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Multi-species assemblages can help identify key resources in their habitat by evaluating how they are partitioning their resources. Here we used the isotopic niche of loggerhead, Kemp's ridley, and green sea turtles to assess their ecological niche within a Gulf of Mexico bay. Additionally, we assessed temporal and size-class variation in their diets by comparing the [delta].sup.13C and [delta].sup.15N values over various capture years and size classes. Based on the isotopic niche overlap results, interspecific competition occurs among loggerhead, Kemp's ridley, and smaller green turtles. Green turtle and Kemp's ridley diet varied by size class, while Kemp's ridley diet also varied temporally. The three species partition resources by selecting different preferred diet items, although some overlap in diet, including between the herbivorous (green) and carnivorous (Kemp's ridley, loggerhead) species, appears to occur. The high quality of this habitat may allow species co-existence and population recovery despite the possible use of shared resources., Author(s): Carson L. Arends [sup.1] [sup.2] , Hannah B. Vander Zanden [sup.2] , Margaret M. Lamont [sup.1] Author Affiliations: (1) https://ror.org/05qtybq80, U.S. Geological Survey, Wetland and Aquatic Research Center, , [...]

Because subpopulations can differ geographically, genetically and/or phenotypically, using data from one subpopulation to derive vital rates for another, while often unavoidable, is not optimal. We used a two-state open robust design model to analyze a 14-year dataset (1998-2011) from the St. Joseph Peninsula, Florida (USA; 29.748°, -85.400°) which is the densest loggerhead (Caretta caretta) nesting beach in the Northern Gulf of Mexico subpopulation. For these analyses, 433 individuals were marked of which only 7.2% were observed re-nesting in the study area in subsequent years during the study period. Survival was estimated at 0.86 and is among the highest estimates for all subpopulations in the Northwest Atlantic population. The robust model estimated a nesting assemblage size that ranged from 32 to 230 individuals each year with an annual average of 110. The model estimates indicated an overall population decline of 17%. The results presented here for this nesting group represent the first estimates for this subpopulation. These data provide managers with information specific to this subpopulation that can be used to develop recovery plans and conduct subpopulation-specific modeling exercises explicit to the challenges faced by turtles nesting in this region., Introduction The population is a central concept for ecology (Berryman 2002), and its complexities must be taken into account for effective management (Schaefer 2006; Harwood 2009). However, resolution of population [...]

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 (, Introduction A long-term regional approach is essential to understand the somatic growth dynamics of the Northwest Atlantic (NWA) loggerhead sea turtle (Caretta caretta) stock that nests along the southeast coast [...]

Erratum to: Mar Biol (2014) 161:2659-2668 DOI 10.1007/s00227-014-2537-0 The Open Robust Model methods used for analysis in this study were developed by Kendall and Bjorkland (2001) and Kendall (2010). The [...]