Modelling the fate of marine turtle hatchlings

The SLIM oceanographic model was used to examine the fate of hatchling flatback turtles (Natator depressus) in the first two weeks of their dispersal starting at Wild Duck Island, a major turtle-nesting site in the central Great Barrier Reef region of Australia. We ran simulations to investigate the effects of spring versus neap tides, hatchling's swimming behaviour during their first three days at sea, and the location of nesting beaches. The model predicted that up to 50% of the turtle hatchlings entering the sea from the windward, southern beach remained after 14 days in shallow, nearshore waters, irrespective of tides and swimming. These waters are turbid and may be inhospitable to hatchlings. In contrast >80% of hatchlings dispersing from the leeward, northern beach were dispersed to deeper water (10-40 m) in a quasi-stationary dispersion core centred around 10 km north of the nesting beach after 14 days and the offshore spread of the turtle plume was enhanced by the hatchling's seaward swimming during the first three days. This was due to the presence of a coastal boundary layer and a stagnation zone around the northern side of island, but not the southern side. The model confirmed that dispersal from eastern Queensland flatback turtle rookeries is restricted to the lagoons and coastal waters, and that water circulation and hatchling's swimming control dispersion. The model explains why more turtles nest on the northern than the southern side. This study highlights the usefulness of oceanographic models to increase knowledge about a cryptic life stage of marine turtles.     

Discrimination of predatory versus nonpredatory mammals by box turtles, <Emphasis Type="Italic">Terrapene carolina</Emphasis>

Summary. Although terrestrial turtles have served as a model for studies of olfactory neurophysiology, little is known about how they use chemical information in an ecological sense. We tested whether box turtles (Terrapene carolina) use chemical information to distinguish between predatory and nonpredatory mammals. Box turtles in our study exhibited more escape behavior when exposed to urine from a predator (coyote, Canis latrans) than when exposed to urine from a nonpredator (white-tailed deer, Odocoileus virginianus) or a blank control. Escape behavior is consistent with an antipredator response. In addition, the turtles decreased their handling time for food when in the presence of urine from either species of mammal in comparison to the blank, indicating that chemical cues from mammals in general may result in increased vigilance by terrestrial turtles. Examination of a variety of response variables may be important for adequate assessment of the ecological role of chemosensory behavior.     

用12SrRNA基因序列研究潮龟科（BATAGURIDAE）闭壳龟类的进化

测定了潮龟科（Ｂａｔａｇｕｒｉｄａｅ）具闭壳结构的齿缘摄龟属（Ｃｙｃｌｅｍｙｓ）、锯缘摄龟属（Ｐｙｘｉｄｅａ）、闭壳龟属（Ｃｕｏｒａ）共６种线粒体１２ＳｒＲＮＡ基因片段的序列,结合潮龟科其它一些属的序列数据,探讨了具闭壳结构龟类的起源与进化以及闭壳龟属的分类学问题．认为闭壳龟属与锯缘摄龟属为姐妹群,两者与齿缘摄龟属的亲缘关系较远,提示这些具闭壳结构的龟类可能不是由一个共同祖先分化而来．本文的结果不支持将闭壳龟属拆分为闭壳龟属和盒龟属两属     

Effects of Illegal Harvest of Eggs on the Population Decline of Leatherback Turtles in Las Baulas Marine National Park,Costa Rica

