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At least 37 records · Page 2Linked to original sources
USGS2017

Sea turtles, light pollution, and citizen science: A preliminary report

Sea turtles are an important ecological resource for Gulf Islands National Seashore’s (Gulf Islands) waters and shorelines. Regionally, sea turtles face anthropogenic threats from situations such as entanglement in fishing gear and ingestion of marine debris, as well as possible changes in sex ratios due to increasing temperatures related to human-induced global warming. Locally, light pollution from residential, commercial, and industrial neighborhoods from nearby cities impacts the entirety of Gulf Islands, which spans 160 miles along the Gulf Coast, from Florida to Mississippi, and includes critical habitat for threatened and endangered sea turtles. Because light pollution has been hypothesized to negatively impact sea turtle nesting and hatchling survival, Gulf Islands undertook an effort to understand the relationship between light pollution and sea turtles and create unique educational and outreach opportunities by launching a citizen science program called Turtle Teens Helping in the Seashore (Turtle THIS). At the onset, the Turtle THIS program had two primary goals: quantify the association between light pollution and sea turtle nesting and hatching events using rigorous scientific methods; and initiate a citizen science volunteer program to provide youth with hands-on science and environmental stewardship roles, where they also gain employable skills and career opportunities. With multiple scientific hypotheses to consider, the development of a citizen science program became crucial. Such circumstances allowed Turtle THIS to grow a volunteer and intern program, quantify hypothesized light effects on sea turtles through developed methods, and begin to gather preliminary findings.

Florida↗
USGS2015

Nest-site characteristics of Glyptemys muhlenbergii (Bog Turtle) in New Jersey and Pennsylvania

Nest-site selection can affect both the survival and fitness of female turtles and their offspring. In many turtle species, the nest environment determines the thermal regime during incubation, length of incubation period, sex ratio of the hatchlings, and exposure to predators and other forms of mortality for both mothers and their offspring. Between 1974 and 2012, we collected detailed data on habitat variables at 66 Glyptemys muhlenbergii (Bog Turtle) nests in 9 different bogs, fens, and wetland complexes in New Jersey and Pennsylvania. The nests had a mean elevation above the substrate of 8.2 cm, and many were shallow and located in raised tussocks of grass or sedges. Females covered most nests, but we also observed partially or completely uncovered eggs. Some females deposited eggs in communal nests; we found 4 nests with 2 separate clutches, and 2 nests with 3 clutches. Principal component analysis confirmed the importance of cover and vegetation to nest-site selection in this species. Availability of open, shade-free, wet nesting areas is an important habitat requirement for Bog Turtles.

New Jersey, Pennsylvania↗
USGS2020

Brackish tidal marsh management and the ecology of a declining freshwater turtle

Water management practices in tidal marshes of the San Francisco Bay Estuary, California are often aimed at increasing suitable habitat for threatened fish species and sport fishes. However, little is known about how best to manage habitat for other sensitive status species like the semiaquatic freshwater Western Pond Turtle (Actinemys marmorata) that is declining throughout much of its range. Here, we examined the basking activity, abundance, survival, and growth of Western Pond Turtles at two brackish water study sites in Suisun Marsh, California that differed in how they were managed, with one having passive management (i.e., no active water regulation) and another having active management (i.e., water regulated for seasonal hunting). Our results revealed that basking activity was greatest when salinity, water stage, and air temperatures were low, shortwave radiation was high, and wind levels were intermediate. These preferred habitat characteristics often reflected conditions that were naturally maintained at the passively managed, muted tidal site. We also found that turtles were more abundant and had higher survival rates in the passively managed habitat compared to the actively managed habitat (201-323 turtles/km 2 and 96% survival versus 11-135 turtles/km 2 and 77% survival, respectively). Finally, characteristic growth constants from von Bertalanffy models showed that turtles grew more quickly in passively managed habitat compared to the actively managed habitat. Our results suggest that management strategies for this sensitive status species may be more effective if they protect passively managed muted tidal systems that limit or delay extreme cycles of salinity and water levels and conserve elevated terrestrial buffer zones adjacent to muted and full tidal systems.

