Spatial variation of otolith elemental signatures among juvenile gray ...

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Mar 1, 2007 - gray snapper (Lutjanus griseus) inhabiting southern Florida waters. Monica R. .... ida Bay, Lower Florida Keys, Dry Tortugas, and Ten Thou-.
Mar Biol DOI 10.1007/s00227-007-0799-5

R ES EA R C H A R TI CLE

Spatial variation of otolith elemental signatures among juvenile gray snapper (Lutjanus griseus) inhabiting southern Florida waters Monica R. Lara · David L. Jones · Zhongxing Chen · John T. Lamkin · Cynthia M. Jones

Received: 16 May 2006 / Accepted: 20 August 2007 © Springer-Verlag 2007

Abstract Juvenile gray snapper, Lutjanus griseus, are believed to use bays and estuaries in southern Florida as nurseries before moving out to the adjoining reef tract as adults. Using high-resolution sector Weld-inductively coupled plasma-mass spectrometry (SF-ICP-MS), the elemental chemistry of the otoliths of juveniles from Wve nursery regions was resolved by establishing elemental “signatures” for each region. In this study we simultaneously analyzed 32 elements including a suite of rare earth elements. A stepwise variable selection procedure retained a subset of

Communicated by P.W. Sammarco. M. R. Lara (&) · D. L. Jones Cooperative Institute for Marine and Atmospheric Studies, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA e-mail: [email protected] D. L. Jones e-mail: [email protected] Z. Chen Department of Earth and Planetary Sciences, Harvard University, 20 Oxford street, Cambridge, MA 02138, USA e-mail: [email protected] J. T. Lamkin National Oceanographic and Atmospheric Administration, National Marine Fisheries Service, Southeast Fisheries Science Center, 75 Virginia Beach Drive, Miami, FL 33149, USA e-mail: [email protected] C. M. Jones Center for Quantitative Fisheries Ecology, Old Dominion University, 4541 Hampton Boulevard, Norfolk, VA 23529, USA e-mail: [email protected]

eight elements that contributed substantially to separating otolith samples, including two rare earth elements; this is one of the Wrst studies in which rare earth elements in otoliths have contributed to separation of Wsh stocks. The classiWcation success rate in assigning Wshes to the correct region of origin was 82%. Resolution of sites less than 10 km apart suggested high site Wdelity in juvenile gray snapper and little mixing of water masses between sites. The juvenile nursery signatures will be used to determine the relative contribution of diVerent nurseries to the adult population on an adjoining reef tract.

Introduction Gray snapper The subtropical marine ecosystems of southern Florida are habitat for a large population of gray snapper (Lutjanus griseus). Gray snapper are a commercially (USDOC 2003; Browder et al. 2003) and ecologically important Wsh in Florida and recruit to the reef from other areas such as seagrass meadows and mangrove habitats of Florida Bay where they may spend their juvenile phase (Starck 1970; Chester and Thayer 1990) before migrating to the coral reefs oV the Florida Keys as young adults. These protected coral reef areas need established and protected sources of recruits to function eVectively as reef Wsh sanctuaries. Identifying the sources of recruits to coral reefs is of particular importance in current eVorts to restore Florida Bay and establish Marine Protected Areas (MPAs) oV southern Florida. Therefore, it is critical to understand the role of regions adjacent to the reef in the life history of the gray snapper. Mature gray snapper occur within the Bay as well as on the oVshore reefs, but ripe adults are rarely found within the

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Bay (Croker 1962; Rutherford et al. 1983). OV southern Florida gray snapper migrate to oVshore areas to spawn during the new moon from June to September (Starck 1970; Rutherford et al. 1989; Domeier and Colin 1997). The resulting larvae have an oVshore pelagic phase that has been described for laboratory-reared (Richards and Saksena 1980) and wild-caught specimens (Richards et al. 1994). The pelagic larval phase of gray snapper recruiting to Florida Bay ranges from 36 to 42 days (Jones et al. 2001). Juveniles (