Abstract. In regions where rapid and extensive environmental changes have occurred, particularly in South America, reliable time markers are essential for dating sediment sequences and quantifying environmental degradation. In this respect, the use of 239Pu and 240Pu isotopes in South American sediments may help to identify distinct sources of fallout radionuclides, including radioactive fallout from French atmospheric nuclear weapons tests (NWTs) conducted between 1966 and 1974 at the Mururoa and Fangataufa atolls (French Polynesia). Here, we present post-1900 continuous records of 240Pu/239Pu isotope ratios in sediments cores from sites located between 32° and 52°S latitude: Lakes Natri and Laja in Chile; Lakes La Barrancosa, Melincué, Ñe Luan, and Roca in Argentina; and the Rincón del Bonete Reservoir and La Estanzuela Pond in Uruguay. Depth profiles revealed two 240+239Pu activity peaks, from which the more recent is not concomitant to the 137Cs maximum activity peak dated back to 1964-1965. The low 240Pu/239Pu atom ratio (< 0.08) associated with this more recent Pu peak confirms a contribution from French fallout, dated to the late 1960s to early 1970s. The investigated lakes exhibited similar patterns in Pu isotope ratios: (i) an initial phase dominated by the U.S. NWTs signature (240Pu/239Pu > 0.20, also often referred to pre-moratorium), followed by (ii) increasing Pu activities characterized by a Pu isotopic signature consistent with global fallout (240Pu/239Pu ~ 0.18) and, finally, (iii) a period of increased Pu activities from French NWTs fallout (0.03 <240Pu/239Pu < 0.08). The 239Pu and 240Pu isotopes revealed a consistent nuclear source pattern with a distinct French fallout contribution, confirming their suitability as an additional time marker for environmental reconstruction in South America.

Understanding the long-term effects of land-use change on coastal ecosystems is essential for effective environmental management and conservation. This study presents a high-resolution 238-year (1778-2015) reconstruction of terrigenous influence on a coral reef within the Sabana-Camagüey Ecosystem (north-central Cuba), a region of high ecological value that includes Ramsar sites and a Particularly Sensitive Sea Area (PSSA). Annual Ba/Ca ratios were measured in a dated core of Orbicella faveolata and used as a proxy for variations in terrigenous input. The record reveals a long-term increase in Ba/Ca beginning around 1900 and accelerating during the twentieth century, broadly coinciding with historical deforestation, agricultural expansion, and coastal development in adjacent watersheds. Several prominent Ba/Ca peaks also correspond to periods affected by major tropical cyclones, suggesting episodic enhancement of terrestrial material delivery. Coral linear extension rates exhibited a significant long-term decline over the study period, while Ba/Ca values increased. Although a significant inverse relationship was observed between Ba/Ca and coral extension during the post-1936 interval, additional analyses using detrended series and first differences indicate that this relationship is primarily associated with shared long-term trends rather than strong year-to-year coupling. These findings suggest that coral skeletal Ba/Ca provides a valuable archive of long-term changes in terrigenous influence in the Sabana-Camagüey Ecosystem and highlight the enduring legacy of historical land-use change on coastal environments. The study underscores the importance of integrated watershed-coastal management strategies for protecting coral reef ecosystems in regions exposed to sustained terrestrial pressures.

Abstract. Tropical corals preserve geochemical 238U/234U ratios that provide valuable records of past seawater uranium isotope compositions. Variations in the coral skeletons and thus seawater are likely indicative of freshwater contributions from submerged groundwater discharge and river runoff, or reflecting coral diagenesis. Advances in multi-collector ICP-MS allow precise determinations of 238U/234U ratios, enabling the reconstruction of subtle (typically >1 ‰) environmental changes in these marine records. In this study, we evaluate the reliability of coral-based δ234U records across multiple genera, sampling strategies, and intra-skeletal variability. Analyses of reference material NBS-CRM-112A demonstrate reproducibility within ±0.4 ‰. Replicate sampling across coral structures and colonies indicates measurable intra-band heterogeneity (±0.6 ‰), although local hydrodynamics and submarine groundwater discharge can introduce small inter-colony offsets. No species-dependent isotope fractionation was detected, underscoring the robustness of δ234U as a geochemical proxy. These findings demonstrate that coral skeletons provide reliable archives of up to sub-annual δ234Usw for detecting subtle climatic and hydrological signals.

