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Stable‐isotope comparisons between embryos and mothers of a placentatrophic shark species
Author(s) -
McMeans B. C.,
Olin J. A.,
Benz G. W.
Publication year - 2009
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.2009.02402.x
Subject(s) - biology , embryo , anatomy , yolk , trophic level , gestation , δ15n , yolk sac , embryogenesis , pregnancy , δ13c , andrology , stable isotope ratio , ecology , genetics , medicine , physics , quantum mechanics
Stable nitrogen (δ 15 N) and carbon (δ 13 C) isotopes of Atlantic sharpnose shark Rhizoprionodon terraenovae embryos and mothers were analysed. Embryos were generally enriched in 15 N in all studied tissue relative to their mothers' tissue, with mean differences between mother and embryo δ 15 N (i.e. Δδ 15 N) being 1·4‰ for muscle, 1·7‰ for liver and 1·1‰ for cartilage. Embryo muscle and liver were enriched in 13 C (both Δδ 13 C means = 1·5‰) and embryo cartilage was depleted (Δδ 13 C mean = −1·01‰) relative to corresponding maternal tissues. While differences in δ 15 N and δ 13 C between mothers and their embryos were significant, muscle δ 15 N values indicated embryos to be within the range of values expected if they occupied a similar trophic position as their respective mothers. Positive linear relationships existed between embryo total length ( L T ) and Δδ 15 N for muscle and liver and embryo L T and Δδ 13 C for muscle, with those associations possibly resulting from physiological differences between smaller and larger embryos or differences associated with the known embryonic nutrition shift (yolk feeding to placental feeding) that occurs during the gestation of this placentatrophic species. Together these results suggest that at birth, the δ 15 N and δ 13 C values of R. terraenovae are likely higher than somewhat older neonates whose postpartum feeding habits have restructured their isotope profiles to reflect their postembryonic diet.