Matthew W Ware

The distribution of individual body sizes within a population can have substantial impacts on recovery estimates for endangered species. Recent studies have observed a reduction in the size of nesting sea turtles with potential implications for fecundity. To investigate the size of reproductive individuals and subsequent impacts on hatchling production for loggerhead turtles in northwest Florida, we evaluated a seven-year dataset from St. George Island, Florida, USA-the dominant nesting site in this region. Morphometric measurements and GPS locations were collected during nighttime surveys, whereas nest disturbances and hatchling production were reported from morning surveys. Mean minimum curved carapace length (CCL ) was 94.3 cm ± 5.7 cm SD (range: 80.2-109.1 cm). Out of 232 individuals, 9.1% fell below the 87 cm CCL threshold currently adopted by U.S. agencies as the minimum size at maturity. For each 1 cm increase in CCL , an increase by 1 egg was observed in clutch size, and wash-out rates increased by 0.52%. Though the largest turtles laid the largest clutches, these nests also had a greater probability of wave wash-out, potentially moderating overall hatchling production from these individuals. These results highlight size-mediated factors related to fecundity-important elements for demographic modeling and management decisions.

The Guajira Peninsula is one of the most important foraging grounds areas for marine turtles in Venezuela. There, five species converging: the green turtle, hawksbill, loggerhead, leatherback, and olive ridley. The Wayuú indigenous people are inhabits of the Guajira Peninsula. They have a close relationship with these animals, and for generations, they have used these species as subsistence resources. Marine turtle take has always occurred in this area and has historically been high; it is still happening now, but the current extent is unknown. For that reason, we aim to assess and update the estimate for marine turtles take in the Guajira Peninsula. We conducted 25 field surveys between February and March 2022 by visiting 15 locations to seek for alive turtles and remains on landing sites. We recorded the species, date, location of each encounter, and curve carapace length (CCL) measurements. Additionally, 15 semi-structured interviews were conducted with members of the Wayuú community. During field surveys, an estimated 81 marine turtles were identified. The most affected species were green turtles (91.3%, n = 74), followed by hawksbills (3.7%, n = 3), loggerheads (3.7%, n = 3), and leatherbacks (1.2%, n = 1). The majority of green turtles were subadults, with an average CCL size of 64.7 ± 16.5 cm (82.2%, n = 52). Interviewees mentioned that marine turtles were caught for cultural practices, consumption, ancient medicine, and commerce. Further monitoring activities are needed to understand the take level and its implications for marine turtle populations in the Caribbean Basin. 

Warming temperatures due to climate change are feminizing sea turtle primary sex ratios, reducing hatchling fitness, and, in extreme cases, limiting hatchling production, including for temperate nesting species such as loggerhead turtles (Caretta caretta). Though more females may lead to short‐term population growth through increased egg production, long‐term gains may be threatened by the scarcity of males for mating and reduced survival rates of early life stages. Beaches near the limits of sea turtle nesting ranges are typically cooler and thus critical for species conservation efforts as they contribute a higher percentage of males to regional breeding grounds both now and in the future. A feminizing trend up to 88% was previously estimated for loggerhead hatchlings through 2015 on Bald Head Island, North Carolina, USA, near the northern extent of the northwest Atlantic loggerhead nesting range. However, despite a continued increasing trend in air temperature, average incubation durations and modeled primary sex ratios over the past 5 years (67% female) are more similar to those from the mid‐2000s. Environmental conditions during incubation, behavioral changes in nest site selection and timing, and physiological variables including clutch size and maternal identity were investigated using a generalized additive model to explain this recent reversal. Increased rainfall, alongshore local movement of nest placement toward cooler conditions, and a minor shift in nesting phenology earlier in the year combined to counteract the 1.1°C increase in average air temperature experienced by incubating nests now versus 20 years ago. Behavioral adaptations may thus mitigate some of the projected impacts from climate change but are insufficient on their own as rainfall had a larger effect size than behavior. Without significant behavioral changes or management interventions, sustained future male hatchling production at many nesting beaches will likely depend on increased rainfall—an uncertain projection for many such beaches.

Marine turtles are vital to marine ecosystems, serving as indicators of ocean health and contributing to the ecological balance of marine habitats (Aguirre and Lutz, 2004). However, the Anthropocene has introduced a multitude of human-induced stressors on natural systems, necessitating innovative solutions to mitigate these impacts (Davenport, 2024; Syvitski et al., 2020). Significant aspects of marine turtle biology remain poorly understood (Hamann et al., 2010; Rees et al., 2016; Wildermann et al., 2018), especially in regions of the Global-South (Robinson et al., 2022; 2023; Shanker et al., 2023).

