Observations on loggerhead sea turtle Caretta caretta activity during three nesting seasons (1977–1979) in Zakynthos,Greece

Data collected during the 1977, 1978 and 1979 seasons showed that a remarkable sea turtle population of unknown size and origin utilizes Zakynthos' small southern beaches as nesting areas. Preliminary surveys indicate that nesting activity on Sekania, Dafni and Gherakas beaches averaged 18·1 emergences and 10·77 nestings per night, most of which were concentrated on Sekania beach. Observed adults and young were identified as Caretta caretta with a mean carapace length of 80·4 cm for females and 40·4 mm for hatchlings. The importance of this newly discovered rookery is emphasized and the need to maintain present population levels through realistic conservation measures is discussed.     

A review of sea turtle nesting activity along the Mediterranean coast of Turkey

Many parts of the Turkish coastline are important nesting grounds for sea turtles. The aim of this study was to assess the present state of sea turtle populations along the coastline of Turkey, by evaluating research conducted at various nesting grounds from 1979 to 2000. The results of the evaluation indicate that the Turkish coastline is the most important nesting area for Chelonia mydas, and the third most important nesting area for Caretta caretta after Greece and Libya (if nesting estimates for Libya are correct) in the entire Mediterranean. The most important C. caretta nesting beaches in Turkey are Dalyan (11.9%), Kumluca (11.3%), Belek (27.9%), Kizilot, (8.9%) and Anamur (8.8%), while those for C. mydas are Kazanli (24.1%) and Akyatan (54.4%). These sites are classified as “Nesting Areas of 1st Degree Importance”. Annual mean nest numbers along the coastline of Turkey are estimated to be ca. 2000 for C. caretta and 650 for C. mydas. Assuming that each adult female sea turtle nests three times per season, the annual numbers of nesting females along the beaches of Turkey range between about 500 and 800 for C. caretta and 130 and 300 for C. mydas. Annual nesting densities along the 204 km beach strip, which includes 17 important nesting grounds in Turkey, were 11.3 nests/km for C. caretta and 19.2 nests/km for C. mydas.     

Conservation and the scarecrow effect: Can human activity benefit threatened species by displacing predators?

Most wild animals show direct negative responses to human disturbance; however, disturbance may also have positive indirect effects by altering species interactions. In the Caribbean, introduced mongooses (Herpestes javanicus) are an important diurnal predator of the nests of critically endangered hawksbill sea turtles (Eretmochelys imbricata). We asked whether daytime visitor activity could benefit hawksbills by reducing mongoose activity in nesting habitat. We used track monitoring sites to measure how mongooses alter their space use in response to fluctuating human beach use and availability of hawksbill nests, and we estimated the indirect impact of human disturbance on nest predation for 5 years of hawksbill nesting. Human activity substantially decreased mongoose use of nesting habitat. Mongoose activity increased with abundance of nests and was lower at the edge than the interior of patches of beach vegetation, but neither factor altered relative sensitivity to disturbance. We estimated that, in addition to deterring mongooses from accessing nests on the open beach, human activity has the potential to reduce predation of nests in vegetation by up to 56% at our site, with the greatest per capita impact at low (<50) visitor numbers. Many forms of human activity negatively affect sea turtles, but our study indicates that there are positive aspects of daytime use of nesting beaches. Optimizing the trade-off between positive and negative impacts of disturbance could provide a useful approach for regulating tourist activity in critical habitat for threatened species.     