California↗
USGS2018

Overwintering behavior of juvenile sea turtles at a temperate foraging ground

Most freshwater and terrestrial turtle species that inhabit temperate environments hibernate to survive extreme cold periods. However, for sea turtles, the question of whether these species use hibernation as an overwintering strategy has not been resolved (Ultsch 2006 ). Felger et al. ( 1976 ) suggested that sea turtles bury themselves in mud on the seafloor and remain dormant throughout the winter, presumably not surfacing during that time. Additional researchers have described sea turtles in temperatures <15°C as lethargic, mud‐covered and buried in bottom sediment (Carr et al. 1980 , Mendonça 1983 , Ogren and McVea 1995 ). However, more recent studies suggest that sea turtles may not be as dormant in cold temperatures as previously suggested (Hochscheid et al. 2007 ). Resolving this question is difficult due to the unpredictability of winter weather patterns and the cost of advanced tracking tools required to assess these fine‐scale behaviors. However, in January 2018, unusually calm and clear marine conditions coupled with exceptionally cold weather provided us the opportunity to observe and film turtle behavior at a foraging ground in the northern Gulf of Mexico. These images, combined with previously gathered data from vessel‐based surveys and water temperature loggers, have enabled us to piece together one of the most comprehensive views of sea turtle overwintering behavior to date.

Ecology↗
USGS2024

Aspects of the demography of a relict population of southwestern pond turtles (Actinemys pallida) in a West Mojave Desert stream in California

We studied Actinemys pallida (Southwestern Pond Turtle) in Amargosa Creek, near Palmdale, CA, from 1997 to 2023. The population in the upper creek was the focus of a mark–recapture study from 1997 to 2003 during monitoring required by a road-construction project. An estimated 193 (95% CI = 142–256) turtles were present in 1997 or recruited to the upper creek population between 1997 and 2003. Total abundance and recruitment declined after 2001, coincident with the onset of a multi-decadal megadrought. Turtles in upper Amargosa Creek are presumed to be extirpated because the creek dried up in the ensuing years. As part of a separate research project, we resurveyed the lower creek at Piute Ponds on Edwards Air Force Base from 2019 to 2023. As of 2023, there was a remnant breeding population of at least 22 turtles there. We did not find any marked turtles from the upper creek in the ponds. Only 2 populations of Southwestern Pond Turtles are known to survive in the Mojave Desert, one at Piute Ponds and another in the Mojave River.

California↗
USGS2019

Satellite tracking of hawksbill turtles nesting at Buck Island Reef National Monument, US Virgin Islands: Inter-nesting and foraging period movements and migrations

To conserve imperiled marine species, an understanding of high-density use zones is necessary prior to designing and evaluating management strategies that improve their survival. We satellite-tracked turtles captured after nesting at Buck Island ReefNational Monument (BIRNM), St. Croix, US Virgin Islands to determine habitat-use patterns of endangered adult female hawksbills ( Eretmochelys imbricata ). For 31 turtles captured between 2011 and 2014, switching state-space modeling and home range analyses showed that inter-nesting (IN) core-use areas (i.e., 50% kernel density estimates [KDEs]) were 9.6 to 77.7 km 2 in area, occupied for 21 to 85 days, and in shallow water(21 of 26 centroids > −10 m). The IN zones overlapped with areas both within the protected borders of BIRNM, and outside BIRNM (32% of turtle-tracking days outside during IN). Turtles migrated to their foraging grounds between July and October with path lengths ranging from 52 to 3524 km; foraging areas included 14 countries. Core-use foraging areas (50% KDEs) where turtles took up residence were 6.3 to 95.4 km 2 , occupied for 22 to 490 days, with mean centroid depth − 66 m. Our results show previously unknown habitat-use patterns and highlight concentrated areas of use both within and adjacent to a US protected area during the breeding season. Further, our results clearly demonstrate the need for international conservation to protect hawksbills, as migrating turtles crossed between two and eight different jurisdictions. Our results provide critical spatial and temporal information for managers charged with designing strategies to minimize human impact to and maximize survival for this globally imperiled species.