This Research Topic presents a collection of seven studies that advance our understanding of marine turtles in need of conservation action, with research spanning Saudi Arabia, Mexico, Dominica, Uruguay, Brazil, Martinique, and Ecuador. This editorial summarizes four original research manuscripts, one review, one mini review, and one brief research report; all highlighting the complex threats that marine turtles face and underscoring the need for multidisciplinary approaches to develop effective conservation strategies.

Sea turtles are an iconic group of marine megafauna that have been exposed to multiple anthropogenic threats across their different life stages, especially in the past decades. This has resulted in population declines, and consequently many sea turtle populations are now classified as threatened or endangered globally. Although some populations of sea turtles worldwide are showing early signs of recovery, many still face fundamental threats. This is problematic since sea turtles have important ecological roles. To encourage informed conservation planning and direct future research, we surveyed experts to identify the key contemporary threats (climate change, direct take, fisheries, pollution, disease, predation, and coastal and marine development) faced by sea turtles. Using the survey results and current literature, we also outline knowledge gaps in our understanding of the impact of these threats and how targeted future research, often involving emerging technologies, could close those gaps.

Introduction Microplastics (i.e., plastic debris smaller than 5mm) found in coastal areas can impact the marine habitat used by endangered species since they may alter sand properties including temperature and permeability. Such alterations may pose a significant threat to marine turtle populations as nest productivity, sexual development, and hatchling fitness are dependent on conditions within the nest, which incubate in the sand. Given that there is a record of microplastic presence at marine turtle nesting sites, this study was conducted to explore the potential influence of microplastics on the thermal profile of sediment typical of marine turtle nesting habitat. MethodsThe experiment was conducted at the Florida State University Coastal and Marine Laboratory where the temperatures of containers of sand mixed with 5-30% v/v of either black or white microplastics were recorded from July to September 2018. ResultsThe addition of microplastics in the sand resulted in an increase in temperature - 0.017 degrees C for each 1% v/v increase in microplastic. However, the color of the microplastic did not have a significant effect on sand temperature. Overall, the container with 30% v/v black particles had the highest mean temperature increase of 0.58 degrees C (+/- 0.34 degrees C) over the control. DiscussionThe results obtained from this study indicate that extreme concentrations of microplastics could be an issue for marine turtles as any changes in sand temperature may affect the sex ratio of hatchlings and/or alter nest productivity.

Sandy areas between rocky uplands, or natural pocket beaches, provide important habitat for coastal wildlife. On developed coasts, similar sandy areas, called urban pocket beaches, occur in the gaps between properties with coastal armoring (sea walls or revetments). These urban pocket beaches provide important nesting, foraging, and resting habitat for wildlife, particularly on extensively armored beaches. However, it is unclear if urban pocket beaches provide the same function as natural pocket beaches or offer benefits (e.g., reduced risk of inundation or erosion) lost at nearby armored areas. To address these knowledge gaps, we analyzed loggerhead marine turtle nesting patterns and reproductive success to determine if urban pocket beaches represent preferred nesting habitat along armored coastlines. We also determined if nests at urban pocket beaches are more likely than nearby armored and unarmored beaches to be inundated from wave runup, which could alter the incubation environment and nest productivity of marine turtles. The linear extent of urban pocket beaches in Florida was identified, then loggerhead marine turtle nesting success, nest density, and hatching success was compared between urban pocket beaches with armoring and beaches without armoring. We also modeled differences in wave runup exposure at these beaches under current conditions (2016–2019) without and with tropical storms and future (2060) intermediate-low and high sea level rise scenarios. Overall, pocket beaches account for less than 2% of Florida’s nesting beaches with higher abundance on more heavily armored shorelines. Nesting density in pocket beaches were similar to nearby beaches without armoring. However, female turtles were more likely to nest in urban pocket beaches compared to adjacent armored areas, and pocket beach nests had a higher hatchling success rate than unarmored and armored beaches. Our models suggest that exposure to wave runup varies by geographic location, but overall pocket beaches provided viable nesting habitat in all areas surveyed. Thus, managers should advocate for preserving urban pocket beaches on armored shorelines.
•We determined the importance of urban pocket beaches as marine turtle nesting habitat.•Urban pocket beaches comprise a small percentage (2%) of nesting beaches in Florida.•Nesting success was higher on urban pocket beaches as compared to armored beaches.•In NW Florida pocket beaches were less exposed to inundation than armored beaches.•Managers should advocate for preserving pocket beaches on armored shorelines.