Nesting ecology, current status, and conservation of sea turtles on an uninhabited beach in Florida, USA

Although nesting beaches are critical resources for sea turtles, most beaches in the United States are disturbed by human influence, including human access, artificial lighting, and habitat alteration. In contrast, very few undisturbed beaches remain along the Atlantic coast, and these areas represent unique habitats that can help decipher the impacts of development on various species. We monitored nesting patterns and hatching success of three sea turtle species (Caretta caretta, Chelonia mydas, and Dermochelys coriacea) from 1985 to 2003 on Canaveral National Seashore, an uninhabited 38.3 km stretch of beach in Florida. We monitored the number of nests deposited annually, hatching success, predation rates, and spatial nesting patterns. Clutch sizes varied within, but not among years, most likely due to variation in size of nesting females rather than climate change or resource availability. The number of nests increased over the study period for all three species, indicating growing populations. Higher numbers of nests were deposited on the southern end of our beach than on the northern end. Hatching success did not vary by species, but was dependent on nest-protection effort, which increased during the study period. Protecting more nests with wire screens resulted in lower predation rates. We did not find any evidence suggesting that predators are using nest markers to locate eggs, even after using the same method of marking nests for 19 years. Our conservation efforts have lowered predation levels through increased screening effort, and over time the number of nests laid increased for each species. Collecting baseline data on nesting patterns in undisturbed locations will allow comparisons to be made on nesting trends and patterns at geographically close, but disturbed, localities.     

Influence of artificial lights, logs and erosion on leatherback sea turtle hatchling orientation at Pongara National Park, Gabon

The coast of Gabon is one of the most important nesting sites for the endangered leatherback sea turtle Dermochelys coriacea. In this study, hatchling orientation was recorded during natural emergences at Pongara National Park, Gabon. This nesting beach is located close to both the capital of Gabon and a developing resort area, Pointe Denis. Under natural conditions most sea turtle hatchlings emerge at night and orient to the ocean by crawling away from dark, high silhouettes landward towards the bright, low seaward horizons. Artificial lights interfere with natural cues and disrupt hatchling orientation. The relative influence of artificial lights, logs and erosion were assessed on the nesting beach in Pongara National Park using a linear mixed model. We found that the attraction to artificial lights was higher than the effect of silhouette cues landward alone, but could be balanced by the simultaneous presence of the moon. Based upon these results, we recommend combining light management in the resort area to reduce the light pollution on the nesting beach and reinforcement of natural cues landward to minimize the effect of the remaining light pollution from the capital.     

Sea turtles nesting at Melbourne Beach,Florida, I. Size,growth and reproductive biology

From 1972 to 1978, 2910 loggerheads Caretta caretta and 18 green turtles Chelonia mydas were tagged as they came ashore to nest on Melbourne Beach, the area with the greatest density of sea turtle nesting in Florida. The nesting loggerheads averaged 92·0 cm in straight-line carapace length and grew at a mean rate of 0·57 cm per year. The most common remigration intervals observed for loggerheads were two and three years. In 46 cases, turtles tagged on Melbourne Beach moved to other beaches in later nesting seasons, and 82 Melbourne Beach turtles shifted to other beaches during the same season. Interseasonal nesting movements spanned 700 km of coastline; intraseasonal movements ranged over 290 km. The 18 green turtles nested from early June to late August. The mean straight-line carapace length was 110 cm. A two-year remigration interval predominated. No green turtle tagged on Melbourne Beach has been seen on other beaches.     

Increase of a Caribbean leatherback turtle Dermochelys coriacea nesting population linked to long-term nest protection

The leatherback turtle Dermochelys coriacea is considered to be at serious risk of global extinction, despite ongoing conservation efforts. Intensive long-term monitoring of a leatherback nesting population on Sandy Point (St. Croix, US Virgin Islands) offers a unique opportunity to quantify basic population parameters and evaluate effectiveness of nesting beach conservation practices. We report a significant increase in the number of females nesting annually from ca. 18-30 in the 1980s to 186 in 2001, with a corresponding increase in annual hatchling production from ca. 2000 to over 49,000. We then analyzed resighting data from 1991 to 2001 with an open robust-design capture-mark-recapture model to estimate annual nester survival and adult abundance for this population. The expected annual survival probability was estimated at ca. 0.893 (95% CI: 0.87-0.92) and the population was estimated to be increasing ca. 13% pa since the early 1990s. Taken together with DNA fingerprinting that identify mother-daughter relations, our findings suggest that the increase in the size of the nesting population since 1991 was probably due to an aggressive program of beach protection and egg relocation initiated more than 20 years ago. Beach protection and egg relocation provide a simple and effective conservation strategy for this Northern Caribbean nesting population as long as adult survival at sea remains relatively high.     

