ARTICLE Instability of statolith elemental signatures revealed in newly metamorphosed sea lamprey (Petromyzon marinus) Aude Lochet, J. Ellen Marsden, Brian J. Fryer, and Stuart A. Ludsin Abstract: Techniques that use calcified structures to identify the natal origin of organisms assume that reworking of previously deposited material does not occur. While verified for otoliths, this assumption remains unverified for statoliths. Herein, we test the stability of sea lamprey (Petromyzon marinus) statolith microchemistry during metamorphosis. Using laser ablation induc- tively coupled plasma mass spectrometry, we quantified the concentrations of nine elements in statoliths from sea lamprey larvae (n = 118) and newly metamorphosed (n = 115) individuals that were collected across six tributaries of varying alkalinity in the Laurentian Great Lakes and Lake Champlain basins. In newly metamorphosed individuals from all streams, the portion of the statolith deposited during the larval stage was enriched in rubidium (Rb), strongly suggesting a chemical reworking of statoliths during metamorphosis. As the ability to discriminate among sea lamprey from different streams in the Great Lakes and Lake Champlain mostly relies on premetamorphic levels of Rb, strategies for the use of statoliths to identify the natal origin of sea lamprey parasitic juveniles and spawners (postmetamorphic stages) should take into account the chemical changes associ- ated with metamorphosis. Résumé : Les techniques d'identification de l'origine des organismes vivants a ` partir de leurs structures calcifiées supposent que les concentrations élémentaires ne soient pas modifiées une fois les éléments déposés dans les structures calcifiées. Bien que vérifiée pour les otolithes, cette supposition n'a pas encore été vérifiée pour les statolithes. Dans la présente étude, nous testons la stabilité microchimique des statolithes de lamproies marines (Petromyzon marinus) au cours de la métamorphose. Nous avons utilisé un spectromètre de masse a ` plasma induit couplé a ` l'ablation laser pour mesurer les concentrations de neuf éléments dans les statolithes de larves de lamproies marines (n = 118) et de lamproies marines récemment transformées (n = 115). Les individus ont été collectés dans six tributaires d'alcalinité différente des Grands Lacs Laurentiens et du Lac Champlain. Pour tous les tributaires, les statolithes de lamproies récemment transformées étaient enrichis en rubidium (Rb) dans la portion du statolithe déposée au cours de la phase larvaire, suggérant ainsi une modification chimique des statolithes durant la métamor- phose. Etant donné l'importance des concentrations pré-métamorphose en Rb pour discriminer l'origine des lamproies marines dans les Grands Lacs Laurentiens et le Lac Champlain, l'utilisation des statolithes pour identifier l'origine des lamproies juvéniles parasites et des adultes reproducteurs (stades post-métamorphose) nécessite de tenir compte des modifications chimiques liées a ` la métamorphose. Introduction Determination of the natal origin of aquatic organisms can al- low for cost-effective, efficient species management by providing insight into recruitment mechanisms, dispersal patterns, repro- ductive life-history strategies, and population connectivity (e.g., metapopulation dynamics, stock structure) (Thorrold et al. 2001; Fromentin and Powers 2005; Cowen and Sponaugle 2009). Tech- niques to identify the natal origin of species such as sea lamprey (Petromyzon marinus) still need to be determined. Sea lamprey are stream dwellers as larvae for several years until they metamor- phose into a parasitic juvenile stage that migrates to lakes (land- locked form) or to the sea (anadromous form) to feed on the blood of fishes (Beamish 1980a; Maitland 1980). The management of sea lamprey across its distributional range would benefit from a bet- ter knowledge of natal origin. In the Laurentian Great Lakes, where sea lamprey are invasive and have decimated several native fisheries (Smith and Tibbles 1980), the ability to discern natal origins of juvenile parasites and adult spawners would allow for cost-effective control of populations based on the eradication of individuals before they leave their natal streams (Fenichel and Hansen 2010). By contrast, in Europe, sea lamprey are native but populations have declined owing to water pollution, construction of dams, and channel dredging (Taverny and Elie 2010). In this case, ability to identify natal origins of successful recruits to older life stages could facilitate conservation efforts. Natural chemical tags recorded in otoliths, concretions that form part of the inner ear of teleosts (Popper and Lu 2000), are increasingly being used to identify the natal origin of fish species (Secor 2010). The success of using otoliths to record past environ- mental history mostly relies on two fundamental properties: (i) otolith elemental composition reflects the chemical properties of the surrounding water in which the otolith was formed; and (ii) no metabolic reworking occurs after the material is deposited in the otoliths (Campana and Thorrold 2001). More recently, interest has grown in using statoliths, inner ear concretions of cyclostomes (e.g., lampreys) and molluscs (e.g., squids) that are analogous to the otoliths of teleosts, in ecological and management applications (Arkhipkin et al. 2004; Brothers and Thresher 2004; Hand et al. 2008). Teleost otoliths and mollusc statoliths are made of calcium carbonate (CaCO 3 ) in the mineral- Received 20 September 2012. Accepted 27 January 2013. Paper handled by Associate Editor Bronwyn Gillanders. A. Lochet and J.E. Marsden. Rubenstein School of Environment and Natural Resources, University of Vermont, 81 Carrigan Drive, Burlington, VT 05405, USA. B.J. Fryer. Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON N9B 3P4, Canada. S.A. Ludsin. Aquatic Ecology Laboratory, Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, 1314 Kinnear Road, Columbus, OH 43212, USA. Corresponding author: Aude Lochet (e-mail: audelochet@yahoo.fr). Pagination not final/Pagination non finale 1 Can. J. Fish. Aquat. Sci. 70: 1–9 (2013) dx.doi.org/10.1139/cjfas-2012-0410 Published at www.nrcresearchpress.com/cjfas on xx xx 2013. Can. J. Fish. Aquat. Sci. Downloaded from www.nrcresearchpress.com by GUY W. 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