Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Individual strategies and phenotypic plasticity of sea turtles in response to environmental changes: Loggerhead turtles nesting in Cabo VerdePublication . Martins, Samir; Loureiro, Nuno de Santos; Marco, AdolfoThe archipelago of Cabo Verde probably hosts the largest loggerhead turtle (Caretta caretta) rookery in the world. Nesting activities occur in all islands, with emphasis on Boa Vista, with more than 55% of the nest’s activities. The ecology of this population is still poorly understood and the studies presented here, carried out in the Sea Turtle Natural Reserve, aims to contribute to overcoming some relevant gaps. Our attention focused on: i. the influence of body size, estimated through the curved carapace length (CCL), the possible indicator of age on the fecundity of nesting females; ii. the influence of parameters such as temperature and moisture of the sand related to clutch location for the survival of offsprings; iii. the influence of nest location characterised by their proximity to the upper limit of the beach and to the water for the predation of hatchlings during their crawl to the sea; iv. the influence of hatcheries on hatching success and viability of hatchlings; and v. the impact of small-scale fishery on the nesting loggerhead turtle. We observed that: i. females nested along the entire width of the beach with a preference for the open area to the detriment of proximity to the tide line and vegetation; ii. only 8% of nesting females had CCL > 90 cm, laying less than 12% of the total annual number of clutches; iii. for higher values of temperature and moisture, the hatching success was lower and produced weaker offsprings; ghost crab predation decreased with increased hatchling group size; iv. hatcheries contributed to the hatching success without causing phenotypic differences; vi. small-scale fishery in Cabo Verde has relevant impacts on the population of C. caretta.
- High variability in nest site selection in a loggerhead turtle rookery, in Boa Vista Island, Cabo VerdePublication . Martins, Samir; Patrício, Rita; Clarke, Leo J.; Loureiro, Nuno de Santos; Marco, AdolfoAmong sea turtles, nest site selection is a crucial factor for hatching success and population viability. The relocation of otherwise doomed clutches to safe hatcheries has been widely promoted as a conservation strategy, although this may promote artificial selection of poorly adapted genotypes. In this study, we used multiyear spatial nesting data of individual loggerhead turtles (Caretta caretta) from one of the largest Atlantic rookeries, in Cabo Verde, across six consecutive nesting seasons (2013-2018), to identify spatial nesting patterns, assess how individual nest site selection is influenced by female size and age, and estimate the impacts on the reproductive output. Although females nested across the entire beach width, they preferentially nested in the middle of the beach, avoiding to nest both close to the tideline and close to the vegetation line. Hatching success decreased towards the waterline, while the risk of nest inundation or predation was high, regardless of nest location. In general, females showed high variability in nest site selection, except larger females (> 93 cm curved carapace length) that showed higher repeatability (r = 0.50, SE = 0.14, 95% CI: 0.16-0.72) in distances to the vegetation. We therefore suggest that the relocation of doomed clutches should be considered for this endangered rookery, as clutch relocation should not substantially distort the gene pool, assuming nest choice is a heritable trait. In addition, we recommend the preservation of beach vegetation, particularly in areas with human development.