Studies on the ecology of actinomycetes in soil— VII. Actinomycetes in a coastal sand belt

Distribution of actinomyeetes in beach and dune sand at two sites was studied. At one site. dunes were eroding while at the other accretion of sand and dune development occurred. Actinomycetes occurred in low numbers in beach sand hul increased sharply when dunes were colonized by Ammophila arenaria (L) Link or Agropyron junceiforme (A & D Löve) A & D Löve. Micromonospora strains predominated in beach sand but Streptomyces was the predominant genus in dunes.Salinity tolerance of isolates was not clearly related to their source but tolerance of dune isolates was generally greater than those from the beach. Tolerance of Streptomyces strains varied but all Micromonospora isolates were intolerant of salinities above that of sea water.Evidence for increased growth of actinomycetes in the root region of A. arenaria and A. junceiforme was obtained but there was little qualitative difference between those in the root region and root-free sand. In laboratory experiments actinomycetes colonized old. dead Ammophila roots more readily than young ones and arose carly in succession on the former. Young, living roots stimulated bacteria and fungi but not actinomyeetcs. It was concluded that most activity of actinomycetes in the Ammophila root region occurred on old root tissue and it was suggested that this might be true of other plants.     

Spatiotemporal patterns of annual sea turtle nesting behaviors along an East Central Florida beach

The Florida coastline from Melbourne Beach to Wabasso Beach is one the most important nesting areas for loggerhead turtles (Caretta caretta) in the Western Hemisphere and for green turtles (Chelonia mydas) in the United States. In this study, we quantified the spatial patterns of numerous loggerhead (N≈400,000) and green turtle (N≈14,000) and less numerous (N≈100) leatherback (Dermochelys coriacea) beach ascents from 1989-1999 in terms of their autocorrelative properties along 40.5 km within this critical reproductive zone. Nesting and non-nesting emergence patterns of loggerhead and green turtles were non-random, favoring the southern half of the study area. Perhaps due to low numbers or differences in nesting behavior, leatherback nest distributions were not significantly different from random. Loggerhead and green turtle nest locations exhibited similar clinal patterns. They were positively autocorrelated at distances less than 10 km and negatively at distances greater than 30 km. These patterns were significantly correlated interannually.     

Ecology and nest-site selection of leatherback turtles Dermochelys coriacea

Leatherback turtles Dermochelys coriacea often nest in places where their eggs are destroyed by high tides. Poor nest-site selection ranges from <2·5% in Malaysia to around 40% in the Guianas and appears to be related to beach topography. In the Guianas sparse tree lines and lagoons on the landward side of the nesting areas make sea-finding by the hatchlings more difficult if nests are dug too far away from the sea. It is suggested that, faced with the predicament of not nesting too near the water and not testing too far back from it, leatherbacks have adopted a scatter nesting strategy that ensures that at least some of their nests will be appropriately sited. Relocating poorly sited nests poses certain problems for conservation programmes.     

