Quick fix GPS technology highlights risk to dugongs moving between protected areas

Incidental capture in fishing gear is the most serious threat to the survival of many species of marine mammals. Fisheries closures developed to protect marine mammals have tended to concentrate on areas of high marine mammal density. Movement corridors have generally been less protected because they are often unknown and difficult to detect. Seagrass meadows in Moreton and Hervey Bays in south-eastern Queensland support significant populations of dugongs Dugong dugon. Pedigree analysis based on genetic and ancillary biological data indicates that there is substantial movement of dugongs between these bays, which are separated by open surf coasts where dugongs are occasionally caught in inshore shark nets set for the protection of bathers. This bycatch suggests that the dugong movement corridor between Moreton and Hervey Bays is close to the coast, a hypothesis not confirmed by nearly 30 yr of dugong satellite tracking using platform transmitter terminal (PTT) technology. Twenty-nine dugongs were captured in seagrass habitats on the eastern banks of Moreton Bay in 2012-2014 and were fitted with Quick Fix GPS and acoustic transmitters. One animal was captured and tracked twice. Four dugongs were tracked moving from Moreton Bay to Hervey Bay covering distances of 278-338 km over 5-9 d; 1 dugong made the return journey. Three of the 4 animals travelled along and very close to the coast; the exact track of the fourth animal is uncertain. These results suggest that dugongs would benefit from netting closures that extend beyond seagrass meadows

Body Temperatures and Winter Feeding in Immature Green Turtles, Chelonia mydas, in Moreton Bay, Southeast Queensland

Body temperatures of immature Clenonia mydas does not deviate significantly from water temperature in the range of 15-22.7 degrees C. Additionally, there was no correlation between Tb and body mass, indicating that larger turtles in the sampled range of sizes (9.2 - 39.5 kg) were not gaining a thermal advantage over smaller individuals

Satellite tagging and flipper tag recoveries reveal migration patterns and foraging distribution of loggerhead sea turtles (Caretta caretta) from eastern Australia

Marine turtles encounter different threats during various life-history stages. Therefore, understanding their movements and spatial distribution is crucial for effectively managing these long-lived migratory organisms. This study combines satellite telemetry data with long-term capture-mark-recapture data derived from flipper tag studies to determine distribution patterns of endangered loggerhead turtles (Caretta caretta) during post-nesting migrations from different eastern Australian nesting sites. Individuals from the K’gari-Fraser Island and Great Barrier Reef island rookeries typically migrated northward, whereas individuals from mainland rookeries migrated equally northward and southward. Despite this difference in foraging distribution, loggerheads from the different rookeries did not differ substantially in their migration duration or distance travelled. The foraging distribution identified from successful satellite tag deployments represented 50% of the foraging distribution identified from a large long-term flipper tag recovery database. However, these satellite telemetry results have identified new migration and foraging habitats not previously recognised for loggerhead turtles nesting in eastern Australia. Additionally, they support the conclusion from a past study using flipper tag recovery data that the mainland nesting turtles migrate to different foraging grounds than the turtles nesting on Great Barrier Reef islands. Collectively, the two data sources provide valuable data on the migration route, habitat distribution and ecological range for a threatened genetic stock of loggerhead turtles

Spatial distribution of fibropapillomatosis in green turtles along the Queensland coast and an investigation into the influence of water quality on prevalence

Fibropapillomatosis (FP) is a tumor-forming disease which affects all species of marine turtle, but predominantly the green turtle (Chelonia mydas). Expression of this disease is thought to be precipitated by poor environmental conditions and often linked to anthropogenically induced environmental changes. Although FP is a globally distributed disease, targeted studies on the spatial distribution of the disease in Australia are limited. Here, we present the first comprehensive report of FP prevalence in Queensland, Australia. A retrospective analysis of 25,645 capture records for 15 sites along the Queensland coast were used to determine FP prevalence and trends in foraging green turtles. Within this data set, 791 turtles (3.1%) with FP tumors were recorded. Our analysis showed that prevalence varies between sites and years, with juvenile turtles being the most frequently affected by the disease. We found that survey method has a significant influence on the apparent FP prevalence detected at each site. That is, surveys which were explicitly FP-targeted detected higher numbers of individual turtles with FP, and therefore generated higher prevalence rates than comprehensive population surveys. We also report the first attempt at developing water quality indices (WQIs) to compare with FP prevalence data in foraging green turtles. The WQIs were built from metrics published in a range of peer-reviewed papers, reports, and based on expert opinion. Despite utilizing an extensive data set, a relationship between FP prevalence and WQI rankings at each site could not be quantified. The analysis was confounded by a range of limitations, including data gaps, varying temporal scales and data capture methods in the FP prevalence, and water quality data sets. This study has significant implications for management as it highlights the benefits of designing and collecting centralized data that can be integrated and used across multiple projects or programs

