Assessing trace elements in striped dolphins from the Strait of Gibraltar: Clues to link the bioaccumulation in the westernmost Mediterranean Sea area and nearest Atlantic Ocean Elisa Rojo-Nieto a, c, * , Carolina Fern  andez-Maldonado b a Department of Environmental Technologies, Andalusian Center for Marine Science and Technology (CACYTMAR/INMAR), International Campus of Excellence of the Sea, University of C adiz, Spain b Center for the Management of the Marine Environment (CEGMA), Andalusian Agency for Environment and Water, (Andalusian Environmental and Spatial Planning Council), Avda. Johan Gütemberg 1, Isla de la Cartuja, Sevilla, Spain c Stranding-Supporting Network, DELPHIS - Ecologistas en Acci on C adiz, c/ San Alejandro s/n., Puerto Real, Spain highlights  Stranded dolphins are good bioindicators showing great potential as monitoring tools.  Trace elements were first measured in stranded dolphins in the Strait of Gibraltar.  Trace elements are compared among target organs and correlated to biological parameters.  First report of Se/Hg ratio in cetaceans from this relevant transitional region.  This region can be considered a transitional area between Mediterranean and Atlantic basins. article info Article history: Received 21 July 2016 Received in revised form 24 October 2016 Accepted 3 December 2016 Available online 4 December 2016 Handling Editor: Caroline Gaus Keywords: Bioaccumulation Marine mammals Stranded cetaceans Heavy metals Target organs Se/Hg molar ratio abstract Dolphins are considered sentinel species in the marine environment. The Strait of Gibraltar is the only passage between the Mediterranean Sea and the Atlantic Ocean, being the transitional region which connects these two basins and one of the most important routes of cetacean migration worldwide. In this work, eight trace elements (TE) were studied in 45 samples of liver, kidney and muscle, from 15 spec- imens stranded in this study area. The preliminary results show, among others, the patterns of distri- bution of the TE in the target organs studied, the influence of sex, length and developmental stage in these TE concentrations and the Se/Hg ratio. Subsequently, the results of TE concentrations in liver have being compared to previous data on S. coeruleoalba from the westernmost Mediterranean Sea and the nearest Atlantic Ocean. For some elements (e.g. for As), concentrations are similar to those obtained from Atlantic samples, despite in other cases (e.g. for Cd) results are lined up with those observed in Medi- terranean studies. In addition, in the case of some TE (e.g. Se and Zn) the results are in the middle of those reported for both basins, reinforcing the idea of the Strait of Gibraltar being a transitional zone. Present study is the first research regarding this issue in this outstanding region, aiming to give insights of how this matchless area can help to link TE concentrations observed in these Atlantic and Mediter- ranean threatened species. © 2016 Published by Elsevier Ltd. 1. Introduction Presently, several EU directives on protecting the marine envi- ronment are in force. The Water Framework Directive (WFD, Council Directive, 2000/60/EC) and the Marine Strategy Framework Directive (MSFD, Council Directive, 2008/56/EC) are regulatory frameworks, with the latter being aimed at achieving “Good Envi- ronmental Status” by 2020. The WFD has established a list of Pri- ority Substances and Environmental Quality Standards (EQSs) for Priority Substances and certain other pollutants (reviewed and amended by Council Directive, 2013/39/EU). The MSFD considers this Priority Substances list for the assessment of chemical con- taminants in the marine environment and emphasizes the need to * Corresponding author. Department of Environmental Technologies, Andalusian Center for Marine Science and Technology (CACYTMAR/INMAR), International Campus of Excellence of the Sea, University of C adiz, Spain. E-mail address: elisa.rojo@uca.es (E. Rojo-Nieto). Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere http://dx.doi.org/10.1016/j.chemosphere.2016.12.009 0045-6535/© 2016 Published by Elsevier Ltd. Chemosphere 170 (2017) 41e50