Michael L. Guinea

Blood chemistry reference values for two ecologically distinct populations of foraging green turtles, eastern Indian Ocean

Blood chemistry reference values are important to allow the monitoring of the health of individuals and populations. Blood chemistry reference values were obtained from individuals of two ecologically distinct foraging populations of green turtles (Chelonia mydas) in the eastern Indian Ocean. Samples were taken from 51 resident green turtles from Ashmore Reef (a shelf-edge platform reef) with a predominant seagrass diet, and 59 samples were taken from green turtles from Fog Bay, an inshore coastal embayment in the Northern Territory of Australia with a predominant algal diet. Reference values were different between habitats and showed the importance of regional and habitat-specific reference values for green turtles if they are to be used as a diagnostic tool. Green turtles with a diet of seagrass showed higher levels of total protein than turtles of the same size with algal diets. Clinically sick turtles from Fog Bay had significantly higher levels of urea and AST and lower PCV values than healthy turtles from the same population. Newly recruited turtles from Fog Bay also had higher levels of urea and AST compared to other turtles from the same area. Low levels of internal parasites did not affect blood reference values in clinically healthy turtles.

Recent rapid speciation and ecomorph divergence in Indo‐Australian sea snakes

The viviparous sea snakes (Hydrophiinae) are a young radiation of at least 62 species that display spectacular morphological diversity and high levels of local sympatry. To shed light on the mechanisms underlying sea snake diversification, we investigated recent speciation and eco‐morphological differentiation in a clade of four nominal species with overlapping ranges in Southeast Asia and Australia. Analyses of morphology and stomach contents identified the presence of two distinct ecomorphs: a ‘macrocephalic’ ecomorph that reaches >2 m in length, has a large head and feeds on crevice‐dwelling eels and gobies; and a ‘microcephalic’ ecomorph that rarely exceeds 1 m in length, has a small head and narrow fore‐body and hunts snake eels in burrows. Mitochondrial sequences show a lack of reciprocal monophyly between ecomorphs and among putative species. However, individual assignment based on newly developed microsatellites separated co‐distributed specimens into four significantly differentiated clusters corresponding to morphological species designations, indicating limited recent gene flow and progress towards speciation. A coalescent species tree (based on mitochondrial and nuclear sequences) and isolation‐migration model (mitochondrial and microsatellite markers) suggest between one and three transitions between ecomorphs within the last approximately 1.2 million to approximately 840 000 years. In particular, the macrocephalic ‘eastern’ population of Hydrophis cyanocinctus and microcephalic H. melanocephalus appear to have diverged very recently and rapidly, resulting in major phenotypic differences and restriction of gene flow in sympatry. These results highlight the viviparous sea snakes as a promising system for speciation studies in the marine environment.

Asynchronous Emergence of Flatback Seaturtles, Natator depressus, from a Beach Hatchery in Northern Australia

Abstract The timing and synchrony of sea turtle emergences from the nests are primary factors in determining hatchling vigor and likelihood of survival. A clear benefit of synchronous emergence is a reduction in energy expenditure through social facilitation, but disadvantages also result from reduction in energy stores if hatchlings have to wait any appreciable time in the nest. We investigated hatchling emergence times throughout emergence of the entire clutch for 21 clutches of Flatback Seaturtles, Natator depressus, incubating in a beach hatchery at three clutch sizes and three nest depths. Emergence of the entire clutch spanned an average of 3.1 days, with shallower nests exhibiting greater emergence asynchrony (mean20cm  =  4.0 days, mean35cm  =  4.5 days) than deeper nests (mean50cm  =  1.7 days). Hatchlings emerged through the night, peaking between 2100 and 2200 h, with hatchlings from shallower nests emerging earlier in the night. For natural nests, hatchlings generally emerged within a single night, evident from the low number of hatchlings remaining in the nest the day after emergence. The disparate observations between a beach hatchery, and natural nests provide important conservation implications for hatchery management.

Effects of sand erosion and current harvest practices on incubation of the flatback sea turtle (Natator depressus)

A suitable gaseous, hydrous and thermal nest environment is essential for the development of sea turtle embryos. The harvest of partial clutches by indigenous people and changes in nest depth from wind erosion or predation have prompted questions about the impact of clutch size and nest depth on nest success and hatchling output. We investigated the impact of reduced clutch sizes and nest depths on flatback sea turtle (Natator depressus) eggs, using a hatchery on a natural beach and clutch sizes of 10, 30 and 50 eggs, deposited at depths of 25, 35 and 50 cm. Hatchlings were collected on emergence and their size, mass, scalation and locomotor performance were measured. Neither clutch size nor nest depth had a significant effect on hatching success, emergence success or escape success in this study. Smaller clutches had longer incubation durations due to the lower temperatures within the nest, presumably from the lower metabolic heat produced. Hatchlings from deeper nests emerged later in the night than did those from shallower nests. Within the context of this study, changes to clutch size and nest depth appear to have no detrimental effect on the fate of the remaining eggs and the condition and performance of hatchlings.