Virgin Islands↗
USGS2019

Captive-rearing duration may be more important than environmental enrichment for enhancing turtle head-starting success

Raising captive animals past critical mortality stages for eventual release (head-starting) is a common conservation tactic. Counterintuitively, post-release survival can be low. Post-release behavior affecting survival could be influenced by captive-rearing duration and housing conditions. Practitioners have adopted environmental enrichment to promote natural behaviors during head-starting such as raising animals in naturalistic enclosures. Enrichment might be especially beneficial for animals held in captivity long-term to prevent degradation of adaptive behaviors. Using 32 captive-born turtles ( Terrapene carolina ), half of which were raised in enriched enclosures, we employed a factorial design to explore how enrichment and rearing duration affected post-release growth, behavior, and survival. Six turtles in each treatment (enriched or unenriched) were head-started for nine months (cohort one). Ten turtles in each treatment were head-started for 21 months (cohort two). At the conclusion of captive-rearing, turtles in cohort two were overall larger than cohort one, but unenriched turtles were generally larger than enriched turtles within each cohort. Once released, enriched turtles grew faster than unenriched turtles in cohort two, but we otherwise found minimal evidence suggesting enrichment affected post-release survival or behavior. Cohort two dispersed farther and had generally higher active season survival than cohort one (0.50 vs. 0.33). Body mass was positively associated with daily survival probability. Our findings suggest attaining larger body sizes from longer captive-rearing periods to enable greater movement and alleviate susceptibility to predation (the primary cause of death) could be more effective than environmental enrichment alone in chelonian head-starting programs where substantial predation could hinder success.

Global Ecology and Conservation↗
USGS2005

Management and protection protocols for nesting sea turtles on Cape Hatteras National Seashore, North Carolina

Executive Summary 1. The southeast U.S. population of the loggerhead turtle (Caretta caretta) has increased since the species was listed as federally threatened in 1978. Since standardized monitoring began in North Carolina in 1995, the number of nests at Cape Hatteras National Seashore (CAHA) fluctuated from year to year, and was lowest in 1996 and 1997 (39 nests) and highest in 2003 (101 nests). Green turtles (Chelonia mydas) and leatherback turtles (Dermochelys coriacea) have nested in small numbers at CAHA, sporadically over time. 2. Hatching success of sea turtle nests typically approaches 80%. At CAHA hatching success from 1999-2003 was low when hurricanes hit during the nesting season (30%-38%), and ranged from 52%-70% otherwise. Hatching success at CAHA is usually correlated with hatching success in the surrounding subpopulation (north Florida to North Carolina). 3. Inclement weather, predation, and human recreation can negatively impact nesting rate and hatching success. 4. Currently there is little protection from recreation at CAHA for nesting females and nests that have not been found by monitors. We propose three management options to provide such protection, and to increase protection for known nests and hatchlings. We propose an adaptive management framework for assessing the effectiveness of these management options in improving sea turtle nesting rate and nest and hatchling survival. 5. We recommend continued efforts to trap and remove mammalian predators from all sea turtle habitat. We further recommend intensive monitoring and surveillance of protected areas to determine the extent and timing of threats to nests and broods, including nest overwash, predation, and disturbance or vandalism by humans. 6. Continue to relocate nests and assist stranded turtles according to North Carolina Wildlife Resources Commission guidelines. 7. Artificial light sources pose a serious threat to sea turtles in some parts of CAHA, which must be remedied immediately. We recommend that CAHA enact turtle-friendly lighting regulations and work with the communities within its borders to reduce light pollution and to eliminate artificial light sources that are directly visible from sea turtle nesting areas. 8. We recommend increased education and outreach to CAHA visitors, including requiring participation in an educational program before being granted nighttime beach access. The long-term success of sea turtle recovery will depend on public cooperation and positive public attitudes toward sea turtles and turtle management actions.

