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Box Elder, United States

Lasala J.A.,Georgia Southern University | Lasala J.A.,Florida Atlantic University | Harrison J.S.,Georgia Southern University | Williams K.L.,Caretta Research Project | Rostal D.C.,Georgia Southern University
Ecology and Evolution

Characterization of a species mating systems is fundamental for understanding the natural history and evolution of that species. Polyandry can result in the multiple paternity of progeny arrays. The only previous study of the loggerhead turtle (Caretta caretta) in the USA showed that within the large peninsular Florida subpopulation, multiple paternity occurs in approximately 30% of clutches. Our study tested clutches from the smaller northern subpopulation for the presence of multiple paternal contributions. We examined mothers and up to 20 offspring from 19.5% of clutches laid across three nesting seasons (2008-2010) on the small nesting beach on Wassaw Island, Georgia, USA. We found that 75% of clutches sampled had multiple fathers with an average of 2.65 fathers per nest (1-7 fathers found). The average number of fathers per clutch varied among years and increased with female size. There was no relationship between number of fathers and hatching success. Finally, we found 195 individual paternal genotypes and determined that each male contributed to no more than a single clutch over the 3-year sampling period. Together these results suggest that the operational sex ratio is male-biased at this site. Our study uses microsatellites in conjunction with exclusion analysis of multiple paternity to establish the number of males contributing to a nesting population of loggerhead sea turtles. We suggest that the operational sex ratio is male biased at this site. © 2013 The Authors. Source

Rocha J.C.,Jr. | Rocha J.C.,Vale do Itajai University | Pfaller J.B.,University of Florida | Pfaller J.B.,Caretta Research Project | And 2 more authors.
Journal of the Marine Biological Association of the United Kingdom

Studies of sea turtle epibiosis have focused on the diversity and ecology of facultative commensalisms and less attention has been given to parasitic associations, in which the epibiont species derives nutrients from the tissue of the host turtle. We present the first description and quantitative survey of the parasitic isopods Excorallana costata, Excorallana bicornis and Excorallana oculata on loggerhead (N = 79) and hawksbill turtles (N = 23), and E. costata on olive ridley turtles (N = 9), nesting on Praia do Forte, Bahia, Brazil during the 2009-2010 season. Excorallana costata was the most common isopod species (N = 651), followed by E. bicornis (N = 77) and E. oculata (N = 20). Patterns include: (1) E. costata exhibited a higher frequency and intensity of parasitism than E. bicornis and E. oculata and (2) loggerheads hosted parasitic isopods at a higher frequency and intensity than hawksbills and olive ridleys. We also detected temporal shifts in the occurrence and intensity of parasitism across the nesting season, which strongly suggests that turtles were parasitized by all three isopod species during their internesting periods. Because parasitic isopods were observed only rarely prior to the 2009-2010 turtle-nesting season and have continued to be common in subsequent seasons, it is important to gain a better understanding of the basic biology of these interactions, the reasons for their recent emergence, and the potential biological impacts on turtle, as well as isopod, populations. Copyright © Marine Biological Association of the United Kingdom 2014. Source

Pfaller J.B.,University of Florida | Pfaller J.B.,Caretta Research Project | Alfaro-Shigueto J.,ProDelphinus | Alfaro-Shigueto J.,University of Exeter | And 7 more authors.
Marine Biology

Studies that incorporate information from habitat-specific ecological interactions (e.g., epibiotic associations) can reveal valuable insights into the cryptic habitat-use patterns and behavior of marine vertebrates. Sea turtles, like other large, highly mobile marine vertebrates, are inherently difficult to study, and such information can inform the implementation of conservation measures. The presence of epipelagic epibionts, such as the flotsam crab Planes major, on sea turtles strongly suggests that neritic turtles have recently occupied epipelagic habitats (upper 200 m in areas with >200 m depth) and that epipelagic turtles spend time at or near the surface. We quantified the effects of turtle species, turtle size, and habitat (neritic or epipelagic) on the frequency of epibiosis (F 0) by P. major on sea turtles in the Pacific Ocean. In neritic habitats, we found that loggerhead (F 0 = 27.6 %) and olive ridley turtles (F 0 = 26.2 %) host crabs frequently across a wide range of body sizes, and green turtles almost never host crabs (F 0 = 0.7 %). These results suggest that loggerheads and olive ridleys display variable/flexible epipelagic-neritic transitions, while green turtles tend to transition unidirectionally at small body sizes. In epipelagic habitats, we found that loggerheads host crabs (F 0 = 92.9 %) more frequently than olive ridleys (F 0 = 50 %) and green turtles (F 0 = 38.5 %). These results suggest that epipelagic loggerheads tend to spend more time at or near the surface than epipelagic olive ridleys and green turtles. Results of this study reveal new insights into habitat-use patterns and behavior of sea turtles and display how epibiont data can supplement data from more advanced technologies to gain a better understanding of the ecology of marine vertebrates during cryptic life stages. © 2014 Springer-Verlag Berlin Heidelberg. Source

