TY - JOUR
T1 - Lifetime coastal and oceanic foraging patterns of male Guadalupe fur seals and California sea lions
AU - Aurioles-Gamboa, David
AU - Szteren, Diana
N1 - Publisher Copyright:
© 2019 Society for Marine Mammalogy
PY - 2020/1/1
Y1 - 2020/1/1
N2 - Carcasses of adult and subadult male Guadalupe fur seals (GFSs) are beached on Isla Magdalena, representing about 73% of all GFSs beachings since 2003. Analysis of carbon and nitrogen stable isotopes in dentin collagen from male GFSs was used in an attempt to distinguish animals from two possible locations of origin: the oceanic Guadalupe Island (GI) and the coastal San Benito Islands (SBI). Samples of conterminous and contemporary California sea lions (CSLs) were included as representative of coastal predators. Two distinct groups of GFSs were evident based on δ13C values: coastal GFSs with higher δ13C values than CSLs, and oceanic GFSs with lower δ13C values than CSLs. Significant temporal trends were observed in the δ15N values; values for oceanic GFSs and CSLs increased annually (0.082‰ and 0.089‰, respectively), while those for coastal GFS decreased annually by 0.183‰. The isotopic segregation of oceanic and coastal GFS males, presumably from GI and SBI respectively, has been present at least since the mid-1990s. This segregation may be due to dissimilar ingestion of prey from oceanic vs. coastal origin prior to their seasonal co-occurrence in the Gulf of Ulloa.
AB - Carcasses of adult and subadult male Guadalupe fur seals (GFSs) are beached on Isla Magdalena, representing about 73% of all GFSs beachings since 2003. Analysis of carbon and nitrogen stable isotopes in dentin collagen from male GFSs was used in an attempt to distinguish animals from two possible locations of origin: the oceanic Guadalupe Island (GI) and the coastal San Benito Islands (SBI). Samples of conterminous and contemporary California sea lions (CSLs) were included as representative of coastal predators. Two distinct groups of GFSs were evident based on δ13C values: coastal GFSs with higher δ13C values than CSLs, and oceanic GFSs with lower δ13C values than CSLs. Significant temporal trends were observed in the δ15N values; values for oceanic GFSs and CSLs increased annually (0.082‰ and 0.089‰, respectively), while those for coastal GFS decreased annually by 0.183‰. The isotopic segregation of oceanic and coastal GFS males, presumably from GI and SBI respectively, has been present at least since the mid-1990s. This segregation may be due to dissimilar ingestion of prey from oceanic vs. coastal origin prior to their seasonal co-occurrence in the Gulf of Ulloa.
KW - California sea lions
KW - Guadalupe fur seals
KW - dentin
KW - males
KW - oceanic and coastal habitats
KW - stable isotopes
UR - http://www.scopus.com/inward/record.url?scp=85074864535&partnerID=8YFLogxK
U2 - 10.1111/mms.12649
DO - 10.1111/mms.12649
M3 - Artículo
AN - SCOPUS:85074864535
SN - 0824-0469
VL - 36
SP - 246
EP - 259
JO - Marine Mammal Science
JF - Marine Mammal Science
IS - 1
ER -