Book↗
USGS2013

An evaluation of liquid ammonia (ammonium hydroxide) as a candidate piscicide

Eradication of populations of nonnative aquatic species for the purpose of reintroducing native fish is often difficult because very few effective tools are available for removing aquatic organisms. This creates the need to evaluate new chemicals that could be used as management tools for native fish conservation. Ammonia is a natural product of fish metabolism and is naturally present in the environment at low levels, yet is known to be toxic to most aquatic species. Our objective was to determine the feasibility of using liquid ammonia as a fisheries management tool by evaluating its effectiveness at killing undesirable aquatic species and its persistence in a pond environment. A suite of invasive aquatic species commonly found in the southwestern USA were introduced into two experimental outdoor ponds located at the Rocky Mountain Research Station in Flagstaff, Arizona. Each pond was treated with ammonium hydroxide (29%) at 38 ppm. This target concentration was chosen because previous studies using anhydrous ammonia reported incomplete fish kills in ponds at concentrations less than 30 ppm. Water quality was monitored for 49 d to determine how quickly the natural bacteria in the environment converted the ammonia to nitrate. Ammonia levels remained above 8 ppm for 24 and 18 d, respectively, in ponds 1 and 2. Nitrite levels in each pond began to rise approximately 14 d after dosing with ammonia and stayed above 5 ppm for an additional 21 d in pond 1 and 18 d in pond 2. After 49 d all water in both ponds was drained and no fish, crayfish, or tadpoles were found to have survived the treatment, but aquatic turtles remained alive and appeared unaffected. Liquid ammonia appears to be an effective tool for removing many problematic invasive aquatic species and may warrant further investigation as a piscicide.

North American Journal of Fisheries Management↗
USGS2011

Demographic and genetic status of an isolated population of bog turtles (Glyptemys muhlenbergii): Implications for managing small populations of long-lived animals

In this study, we sought to determine the population stability and genetic diversity of one isolated population of the federally-threatened bog turtle ( Glyptemys muhlenbergii ) in North Carolina. Using capture–recapture data, we estimated adult survival and population growth rate from 1992 to 2007. We found that the population decreased from an estimated 36 adult turtles in 1994 to approximately 11 adult turtles in 2007. We found a constant adult survival of 0.893 (SE = 0.018, 95% confidence interval, 0.853–0.924) between 1992 and 2007. Using 18 microsatellite markers, we compared the genetic status of this population with five other bog turtle populations. The target population displayed allelic richness (4.8 ± 0.5) and observed heterozygosity (0.619 ± 0.064) within the range of the other bog turtle populations. Coalescent analysis of population growth rate, effective population size, and timing of population structuring event also indicated the genetics of the target population were comparable to the other populations studied. Estimates of effective population size were a proportion of the census size in all populations except the target population, in which the effective population size was larger than the census size (30 turtles vs. 11 turtles). We attribute the high genetic diversity in the target population to the presence of multiple generations of old turtles. This study illustrates that the demographic status of populations of long-lived species may not be reflected genetically if a decline occurred recently. Consequently, the genetic integrity of populations of long-lived animals experiencing rapid demographic bottlenecks may be preserved through conservation efforts effective in addressing demographic problems.

Conservation Genetics↗
USGS2009

Environmental forcing on life history strategies: Evidence for multi-trophic level responses at ocean basin scales

Variation in life history traits of organisms is thought to reflect adaptations to environmental forcing occurring from bottom-up and top-down processes. Such variation occurs not only among, but also within species, indicating demographic plasticity in response to environmental conditions. From a broad literature review, we present evidence for ocean basin- and large marine ecosystem-scale variation in intra-specific life history traits, with similar responses occurring among trophic levels from relatively short-lived secondary producers to very long-lived apex predators. Between North Atlantic and North Pacific Ocean basins, for example, species in the Eastern Pacific exhibited either later maturation, lower fecundity, and/or greater annual survival than conspecifics in the Western Atlantic. Parallel variations in life histories among trophic levels also occur in adjacent seas and between eastern vs. western ocean boundaries. For example, zooplankton and seabird species in cooler Barents Sea waters exhibit lower fecundity or greater annual survival than conspecifics in the Northeast Atlantic. Sea turtles exhibit a larger size and a greater reproductive output in the Western Pacific vs. Eastern Pacific. These examples provide evidence for food-web-wide modifications in life history strategies in response to environmental forcing. We hypothesize that such dichotomies result from frequency and amplitude shifts in resource availability over varying temporal and spatial scales. We review data that supports three primary mechanisms by which environmental forcing affects life history strategies: (1) food-web structure; (2) climate variability affecting the quantity and seasonality of primary productivity; (3) bottom-up vs. top-down forcing. These proposed mechanisms provide a framework for comparisons of ecosystem function among oceanic regions (or regimes) and are essential in modeling ecosystem response to climate change, as well as for creating dynamic ecosystem-based marine conservation strategies.

