Karumbé

The leatherback turtle (Dermochelys coriacea) undertakes extensive migrations between nesting and foraging areas, where it is exposed to threats such as fisheries bycatch, coastal development, and pollution. Although classified globally as Vulnerable by the IUCN, the Southwest Atlantic subpopulation is considered Critically Endangered, with nesting restricted to Brazil. While satellite telemetry and previous mitochondrial DNA (mtDNA) Genetic Mixed Stock Analysis (MSA) studies have indicated that leatherbacks from West African rookeries migrate to foraging grounds off Argentina and Uruguay, the potential for connectivity with rookeries from other regions remains an open question. Genetic Stock Identification (GSI) using 15 nuclear DNA (nDNA) microsatellite markers was conducted on 78 stranded or incidentally caught leatherbacks from feeding grounds off the coasts of Argentina and Uruguay. Assignment analysis results demonstrated that 92% of the foraging leatherbacks originated from Ghana and Gabon in the Southeast Atlantic (SEA), with lesser contributions from the rookeries in the Northwest Atlantic (NEA; 6%) and the Southwest Indian Ocean (SWI; 1%) rookery in South Africa, all with assignment probabilities (AP) exceeding 95%. Our findings corroborate and extend previous mtDNA studies by enhancing the precision of GSI for individuals possessing common haplotypes and by clarifying the unknown origin of individuals with 'orphan' mtDNA haplotypes, such as Dc7.1, which were assigned to the SEA rookeries (AP = 99%). Furthermore, we directly assigned one individual, previously of uncertain mtDNA origin (Dc9.1), to the South Africa rookery (AP = 97%), highlighting the need to consider the extension of the SWI Regional Management Unit (RMU) boundaries to Southwest Atlantic waters in future assessments. The absence of detected connectivity with Brazilian nesting populations underscores the necessity for increased sample sizes and the application of advanced molecular markers. These results advance the understanding of population connectivity across oceanic scales and emphasize the crucial role of international collaboration in conservation endeavors.

Synthetic plastics have become an indispensable component of modern life, and the amount of plastics disposal has increased dramatically as a result. With human population increasing, it is expected that the prevalence of plastic debris in the environment will also increase, unless sustainable daily habits are incorporated, waste management improved, and new alternative materials are discovered and popularized. To date, several reports show negative effects of plastic debris on marine and freshwater fauna (e.g. invertebrates, birds, turtles, marine mammals).

BackgroundResolving threats to widely distributed marine megafauna requires definition of the geographic distributions of both the threats as well as the population unit(s) of interest. In turn, because individual threats can operate on varying spatial scales, their impacts can affect different segments of a population of the same species. Therefore, integration of multiple tools and techniques — including site-based monitoring, genetic analyses, mark-recapture studies and telemetry — can facilitate robust definitions of population segments at multiple biological and spatial scales to address different management and research challenges.Methodology/Principal FindingsTo address these issues for marine turtles, we collated all available studies on marine turtle biogeography, including nesting sites, population abundances and trends, population genetics, and satellite telemetry. We georeferenced this information to generate separate layers for nesting sites, genetic stocks, and core distributions of population segments of all marine turtle species. We then spatially integrated this information from fine- to coarse-spatial scales to develop nested envelope models, or Regional Management Units (RMUs), for marine turtles globally.Conclusions/SignificanceThe RMU framework is a solution to the challenge of how to organize marine turtles into units of protection above the level of nesting populations, but below the level of species, within regional entities that might be on independent evolutionary trajectories. Among many potential applications, RMUs provide a framework for identifying data gaps, assessing high diversity areas for multiple species and genetic stocks, and evaluating conservation status of marine turtles. Furthermore, RMUs allow for identification of geographic barriers to gene flow, and can provide valuable guidance to marine spatial planning initiatives that integrate spatial distributions of protected species and human activities. In addition, the RMU framework — including maps and supporting metadata — will be an iterative, user-driven tool made publicly available in an online application for comments, improvements, download and analysis.