Molecules and Morphology Reveal Overlooked Populations of Two Presumed Extinct Australian Sea Snakes (Aipysurus: Hydrophiinae)

The critically endangered leaf-scaled (Aipysurus foliosquamaI) and short-nosed (A. apraefrontalis) sea snakes are currently recognised only from Ashmore and Hibernia reefs ~600km off the northwest Australian coast. Steep population declines in both species were documented over 15 years and neither has been sighted on dedicated surveys of Ashmore and Hibernia since 2001. We examine specimens of these species that were collected from coastal northwest Australian habitats up until 2010 (A.foliosquama) and 2012 (A. apraefrontalis) and were either overlooked or treated as vagrants in conservation assessments. Morphological variation and mitochondrial sequence data confirm the assignment of these coastal specimens to A. foliosquama (Barrow Island, and offshore from Port Hedland) and A.apraefrontalis (Exmouth Gulf, and offshore from Roebourne and Broome). Collection dates, and molecular and morphological variation between coastal and offshore specimens, suggest that the coastal specimens are not vagrants as previously suspected, but instead represent separate breeding populations. The newly recognised populations present another chance for leaf-scaled and short-nosed sea snakes, but coastal habitats in northwest Australia are widely threatened by infrastructure developments and sea snakes are presently omitted from environmental impact assessments for industry. Further studies are urgently needed to assess these species’ remaining distributions, population structure, and extent of occurrence in protected areas.

A Comparison of Hatchling Locomotor Performance and Scute Pattern Variation between Two Rookeries of the Flatback Turtle (Natator depressus)

Marine turtle species consist of several genetically discrete ‘evolutionarily significant units’ (ESUs) which do not interbreed. We studied Flatback turtle (Natator depressus) hatchlings from two rookeries (Mon Repos Conservation Park and Bare Sand Island, Australia) representing two separate ESUs. Turtles from these ESUs differ in several key life history traits, including body size, and we predicted hatchlings would also differ in locomotor performance. We also investigated the proportion of hatchlings with non-modal scute patterns to determine whether this varies between ESUs. We collected newly emerged hatchlings, and measured mass, carapace length and width, and recorded the scute pattern. We then measured self-righting ability and crawling speed. Our results confirmed a difference in hatchling size between the two ESUs, with Mon Repos rookery hatchlings being larger. However the size difference did not translate into a difference in self-righting ability or crawling speed. The Mon Repos rookery also produced a larger proportion of hatchlings with major non-modal scute pattern compared to Bare Sand Island rookery. The differences suggest hatchling survival rates may differ between ESUs, and that ESUs should be studied separately when implementing conservation measures.

Plasma biochemical and PCV ranges for healthy, wild, immature hawksbill (Eretmochelys imbricata) sea turtles

In recent years, the use of blood chemistry as a diagnostic tool for sea turtles has been demonstrated, but much of its effectiveness relies on reference intervals. The first comprehensive blood chemistry values for healthy wild hawksbill (Eretmochelys imbricata) sea turtles are presented. Nineteen blood chemistry analytes and packed cell volume were analysed for 40 clinically healthy juvenile hawksbill sea turtles captured from a rocky reef habitat in northern Australia. We used four statistical approaches to calculate reference intervals and to investigate their use with non-normal distributions and small sample sizes, and to compare upper and lower limits between methods. Eleven analytes were correlated with curved carapace length indicating that body size should be considered when designing future studies and interpreting analyte values.

Measuring behavioral responses of sea turtles, saltwater crocodiles, and crested terns to drone disturbance to define ethical operating thresholds

Drones are being increasingly used in innovative ways to enhance environmental research and conservation. Despite their widespread use for wildlife studies, there are few scientifically justified guidelines that provide minimum distances at which wildlife can be approached to minimize visual and auditory disturbance. These distances are essential to ensure that behavioral and survey data have no observer bias and form the basis of requirements for animal ethics and scientific permit approvals. In the present study, we documented the behaviors of three species of sea turtle (green turtles, Chelonia mydas, flatback turtles, Natator depressus, hawksbill turtles, Eretmochelys imbricata), saltwater crocodiles (Crocodylus porosus), and crested terns (Thalasseus bergii) in response to a small commercially available (1.4 kg) multirotor drone flown in Northern Territory and Western Australia. Sea turtles in nearshore waters off nesting beaches or in foraging habitats exhibited no evasive behaviors (e.g. rapid diving) in response to the drone at or above 20–30 m altitude, and at or above 10 m altitude for juvenile green and hawksbill turtles foraging on shallow, algae-covered reefs. Adult female flatback sea turtles were not deterred by drones flying forward or stationary at 10 m altitude when crawling up the beach to nest or digging a body pit or egg chamber. In contrast, flyovers elicited a range of behaviors from crocodiles, including minor, lateral head movements, fleeing, or complete submergence when a drone was present below 50 m altitude. Similarly, a colony of crested terns resting on a sand-bank displayed disturbance behaviors (e.g. flight response) when a drone was flown below 60 m altitude. The current study demonstrates a variety of behavioral disturbance thresholds for diverse species and should be considered when establishing operating conditions for drones in behavioral and conservation studies.