Hawkes L.A.,University of Exeter | Hawkes L.A.,Bangor University | Witt M.J.,University of Exeter | Broderick A.C.,University of Exeter | And 10 more authors.
Diversity and Distributions

Aim Although satellite tracking has yielded much information regarding the migrations and habitat use of threatened marine species, relatively little has been published about the environmental niche for loggerhead sea turtles Caretta caretta in north-west Atlantic waters. Location North Carolina, South Carolina and Georgia, USA. Methods We tracked 68 adult female turtles between 1998 and 2008, one of the largest sample sizes to date, for 372.2±210.4days (mean±SD). Results We identified two strategies: (1) 'seasonal' migrations between summer and winter coastal areas (n=47), although some turtles made oceanic excursions (n=4) and (2) occupation of more southerly 'year-round' ranges (n=18). Seasonal turtles occupied summer home ranges of 645.1km2 (median, n = 42; using α-hulls) predominantly north of 35° latitude and winter home ranges of 339.0km2 (n=24) in a relatively small area on the narrow shelf off North Carolina. We tracked some of these turtles through successive summer (n=8) and winter (n=3) seasons, showing inter-annual home range repeatability to within 14.5km of summer areas and 10.3km of winter areas. For year-round turtles, home ranges were 1889.9km2. Turtles should be tracked for at least 80days to reliably estimate the home range size in seasonal habitats. The equivalent minimum duration for 'year-round' turtles is more complex to derive. We define an environmental envelope of the distribution of North American loggerhead turtles: warm waters (between 18.2 and 29.2°C) on the coastal shelf (in depths of 3.0-89.0m). Main conclusions Our findings show that adult female loggerhead turtles show predictable, repeatable home range behaviour and do not generally leave waters of the USA, nor the continental shelf (<200m depth). These data offer insights for future marine management, particularly if they were combined with those from the other management units in the USA. © 2011 Blackwell Publishing Ltd. Source

Vander Zanden H.B.,University of Florida | Vander Zanden H.B.,University of Utah | Pfaller J.B.,University of Florida | Pfaller J.B.,Caretta Research Project | And 9 more authors.
Marine Biology

Diet items and habitat constitute some of the environmental resources that may be used differently by individuals within a population. Long-term fidelity by individuals to particular resources exemplifies individual specialization, a phenomenon that is becoming increasingly recognized across a wide range of species. Less is understood about the consequences of such specialization. Here, we investigate the effects of differential foraging ground use on reproductive output in 183 loggerhead sea turtles (Caretta caretta) nesting at Wassaw Island, Georgia (31.89°N, 80.97°W), between 2004 and 2011 with resulting possible fitness effects. Stable isotope analysis was used to assign the adult female loggerheads to one of three foraging areas in the Northwest Atlantic Ocean. Our data indicate that foraging area preference influences the size, fecundity, and breeding periodicity of adult female loggerhead turtles. We also found that the proportion of turtles originating from each foraging area varied significantly among the years examined. The change in the number of nesting females across the years of the study was not a result of uniform change from all foraging areas. We develop a novel approach to assess differential contributions of various foraging aggregations to changes in abundance of a sea turtle nesting aggregation using stable isotopes. Our approach can provide an improved understanding of the influences on the causes of increasing or decreasing population trends and allow more effective monitoring for these threatened species and other highly migratory species. © 2013 Springer-Verlag Berlin Heidelberg. Source

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