Stable isotopes indicate differing foraging strategies in two sympatric otariids of the Galapagos Islands

Páez‐Rosas, Diego; Aurioles‐Gamboa, David; Alava, Juan José; Palacios, Daniel M.

doi:10.1016/j.jembe.2012.05.001

Cited by 58 publications

(76 citation statements)

References 69 publications

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“…Based on the 15 Nvalues, the trophic level (TL) measured here for the Galapagos sea lion ( 15 N = 13.0; TL = 4.2) fall within the range of those recently reported (i.e., 15 N =12.6−13.4; TL = 4.1−4.4) elsewhere [30,31,43]. The 15 N values for thread herrings and mullets were 9.4‰ ± 1.77‰ (TL = 3.1), and 12.7‰ ± 1.10‰ (TL = 4.1), respectively, while the 13 C values for thread herrings and mullets were -17.0 ±0.70 and -9.34 ±0.80.…”

Section: Stable Isotope Profiles and Trophic Levelssupporting

confidence: 86%

“…fish) and the predator (Galapagos sea lion) were determined relative to the baseline 15 N (assumed to occupy a trophic level 2), using the following algorithm [37,38] [31,40], which is relatively close to the 15 N value of 7.3‰, reported recently for phytoplankton in the Galapagos [30]. The rationale for using this signature is supported by the fact that the assimilation of nitrogen (i.e., NO3¯) up taken from near surface marine waters by phytoplankton is reflected by 15 N values of POM, which is also a major component of the carbon flux and sediments [40].…”

Section: Trophic Level Estimationsmentioning

confidence: 99%

“…The Galapagos sea lion diet includes Cupleidae (thread herrings and sardines), Engraulidae (anchovies), Carangidae (bigeye scads), Serranidae (groupers, whitespotted sand bass or camotillo), Myctophidae (lantern fishes), Mugilidae (mullets) and Chlorophtalmidae fishes, and a low proportion of squid, as reported in the existing literature [28][29][30][31]. Although the information about diet and trophic level is limited for sea lions at several rookeries in the Galapagos Islands, it is known that the dietary preferences of Galapagos sea lions are also a function of the local variation in prey availability and regional climate-oceanic variability such as the El Niño events, when sea lions can switch their diet composition to more abundant fish items [30,32,33]. The Galapagos sea lion has been recognized as a key species for the functioning and health of the marine ecosystem of the islands under the environmental management action plan of the Galapagos Marine Reserve (GMR) [33].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Assessing Biomagnification and Trophic Transport of Persistent Organic Pollutants in the Food Chain of the Galapagos Sea Lion (Zalophus wollebaeki): Conservation and Management Implications

Alava¹,

Gobas²

2012

New Approaches to the Study of Marine Mammals

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Section: Stable Isotope Profiles and Trophic Levelssupporting

confidence: 86%

Section: Trophic Level Estimationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Assessing Biomagnification and Trophic Transport of Persistent Organic Pollutants in the Food Chain of the Galapagos Sea Lion (Zalophus wollebaeki): Conservation and Management Implications

Alava¹,

Gobas²

2012

New Approaches to the Study of Marine Mammals

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“…These changes cause top predators to respond by diversifying their foraging strategies (Villegas-Amtmann et al, 2008;Baque-Menoscal et al, 2012;Páez-Rosas et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Spatial variation in the foraging behaviour of the Galapagos sea lions (Zalophus wollebaeki) assessed using scat collections and stable isotope analysis

Páez‐Rosas

Aurioles‐Gamboa

2013

J. Mar. Biol. Ass.

Self Cite

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This study focuses on the comparative analysis of variables related to the trophic niche plasticity in the Galapagos sea lion (Zalophus wollebaeki). There is great concern regarding the future of this species, so study of the diet and the way these animals obtain their food is useful to understand and predict their survival possibilities in the long term. The combined use of scat analysis and stable isotopes helps to determine foraging habits of this species in greater detail. The objective of the study was to assess the feeding habits of Z. wollebaeki and its space -time variation. The scat analysis (n ¼ 200) gave as a result space -time changes in the foraging strategies of this species. The isotopic values (n ¼ 80) showed differences in relation to foraging grounds (d 13 C: P ¼ 0.001), but also suggested an apparent stability in the trophic level of their diet (d 15 N: P ¼ 0.084). These results constitute a relevant finding in the evolutionary behaviour of the species, showing that Z. wollebaeki has developed a high degree of plasticity in its foraging habits that may improve its survival in a highly demanding ecosystem in terms of limited and fluctuating resources.

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“…Two endemic species of otariids, the Galapagos sea lion (GSL) Zalophus wollebaeki and the Galapagos fur seal Arctocephalus galapagoensis, live under such conditions in the Galapagos Archipelago. Morphological, physiological, and behavioral adaptations have allowed them to survive in this environment, where they face a periodic lack of feeding resources (Villegas-Amtmann et al 2009, Jeglinski et al 2012, Páez-Rosas et al 2012). …”

Section: Introductionmentioning

confidence: 99%

Environment-driven changes in terrestrial habitat use and distribution of the Galapagos sea lion

Montero¹,

Páez‐Rosas²,

Murillo³

et al. 2014

Endang. Species. Res.

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Understanding habitat use patterns of marine apex predators is of paramount importance for the effective design of conservation plans. Due to their amphibious life cycle, pinnipeds are one of the most vulnerable groups to habitat loss and degradation. Reducing knowledge gaps that still exist regarding temporal changes in tropical pinniped habitat use is therefore of particular importance for conservation efforts. We analyzed terrestrial habitat use phenology of a tropical otariid, the Galapagos sea lion Zalophus wollebaeki. Regular land-based censuses were carried out in Wreck Bay of San Cristóbal Island, Galapagos, between 2008 and 2012 to explore seasonal changes in sea lion abundance, distribution, and preferences among different habitat types. A daily cycle of haul-out patterns was observed. Animals aggregated on sandy beaches during the coldest periods of the day and were more abundant on rocky and artificial structures when air temperature was warmer. The use of artificial floating platforms as resting places by Z. wollebaeki was described for the first time and linked to environmental variability, suggesting that this may be a successful management tool for pinnipeds inhabiting low latitudes. Further, this species demonstrated seasonal distribution changes, aggregating in high densities during warm seasons and maintaining more even distributions during cold seasons. Sea surface temperature, air temperature, and the onset of the breeding season were the variables that most significantly influenced haul-out patterns of Z. wollebaeki, indicating that this species can adapt to changing environmental conditions by displaying a high degree of plasticity regarding its distribution and terrestrial microhabitat preferences.

show abstract

Stable isotopes indicate differing foraging strategies in two sympatric otariids of the Galapagos Islands

Cited by 58 publications

References 69 publications

Assessing Biomagnification and Trophic Transport of Persistent Organic Pollutants in the Food Chain of the Galapagos Sea Lion (Zalophus wollebaeki): Conservation and Management Implications

Assessing Biomagnification and Trophic Transport of Persistent Organic Pollutants in the Food Chain of the Galapagos Sea Lion (Zalophus wollebaeki): Conservation and Management Implications

Spatial variation in the foraging behaviour of the Galapagos sea lions (Zalophus wollebaeki) assessed using scat collections and stable isotope analysis

Environment-driven changes in terrestrial habitat use and distribution of the Galapagos sea lion

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