No abstract

Characterization of a population of green turtles inhabiting the northeastern Gulf of Mexico was made possible by the mortality of a subset of > 4500 sea turtles that stranded during a mass cold stunning event in Florida, USA, during January 2010. In total, 434 dead, stranded green turtles Chelonia mydas were evaluated through necropsy and skeletochronological analysis to characterize morphology, sex, body condition, disease status, age structure, and growth patterns. Standard straightline carapace lengths ranged from 18.1 to 78.5 cm (mean ± SD = 36.3 ± 10.4 cm) and did not significantly differ from those of stranded green turtles that survived this event. Prevalence of fibropapilloma (FP) was low, at 6%, and sex ratio was significantly biased toward females (2.45F:1M). Age estimates ranged from 2 to 22 yr (mean ± SD = 9 ± 4 yr) and female age distribution was significantly greater than that of males. Mean stage durations, as calculated through sum mation of size class-specific growth rates and fitting smoothing spline models to length-at-age data, were similar and ranged from 17 to 20 yr. Generalized additive models and generalized additive mixed models were used to assess the potential influence of discrete and continuous covariates on growth rates. Somatic growth was significantly influenced by size, age, and calendar year; however, no effect of sex, FP status, or body condition was found. Increased understanding of population parameters will improve population models for the species and can also serve as a reference for assessing potential effects of the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. 458: 213-229, 2012 mation was recently emphasized in the aftermath of the April 20, 2010, Deepwater Horizon (DWH) MC-252 oil spill in the Gulf of Mexico during initiation of efforts to assess the effects to sea turtles of this catastrophic event (Bjorndal et al. 2011, Crowder & Heppell 2011. However, collection of these data is made difficult by deficiencies in the ability to assess sea turtle populations in an unbiased manner (Heppell et al. 2003). Population characterizations based on nesting beach studies, while prevalent due to the relative accessibility of the females on the beach, are necessarily focused in their scope (NRC 2010). In-water studies are often restricted to limited geographic areas (Bjorndal & Bolten 2000) and the proportion of individuals available to be sampled can be influenced by stage-and population-specific partitioning of habitat use (Musick & Limpus 1997, Plotkin 2003 and sex-specific behavior (Wibbels 2003). In addition, the time frames over which data collection must occur to adequately assess population parameters for these generally slow-to-mature, long-lived species are daunting (Heppell et al. 2003). OPEN PEN ACCESS CCESSMar Ecol Prog SerLife history data obtained from dead, stranded sea turtles can be informative, but often need to be interpreted with caution given the general lack of information regarding cause of death (natural vs. anthropogenic) (NRC 2...

Although significant amounts of research have been dedicated to increasing the knowledge of the life history of green turtles (Chelonia mydas), large gaps exist in our understanding of juvenile migratory behavior. These gaps can be filled by genetic studies of foraging ground aggregations. Using mitochondrial DNA markers and Bayesian analyses, samples (n = 106) from a foraging aggregation in North Carolina indicated that animals from the east coast of the United States (54%) and Mexico (27%) dominate the composition with the remainder coming from other Caribbean and Atlantic nesting aggregations. These findings prompted a reanalysis of 4 regional foraging aggregations using Bayesian mixed stock analysis, analysis of molecular variance, and diversity measures. Significant regional population structure between northern and southern foraging aggregations in the Caribbean was detected (phiST = 0.27, P = 0.000) in addition to significant nesting aggregation structure (phiST = 0.87, P = 0.000). Haplotype diversity levels were highest at foraging aggregations located within the confluence of major current systems. These findings indicate that both currents and behavior have strong influences on the composition of foraging aggregations. In addition, our results provide evidence of juvenile homing to regional foraging grounds and highlight the difficulties of separating historical and current effects on recruitment patterns at foraging locations.

Health status of a total of 57 loggerhead sea turtles (Caretta caretta; 42 migratory and 15 residential turtles) was analyzed using body condition and hematologic parameters. A subset of 18 juvenile migratory loggerhead sea turtles in the fall of 1997 and 15 residential turtles in the summer of 2000 were analyzed for barnacle epibiota. The migratory group had significantly higher red blood cell counts and percent heterophils and significantly lower percent lymphocyte and absolute eosinophil counts, as well as significantly lower plasma concentrations of calcium, sodium, chloride, potassium, glucose, alkaline phosphatase, and anion gap. Many of these variations may be because of physiology of migration. A positive association between turtle weight and hematocrit was detected and may be because of larger turtles diving for longer periods of time. There were no significant differences of epibiota load, health of the turtles, or condition index between turtles captured during the two events.