Heavy Metal Monitoring Around the Nesting Environment of Green Sea Turtles in Turkey

The concentrations of Cd, Pb, Fe, Cr, Ni, Se, Sb, As and Cu were investigated in the nesting environment of green turtles in Mediterranean Sea near Kazanl?, Mersin-Turkey. Tissues of plants growing on the beach and the adjacent environment, beach sand, sea ground sediment, sea grass as well as the egg shells from the nests were analyzed and the results showed no significant high levels of heavy metals detected. The higher levels of metals (Cr, Cu, Pb, Cd and As) were found in the samples from ground sea sediments. Ni and Sb were found at higher levels in river waters and Fe was at the highest in field soil. The high levels of Pb, Fe and Cd were also detected in sea grass, and the Cr, Cu and Ni in sea lily when comparison made with other plants. The levels of essential elements such as Fe and Cu were detected as the highest in most of the specimens. The herbivorous green turtles might be affected from the heavy metal concentrations in the future, since they feed on mainly sea grass. The accumulation of heavy metals via rivers into the sea might cause some pollution problems.     

Intensive beach management as an improved sea turtle conservation strategy in Mexico

We evaluate the role of intensive beach management, meaning intense patrolling and nest reburial to a central hatchery, as a strategy for improving the success of sea turtle conservation at nesting sites in Mexico. We report the results of an experimental program at Playa Cuixmala, Jalisco, western Mexico. Sea turtle conservation efforts in Mexico have, in general, poor results because of lack of funds, which leads to insufficient beach protection and severe negative effects of nest removal on hatching success and sex ratios. Alternative strategies are needed to optimize limited resources. We predicted that intensive beach management, which included intense patrolling and careful nest reburial, could be an effective way to maximize nest survival and hatchling release under limited financial and human resources. The results of our 9-year study were very positive. Survival rate increased several fold during the study period. Hatching success and sex ratios were not significantly different between in-situ and removed nests. Survival in removed nests was, however, much higher that in-situ nests, because of predation and beach erosion. In total, the small (3 km length) Playa Cuixmala became the second most productive sea turtle nesting beach in the region because of these concentrated efforts. Intense beach management can be an important technique for sea turtle conservation, and can be properly applied to small beaches or the most productive sections of large beaches.     

Shoreline stabilization approaches in response to sea level rise: U.S. experience and implications for Pacific Island and Asian nations

Coastal erosion is a worldwide problem; it is estimated that over 70% of the world's beaches are currently experiencing erosion (Bird, 1985), and this number may approach 90% in the United States. Almost every conceivable form of shore protection has been attempted in the United States, including construction of seawalls, groins, and jetties as well as beach nourishment. The principal approach to protecting coastal property and maintaining recreational beaches in the United States today is beach nourishment. Engineering structures such as groins and seawalls have often been shown to have detrimental effects on adjacent beaches. Also, their construction and maintenance costs are quite high. Therefore, coastal communities have come to rely on a “soft” engineering solution — beach nourishment —because it is environmentally sound, aesthetically pleasing, and, so far, economically feasible. However, global warming and accelerated sea level rise will cause more rapid rates of beach loss and could make even this alternative too costly for many resort areas along the U.S. shoreline. The cost to nourish all the major recreational oceanic beaches in the United States was estimated based on various sea level rise scenarios. The beach nourishment approach involves placing enough sand on the beach to maintain stable (nonretreating) conditions in response to rising sea level. The quantity of sand required to “hold the line” is evaluated under various sea level rise scenarios from the baseline scenario to the 1-m estimate of the Intergovernmental Panel on Climate Change. Beach nourishment is not a practical alternative for most Pacific island nations because sand is a scarce resource. In fact, beaches are often mined for sand for construction, contributing to beach erosion. For mainland countries, beach fill projects are more practical. Singapore was one of the first countries to use this technology in combination with building offshore breakwaters to form artificial headlands. As Western style sunbathing and the overall popularity of beaches for recreation continue to grow, beach nourishment can be expected to become a more common way to deal with sea level rise induced coastal erosion for highly developed beach resort areas.     

