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Novel insights into the dynamics of green turtle fibropapillomatosis

Publication . Patrício, Ana Rita; Diez, Carlos E.; Dam, Robert P. van; Godley, Brendan John

Outbreaks of fibropapillomatosis (FP), a neoplastic infectious disease of marine turtles, have occurred worldwide since the 1980s. Its most likely aetiological agent is a virus, but disease expression depends on external factors, typically associated with altered environments. The scarcity of robust long-term data on disease prevalence has limited interpretations on the impacts of FP on turtle populations. Here we model the dynamics of FP at 2 green turtle foraging aggregations in Puerto Rico, through 18 yr of capture-mark-recapture data (1997−2014). We observed spatiotemporal variation in FP prevalence, potentially modulated via individual site-fidelity. FP ex pression was residency dependent, and FP-free individuals developed tumours after 1.8 ± 0.8 yr (mean ± SD) in the infected area. Recovery from the disease was likely, with complete tumour regression occurring in 2.7 ± 0.7 yr (mean ± SD). FP does not currently seem to be a major threat to marine turtle populations; however, disease prevalence is yet unknown in many areas. Systematic monitoring is highly advisable as human-induced stressors can lead to deviations in host− pathogen relationships and disease virulence. Finally, data collection should be standardized for a global assessment of FP dynamics and impacts.

2016Journal article

Open access

Dispersal of green turtles from Africas' largest rookery assessed through genetic markers

Publication . Patrício, Ana Rita; Formia, Angela; Barbosa, Castro; Broderick, Annette C.; Bruford, Michael; Carreras, Carlos; Catry, Paulo; Ciofi, Claudio; Regalla, Aissa Said; Godley, Brendan John

Marine turtles are highly migratory species that establish multiple connections among distant areas, through oceanic migration corridors. To improve the knowledge on the connectivity of Atlantic green turtles Chelonia mydas, we analysed the genetic composition and contribution to juvenile aggregations of one of the world's largest rookeries at Poilao Island, Guinea-Bissau. We amplified 856 bp mitochondrial DNA (mtDNA) control region sequences of this population (n = 171) containing the similar to 490 bp haplotypes used in previous studies. Haplotype CM-A8 was dominant (99.4%), but it divided in 2 variants when the whole 856 bp was considered: CM-A8.1 (98.8%) and CM-A8.3 (0.6%). We further identified the haplotype CM-A42.1 (0.6%), found previously only in juvenile foraging grounds at Argentina, Brazil and Equatorial Guinea. The Poilao breeding population was genetically different from all others in the Atlantic (FST range: 0.016-0.961, p < 0.001). An extensive 'many-to-many' mixed-stock analysis (MSA) including 14 nesting populations (1815 samples) and 17 foraging grounds (1686 samples) supported a strong contribution of Poilao to West Africa (51%) but also to the Southwest Atlantic (36%). These findings, in particular the strong connectivity within West Africa, where illegal harvesting is still common, should motivate conservation partnerships, so that population protection can be effectively extended through all life stages. Our study expands the knowledge on migration patterns and connectivity of green turtles in the Atlantic, evidences the importance of larger sample sizes and emphasizes the need to include more finely resolved markers in MSAs and more genetic sampling from West African foraging grounds to further resolve the connectivity puzzle for this species.

2017Journal article

Open access

Nest site selection repeatability of green turtles, Chelonia mydas , and consequences for offspring

Publication . Patrício, Ana Rita; Varela, Miguel R.; Barbosa, Castro; Broderick, Annette C.; Airaud, Maria B.Ferreira; Godley, Brendan John; Regalla, Aissa Said; Tilley, Dominic; Catry, Paulo

Nest site selection is a critical behaviour, particularly in species with no parental care, as it can greatly impact offspring survival. Marine turtles depend on sandy beaches to nest, where they select from a range of microhabitats that may differently affect hatchling survival and phenotype. Here we describe the degree of nest site selection at one of the largest green turtle rookeries globally, in Guinea-Bissau, West Africa, and how this impacts offspring. In 2013 and 2014 we recorded the spatial distribution of 1559 nests, and monitored 657 females during oviposition, to assess population and individual preferences on nesting site. Overall, females tended to nest close to the vegetation, at a preferred elevation of 4.8e5.0 m, which was above the highest spring tide (4.7 m), enhancing clutch survival. Individuals displayed high repeatability in nesting microhabitat type (open sand, forest border and forest), distance along the beach, distance to the vegetation and elevation, which may result from this behaviour having a genetic basis or from fine-scale nest site philopatry. Hatchlings from cooler nests were larger, potentially dispersing faster and more able to evade predators, while smaller hatchlings, from warmer nests, retained more energetic reserves (residual yolk), which may also be advantageous for initial dispersal, particularly if food is scarce. Thus, individual preferences in nest site selection led to trade-offs in offspring phenotype, but overall, most nesting females selected sites that increased offspring survival, suggesting that nest site selection is an adaptive trait that has been under selection. As under future climate change scenarios females nesting in upper shaded areas should have higher fitness, individual consistency in nesting microhabitat provides opportunity for natural selection to occur.

2018Journal article

Restricted access

Genetic composition and origin of juvenile green turtles foraging at Culebra, Puerto Rico, as revealed by mtDNA

Publication . Patrício, Ana Rita; Velez Zuazo, Ximena; van Dam, Robert P.; Diez, Carlos E.

Marine migratory species encounter a range of threats as they move through coastal and oceanic zones. Understanding the connectivity and dispersal patterns of such species is critical to their effective conservation. Here we analyzed the temporal genetic composition and the most likely origin of juvenile green turtles foraging at Puerto Manglar and Tortuga Bay, Culebra, Puerto Rico, using mitochondrial DNA control region sequences. We identified 17 haplotypes, of which CM-A3 (51.5%), CM-A5 (19.4%) and CM-A1 (13.6%) were the most common. Haplotype (h) and nucleotide (π) diversities were 0.680 and 0.008, respectively. There was no evidence of significant variation in the genetic composition of these aggregations throughout seven years (2000-2006), suggesting that relative contributions from source populations did not significantly change during this period. Mixed Stock Analysis (MSA), incorporating 14 Atlantic nesting populations as possible sources, indicated four main contributing stocks to the Culebra foraging grounds: Costa Rica (34.9%), Mexico (29.2%), East Central Florida (13.2%), and Suriname (12.0%). The regional pattern of connectivity among Wider Caribbean rookeries and Culebra was further evidenced by a second MSA using Atlantic Regional Management Units (RMUs) as sources, with 94.1% of the mixed stock attributed to this area. This study addresses the information gap on the connectivity of the green turtle in the North Atlantic, and establishes an important baseline that can be used to determine future changes in stock composition.

2017Journal article

Open access