ABSTRACT Microplastics are an increasing threat to marine fauna and oceanic habitats, potentially affecting sea turtle nesting beaches. Hawksbill sea turtles (Eretmochelys imbricata) are a Critically Endangered species with decreasing population trends. There are several hawksbill rookeries in the southern Caribbean Sea, particularly on Los Garzos Beach, the main nesting site of continental Venezuela. A preliminary physical analysis of microplastics sampled from 10 sites on Los Garzos Beach reported high numbers (94 ± 2.5 items) of 14 different materials and colors. Microplastic counts at 10 sites averaged 1504 ± 405.61 items m−2, higher than other sea turtle nesting sites worldwide. There were no statistical differences in the concentration of microplastics at the sampled sites of Los Garzos Beach. However, the concentration of microplastics on this beach is higher at the midpoint of the falling tide (3520 ± 405.61 items m−2) and the top of the sea turtle nesting area (3840 ± 405.61 items m−2). We speculate that this debris could harm the nesting environment of hawksbill sea turtles in the region. While this study presents preliminary values for microplastics in an important hawksbill turtle nesting beach in Venezuela, it also serves as a baseline for long-term studies that can help determine the impact and sources of plastic pollution in sea turtle rookeries.

Abstract The nesting characteristics (number of nests and eggs, time of year, nesting initiation, and nesting length) of leatherback (Dermochelys coriacea) and hawksbill (Eretmochelys imbricata) sea turtles of the southern Caribbean Sea (specifically in the Gulf of Paria in Venezuela), were examined in association with weekly precipitation averages and number of rainy days per week during the period between 2009 and 2018. We hypothesized about the influence of rainfall intensity and patterns as the main abiotic factor for sea turtle nesting. On average, leatherbacks preferred nesting during the drier season of each year (March, April, and May), while hawksbills nested during the rainy season (June to September). For both species, we found few significant correlations between the number of nests or clutch size (number of eggs per nest) and weekly averages of seasonal precipitation rates in the region. Average hawksbill clutch sizes were not correlated with average precipitation rates but were positively correlated with the number of rainy days per week (r=0.66, P≤0.05). Average hawksbill clutch sizes decreased each year on average (-3.3 eggs/year, r=-0.88, P≤0.001), which coincided with a negative long-term trend in the number of rainy days (-0.11 rainy days/week, r=-0.69, P≤0.05). During the study period, nesting activities for both leatherback and hawksbills started progressively later (0.9 and 0.6 weeks/year, respectively p≤0.05) and were shorter (-0.9 and -0.8 weeks /year, P≤0.1 and P≤0.05, respectively).

ABSTRACT Following classical literature in herpetology, we built two five-stage life tables for the endangered hawksbill sea turtle Eretmochelys imbricata in the Gulf of Paria, eastern Venezuela, using data from incidental captures by industrial trawl fisheries from 1991 until 2000, artisanal fisheries effect and regional stranding from 1999 to 2017, and a local conservation project with the nesting females from 2003 to 2018. We estimated the survivorship for the managed, translocated nests, and a portion of the natural in situ nests (≈31%). We used the resultant life graph and matrices to estimate the hawksbills population status in the region and determine differences in population growth rate and elasticity between translocated and in situ nests. Eggs/hatchlings (stage 1) and small juveniles of less than three years old (stage 2), had high mortalities. We controlled stage 1 mortality by translocating nests into a hatchery. The in situ nests suffered almost 88% predation or poaching. Conversely, these non-translocated nests' emergence success was greater than that of managed nests, but overall survivorship was the lower. We propose that fecundity could begin with sub-adults (stage 4) after the 7th year with 60 cm of curved carapace length. Finite rates of increase of both populations, managed and natural, were significantly higher than 1, and that of the managed population is significantly higher than that of the natural one, meaning that both populations would grow and that the managed one would grow faster than the natural one. Then protection of stage 1 is essential to the population of hawksbills in the region, although uncertainties of survivorship of stage 2 and fecundity of stage 4 were not properly confirmed locally. Notwithstanding, elasticity analysis indicated that the population growth rate was more affected by proportional changes in sub-adults and adults' fecundity than any other life-history element.