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Marine Ecology Progress Series

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MEPS 433:221-236 (2011)  -  DOI:

Nursery habitat use and foraging ecology of the brown stingray Dasyatis lata determined from stomach contents, bulk and amino acid stable isotopes

Jonathan J. Dale1,2,*, Natalie J. Wallsgrove3, Brian N. Popp4, Kim N. Holland1

1Hawai‘i Institute of Marine Biology, University of Hawai‘i at Mānoa, Kāne‘ohe, Hawaii 96744, USA
2Department of Zoology, 3Department of Oceanography, and 4Department of Geology and Geophysics, University of Hawai‘i at Mānoa, Honolulu, Hawaii 96822, USA

ABSTRACT: Identification of nursery habitats and knowledge of the trophic ecology and habitat use of juvenile fishes within these habitats are fundamental in developing sound management and conservation strategies. The brown stingray Dasyatis lata is a large benthic predator that inhabits the coastal waters of Hawai‘i. Although abundant in these ecosystems, little is known about its basic ecology. Stomach content, bulk and amino acid stable isotope analyses were used to assess diet and habitat use of juvenile brown stingrays and to examine the possibility of competitive interactions with juvenile scalloped hammerhead sharks Sphyrna lewini that are sympatric with brown stingrays in Kāne‘ohe Bay, Oahu. Based on stomach contents, brown stingrays fed almost exclusively on crustaceans. An ontogenetic shift in stingray diet and an increase in relative trophic position (TP) were apparent from stomach content and stable isotope analysis. Stingray bulk δ13C and δ15N values indicated long-term foraging fidelity to subregions of the bay. Use of Kāne‘ohe Bay as a nursery habitat was supported by nitrogen isotopic analysis of individual amino acids from stingray muscle samples. Our results clearly demonstrated that stingrays foraged within the bay for the majority of their juvenile lives then shifted to offshore habitats with the onset of sexual maturity. Trophic enrichment factors used to estimate TPs from amino acid analysis in previous studies may underestimate TPs in elasmobranchs owing to urea retention for osmoregulation. Potential prey resources were partitioned between stingrays and juvenile scalloped hammerhead sharks, and TP estimates from each analytical method indicated that juvenile scalloped hammerhead sharks forage on higher TP prey than do juvenile brown stingrays. These results show that the study of foraging ecology and habitat use of marine animals can greatly benefit from integrating traditional stomach content and bulk stable isotopic analyses with nitrogen isotopic analyses of individual amino acids.

KEY WORDS: Elasmobranch · Amino acids · Trophic position · Ontogenetic shift · Resource partitioning

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Cite this article as: Dale JJ, Wallsgrove NJ, Popp BN, Holland KN (2011) Nursery habitat use and foraging ecology of the brown stingray Dasyatis lata determined from stomach contents, bulk and amino acid stable isotopes. Mar Ecol Prog Ser 433:221-236.

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