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

Abstract

ABSTRACT. 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)(2001)(2002)(2003)(2004)(2005)(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.

Movements, connectivity, and space use of immature green turtles within coastal habitats of the Culebra Archipelago, Puerto Rico: implications for conservation

“…Furthermore, while genetic sampling suggested the recruitment origins for juvenile green turtles were similar across the 2 bays in Culebra (Patrício et al 2017), somatic growth was significantly greater in Manglar Bay than in Tortuga Bay, with minimum ages at maturity of 14 and 22 yr, respectively (Patrício et al 2014). Since no differential recruitment (Patrício et al 2017) or movement across bays exists, habitat quality and availability (Bjorndal et al 2000) in combination with predation risk (innate or learned) are likely driving these different rates of somatic growth. Manglar Bay is comprised of macroalgae and the seagrass Thalassia testudinum, the primary diet of green turtles in the Greater Caribbean (Bjorndal 1980), while Tortuga Bay is predominantly covered by seagrasses Syringodium filiforme and Halodule wrightii.…”

“…Considering turtles in Culebra exhibit high fidelity within the bays, it is imperative to protect these distinct habitats that serve as both shelter and foraging areas. This is especially pertinent since the survival of immature turtles in Culebra could positively affect Caribbean-wide nesting populations, specifically those of Costa Rica, Mexico, east-central Florida, and Suriname (Patrício et al 2017). The protection of these essential juvenile turtle developmental habitats ensures continued recruitment into recovering green turtle populations.…”

“…Recognizing the area's importance, the US National Marine Fisheries Service designated Culebra as Resource Category I critical habitat for the green turtle in 1998 (Federal Register;63 FR 46693, September 2, 1998), and federal management and conservation measures are required within all coastal habitats within 3 nm (5.6 km) from Culebra. Green turtles have been most intensively studied in 2 bays around Culebra, on the easternmost side of Culebra in Manglar Bay and the on the small island of Culebrita (east of Culebra) in Tortuga Bay (Collazo et al 1992, Velez-Zuazo et al 2010, Patrício et al 2011, 2017. Although these 2 bays are in close proximity, there are relatively few records of green turtles moving between the bays based on a mark-recapture study with sampling occurring approximately twice during a given year (Patrício et al 2011).…”

Tracking nest-rescued green sea turtles in oceanic currents sheds light on eastern Caribbean “lost years”

“…Given the importance of key foraging grounds of juvenile turtles originating not only from areas adjacent to the foraging grounds but also from smaller islands thousands of kilometers away like Dominica, it is vital to ensure the appropriate level of conservation for key coastal habitats for the growth and survival of these endangered marine megafauna. Genetic analyses on juvenile C. mydas gathered at seagrass foraging grounds off Culebra, Puerto Rico (Patricio et al, 2017), the British Virgin Isles (McGowan et al, 2007), andColombia (Vasquez-Carrillo et al, 2020)all locations where juveniles from the current study were tracked within or neardetermined a mixed stock. Since Dominica's turtle population has not been genetically analyzed, it is within reason to conclude that the mixed juvenile green turtle populations within the wider Caribbean region include Dominica turtles as demonstrated by the juveniles from the current study migrating to areas on opposite ends of the Caribbean, specifically Colombia, the Gulf of Venezuela, the British Virgin Isles, and Puerto Rico.…”

Filling the gaps in sea turtle research and conservation in the region where it began: Latin America

“…Applying tools drawn from the field of molecular ecology, these studies provide further evidence of the large geographic areas sea turtles traverse during their ontogenic migrations and the regional perspective local initiatives should take when designing and implementing conservation actions. Zúñiga-Marroquín & Espinosa de los Monteros (2017) found that Eastern Pacific hawksbills establish local and trans-Pacific connections during their life history, while Patrício et al (2017) filled a gap for understanding the complex spatial connections Caribbean green sea turtles establish as a result of their migratory behavior. Two studies revealed new foraging habitats.…”