Abstract: Within 19 years the nesting population of leatherback turtles (Dermochelys coriacea) at Parque Nacional Marino Las Baulas declined from 1500 turtles nesting per year to about 100. We analyzed the effects of fishery bycatch and illegal harvesting (poaching) of eggs on this population. We modeled the population response to different levels of egg harvest (90, 75, 50, and 25%) and the effect of eradicating poaching at different times during the population decline. We compared effects of 90% poaching with those of 20% adult mortality because both of these processes were present in the population at Las Baulas. There was a stepwise decline in number of nesting turtles at all levels of egg harvest. Extirpation times for different levels of poaching ranged from 45 to 282 years. The nesting population declined more slowly and survived longer with 20% adult mortality (146 years) than it did with 90% poaching (45 years). Time that elapsed until poaching stopped determined the average population size at which the population stabilized, ranging from 90 to 420 nesting turtles. Our model predicted that saving clutches lost naturally would restore the population when adult mortality rates were low and would contribute more to population recovery when there were short remigration intervals between nesting seasons and a large proportion of natural loss of clutches. Because the model indicated that poaching was the most important cause of the leatherback decline at Las Baulas, protecting nests on the beach and protecting the beach from development are critical for survival of this population. Nevertheless, the model predicted that current high mortality rates of adults will prevent population recovery. Therefore, protection of the beach habitat and nests must be continued and fishery bycatch must be reduced to save this population.     

Do Open-Cycle Hatcheries Relying on Tourism Conserve Sea Turtles? Sri Lankan Developments and Economic–Ecological Considerations

By combining economic analysis of markets with ecological parameters, this article considers the role that tourism-based sea turtle hatcheries (of an open-cycle type) can play in conserving populations of sea turtles. Background is provided on the nature and development of such hatcheries in Sri Lanka. The modeling facilitates the assessment of the impacts of turtle hatcheries on the conservation of sea turtles and enables the economic and ecological consequences of tourism, based on such hatcheries, to be better appreciated. The results demonstrate that sea turtle hatcheries serving tourists can make a positive contribution to sea turtle conservation, but that their conservation effectiveness depends on the way they are managed. Possible negative effects are also identified. Economic market models are combined with turtle population survival relationships to predict the conservation impact of turtle hatcheries and their consequence for the total economic value obtained from sea turtle populations.     

Levels of organochlorine pesticides in Amazon turtle (Podocnemis unifilis) in the Xingu River,Brazil

Abstract

Due to the toxicity and high environmental persistence of organochlorine pesticides in aquatic organisms, turtles have been studied as environment biomonitors. These animals are important sources of protein for the riverside and indigenous peoples of the Brazilian amazon. In the present study, organochlorine pesticide contamination was investigated in Podocnemis unifilis. Liver, muscle and fatty tissue samples were removed from 50 specimens collected from five sampling points located in the Xingu River basin. Fourteen organochlorine pesticides were analysed via gas chromatography with an electron capture detector (CG-ECD). Eight organochlorine pesticides were detected with average concentrations of ∑DDT, ∑Endossulfan and ∑HCH which were 26.17?±?26.35, 14.38?±?23.77 and 1.39?±?8.46?ng g^?1 in moisture content, respectively. DDT compounds were the most predominant, with a greater concentration of pp′-DDT in the liver and pp′-DDD in the muscle. Significant differences were noted between the types of tissues studied, and the concentration of OCPs varied between sampling sites.     

Nest-Site Selection in Individual Loggerhead Turtles and Consequences for Doomed-Egg Relocation

Abstract:  Relocation of eggs is a common strategy for conservation of declining reptilian populations around the world. If individuals exhibit consistency in their nest-site selection and if nest-site selection is a heritable trait, relocating eggs deposited in vulnerable locations may impose artificial selection that would maintain traits favoring unsuccessful nest-site selection. Conversely, if most individuals scatter their nesting effort and individuals that consistently select unsuccessful nest sites are uncommon, then artificial selection would be less of a concern. During the 2005 nesting season of loggerhead turtles ( Caretta caretta ) at Mon Repos beach, Queensland, Australia, we measured the perpendicular distance from the original nest site to a stationary dune baseline for in situ (unrelocated) and relocated clutches of eggs. We observed the fate of in situ clutches and predicted what would have been the fate of relocated clutches if they had not been moved by mapping tidal inundation and storm erosion lines. In 2005 turtles deposited an average of 3.84 nests and did not consistently select nest sites at particular distances from the stationary dune baseline. Selection of unsuccessful nest sites was distributed across the nesting population; 80.3% of the turtles selected at least one unsuccessful nest site and when previous breeding seasons were included, 97% selected at least one unsuccessful nest site. Females with nesting experience selected more successful nest sites than females with little or no experience. Relocating eggs vulnerable to tidal inundation and erosion saves the progeny from a large percentage of the population and the progeny from individuals who may in subsequent years nest successfully. Our results suggest that doomed-egg relocation does not substantially distort the gene pool in the eastern Australian loggerhead stock and should not be abandoned as a strategy for the conservation of marine turtle populations.     