Progress in Oceanography↗
USGS2005

Demographics of an ornate box turtle population experiencing minimal human-induced disturbances

Human-induced disturbances may threaten the viability of many turtle populations, including populations of North American box turtles. Evaluation of the potential impacts of these disturbances can be aided by long-term studies of populations subject to minimal human activity. In such a population of ornate box turtles (Terrapene ornata ornata) in western Nebraska, we examined survival rates and population growth rates from 1981–2000 based on mark–recapture data. The average annual apparent survival rate of adult males was 0.883 ( se = 0.021) and of adult females was 0.932 ( se = 0.014). Minimum winter temperature was the best of five climate variables as a predictor of adult survival. Survival rates were highest in years with low minimum winter temperatures, suggesting that global warming may result in declining survival. We estimated an average adult population growth rate ( λ^ ) of 1.006 ( se = 0.065), with an estimated temporal process variance ( σ^ 2 ) of 0.029 (95% ci = 0.005–0.176). Stochastic simulations suggest that this mean and temporal process variance would result in a 58% probability of a population decrease over a 20-year period. This research provides evidence that, unless unknown density-dependent mechanisms are operating in the adult age class, significant human disturbances, such as commercial harvest or turtle mortality on roads, represent a potential risk to box turtle populations.

Nebraska↗
USGS2023

Thirteen years of turtle capture–mark–recapture in a small urban pond complex in Louisiana, USA

Turtles are one of the most imperiled vertebrate groups in the world. With habitat destruction unabated in many places, urban and suburban greenspaces may serve as refugia for turtles, at least those species able to tolerate heavily altered landscapes. In south-central Louisiana, we have conducted a turtle capture–mark–recapture effort in two ponds in an urban greenspace for 13 yr to understand species composition, survival, and individual growth rates. We had 574 total captures of 251 individuals of five species from 2009–2021, with Trachemys scripta elegans (Red-Eared Sliders) and Sternotherus odoratus (Eastern Musk Turtles) being the most common. Apparent annual survival for T. scripta (0.79) was similar to estimates reported in other studies in altered habitats, whereas apparent annual survival for S. odoratus (0.89) was slightly or much higher than other published studies. Growth rates of T. scripta were comparable to other studies and showed both sexes have similar rates of growth until maturity, which is earlier and at a smaller size in males. The two ponds showed marked differences in captures by size, with significantly more juvenile T. scripta captured in the pond with more vegetation, depth, and a softer bottom. Most T. scripta (78.5%) that were recaptured came from the same pond from which they were originally captured. The basic demographic data gained in this study can serve as a starting point for broader questions on urbanization effects and as a comparison to more natural populations.

Louisiana↗
USGS1998

Three closely related herpesviruses are associated with fibropapillomatosis in marine turtles

Green turtle fibropapillomatosis is a neoplastic disease of increasingly significant threat to the survivability of this species. Degenerate PCR primers that target highly conserved regions of genes encoding herpesvirus DNA polymerases were used to amplify a DNA sequence from fibropapillomas and fibromas from Hawaiian and Florida green turtles. All of the tumors tested (n= 23) were found to harbor viral DNA, whereas no viral DNA was detected in skin biopsies from tumor-negative turtles. The tissue distribution of the green turtle herpesvirus appears to be generally limited to tumors where viral DNA was found to accumulate at approximately two to five copies per cell and is occasionally detected, only by PCR, in some tissues normally associated with tumor development. In addition, herpesviral DNA was detected in fibropapillomas from two loggerhead and four olive ridley turtles. Nucleotide sequencing of a 483-bp fragment of the turtle herpesvirus DNA polymerase gene determined that the Florida green turtle and loggerhead turtle sequences are identical and differ from the Hawaiian green turtle sequence by five nucleotide changes, which results in two amino acid substitutions. The olive ridley sequence differs from the Florida and Hawaiian green turtle sequences by 15 and 16 nucleotide changes, respectively, resulting in four amino acid substitutions, three of which are unique to the olive ridley sequence. Our data suggest that these closely related turtle herpesviruses are intimately involved in the genesis of fibropapillomatosis.