Benthic or epibenthic dinoflagellates (EDs) are a potential risk to the environment and human health due to the production of toxins by some species. This study explored for the first time the presence of EDs mainly associated with macrophytes (macroalgae and seagrass) at 2 sites influenced by upwellings: Estero de Urías Lagoon (EUL), at the entrance of the Gulf of California, and Paracas Bay (PB), on the southern Peruvian coast. Prorocentrum lima complex was present at low abundances: ≤ 25 cells g-1 wet weight in EUL and ≤ 867 cells g-1 wet weight in PB. It was recorded in a wide range of temperatures from 22.2 to 31.6 °C in EUL and from 18.0 to 22.2 °C in PB. Despite its low abundance, monitoring the EDs community is essential to detect changes in the distribution patterns of harmful species in the context of climate change.

Accurate reconstructions of past environmental changes are crucial in paleoecological research and require reliable chronologies of sedimentary archives. Establishing robust age-models and obtaining the most appropriate proxies for analysis is a complex scientific endeavor, requiring extensive resources and collaboration among specialists, including radiochronologists. Radiometric dating methods, such as Pb-210 and radiocarbon (C-14), are frequently employed to establish chronologies in aquatic sedimentary deposits and peat bogs. In this study, we review key aspects of sampling, analysis, and the principles underlying Pb-210 and C-14 age-models, focusing on methods for developing robust joint chronologies for paleoenvironmental research. Drawing largely from the authors' experiences and group discussions during and after a scientific workshop in 2022, we discuss important considerations for site selection, sampling strategies, and radiometric dating to construct integrated Pb-210 -C-14 age-models. Using expert consensus, this group - called Paleostats - aims to provide a set of best practices for other geochronologists with this methods paper. Among our conclusions, we emphasize the importance of accounting for site-specific factors such as prior information on sedimentation rates to establish appropriate sampling and analytical strategies. The use of appropriate coring devices can minimize disturbance to sediments and ensure the core surface remains intact and preserved until sectioning. Where excess Pb-210 (Pb-210(ex)) is expected, sectioning at intervals of <= 1 cm provides an adequate sampling resolution for Pb-210 dating. Exceptions are possible, allowing for similar to 2-3 cm sections in areas with confirmed high sedimentation rates (e.g., > 1 cm yr(-1)). Recovering deeper core sections for C-14 dating with sufficient overlap allows for accounting errors in depth estimates made in the field. Special attention is advised during time intervals where validation proxies, such as the human-made radionuclides Cs-137 or post-bomb C-14, are expected, and to determine the depth of secular equilibrium between Pb-210 and Ra-226. Radiocarbon analyses are commonly performed by accelerator mass spectrometry, and age models are constructed mainly using Bayesian statistics with Markov Chain Monte Carlo techniques (e.g., Bacon). A Bayesian approach (Plum) is now available for producing Pb-210 age-models, which infers the Pb-210(ex) flux, eliminates the need for selecting an equilibrium depth, and allows dating cores with incomplete Pb-210(ex) inventory. Plum offers improved chronologies by integrating raw Pb-210 and C-14 data, and these age-models can be enriched with other dating methodologies, such as identifying tephras and other well-recorded historical events. Harmonized reporting would contribute to making radiometric age-models reproducible, which would benefit from an international effort. Using Pb-210 and C-14 to produce integrated age-models may yield better insights into the interplay between natural and recent anthropogenic forcings on ecosystems. This can enhance our understanding of environmental processes and their impacts on climate change, ultimately supporting science-based assessments and decisions.

Mercury (Hg) contamination in coastal sediments poses significant ecological and health risks, necessitating comprehensive assessments under the Minamata Convention. This study investigates the spatial distribution and potential ecological risks of Hg in surface sediments from 15 diverse Cuban coastal environments. Sediment samples were collected and analyzed for total Hg (ranging from 0.001 to 16.5 mg·kg-1), and a reference value of 0.090 ± 0.059 mg·kg-1, defined as the geochemical background level for Hg in marine sediments, was derived using a cumulative distribution function method. Contamination degree was assessed using the Contamination Factor (CF), and the ecological risk was quantified using the Ecological Risk Index, the Threshold Effect Level (TEL), the Probable Effect Level (PEL), and the novel Composite Environmental Vulnerability Index (CEVI). Results revealed pronounced Hg enrichment in anthropogenically influenced sites, with Sagua la Grande River and Havana Bay exhibiting extremely high CF values and frequent exceedances of the PEL, identifying them as regional hotspots driven by industrial legacies and urban pressures. The CEVI effectively linked Hg levels to industrial and population factors. Compared to global hotspots, these findings provide a critical baseline for Cuba, supporting Minamata Convention monitoring and urging future studies to focus on temporal data, speciation, and bioaccumulation.

