AB 6:25-30 (2009)  -  DOI: https://doi.org/10.3354/ab00157

Total lead and its stable isotopes in the digestive gland of Octopus vulgaris as a fingerprint

J. Raimundo1,2,*, C. Vale1, M. Caetano1, R. Cesário1, I. Moura2

1IPIMAR - National Institute of Biological Resources, Av. Brasília, 1449-006 Lisbon, Portugal
2REQUIMTE - CQFB, Department of Chemistry, Faculty of Sciences and Technology, New University of Lisbon, Qta Torre, 2829-516 Monte da Caparica, Portugal

ABSTRACT: We hypothesised that the isotopic signature of Pb in the digestive gland of the common octopus reflects the organisms’ sources of Pb, and investigated whether isotopic Pb ratios are useful in characterising octopus populations. A total of 47 Octopus vulgaris individuals were captured between November 2005 and September 2006 in 2 areas of the Portuguese coast, near Matosinhos (Area A; NW coast) and Olhão (Area B; south coast), and digestive glands were analysed for total Pb and its stable isotopes. The same determinations were performed in 22 samples of surface sediments from the 2 areas. Pb concentrations in the digestive gland of specimens from Area B (2.8 to 13.0 µg g–1) exceeded the values found in Area A (1.3 to 8.3 µg g–1). A similar pattern was found for the isotopic Pb ratios: 206Pb/207Pb was 1.173 to 1.185 for Area A and 1.165 to 1.172 for B; 206Pb/208Pb was 0.476 to 0.487 for Area A and 0.318 to 0.483 for B. The different signatures of the digestive glands are in line with those observed in the surface sediments of the 2 coastal areas (e.g. 206Pb/207Pb was 1.179 to 1.207 for Area A and 1.171 to 1.181 for B). However, the isotopic Pb signature of octopus was less radiogenic than that of sediments. Because octopus has a short life span (up to 24 mo) the signature reflects recent sources of Pb that have a less radiogenic signature. The Pb signature of surface sediments tends to integrate the record of the previous few years or decades, due to the frequent resuspension of the upper layer of coastal sediments. The mixing of sediments deposited during those periods results in higher isotopic Pb ratios (more radiogenic). The consistent differences between the 2 areas, in sediments and octopus, points towards  the isotopic Pb signature as a possible useful tool to distinguish octopus populations.

KEY WORDS: Cephalopods · Lead · Stable lead isotopes · Bioaccumulation · Portugal

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Cite this article as: Raimundo J, Vale C, Caetano M, Cesário R, Moura I (2009) Total lead and its stable isotopes in the digestive gland of Octopus vulgaris as a fingerprint. Aquat Biol 6:25-30. https://doi.org/10.3354/ab00157

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