Lighting the way: Towards reducing misorientation of olive ridley hatchlings due to artificial lighting at Rushikulya, India

Sea-finding behavior in sea turtle hatchlings is modified by the visual cues provided by artificial beach front lighting. The consequent landward movement of hatchlings in response to coastal electric lighting reduces their survival rates. We assessed the potential impact of coastal lighting at Rushikulya, an important mass nesting site of the olive ridley sea turtle (Lepidochelys olivacea) in the Indian Ocean region. We examined the response of hatchlings to light characteristics in an experimental setup, as well as to the existing lighting regimes along the beach, using arena trials. Previous studies on other species indicate preferential orientation towards low wavelength and high intensity light. Our study confirms these preferences among hatchlings from the Indian Ocean population of olive ridleys. In addition we also found that wavelength and intensity could have an interactive effect upon hatchling orientation. Hatchlings at the study site respond both to visible point sources of light and to sheer glows of light. Though beach plantations of introduced Casuarina equisetifolia are generally considered to have negative impacts on sea turtle nesting beaches, we found that they acted as an effective light barrier when planted about 50 m away from the high tide line. We developed a model of the expected impact of artificial lighting on hatchling orientation during mass hatching events of previous years, and predict as much as 50% misorientation in some years. We also developed a map representing the misorientation of hatchlings due to artificial lighting based on arena trials in different regions of the beach. The results of the study helped identify focal areas for light management on the beach, which could be critical for the survival of this population.     

Estimates of sea turtle mortality from poaching and bycatch in Bahía Magdalena, Baja California Sur, Mexico

Bahia Magdalena on the Pacific coast of Baja California Sur, Mexico, is an important feeding and nursery ground for black turtles Chelonia mydas, loggerhead turtles Caretta caretta, olive ridley turtles Lepidochelys olivacea, and hawksbill turtles Eretmochelys imbricata. Despite international and national protection, sea turtles continue to be caught incidentally and hunted for consumption in large numbers. This study examines the mortality of sea turtles in Bahia Magdalena, focusing on (1) species distribution and number of carcasses found, (2) causes of death, (3) size frequency distribution and % juveniles in the catch, and (4) changes in average size over the past years. A total of 1945 turtle carcasses were found from April 2000 to July 2003 along beaches and in towns of the region with loggerhead (44.1%) and black turtles (36.9%) being the dominant species. Slaughter for human consumption was the primary cause of death of carcasses found in towns (95-100%), while carcasses on beaches mostly died of unknown causes (76-100%). Circumstantial evidence suggests however, that incidental bycatch was the main mortality cause on beaches. Black turtles suffered the highest consumption mortality overall (91%), followed by olive ridley (84%), hawksbill (83%) and loggerhead turtles (63%). Over 90% of all turtles found were juveniles or subadults. Carapace length of black turtles declined consistently over the sampling period, while that of loggerhead turtles increased. Our results strongly suggest that turtles are being taken at high and unsustainable rates; this may partially explain why the populations have not recovered despite widespread protection on nesting beaches.     

Methods for the conservation of maleo birds, Macrocephalon maleo on the island of Sulawesi,Indonesia

The maleo Macrocephalon maleo is a large megapode endemic to Sulawesi which buries eggs in communal nesting areas of warm sand. The species is endangered as a result of uncontrolled harvesting of eggs by villagers. The present paper examines the problem and suggests methods for control involving the use of artificial hatcheries. In a hatchery experiment a 78% hatching success rate was achieved. Details of the breeding biology and hatching experiments are presented. Other methods of control suggested are the poisoning of natural predators such as pigs and monitor lizards and the improvement of natural nesting sites by partially clearing undergrowth vegetation, particularly the exotic weed Lantana camara.     