This study aimed to reconstruct the temporal variations of potentially toxic element (PTE) concentrations and enrichment levels in four 210Pb-dated sediment cores, collected in Molinito Dam, NW Mexico, to assess the impacts of the 2014 mining spill on the Sonora River Basin. Sediment cores were collected with a gravity corer in February 2023; major and trace elements were analyzed through X-ray fluorescence spectrometry, except Hg and Cd, measured by atomic absorption spectrometry. Contamination degree was assessed via enrichment factor, and PTE sources were identified through factor analysis. The sediment cores spanned between 10 and 30 years; sediments were mostly composed of clayey silts, with organic matter and carbonate contents below 4 %. Element concentrations were similar in magnitude among cores, exhibiting minimal variations throughout their temporal profiles, except for distinct maxima of Mn, Fe, As, Cu, Pb, Ni, Cr, and Zn that reached different depths within each core. Most elements showed null to minor enrichment, except As, Cd, and Hg, which exhibited moderate to severe enrichment in some cores. PTE maxima were observed in sediment sections dated near 2014, which, considering the age model uncertainties, aligned with the timing of the 2014 mining spill. Additional maxima in older or younger sections were likely associated with hydrometeorological events or unreported spills. Although the enrichment factor for most PTEs was null or minor, the spill left a clear mark in the sediment record, which also showed that PTE concentrations returned to pre-event levels. These findings underscore the importance of reconstructing historical environmental conditions through sediment analysis to understand changes and evolution of aquatic ecosystems.

The use of satellite-based remote sensing imagery for water quality monitoring of inland and coastal waters has become widespread over the last few decades, with the expansion of, and investment in, operational Earth-observing missions. Satellite-based sensors are uniquely suited to provide synoptic, system-wide water quality parameter estimates that supplement traditional field-based sampling methods. The remote sensing of water quality parameter estimates is particularly valuable in systems with high temporal and spatial variability, as well as in areas that are difficult to access, or where agencies lack funding for routine monitoring. However, optically complex inland and coastal waters pose additional challenges for developing robust remote sensing retrieval models for optical properties and water quality parameters. One of the biggest challenges is collecting high quality field measurements that are used to calibrate and validate the retrieval algorithms. Here, we present the current status of satellite missions, field methods that include instruments used and commonly measured parameters, and repositories of historical field data that are relevant to inland and coastal water studies. We then present data requirements for model validation and highlight gaps in validation coverage. Finally, we provide considerations for future field campaigns to improve coordination with remote sensing data collection and ensure that field data is well suited for use in model or algorithm development.

Sedimentary processes, ecological risks, and historical trends of mercury (Hg) contamination were assessed through 210Pb-dated sediment cores and sediment traps (period 2017-2019) in Términos Lagoon (TL), a critical coastal ecosystem in the southern Gulf of Mexico. Hg natural background levels in TL cores widely varied (7-153 ng g-1), and Hg concentrations were higher in the cores (median 32 ng g-1, range 6-4240 ng g-1) than in the sediment traps (median 54 ng g-1, range 44-1311 ng g-1). In most cores, enrichment factors ranged from null to moderate, except for very severe levels found in core LT01, indicating the presence of an Hg hotspot. Enrichments (minor to severe) were confined to river discharge areas in the sediment traps. Low to very high ecological risks were observed across the sampling areas. The factor analyses, for the core and trap samples, indicated fine-grained terrigenous sediments and high organic matter content as major drivers of Hg accumulation, with river discharges playing a central role. The sediment records displayed increasing Hg fluxes after the 1970s, coinciding with the local urban-industrial boom, while peak values in recent decades corresponded with population growth around the lagoon. Sediment trap data suggested that Hg fluxes are somewhat independent of rainfall, as peak values were observed during dry and winter storm seasons. These findings highlight the interplay of natural and anthropogenic factors promoting Hg accumulation in TL, offering insights to mitigate the effects of global change in one of Mesoamerica's most important coastal ecosystems.

