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Antecedentes y Objetivos: La restauración ecológica se ha centrado en los componentes físicos y vegetales de los ecosistemas, y ha dejado de lado a la fauna silvestre y sus interacciones. Chelonia mydas es un macroherbívoro en peligro de extinción que anida en playas de México y Cuba, e influye en la vegetación costera con aportaciones de materia orgánica. Los objetivos de este estudio fueron analizar su recuperación poblacional, un índice del verdor de la vegetación de duna, así como la cantidad de materia orgánica estimada de sus nidadas antes y después de la implementación de una Norma Oficial Mexicana. Métodos: Se analizaron datos de entre dos y tres décadas de monitoreo biológico en 16 playas de anidación de Chelonia mydas; a partir de ellos se realizaron tres niveles de análisis de indicadores demográficos, la aportación de materia orgánica de las tortugas en la playa y el vigor vegetal a partir de sensores remotos, además de aplicar los estadísticos pertinentes. Resultados clave: Hubo un crecimiento exponencial del número de anidaciones de tortuga verde (entre 12 y 14% anual), asociado con pulsos de reclutamiento poblacional en los años 2000 y 2008. El aporte de materia orgánica a la playa fue significativamente mayor después de un cambio en la estrategia para manejo de las nidadas en México, y se detectó un incremento en el verdor de la vegetación de duna en zonas de anidación alta de Chelonia mydas. Conclusiones: El incremento de las poblaciones de tortuga verde lleva a reflexionar acerca de las implicaciones que tiene la recuperación de especies de fauna sobre otras comunidades en los ecosistemas que habitan, lo que demanda el análisis de los paradigmas actuales y la adaptación de estrategias que atiendan sus necesidades de manejo, procurando las condiciones de integridad ecológica de sus hábitats.

The stock-recruitment relationship (SR), customarily used in fisheries assessment, can be used to analyze demographic data of sea turtles to infer changes in hatchling production (R) as a function of nester abundance (S), recruitment rates and the influence of environmental conditions on these population features. The SR Cushing model (R=aS^b), where a and b are the model parameters) is well-suited for representing the dynamics of recovering populations, such as the green turtle (Chelonia mydas) in Campeche, Mexico. This study aimed to explore the SR Cushing model using a time series of the abundance of nesters and hatchlings (1984–2020). By applying local regressions (9-yr moving windows), we found that the time series of parameter b (the change in R as a function of S) and the recruitment rate (hatchlings per nester) were inversely correlated with a 26-yr cycle of the Atlantic Multidecadal Oscillation –sea surface temperature (SST), over the Atlantic– (r^2=0.83) and (r^2=0.64), respectively, at a 3-yr lag). Model diagnostics using the time-dependent Cushing model substantiated that the log-normal distribution of hatchlings of C. mydas in Campeche depends on the abundance of nesting females and on a low frequency SST signal (r^2=0.98). The positive trend in nester numbers of green turtles in Campeche during the past 44 years may be the result of persistent conservation efforts, while the drastic and sporadic changes in the growth rate of annual arrivals and hatchling production are suggestive of population dynamics driven by low frequency, basin-wide environmental signals.

Long-term monitoring programs of species at risk are efficacious tools to assess population changes, evaluate conservation strategies, and improve management practices to ensure populations reach levels at which they can fulfill their ecological roles. For sea turtles, annual nesting beach surveys are the most accessible method to estimating the population abundance and reproductive output, especially when these are done in primary nesting sites. However, little data exist on the long-term assessment of these parameters. Here, we present the trends of the nest abundance, female size, hatching, and emergence success of hawksbill (Eretmochelys imbricata) and green (Chelonia mydas) turtles at key nesting beaches in the southern Gulf of Mexico over 31 years (from 1990 to 2021). The nest abundance showed an increasing trend in both species as a result of the sustained protection and conservation effort, but there was no significant temporal trend in the annual female size, clutch size, hatching, and emergence success. However, these indicators showed decreasing mean values over the last decade and should be closely monitored. We suggest these decreases link to the combined effects of ocean warming and anthropogenic pressures affecting the sea turtle foraging grounds. Aside from protecting key nesting sites, protecting and restoring crucial foraging habitats should be an immediate priority requiring international cooperation.

