Daniela Rojas-Cañizales

Olive ridley sea turtles ( Lepidochelys olivacea ) exhibit two nesting behaviors: solitary nesting and synchronized mass-nesting, known as arribada , with females able to switch between behaviors rather than being exclusive to one strategy. Although arribadas are thought to be driven by environmental and/or social cues that promote synchronized breeding, it remains unclear to what extent they can shape the spatial and temporal dynamics of nesting olive ridleys. Our study documents how nesting behavior influences the frequency of inter-beach movements and the length of within-season inter-nesting periods (IP). We examined records of 4,273 tagged and 555 recaptured individuals from 2016 to 2019 at Corozalito, a nascent arribada nesting beach on the Costa Rican Pacific, and its three neighboring solitary-nesting beaches. Inter-beach movements were recorded for 99 turtles (17.8%), primarily from solitary-nesting beaches towards Corozalito during arribadas. IPs of females nesting in arribadas were not consistent across seasons while IPs between consecutive solitary nesting events were stable across years and comparable to values reported for other olive ridley rookeries. We suggest that arribadas at Corozalito prompt inter-beach movements of olive ridleys that nest on solitary neighboring beaches, attracting them to the mass nesting location. Additionally, breeding synchrony may extend the IP of turtles that have already laid their first nest by delaying oviposition until the arribada begins. However, this delay appears to be context-dependent, likely influenced by the timing of arribadas and individual nesting histories. These findings contribute to better understanding the processes involved in the formation of arribadas and their associated nesting dynamics.

Marine megafauna species are affected by a wide range of anthropogenic threats. To evaluate the risk of such threats, species’ vulnerability to each threat must first be determined. We build on the existing threats classification scheme and ranking system of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species by assessing the vulnerability of 256 marine megafauna species to 23 at‐sea threats. The threats we considered included individual fishing gear types, climate‐change‐related subthreats not previously assessed, and threats associated with coastal impacts and maritime disturbances. Our ratings resulted in 70 species having high vulnerability ( v > 0.778 out of 1) to at least 1 threat, primarily drifting longlines, temperature extremes, or fixed gear. These 3 threats were also considered to have the most severe effects (i.e., steepest population declines). Overall, temperature extremes and plastics and other solid waste were rated as affecting the largest proportion of populations. Penguins, pinnipeds, and polar bears had the highest vulnerability to temperature extremes. Bony fishes had the highest vulnerability to drifting longlines and plastics and other solid waste; pelagic cetaceans to 4 maritime disturbance threats; elasmobranchs to 5 fishing threats; and flying birds to drifting longlines and 2 maritime disturbance threats. Sirenians and turtles had the highest vulnerability to at least one threat from all 4 categories. Despite not necessarily having severe effects for most taxonomic groups, temperature extremes were rated among the top threats for all taxa except bony fishes. The vulnerability scores we provide are an important first step in estimating the risk of threats to marine megafauna. Importantly, they help differentiate scope from severity, which is key to identifying threats that should be prioritized for mitigation.

In Corozalito beach, Costa Rica, Olive Ridley turtles (Lepidochelys olivacea) nest both solitarily and in arribadas. The predation of solitary nests was monitored from 2008 to 2021, recording date, time, sector of the beach, zone, status of nest (predated or partially predated) and predator when possible. We recorded 4450 predated nests in total (N = 30,148 nesting events); predation rates showed a fluctuating trend, with recent percentages reaching up to 30%, with four distinctive dips in 2010, 2014, 2016 and 2017. The spatial distribution of predated nests along the beach showed significant differences among the sectors regardless of the seasons (Friedman test, chi-squared = 14.778, df = 2, p-value = 0.000), with most predated nests (47.62%) occurring in the northern sectors of the beach. Predators were identified by their tracks and/or direct observations (N = 896, 24.08%). The most conspicuous predators identified were raccoons (55.69%) and black vultures (22.77%). As seen in Corozalito, predation rates have increased in recent years despite established conservation efforts. A comprehensive assessment of all threats towards the overall hatching success for clutches is needed, considering predation during mass nesting events, poaching and beach erosion, among other factors, to fully understand the nesting dynamics occurring in this beach.