Sediments are microplastics (MP) sinks, capturing long-term accumulation and historical anthropogenic impacts. The analysis of ²¹⁰Pb-dated sediment cores offers temporal insights for evaluating MP pollution trends in coastal ecosystems, aligning with UN Sustainable Development Goal (SDG) 14.1.1b, which seeks to reduce marine pollution through enhanced monitoring and assessment practices. As part of the Research Network of Marine-Coastal Stressors in Latin America and the Caribbean (REMARCO), our efforts contribute toward harmonizing plastic pollution monitoring across the region using nuclear and isotopic techniques. Through the regional project RLA7025, supported by the International Atomic Energy Agency (IAEA), we examined three sediment cores to assess temporal variations in MP abundance (particles kg¯¹) and flux (particles m¯² year¯¹) over the past century in the coastal lagoon Estero de Urias, in the Mexican Pacific.MP particles were extracted via density separation and identified on Nile red-stained filters under visible and UV light. Polymer composition was determined for approximately 10% of the suspected MP particles using Fourier Transform Infrared (FTIR) spectroscopy. We observed the predominance of fibers (66-89% of total particles) over fragments (11-34%), with polyethylene terephthalate (PET) as the most common polymer, followed by semisynthetic cellulosic fibers. No MP particles were detected in sediments before 1950. An accelerated increase in MP burial rates was observed from the mid-20th century, likely linked to population growth and the expansion of plastic use. The highest MP levels were observed in the lagoon’s innermost areas, where the water residence time is highest. This rising contamination poses risks to subsistence fishing and shrimp aquaculture, emphasizing the need for strengthened waste management and pollution control strategies in rapidly industrializing and urbanizing areas to mitigate adverse impacts on ecosystems and human communities reliant on them. Harmonizing monitoring and assessment protocols for plastic pollution across the Latin American and Caribbean region is essential for producing comparable data that can guide regional policies and inform global efforts to mitigate the escalating impacts of plastic pollution on marine and coastal ecosystems.

Coastal wetlands, including seagrass meadows, emergent marshes, mangroves, and temperate tidal swamps, can efficiently sequester and store large quantities of sediment organic carbon (SOC). However, SOC stocks may vary by ecosystem type and along environmental or climate gradients at different scales. Quantifying such variability is needed to improve blue carbon accounting, conservation effectiveness, and restoration planning. We analyzed SOC stocks in 1,284 sediment cores along>6,500 km of the Pacific coast of North America that included large environmental gradients and multiple ecosystem types. Tidal wetlands with woody vegetation (mangroves and swamps) had the highest mean stocks to 1 m depth (357 and 355 Mg ha-1, respectively), 45% higher than marshes (245 Mg ha-1), and more than 500% higher than seagrass (68 Mg ha-1). Unvegetated tideflats, though not often considered a blue carbon ecosystem, had noteworthy stocks (148 Mg ha-1). Stocks increased with tidal elevation and with fine (<63 μm) sediment content in several ecosystems. Stocks also varied by dominant plant species within individual ecosystem types. At larger scales, marsh stocks were lowest in the Sonoran Desert region of Mexico, and swamp stocks differed among climate zones; otherwise stocks showed little correlation with ecoregion or latitude. More variability in SOC occurred among ecosystem types, and at smaller spatial scales (such as individual estuaries), than across regional climate gradients. These patterns can inform coastal conservation and restoration priorities across scales where preserving stored carbon and enhancing sequestration helps avert greenhouse gas emissions and maintains other vital ecosystem services.

The oxygen minimum zone (OMZ) in the Gulf of California entrance (GCE) is a crucial feature of the northeastern tropical Pacific, significantly influencing regional biogeochemical cycles and marine ecosystems. This study investigates the seasonal and interannual variability of the OMZ upper boundaries using a high-resolution physical-biogeochemical coupled model. The model results are evaluated against satellite observations, Argo profiles, and in situ data, demonstrating its capability to capture key dynamical processes, including mesoscale eddies, poleward undercurrents, and coastal-trapped waves (CTWs). The high-resolution CROCO-PISCES model reveals two alternating periods of shoaling and deepening of the OMZ upper boundary in the Gulf of California Entrance, modulated by seasonal mesoscale dynamics and coastal-trapped wave (CTW) propagation. This study provides novel insights into the interannual influence of El Nino Southern Oscillation (ENSO) events on OMZ dynamics, with El Nino driving significant deepening and contraction of the OMZ, and La Nina promoting shoaling and expansion. These variations are linked to changes in mesoscale dynamics, particularly the modulation of anticyclonic circulation at the Gulf's entrance by equatorially forced CTWs associated with ENSO. The study highlights the complex interplay between local and remote oceanographic processes in determining the OMZ variability in the GCE. This research provides insights into the mechanisms driving OMZ dynamics in the Gulf of California and underscores the need for integrated observational and modeling approaches to predict the response of OMZs to ongoing climate variability.

