Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles-hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta-exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO)-the strongest on record-combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r = -.94) and the Multivariate ENSO Index (MEI) for all years (r = .74). Granger-causality analysis also supports the latter finding. We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study demonstrates the importance of region-wide collaborations.

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A generalized additive mixed modeling approach was used to assess somatic growth for juvenile green turtles Chelonia mydas at 4 sites in 3 ecologically distinct foraging habitats along the east central coast of Florida, USA. The 3 habitats were a man-made nuclear submarine turning basin (Trident Submarine Basin), an estuary (Indian River Lagoon), and oceanic sabellariid worm rock reefs (Sebastian Inlet and St. Lucie Power Plant). Turtles from the Indian River Lagoon site grew significantly faster than turtles from the Trident Submarine Basin and sabellariid worm rock reef sites. There were no significant differences in growth rates between the sabellariid worm rock reef and Trident Submarine Basin sites. Non-monotonic or dome-shaped growth rate functions reflecting an immature peak in growth rates were observed for all 3 habitats. Growth rates peaked in 1998 for turtles in the Trident Submarine Basin and sabellariid worm rock reef habitats; since then growth rates have declined. This temporal decline in growth rates may reflect density-dependent effects on growth as more juveniles recruit to Florida foraging grounds, a direct result of increases in nest production at the primary rookeries (Costa Rica, Florida and Mexico). Developmental habitats are important for the survival of juvenile marine turtles. This study illustrates the degree to which juvenile growth rates vary among developmental habitats, which ultimately can affect the rate of growth and recovery potential of nesting stocks.

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Reference intervals for concentrations of TP and ELFs for healthy, free-ranging loggerhead sea turtles and green turtles can be used in combination with other diagnostic tools to assess health status of sea turtles.

To collect data on green turtles Chelonia mydas near the Marquesas Keys, Florida, USA, we conducted haphazard, unmarked, nonlinear transect (HUNT) surveys from a moving vessel. During HUNTs, we recorded green turtle locations and made opportunistic captures. We found a unique foraging assemblage of subadult and adult green turtles in open-water seagrass habitat (3 to 5 m deep) at the eastern Quicksands, west of the Marquesas Keys. At an adjacent area in the Marquesas Keys (Mooney Harbor), we observed juvenile green turtles foraging in shallow seagrass habitat (< 2 m). During 267 km of HUNTs, 370 green turtles (153 adults, 216 subadults, 1 juvenile) were recorded from the eastern Quicksands. At the Mooney Harbor site, 190 juvenile green turtles were sighted during 309 km of transects. Green turtles captured at the eastern Quicksands were adult and subadult animals that ranged from 69.3 to 108.5 cm straight carapace length (SCL; mean ± SD = 88.4 ± 10.6 cm, n = 31). Green turtles captured in Mooney Harbor were juveniles ranging from 27.0 to 59.3 cm SCL (mean = 44.0 ± 7.8, n = 41). Six repeatable, linear transects were surveyed during 3 sampling events at the eastern Quicksands. During these transects, 238 green turtles were observed. These spatial data were used in a nearest-neighbor analysis, which indicated that the distribution of green turtles at the eastern Quicksands was non-random and clumped. We hypothesize that adult and large subadult green turtles use deeper water habitats than juveniles, and this size-class partitioning may be due to differing habitat requirements and predation risk. Our analyses indicate that green turtles found at the eastern Quicksands form foraging herds.

In order to provide information to better inform management decisions and direct further research, vessel-based visual transects, snorkel transects, and in-water capture techniques were used to characterize hawksbill sea turtles in the shallow marine habitats of a Marine Protected Area (MPA), the Key West National Wildlife Refuge in the Florida Keys. Hawksbills were found in hardbottom and seagrass dominated habitats throughout the Refuge, and on man-made rubble structures in the Northwest Channel near Cottrell Key. Hawksbills captured (N = 82) were exclusively juveniles and subadults with a straight standard carapace length (SSCL) ranging from 21.4 to 69.0cm with a mean of 44.1 cm (SD = 10.8). Somatic growth rates were calculated from 15 recaptured turtles with periods at large ranging from 51 to 1188 days. Mean SSCL growth rate was 7.7 cm/year (SD = 4.6). Juvenile hawksbills (<50 cm SSCL) showed a significantly higher growth rate (9.2 cm/year, SD = 4.5, N = 11) than subadult hawksbills (50–70 cm SSCL, 3.6 cm/year, SD = 0.9, N = 4). Analysis of 740 base pair mitochondrial control region sequences from 50 sampled turtles yielded 12 haplotypes. Haplotype frequencies were significantly different compared to four other Caribbean juvenile foraging aggregations, including one off the Atlantic coast of Florida. Many-to-one mixed stock analysis indicated Mexico as the primary source of juveniles in the region and also suggested that the Refuge may serve as important developmental habitat for the Cuban nesting aggregation. Serum testosterone radioimmunoassay results from 33 individuals indicated a female biased sex ratio of 3.3 females: 1 male for hawksbills in the Refuge. This assemblage of hawksbills is near the northern limit of the species range, and is one of only two such assemblages described in the waters of the continental United States. Since this assemblage resides in an MPA with intensive human use, basic information on the assemblage is vital to resource managers charged with conservation and species protection in the MPA.

:  We compared glucose concentrations in whole blood and plasma from green turtles ( Chelonia mydas) using a glucometer with plasma glucose analyzed by dry chemistry analyzer. Whole blood glucose (glucometer) and plasma glucose (dry chemistry) had the best agreement ( r=0.85) and a small negative bias (-0.08 mmol/L).