Florida, Hawai'i↗
USGS1995

Turtles

Turtles have existed virtually unchanged for the last 200 million years. Unfortunately, some of the same traits that allowed them to survive the ages often predispose them to endangerment. Delayed maturity and low and variable annual reproductive success make turtles unusually susceptible to increased mortality through exploitation and habitat modifications (Brooks et al. 1991; Congdon et al. 1993). In general, turtles are overlooked by wildlife managers in spite of their ecological significance and importance to humans. Turtles are, however, important as scavengers, herbivores, and carnivores, and often contribute significant biomass to ecosystems. In addition, they are an important link in ecosystems, providing dispersal mechanisms for plants, contributing to environmental diversity, and fostering symbiotic associations with a diverse array of organisms. Adults and eggs of many turtles have been used as a food resource by humans for centuries (Brooks et al. 1988; Lovich 1994). As use pressures and habitat destruction increase, management that considers the life-history traits of turtles will be needed.

Book chapter↗
USGS2021

Movements of marine and estuarine turtles during Hurricane Michael

Natural disturbances are an important driver of population dynamics. Because it is difficult to observe wildlife during these events, our understanding of the strategies that species use to survive these disturbances is limited. On October 10, 2018, Hurricane Michael made landfall on Florida’s northwest coast. Using satellite and acoustic telemetry, we documented movements of 6 individual turtles: one loggerhead sea turtle, one Kemp’s ridley sea turtle, three green sea turtles and one diamondback terrapin, in a coastal bay located less than 30 km from hurricane landfall. Post-storm survival was confirmed for all but the Kemp’s ridley; the final condition of that individual remains unknown. No obvious movements were observed for the remaining turtles however the loggerhead used a larger home range in the week after the storm. This study highlights the resiliency of turtles in response to extreme weather conditions. However, long-term impacts to these species from habitat changes post-hurricane are unknown.

Florida↗
USGS2004

Using open robust design models to estimate temporary emigration from capture-recapture data

Capture-recapture studies are crucial in many circumstances for estimating demographic parameters for wildlife and fish populations. Pollock's robust design, involving multiple sampling occasions per period of interest, provides several advantages over classical approaches. This includes the ability to estimate the probability of being present and available for detection, which in some situations is equivalent to breeding probability. We present a model for estimating availability for detection that relaxes two assumptions required in previous approaches. The first is that the sampled population is closed to additions and deletions across samples within a period of interest. The second is that each member of the population has the same probability of being available for detection in a given period. We apply our model to estimate survival and breeding probability in a study of hawksbill sea turtles ( Eretmochelys imbricata ), where previous approaches are not appropriate.

Biometrics↗
USGS2026

Vulnerability of key sea turtle nesting beaches to future erosion and sea level rise

Threatened sea turtles rely on sandy beaches for nesting, linking their long-term survival to global beach availability. However, beaches worldwide are increasingly threatened by anthropogenic stressors and sea level rise (SLR). Reliable vulnerability assessments require understanding beach dynamics across multiple time scales, informed by long-term coastal change records. While many nesting beaches lie in remote, data-poor environments, recent advances in coastal remote sensing now allow us to monitor coastal change worldwide. Here, we combine satellite-derived shorelines (CoastSat), shoreline modeling (CoSMoS-COAST), and global data sets to investigate shoreline evolution and future vulnerability at nine globally important sea turtle nesting sites. We investigate seasonal and long-term shoreline change, hindcast (1980–2024) and forecast (2025–2100) shoreline positions under various SLR scenarios, and quantify available accommodation space based on backbeach elevation and infrastructure footprints. We find that shoreline evolution and vulnerability vary considerably, with three sites showing historical accretion trends and four sites showing erosion. This demonstrates that the previously widely applied bathtub approach—adding SLR to a static beach profile—is not suitable to assess the vulnerability of sea turtle nesting beaches to erosion. Three eroding beaches emerge as particularly vulnerable due to projected shoreline retreat coupled with limited accommodation space. Despite significant uncertainties arising from long-term shoreline projections, our results provide important insights into seasonal and long-term morphodynamics, identify vulnerable nesting sites, and offer a comprehensive, transferable framework for assessing shoreline evolution and relative erosion vulnerability at other sites. Understanding these dynamics is crucial to inform conservation and management strategies to future-proof these critical nesting habitats.

Earth's Future↗