Stable isotope analysis reveals pelagic foraging by the Southern sea lion in central Chile

Hückstädt, Luis A.; Rojas, Carlos; Antezana, Tarsicio

doi:10.1016/j.jembe.2007.03.014

Cited by 81 publications

(63 citation statements)

References 29 publications

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“…Neither prey-to-predator and female-to-offspring enrichment rates nor the tissue turnover have been determined for the South America sea lion in controlled experiments and hence extrapolation from studies conducted on phylogenetically close organisms is required (Lewis et al, 2006;Hückstädt et al, 2007). Fortunately, the prey-to-predator enrichment rate has been determined in other pinnipeds in captivity (Hobson et al, 1996;Kurle, 2002), the female-to-offspring enrichment rate has been assessed in other carnivores, including pinnipeds (Jenkins et al, 2001;Ducatez et al, 2008), and the turnover rate of blood components has been established for a number of birds and mammals (Hobson and Clark, 1993;Hilderbrand et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

Drago¹,

Cardona²,

Crespo³

et al. 2010

Sci. Mar.

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SUMMARY: This study tests the hypothesis that female South American sea lions shift from off-shore, pelagic prey to coastal, benthic prey after parturition in order to reduce the foraging trip duration and hence the time pups remain unattended on the beach during early lactation. The δ 13 C and δ 15 N values of the serum and blood cells of 26 South American sea lion suckling pups from northern Patagonia were used to track the dietary changes of their mothers from late pregnancy to early lactation, after correction for differential isotopic fractionation between tissues. Primary producers and potential prey species were also analysed to establish a baseline for interpreting the stable isotope concentration of serum and blood cells. Isotopic ratios revealed a generalized increase in the consumption of coastal-benthic prey after parturition. Such a generalized postpartum shift will allow females to spend more time on land and look after their pups. The effects of this foraging strategy on the nutritional quality of the female's diet are discussed.Keywords: South American sea lion, diet, feeding strategy, suckling pup, lactating females, Otaria flavescens, stable isotopes, Bayesian mixing models. RESUMEN: Cambio en la estrategia de alimentación de las hembras del león marino sudamericano (Carnivora: Pinnipedia) tras el parto. -El presente estudio pretende comprobar si las hembras del león marino sudamericano adoptan una dieta más bentónica y costera tras el parto, con el fin de reducir la duración de los viajes de alimentación y reducir así el tiempo durante el cual las crías permanecen desatendidas en la playa. Para ello, se determinaron las concentraciones de isótopos estables de carbono y nitrógeno en el suero y las células sanguíneas de 26 crías lactantes de león marino sudamericano del norte de la Patagonia, con el fin de reconstruir la dieta de la madre durante la parte final de la gestación y el inicio de la lactancia, tras la correspondiente corrección del fraccionamiento isotópico entre tejidos. También se analizaron muestras de productores primarios y de presas potenciales para ayudar en la interpretación de los resultados. Las concentraciones de isótopos estables antes y después del parto confirmaron un incremento en el consumo de presas bentónicas costeras tras el parto. Este cambio generalizado de dieta tras el parto permitiría a las hembras incrementar el tiempo que pasan junto a las crías. Se discuten los efectos que esta estrategia puede tener sobre la calidad de la dieta de las hembras.Palabras clave: león marino sudamericano, dieta, estrategias tróficas, lactancia, Otaria flavescens, isótopos estables, modelos de mezcla bayesianos.

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Section: Discussionmentioning

confidence: 99%

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

Drago¹,

Cardona²,

Crespo³

et al. 2010

Sci. Mar.

View full text Add to dashboard Cite

show abstract

“…The aim of a cut-off of TL at 4.0 is to examine changes within the apex predator community while excluding small and medium pelagic fish, some of which have TLs above 3.25 and which are still subject to large natural fluctuations in abundance. Some examples of these sorts of fishes are the Peruvian anchoveta Engraulis ringens (TL = 3.3 to 3.6; Hückstädt et al 2007, Marzloff et al 2009), herring Clupea harengus on the Western Scotian Shelf, Canada (TL = 3.85; Araújo & Bundy 2012) and anchovy Engraulis capensis off South Africa (TL = 3.00 to 3.50; Shannon et al 2003, Watermeyer et al 2008, Osman 2010, Van der Lingen & Miller 2011. Further, under instances of expansion of fisheries, 'fishing down' trajectories may be masked by increases in the catches of higher TL species, which becomes evident when MTI 4.0 is considered and/or when the Fishingin-Balance index, which indicates periods of expansion and contraction in the fishery (Pauly & Palomares 2005), is monitored (Stergiou 2005).…”

Section: Tl Indicator Series: Catch Surveys and Modelsmentioning

confidence: 99%

Trophic level-based indicators to track fishing impacts across marine ecosystems

Shannon¹,

Coll²,

Bundy³

et al. 2014

Mar. Ecol. Prog. Ser.

132

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Trophic level (TL)-based indicators have been widely used to examine fishing impacts in aquatic ecosystems and the induced biodiversity changes. However, much debate has ensued regarding discrepancies and challenges arising from the use of landings data from commercial fisheries to calculate TL indicators. Subsequent studies have started to examine survey-based and model-based indicators. In this paper, we undertake an extensive evaluation of a variety of TL indicators across 9 well-studied marine ecosystems by making use of model-as well as surveyand catch-based TL indicators. Using detailed regional information and data on fishing history, fishing intensity, and environmental conditions, we evaluate how well TL indicators are capturing fishing effects at the community level of marine ecosystems. Our results highlight that the differences observed between TL indicator values and trends is dependent on the data source and the TL cut-off point used in the calculations and is not attributable to an intrinsic problem with TLbased indicators. All 3 data sources provide useful information about the structural changes in the ecosystem as a result of fishing, but our results indicate that only model-based indicators represent fishing impacts at the whole ecosystem level.

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“…Information on trophic position, spatial variation in diet and geographic sources of prey has been obtained for a variety of species (e.g. Huckstadt et al 2007, Porras-Peters et al 2008. Seasonal, inter-annual and decadal differences in diet have also been detected and related to fluctuations in prey availability and oceanographic conditions (e.g.…”

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

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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Stable isotope analysis reveals pelagic foraging by the Southern sea lion in central Chile

Cited by 81 publications

References 29 publications

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

Change in the foraging strategy of female South American sea lions (Carnivora: Pinnipedia) after parturition

Trophic level-based indicators to track fishing impacts across marine ecosystems

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

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