MEPS 521:249-263 (2015)  -  DOI: https://doi.org/10.3354/meps11158

Ba/Ca ratios in teeth reveal habitat use patterns of dolphins

S. Botta1,*, C. Albuquerque2, A. A. Hohn3, V. M. F. da Silva4, M. C. O. Santos5, C. Meirelles6, L. Barbosa7, A. P. M. Di Beneditto8, R. M. A. Ramos9, C. Bertozzi10, M. J. Cremer11, V. Franco-Trecu12, N. Miekeley13,†, E. R. Secchi1

1Laboratório de Ecologia e Conservação da Megafauna Marinha - EcoMega, Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande RS 96203-900, Brazil
2Departamento Oceanografia e Limnologia, Universidade Federal do Rio Grande do Norte, Natal 59014-100, RN, Brazil
3National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Beaufort, NC 28516, USA
4Laboratório de Mamíferos Aquáticos, Instituto Nacional de Pesquisas da Amazônia, CP 478, Manaus, AM 69011-790, Brazil
5Departamento de Oceanografia Biológica, Instituto Oceanográfico, Universidade de São Paulo, São Paulo, SP 05508-120, Brazil
6Associação de Pesquisa e Preservação de Ecossistemas Aquáticos - AQUASIS, SESC, Caucaia, CE 61627-010, Brazil
7Organização Consciência Ambiental—ORCA, Vila Velha, ES 29101-315, Brazil
8Universidade Estadual do Norte Fluminense, CBB/LCA, Campos dos Goytacazes, RJ 28013-602, Brazil
9Everest Tecnologia em Serviços Ltda. CP 5074, Vitória, ES 29045-970, Brazil
10Projeto BioPesca, Centro Universitário Monte Serrat, Santos, SP 11015-530, Brazil
11Departamento de Ciências Biológicas, Universidade da Região de Joinville, Joinville, SC 89219-710, Brazil
12Proyecto Franciscana, Sección Etología-Facultad de Ciencias, Iguá 4225, Montevideo, CP 11400, Uruguay
13Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, RJ 22453-900, Brazil
*Corresponding author:
Deceased

ABSTRACT: Teeth and otoliths are metabolically inert structures that preserve a chronology of chemical variations that may be related to the environmental histories experienced by each organism. Because of the natural decrease of barium (Ba) and increase of strontium (Sr) bioavailability in water with increasing salinity, these elements may be especially useful to track habitat use in aquatic organisms. Therefore, we tested whether the Ba/Ca and Sr/Ca ratios in the teeth of dolphins represent a salinity gradient. The main aim was to determine whether these elements can be used as a natural tag for different aquatic environments. Teeth from 2 freshwater dolphins (Inia geoffrensis and Sotalia fluviatilis) and 2 marine species (S. guianensis and Pontoporia blainvillei) from Brazil and Uruguay were analyzed using a Laser Ablation Inductively Coupled Plasma-Mass Spectrometer. Intensity ratios of 138Ba/43Ca and 86Sr/43Ca were measured along a line that covered all growth increments in the dentin from the second year of life onwards. Teeth from the freshwater species had mean Ba/Ca values tenfold higher than marine dolphins, confirming the inverse relationship between salinity (and thus ambient Ba/Ca) and elemental ratios in teeth. Furthermore, Ba/Ca ratios could also differentiate dolphins from lower-salinity estuarine areas from those in areas with minimal freshwater discharge. No significant differences were found for Sr/Ca values. Results presented encouraging indications for the application of this technique as a potential new tool for studying habitat use in aquatic mammals.


KEY WORDS: Barium · Strontium · Laser ablation ICP-MS · Habitat use · Odontocetes


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Cite this article as: Botta S, Albuquerque C, Hohn AA, da Silva VMF and others (2015) Ba/Ca ratios in teeth reveal habitat use patterns of dolphins. Mar Ecol Prog Ser 521:249-263. https://doi.org/10.3354/meps11158

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