The temporal variations in abundances (cyst g(-1) and percentages) and fluxes (cyst cm(-2) yr(-1)) of dinoflagellate cysts, including Polysphaeridium zoharyi from the toxic species Pyrodinium bahamense, were analyzed in a Pb-210-dated sediment core from El Colorado Lagoon (Mexico) to investigate potential natural and/or human-driven factors, influencing the proliferation of P. bahamense, by examining the relationship between P. zoharyi abundance and geochemical indicators of sediment provenance and hydrodynamic conditions. P. zoharyi was the most abundant and frequently observed species along the core. The dominance of P. zoharyi was linked to the prevalence of terrigenous influence in most core sections, implying enhanced nutrient delivery. In recent years (similar to 1970s), the decrease in P. zoharyi percentages was associated with a local shift in hydrodynamic conditions, as revealed by an increase in sand content, changes in the delta C-13 and delta N-15 composition, and higher concentrations of marine indicator elements (Br, Ca, Na, and Sr). The change in hydrodynamic conditions suggests enhanced connectivity with the sea, likely triggered by a meteorological event. We highlight the importance of integrating multiple geochemical proxies with cyst analysis to assess changes in species assemblages and how local conditions, such as shifts in hydrodynamic conditions, that can influence species composition. This study contributes to paleoecology and phytoplankton ecology by documenting species responses to natural and anthropogenic disturbances. It confirms the recurrence and dominance of P. bahamense cysts, a toxin-producing species associated with harmful algal blooms. The findings underscore the need for continued monitoring, contingency planning, and water quality protection in coastal ecosystems.

The Guaymas Basin (GB) is a highly productive region in the Gulf of California. Subseafloor sedimentary amorphous bio-opal and Ba/Ti records obtained from its northwestern and central areas reveal significant changes in exported productivity over the past 31,200 years. Millennial-scale variability reflects the influence of wind-driven upwelling, mesoscale eddies, and shifts in climate variability operating at orbital, millennial, and centennial timescales. Spatial heterogeneity in productivity recorded in International Ocean Discovery Program boreholes highlights regional differences in process dominance. We identify seven distinct productivity phases: From ∼31,200 to ∼26,500 cal yr BP, laminated sediments indicate strong seasonal variability and high productivity due to intense upwelling activity caused by northwesterly winds linked to a southward-shifted Intertropical Convergence Zone. The Last Glacial Maximum, from ∼26,500 to ∼19,000 cal yr BP., displayed pronounced fluctuations and a slight decline in productivity compared to the previous interval, owing to the reduced influence of the North Pacific High on the GB during this period. From ∼19,000 to ∼11,700 cal yr BP, there were shifts of high and low productivity, with opal minima coinciding with Heinrich events 2 and 1, as well as the Younger Dryas. Productivity declined slightly between ∼11,700 and ∼7,000 cal yr BP, featuring a short high-productivity period within that timespan (∼10,500 to ∼10,300 cal yr BP). From ∼7,000 to ∼4,200 cal yr BP, productivity decreased in the NW and increased in the central basin. This contrast reflects enhanced winter-spring coastal wind-driven upwellings and reduced eddy activity in the west. From ∼4,200 to ∼130 cal yr BP, productivity increased in both studied areas. The sedimentary Ba/Ti values in both holes generally indicate lower levels during the cold glacial period and higher levels during the warm interglacial period, suggesting reduced biological barite accumulation and less organic matter export from the surface under cold climate conditions. These changes correspond to documented climate transitions, highlighting GB’s sensitivity to global forcings (e.g., ice sheet retreat) and regional ocean-atmosphere interactions. Our findings underscore the key role of dynamic physical processes in shaping long-term productivity patterns in marginal seas at high resolution.