Se evaluaron todos los registros de tortuga guaraguá (Lepidochelys olivacea) disponibles a través de una revisión exhaustiva de diversas fuentes, la cual comprendió entre los años 1977 y 2018 para Venezuela. Se compilaron un total de 35 registros de tortuga guaraguá para el país. Las evidencias confirman la presencia casi permanente durante todo el año de la especie en aguas territoriales venezolanas.

Many conservation projects relocate sea turtle eggs to hatcheries to protect the sea turtle nests from the anthropogenic and natural threats they face in the early stages of development. The Rescue Center for Endangered Marine Species (CREMA) manages four sea turtle conservation projects on the nesting beaches of the Southern Nicoya Peninsula in Costa Rica, where the predominant nesting activity is from olive ridley turtles (Lepidochelys olivacea). Two of these nesting projects are based in Costa de Oro and San Miguel, which are adjacent beaches divided by an estuary. In this study, we compared the dynamics and rates of human and animal predation of nests prior to being relocated to the hatchery on both nesting beaches from 2012 to 2018. We hypothesized that human take and animal predation were compensatory threats, meaning that lower human take may result in higher animal predation, and vice versa, resulting in a similar number of nests lost to predation overall. We discuss the community-based conservation programs on both beaches, one of which has been monitored since 1998 (San Miguel) and the other of which has been monitored since 2012 (Costa de Oro). We found that Costa de Oro exhibited high rates of human take with up to 51% of nests being extracted per season, which has decreased since the conservation project was established. Human take was significantly higher than animal predation on both beaches and human take was significantly higher in Costa de Oro. While San Miguel exhibited higher animal predation, the difference was not statistically significant. Higher depredation by animals corresponded to higher overall nest abundance on both beaches. We were unable to find evidence that human take or animal predation increased in the absence of the other threat, suggesting a lack of compensatory effects of predation. Our findings support further analysis of animal predation and a continuation of patrol-based conservation efforts as well as community outreach to attempt to merge cultural values with sea turtle conservation.

Costa Rica hosts two renowned olive ridley (Lepidochelys olivacea) arribada beaches: Nancite and Ostional. In addition, the country hosts a third nascent arribada beach in Corozalito. We documented the frequency of arribada events in Corozalito (9°50′55.40″ N; 85°22′ 47.67″ W) from 2008 to 2021 and the abundance of egg-laying females during 12 arribadas. Moreover, we report on tag recaptures at Corozalito that were initially deployed at other nesting beaches in Costa Rica. Finally, we estimated incubation temperature, and performed quadrat and nest excavations to estimate hatching rates. We registered 29 arribadas at Corozalito since 2008, all between August and January. We estimated more than 150,000 olive ridleys nested during 12 arribadas from 2019 to 2021. Mean hatching success was 65% in quadrats and 59% for in situ marked nests. The mean incubation temperature was 32.3 °C. We found turtles tagged at other locations on the Pacific coast of Costa Rica nesting at Corozalito, providing evidence of philopatric plasticity. We suggest nascent arribada rookeries form rapidly via recruitment from regional turtle aggregations. Our findings show that hatching success is far higher at Corozalito than Ostional or Nancite. Continued monitoring of nesting dynamics at this site may shed light upon the mechanisms that rule how arribada beaches are born and evolve. Corozalito offers a unique opportunity to study and understand the arribada phenomenon and warrants official protection under official National Wildlife Refuge status.

Marine turtles are considered by people of several cultures to be a gift from God. This belief often leads to the use of these reptiles in the traditional and belief systems among aboriginal peoples. Certainly this is the case among Wayuú people, who are an indigenous group settled between Venezuela and Colombia, in the Guajira Peninsula. To assess the value of marine turtles to Wayuú ancestral people, especially as a medicinal resource, we carried out a comprehensive open-ended question-based survey of traditional healers and caretakers (locally known as Piaches and Oütsüs) from 4 Wayuú communities in the Venezuelan portion of the Guajira Peninsula. We documented customary practices where marine turtles' body parts are used as a key element of the remedies. Eleven marine turtle body parts were identified by respondents as remedies used by Wayuú people, with 7 different ways to administer them (drink, worn, powder, among others). Four of the 5 species of marine turtles present in Venezuelan waters were identified as being used in the traditional pharmacopoeia of Wayuú people; their traditional names are included on this article. Some considerations about the Wayuú's cosmovision, customs, traditions, and belief systems are included here. Our results are important in the context of likely future evaluation of the current Venezuelan legal framework to consider inclusion of traditional use of marine turtles in Venezuela.