian fur seals

Development of foraging strategies with age in a long-lived marine predator

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

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