TY - JOUR
T1 - Niche overlap and habitat use at distinct temporal scales among the California sea lions (Zalophus californianus) and Guadalupe fur seals (Arctocephalus philippii townsendi)
AU - Pablo-Rodríguez, Nereyda
AU - Aurioles-Gamboa, David
AU - Montero-Muñoz, Jorge L.
N1 - Publisher Copyright:
© 2016 Society for Marine Mammalogy.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - The aim of this study was to determine the trophic level, trophic breadth, and dietary overlap of two species of otariids (Zalophus californianus and Arctocephalus philippii townsendi) at the San Benito Islands in Baja California, Mexico, using scat analysis, and stable isotope analyses (SIA) of carbon and nitrogen in pup hair and dental collagen. Scat samples were collected during summer and winter. The most important prey for both species during summer was squid, comprising 74% of the A. p. townsendi diet and 45% of that of Z. californianus. In winter, squid was 87% of the A. p. townsendi diet, whereas fish was the predominant food (76%) for Z. californianus. Both species were specialist feeders and reached maximum trophic overlap during the summer (CH = 0.9). SIA of the hair of otariid pups showed significant differences in δ15N (P = 0.001), coinciding with A. p. townsendi's greater consumption of squid. The average δ13C value was significantly lower for A. p. townsendi (-16.3‰ ± 0.2‰), reflecting the species' consumption of squid from pelagic habitats, whereas that of Z. californianus (-15.9‰ ± 0.3‰) was significantly higher, reflecting their consumption of benthic fish. Difference in habitat use was confirmed in δ13C values of dental collagen.
AB - The aim of this study was to determine the trophic level, trophic breadth, and dietary overlap of two species of otariids (Zalophus californianus and Arctocephalus philippii townsendi) at the San Benito Islands in Baja California, Mexico, using scat analysis, and stable isotope analyses (SIA) of carbon and nitrogen in pup hair and dental collagen. Scat samples were collected during summer and winter. The most important prey for both species during summer was squid, comprising 74% of the A. p. townsendi diet and 45% of that of Z. californianus. In winter, squid was 87% of the A. p. townsendi diet, whereas fish was the predominant food (76%) for Z. californianus. Both species were specialist feeders and reached maximum trophic overlap during the summer (CH = 0.9). SIA of the hair of otariid pups showed significant differences in δ15N (P = 0.001), coinciding with A. p. townsendi's greater consumption of squid. The average δ13C value was significantly lower for A. p. townsendi (-16.3‰ ± 0.2‰), reflecting the species' consumption of squid from pelagic habitats, whereas that of Z. californianus (-15.9‰ ± 0.3‰) was significantly higher, reflecting their consumption of benthic fish. Difference in habitat use was confirmed in δ13C values of dental collagen.
KW - Dental collagen
KW - Dietary overlap
KW - Otariids
KW - Pup hair
KW - San Benito Islands
KW - Stable isotopes
KW - Trophic breadth
KW - Trophic level
UR - http://www.scopus.com/inward/record.url?scp=84945367484&partnerID=8YFLogxK
U2 - 10.1111/mms.12274
DO - 10.1111/mms.12274
M3 - Artículo
SN - 0824-0469
VL - 32
SP - 466
EP - 489
JO - Marine Mammal Science
JF - Marine Mammal Science
IS - 2
ER -