Reproductive ecology of the pond turtle (Emys orbicularis L.) in the Northeastern part of the species range

In Belarussian Polesye, characteristics of reproduction, population dynamics, and factors responsible for a decrease in the abundance of the pond turtle were studied. The main factors limiting pond turtle reproduction in Polesye include the focal distribution of its populations and limited areas of reproductive biotopes. The pond-turtle popuation itself is characterized by a high potential for reproductive growth; in the current situation, the population growth is mainly limited by a high pressure of oophagous predators and anthropogenic destruction of reproductive sites.     

Predicting the Impact of Sea-Level Rise on Caribbean Sea Turtle Nesting Habitat

Abstract:  The projected rise in sea level is likely to increase the vulnerability of coastal zones in the Caribbean, which are already under pressure from a combination of anthropogenic activities and natural processes. One of the major effects will be a loss of beach habitat, which provides nesting sites for endangered sea turtles. To assess the potential impacts of sea-level rise on sea turtle nesting habitat, we used beach profile measurements of turtle nesting beaches on Bonaire, Netherlands Antilles, to develop elevation models of individual beaches in a geographic information system. These models were then used to quantify areas of beach vulnerable to three different scenarios of a rise in sea level. Physical characteristics of the beaches were also recorded and related to beach vulnerability, flooding, and nesting frequency. Beaches varied in physical characteristics and therefore in their vulnerability to flooding. Up to 32% of the total current beach area could be lost with a 0.5-m rise in sea level, with lower, narrower beaches being the most vulnerable. Vulnerability varied with land use adjacent to the beach. These predictions about loss of nesting habitat have important implications for turtle populations in the region.     

Cost‐Effectiveness of Alternative Conservation Strategies with Application to the Pacific Leatherback Turtle

Although holistic conservation addressing all sources of mortality for endangered species or stocks is the preferred conservation strategy, limited budgets require a criterion to prioritize conservation investments. We compared the cost‐effectiveness of nesting site and at‐sea conservation strategies for Pacific leatherback turtles (Dermochelys coriacea). We sought to determine which conservation strategy or mix of strategies would produce the largest increase in population growth rate per dollar. Alternative strategies included protection of nesters and their eggs at nesting beaches in Indonesia, gear changes, effort restrictions, and caps on turtle takes in the Hawaiian (U.S.A.) longline swordfish fishery, and temporal and area closures in the California (U.S.A.) drift gill net fishery. We used a population model with a biological metric to measure the effects of conservation alternatives. We normalized all effects by cost to prioritize those strategies with the greatest biological effect relative to its economic cost. We used Monte Carlo simulation to address uncertainty in the main variables and to calculate probability distributions for cost‐effectiveness measures. Nesting beach protection was the most cost‐effective means of achieving increases in leatherback populations. This result creates the possibility of noncompensatory bycatch mitigation, where high‐bycatch fisheries invest in protecting nesting beaches. An example of this practice is U.S. processors of longline tuna and California drift gill net fishers that tax themselves to finance low‐cost nesting site protection. Under certain conditions, fisheries interventions, such as technologies that reduce leatherback bycatch without substantially decreasing target species catch, can be cost‐effective. Reducing bycatch in coastal areas where bycatch is high, particularly adjacent to nesting beaches, may be cost‐effective, particularly, if fisheries in the area are small and of little commercial value. Rentabilidad de Estrategias de Conservación Alternativas Aplicadas a Tortugas Laúd del Pacífico