Understanding the time scales of water transport in semi-closed ecosystems is essential for assessing the behavior of pollutants in coastal lagoon environments. Terminos Lagoon, Mexico's largest lagoon-estuarine system, is under significant environmental stress. We used a water age tracer combined with a high-resolution 3D hydrodynamic model to evaluate the lagoon's zones of accumulation and exchange. Our findings revealed a year-round counterclockwise circulation in the lagoon, which allows seawater to enter through Puerto Real and exit via Carmen Inlet. The inner littoral of Carmen Island features relatively young water currents, with an average age of 60 days. In contrast, the lagoon's center contains older water parcels, averaging 130 days. The southern and southeastern littoral regions hold older water areas, with the Candelaria Estuary showing the oldest waters, reaching up to 250 days. This emphasizes the Candelaria Estuary as a crucial area at risk of environmental impacts due to contaminant accumulation in the lagoon. As the primary inflow of seawater occurs through the Puerto Real inlet, it is vital to establish management strategies to minimize potential pollutant releases in the area.

High-mountain lakes (HMLs) are relevant indicators of global change due to their capacity to reflect environmental shifts. Temporal changes of concentrations, enrichment factors and fluxes of eleven trace elements (Ag, As, Cd, Co, Cr, Cu, Hg, Ni, Pb, V, and Zn) were assessed in 210Pb-dated sediment cores collected at El Sol and La Luna lakes, the only Mexican HMLs, in the crater of the Nevado de Toluca Volcano (NTV). This study examines the factors contributing to the recent (post-1900) rise in trace element inputs to the lakes, exploring whether this rise is related to soil erosion in NTV hillslopes due to nearby anthropogenic activities. Background (pre-1900) and recent concentrations of most trace elements, along with the magnitude and temporal variations of their fluxes, were similar between lakes. Also, the background values for most elements in the lacustrine sediments were similar to those found in soils surrounding the lakes. The enrichment factors indicated minimal contamination by most trace elements, excepting for the moderate enrichment by Pb in both lakes and by Hg in La Luna Lake. Based on a factor analysis, that evidenced the resemblance in the trace element composition between the soils and solely the oldest lake sediments (undated segment of the cores), this study demonstrates that soil erosion can explain the sediment chemistry for the oldest lake sediments, but not for the recent ones. Given the lakes' remote location, minimally influenced by human activities, Pb and Hg contamination was attributed to aeolian transport, mainly originating from surrounding urban areas (e.g., Toluca City). This research underscores the importance of environmental management to safeguard high-mountain ecosystems, especially in regions threatened by air pollution from nearby industrial cities, but also from rural areas where burning of coal for cooking and heating is still relevant.

Trace element concentrations (V, Cr, Ni, Cu, Zn) were analyzed in surface and core sediments from Playa La Marinera, a protected coastal zone in the Panama Pacific coast that serves as a nesting site for olive ridley sea turtles (Lepidochelys olivacea). Pb-210 dating revealed increased sediment accumulation from the 1950 s, coinciding with intensified rainfall and watershed land-use changes (deforestation and livestock expansion). Trace element concentrations peaked recently (2012-2018) and in the similar to 1950 s. Enrichment factors showed minor enrichment for V and no enrichment for Cr, Ni, Cu, and Zn, suggesting predominantly lithogenic sources. However, Cr and Ni concentrations exceeded the Probable Effect Level (PEL), indicating probable damage to the benthic community. Surface sediments showed spatial variability in trace element concentrations, with the highest levels of V, Cr, Ni, and Zn recorded at the station farthest from the river mouth and local community, possibly due to differential exposure to runoff or sediment resuspension dynamics. Compared to background values reported for other Pacific coastal sites in Panama, such as Coiba Island, most trace element concentrations were higher, except for V, reflecting site-specific environmental and geological conditions. The results establish a geochemical baseline for ongoing and future monitoring, underscoring the influence of both natural and anthropogenic factors on sediment quality in this region of high ecological value. These results establish a historical baseline of sediment contamination in Playa La Marinera, providing essential context for long-term monitoring. Beyond their local relevance, they underscore the need to protect tropical coastal reserves facing increasing land-use pressures and highlight potential implications for biodiversity conservation and risk management in nesting habitats of endangered sea turtles.