The hawksbill turtle (Eretmochelys imbricata) rookeries at the west coast of Yucatan Peninsula (Campeche) are the largest in the Western Atlantic. One of the oldest sea turtle conservation and research programs in Mexico started in Campeche in 1992, becoming a robust long-term research project monitoring and tagging hawksbill individuals at their critical habitats. After 25 years of tagging data, we have evaluated the spatiotemporal variability of vital signs for the immature and reproductive populations, including the assessment of connectivity between and among rookeries in the Yucatan Peninsula, the Gulf of Mexico, and Western Caribbean. This is a reference example of long-term vision for monitoring and conserving long-lived critically endangered species, and how a well-structured tagging project that persisted in time contribute with measurable indicators of the sea turtle populations' condition and becomes a keystone for the species' recovery.

The hawksbill turtle (Eretmochelys imbricata) is a critically endangered species with a global distribution and is broadly distributed along the Yucatan Peninsula in the Gulf of Mexico. To complete its life cycle, this species uses sandy beaches with particular environmental conditions that facilitate nesting and hatching. This study aimed to identify if beach physical characteristics influence biological reproductive parameters (hatching and emergence success). Nesting activity was monitored along 18 km of beach in the state of Campeche, Mexico, during 2014. Seventy-eight nests were recorded, 12 physical and environmental variables were measured in the nests and contiguous areas, and the hatching and emergence success of each nest was determined. Beach slope and width had no significant relationship to nest site selection. Nest depth and nest distance to highest tide and vegetation, including vegetation type, did influence hatching and emergence success. Herbaceous and bushy plants were positive...

A spatially explicit participatory approach was used to collect fishing effort and sea turtle bycatch data from local fishers at 15 ports in the Yucatan Peninsula, Mexico. These data were combined with satellite telemetry data to define potential bycatch hotspots. This is the first participatory and spatially explicit study on sea turtle bycatch rates in the region. Hawksbill turtles (Eretmochelys imbricata) were the most frequently caught bycatch species, followed by loggerheads (Caretta caretta) and green turtles (Chelonia mydas). Gillnets were the most dangerous for sea turtles, with the greatest incidence of dead turtles caught. Three particular bycatch hotspots were identified at the northeast, northwest, and southwest coasts of the peninsula. Identification of bycatch hotspots is recognized worldwide as a key element for protecting these endangered species, particularly in a region such as the Yucatan Peninsula that harbors critical habitats for ≥ 4 sea turtle species, 2 of them categorized...

Although the shores of Campeche, Mexico, are critical breeding grounds for the green turtle (Chelonia mydas), so far there is neither clinical nor ecological information about nesting females at this area; such information could help to improve conservation and management of this species. We describe the blood chemical profile based on 13 analytes, and the effect of prevalence of ectoparasites and epibionts of nesting female green turtles. Although we observed low atypical values for amylase and blood ureic nitrogen, and high atypical values for creatinine, phosphorus, and total bilirubin, these results are likely due to feeding habits and nesting-related stress and not to illness or parasitism.

Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles-hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta-exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO)-the strongest on record-combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r = -.94) and the Multivariate ENSO Index (MEI) for all years (r = .74). Granger-causality analysis also supports the latter finding. We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study demonstrates the importance of region-wide collaborations.

article i nfo The recent decline of nesting hawksbill turtles (Eretmochelys imbricata) in the southern Gulf of Mexico (SGM) has been partly attributed to climate change, but the evidences to support this idea are still developing. In sea turtles, the recruitment success and remigration interval (the interval between two successive nesting sea- sons) are related to interannual variations in oceanographic conditions at the turtles' developmental habitats. However, the effect of low-frequency environmental variability has not been well documented. The relative changes in the numbers of nesting hawksbill turtles related to climate variability in the SGM and North Atlantic, during the 1980-2010 period, were analysed using the time series techniques to determine: 1) whether there are periodic signals in the series, and 2) whether any such signals parallel climate variations of similar frequency at local, regional and basin-wide spatial scales. A 7-year cycle in annual relative number of nesting hawksbill turtles in the SGM was found, which is superimposed upon a neg- ative long-term trend. Both signals are inversely correlated with cycles of similar periodicity in the North Atlantic sea surface temperature (SST). These results suggest that the long-term population dy- namics of hawksbill turtles in the SGM are related to a basin-wide, quasi-decadal environmental fluc- tuation in the North Atlantic. This relationship may be influenced by trophic interactions that are coupled to a decadal alternation between favourable and unfavourable ecological conditions occurring on basin-wide scales. Conservation planning for thi ss pecies should focus on the potential effect of both linear increases in SST, as expected from current global warming trend, and long-term natural en- vironmental variability.

The Yucatan Peninsula harbors the largest nesting population of hawksbill turtle Eretmochelys imbricata in the Atlantic Basin. In Mexico, one of the most significant conservation problems for this species is the lack of knowledge on migratory patterns and the location of feeding grounds for post-nesting hawksbill females. The main goal of this study was to gather information on the hawksbill's migratory patterns and the location of their feeding grounds by tracking 3 post-nest- ing females from Campeche state, Mexico. We attached satellite transmitters and tracked the 3 tur- tles for 166, 446 and 510 d, respectively. The turtles remained within Mexican territorial waters, reaching separate foraging grounds off the coast of Campeche and in the Mexican Caribbean. No significant relationships were observed between turtles' migrating behavior and sea-surface temper- ature or geostrophic currents. Spatial analysis of the data recorded in this study has generated novel information on hawksbill turtle migratory patterns and feeding grounds, which will aid in decision- making for hawksbill turtle conservation in the Yucatan Peninsula.

"A nivel mundial de las 32 subpoblaciones de Chelonia mydas post-anidadoras, 2 se encuentran en las costas de México, una en Michoacán (Océano Pacífico) y la otra en la península de Yucatán (Océano Atlántico). La carencia de información sobre patrones migratorios, ámbitos de hogar, e interacción antropogénica, son factores que contribuyen a la vulnerabilidad intrínseca de las poblaciones de C. mydas en cualquier parte del mundo. El objetivo de esta investigación fue identificar las rutas migratorias y hábitats críticos marinos para individuos de C. mydas post-anidadoras en la península de Yucatán. Entre junio de 2011 y enero de 2012, 4 individuos de C. mydas post-anidadoras se rastrearon utilizando telemetría satelital, 2 desde playas continentales y 2 desde playas insulares. Se utilizó un sistema de información geográfica para integrar la información recabada, y utilizándola para identificar las rutas migratorias de C. mydas, así como estimar sus áreas de ámbitos de hogar. Tres tortugas se desplazaron y se mantuvieron sobre la plataforma marina del Banco de Campeche en territorio Mexicano y una migró fuera de aguas nacionales Mexicanas hasta llegar a Dry Tortuga (Florida, USA). Las áreas abarcadas de los ámbitos de hogar por hembras anidadoras en playas continentales fue ron significativamente mayores y se ubicaron a mayor distancia de la costa respecto a los registrados por las hembras rastreadas desde playas insulares. Con base en los resultados se recomienda la planificación de estr ategias de manejo para la conservación de C. mydas en la península de Yucatán."

We present a long term record (1984–2004) of registered occurrences of Kemp's ridley turtles in the marine zone and nesting beaches of the Yucatan Peninsula, Mexico.