An analysis of the role of local fishermen in the conservation of the loggerhead turtle (Caretta caretta) in Pontal do Ipiranga, Linhares, ES, Brazil

The role of researchers and fishermen in the clutch management of loggerhead sea turtles was evaluated for 10 nesting seasons at Pontal do Ipiranga TAMAR station, Linhares, ES. The comparison of nests transferred by researchers and locals (carebeiros) showed that clutches transferred by researchers presented higher clutch size. Clutch size between nests transferred by carebeiros and left in situ did not show significant differences. Hatching success was significantly higher for clutches left in situ than for those transferred to other places in the beach or to hatcheries. The clutches transferred exclusively by researchers achieved a higher hatching success than those transferred partially or totally by carebeiros. The relocation time of clutches collected by carebeiros and handed to researchers affected hatching success. It is recommended that clutches be left in situ, provided they have adequate conditions for monitoring, but careful clutch translocation, independent of the interval elapsed after laying, may also constitute a viable technique for the conservation of sea turtles in the region.     

Sex ratio bias in hatchling sea turtles from artificially incubated eggs

Artificial incubation of eggs of green sea turtles, Chelonia mydas, above ground in styrofoam boxes results in a 23% drop in the number of hatchlings with ovaries, compared with samples from clutches left on the beach in natural conditions. This masculinization is consistent with the well-known effects of temperature on sexual differentiation in chelonians and with measurements showing that the styrofoam boxes were 1–1·5°C cooler than the sand on the beach at the depth of turtle nests. These findings verify previous suspicions about the use of styrofoam boxes in management programmes for sea turtles, and have implications for the conservation and husbandry of reptiles in general.     

Statistical power and sea turtle nesting beach surveys: How long and when?

Identifying long-term population trends is essential for the conservation of species of concern. With money and personnel often in short supply, the success of a monitoring program to provide an estimate of population trend requires an efficient survey design that can detect biologically important changes within some prescribed budgetary framework. In this paper we illustrate how costs can be reduced while maintaining an efficient design using a nesting beach survey of female hawksbill sea turtles (Eretmochelys imbricata) in the Eastern Caribbean as a specific example. We compared the statistical power of the current, intensive protocol with those of shorter duration and differing start date to generate general guidelines on sampling. Counts of individual turtles from 1987-2003 were analyzed using Poisson log-linear regression and models with both fixed and random effects describing the temporal variability were explored. We estimate that the current 20 week saturation-tagging survey design could detect a 3% per annum growth with acceptable statistical power (>0.8) in less than 14 years. However, by changing the current survey start date and counting for only 10 weeks, it is possible to detect similar trends with little loss of power while reducing monitoring costs by 25-50%. Our analyses indicate that the statistical power of surveys for hawksbills is influenced by the timing and duration of the survey because of their effect on the proportion of the annual number of nesting females that the survey captures. This simplifies estimating the power of a prospective survey program.     

Long-term conservation efforts contribute to positive green turtle Chelonia mydas nesting trend at Tortuguero, Costa Rica

Worldwide, green turtle Chelonia mydas populations have declined and the species is classified as globally endangered. Tortuguero, Costa Rica, hosts the largest remaining green turtle rookery in the Atlantic basin. Tortuguero green turtles have been hunted since pre-Columbian times. Monitoring and conservation of the green turtle population began in 1955. The long-term efforts provide an excellent opportunity to evaluate the success of sea turtle conservation action and policies. Nest counts conducted 1971-2003 were analyzed to: (1) determine the nesting trend, (2) estimate rookery size and (3) identify events and policy decisions influencing the trend. A nonparametric regression model indicates a 417% increase in nesting over the study period. Rookery size was defined as the mean number of nests 1999-2003 and estimated at 104,411 nests year⁻¹, corresponding to 17,402-37,290 nesting females year⁻¹. A comparison with 34 index populations verifies Tortuguero as one of the two largest green turtle rookeries worldwide. Events and policy decisions in Costa Rica, Nicaragua, and Panama that comprise the main nesting, feeding and mating grounds for the Tortuguero population are likely to have had the greatest influence on green turtle survivorship. Conservation efforts and policies catalyzing increased hatchling production and decreased adult and juvenile mortality since 1963 have contributed to the positive nesting trend. The trend demonstrates that long-term conservation efforts can reverse nesting declines and offers hope that adequate management can result in recuperation of endangered sea turtle species.