Marine Biology

, Volume 160, Issue 10, pp 2711–2721

Temporal, spatial, and body size effects on growth rates of loggerhead sea turtles (Caretta caretta) in the Northwest Atlantic

  • Karen A. Bjorndal
  • Barbara A. Schroeder
  • Allen M. Foley
  • Blair E. Witherington
  • Michael Bresette
  • David Clark
  • Richard M. Herren
  • Michael D. Arendt
  • Jeffrey R. Schmid
  • Anne B. Meylan
  • Peter A. Meylan
  • Jane A. Provancha
  • Kristen M. Hart
  • Margaret M. Lamont
  • Raymond R. Carthy
  • Alan B. Bolten
Original Paper

DOI: 10.1007/s00227-013-2264-y

Cite this article as:
Bjorndal, K.A., Schroeder, B.A., Foley, A.M. et al. Mar Biol (2013) 160: 2711. doi:10.1007/s00227-013-2264-y

Abstract

In response to a call from the US National Research Council for research programs to combine their data to improve sea turtle population assessments, we analyzed somatic growth data for Northwest Atlantic (NWA) loggerhead sea turtles (Caretta caretta) from 10 research programs. We assessed growth dynamics over wide ranges of geography (9–33°N latitude), time (1978–2012), and body size (35.4–103.3 cm carapace length). Generalized additive models revealed significant spatial and temporal variation in growth rates and a significant decline in growth rates with increasing body size. Growth was more rapid in waters south of the USA (<24°N) than in USA waters. Growth dynamics in southern waters in the NWA need more study because sample size was small. Within USA waters, the significant spatial effect in growth rates of immature loggerheads did not exhibit a consistent latitudinal trend. Growth rates declined significantly from 1997 through 2007 and then leveled off or increased. During this same interval, annual nest counts in Florida declined by 43 % (Witherington et al. in Ecol Appl 19:30–54, 2009) before rebounding. Whether these simultaneous declines reflect responses in productivity to a common environmental change should be explored to determine whether somatic growth rates can help interpret population trends based on annual counts of nests or nesting females. Because of the significant spatial and temporal variation in growth rates, population models of NWA loggerheads should avoid employing growth data from restricted spatial or temporal coverage to calculate demographic metrics such as age at sexual maturity.

Supplementary material

227_2013_2264_MOESM1_ESM.docx (29 kb)
Supplementary material 1 (DOCX 28 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Karen A. Bjorndal
    • 1
    • 2
  • Barbara A. Schroeder
    • 3
  • Allen M. Foley
    • 4
  • Blair E. Witherington
    • 1
    • 5
    • 6
  • Michael Bresette
    • 6
  • David Clark
    • 6
  • Richard M. Herren
    • 6
  • Michael D. Arendt
    • 7
  • Jeffrey R. Schmid
    • 8
  • Anne B. Meylan
    • 9
    • 10
  • Peter A. Meylan
    • 10
    • 11
  • Jane A. Provancha
    • 12
  • Kristen M. Hart
    • 13
  • Margaret M. Lamont
    • 1
    • 14
  • Raymond R. Carthy
    • 1
    • 14
  • Alan B. Bolten
    • 1
    • 2
  1. 1.Archie Carr Center for Sea Turtle ResearchUniversity of FloridaGainesvilleUSA
  2. 2.Department of BiologyUniversity of FloridaGainesvilleUSA
  3. 3.NOAA, National Marine Fisheries ServiceSilver SpringUSA
  4. 4.Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research InstituteJacksonvilleUSA
  5. 5.Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research InstituteMelbourne BeachUSA
  6. 6.Inwater Research Group, Inc.Jensen BeachUSA
  7. 7.Marine Resources DivisionSouth Carolina Department of Natural ResourcesCharlestonUSA
  8. 8.Environmental Science DepartmentConservancy of Southwest FloridaNaplesUSA
  9. 9.Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research InstituteSt. PetersburgUSA
  10. 10.Smithsonian Tropical Research InstituteBalboaPanamá
  11. 11.Natural Sciences CollegiumEckerd CollegeSt. PetersburgUSA
  12. 12.InoMedic Health ApplicationsKennedy Space CenterMerritt IslandUSA
  13. 13.US Geological Survey, Southeast Ecological Science CenterDavieUSA
  14. 14.US Geological Survey, Florida Cooperative Fish and Wildlife Research UnitUniversity of FloridaGainesvilleUSA

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