Population size estimates are key parameters used in assessments to evaluate and determine a species' conservation status. Typically, sea turtle population estimates are made from nesting beach surveys which capture only hatchling and adult female life stages and can display trends opposite of the full population. As such, in-water studies are critical to improve our understanding of sea turtle population dynamics as they can target a broader range of life stages - though they are more logistically and financially challenging to execute compared to beach-based surveys. Stereo-video camera systems (SVCS) hold promise for improving in-water assessments by removing the need to physically capture individuals and instead extract 3D measurements from video footage, thereby simplifying monitoring logistics and improving safety for the animals and surveyors. To demonstrate this potential, snorkel surveys were conducted at artificial habitats in the northeastern Gulf of Mexico (neGOM) to collect size and photo-identification data on sea turtles in situ using a SVCS. Over 29.86 survey hours, 35 sea turtles were observed across three species (Caretta caretta, Chelonia mydas, and Lepidochelys kempii) and all neritic life stages (juvenile, sub-adult, and adult) utilizing different habitats, including artificial reefs, jetties, and fishing piers. Greens straight carapace length ranged from 28.55 to 66.96 cm (n = 23, mean 43.07 cm +/- 11.26 cm standard deviation; SD) and loggerheads ranged from 59.71 to 91.77 cm (n = 10, mean 74.50 cm +/- 11.35 cm SD), and Kemp's ridleys ranged from 42.23 cm to 44.98 cm (mean 43.61 cm +/- 1.94 cm SD). Using a linear mixed model, we found that species and habitat type were the most important predictors of sea turtle body length distribution. Overall, this case study demonstrates the potential of SVCS surveys to enhance our understanding of the population structure of sea turtle species within the neGOM and elsewhere.

Management of imperiled species facing spatiotemporally dynamic threats is difficult. Systems thinking can inform their management by quantifying the impacts that they face. We apply systems thinking to the Northern Gulf of Mexico (NGM) loggerhead (Caretta caretta) Recovery Unit (RU), one of the smallest subpopulations of loggerheads nesting in the USA. We characterized disturbances to nests, management actions, and hatchling production across 12 nesting beaches used by this RU to explore how hatchling production would increase if disturbances were mitigated. Annual hatchling production at sites ranged from 470 to 18,191 hatchlings/year. Washovers (19.3% nests/year), washouts (17.9% nests/year), and predation (13% nests/year) were the most common annual disturbances across sites. Focusing on the most impactful disturbances at just five sites could increase annual NGM RU hatchling production by 2.2–6.7%. Efforts to mitigate washovers and washouts are ongoing in Alabama, but these may be futile against tropical cyclones, which accounted for >80% of washouts in the present study, and further require careful examination of associated adverse side-effects. Efforts to mitigate predation are common throughout this RU, but require improved knowledge of predator ecology to reach full potential. Systems thinking allowed us to create a simple model for assessing disturbances and management strategies in terms of hatchling sea turtles. This model can be augmented to run dynamic simulations of how disturbances and management actions impact hatchling production, and can be applied to other species with similar reproductive strategies.
•Sea turtle nesting beaches are managed to maximize hatchling production.•Systems thinking can help quantify how disturbances impact hatchling production.•Managers can take actions to mitigate most impactful disturbances.•Nesting beaches in the Northern Gulf of Mexico require tailored management.•Management tailored to individual beaches can contribute to regional management.

Wave wash-over poses a significant threat to sea turtle nests, with sustained exposure to waves potentially resulting in embryonic mortality and altered hatchling locomotor function, size, and sex ratios. Identifying where and under what conditions wave exposure becomes a problem, and deciding what action(s) to take (if any), is a common issue for sea turtle managers. To determine the exposure of sea turtle nests to waves and identify potential impacts to hatchling productivity, we integrated a geographic information system with remote sensing and wave runup modeling across 40 nesting beaches used by the Northern Gulf of Mexico Loggerhead Recovery Unit. Our models indicate that, on average, approximately 50% of the available beach area and 34% of nesting locations per nesting beach face a significant risk of wave exposure, particularly during tropical storms. Field data from beaches in the Florida Panhandle show that 42.3% of all nest locations reported wave exposure, which resulted in a 45% and 46% decline in hatching and emergence success, respectively, relative to their undisturbed counterparts. Historical nesting frequency at each beach and modeled exposure to waves were considered to identify priority locations with high nesting density which either experience low risk of wave exposure, as these are good candidates for protection as refugia for sustained hatchling production, or which have high wave exposure where efforts to reduce impacts are most warranted. Nine beaches in the eastern Florida Panhandle were identified as priority sites for future efforts such as habitat protection or research and development of management strategies. This modeling exercise offers a flexible approach for a threat assessment integration into research and management questions relevant to sea turtle conservation, as well as for other beach species and human uses of the coastal environment.