Anti-predator meshing may provide greater protection for sea turtle nests than predator removal

The problem of how to protect sea turtle nests from terrestrial predators is of worldwide concern. On Queensland's southern Sunshine Coast, depredation of turtle nests by the introduced European red fox (Vulpes vulpes) has been recorded as the primary terrestrial cause of egg and hatchling mortality. We investigated the impact of foxes on the nests of the loggerhead turtle (Caretta caretta) and occasional green turtle (Chelonia mydas) over ten nesting seasons. Meshing of nests with fox exclusion devices (FEDs) was undertaken in all years accompanied by lethal fox control in the first five-year period, but not in the second five-year period. Lethal fox control was undertaken in the study area from 2005 to February 2010, but foxes still breached 27% (range19-52%) of turtle nests. In the second five-year period, despite the absence of lethal fox control, the average percentage of nests breached was less than 3% (range 0-4%). Comparison of clutch depredation rates in the two five-year periods demonstrated that continuous nest meshing may be more effective than lethal fox control in mitigating the impact of foxes on turtle nests. In the absence of unlimited resources available for the eradication of exotic predators, the use of FEDs and the support and resourcing of a dedicated volunteer base can be considered an effective turtle conservation tool on some beaches

Microplastic ingestion ubiquitous in marine turtles

Despite concerns regarding the environmental impacts of microplastics, knowledge of the incidence and levels of synthetic particles in large marine vertebrates is lacking. Here, we utilize an optimized enzymatic digestion methodology, previously developed for zooplankton, to explore whether synthetic particles could be isolated from marine turtle ingesta. We report the presence of synthetic particles in every turtle subjected to investigation (n = 102) which included individuals from all seven species of marine turtle, sampled from three ocean basins (Atlantic [ATL]: n = 30, four species; Mediterranean (MED): n = 56, two species; Pacific (PAC): n = 16, five species). Most particles (n = 811) were fibres (ATL: 77.1% MED: 85.3% PAC: 64.8%) with blue and black being the dominant colours. In lesser quantities were fragments (ATL: 22.9%: MED: 14.7% PAC: 20.2%) and microbeads (4.8%; PAC only; to our knowledge the first isolation of microbeads from marine megavertebrates). Fourier transform infrared spectroscopy (FT‐IR) of a subsample of particles (n = 169) showed a range of synthetic materials such as elastomers (MED: 61.2%; PAC: 3.4%), thermoplastics (ATL: 36.8%: MED: 20.7% PAC: 27.7%) and synthetic regenerated cellulosic fibres (SRCF; ATL: 63.2%: MED: 5.8% PAC: 68.9%). Synthetic particles being isolated from species occupying different trophic levels suggest the possibility of multiple ingestion pathways. These include exposure from polluted seawater and sediments and/or additional trophic transfer from contaminated prey/forage items. We assess the likelihood that microplastic ingestion presents a significant conservation problem at current levels compared to other anthropogenic threats

Freshwater turtle population in the area to be flooded by the Walla Weir, Burnett River, Queensland: baseline study

A baseline turtle study was requested in a review of impacts of changed water levels to follow construction of the Walla Weir on the Burnett River (25o02'S, 152o04'E) at Wallaville, Queensland. Four species of freshwater turtle occur in the area. Emydura krefftii was abundant throughout most of the Walla Weir area. This population's characteristics indicate poor recruitment or survivorship of young turtles, even though adults breed at a very high rate; a size class distribution skewed towards adults; a sex ratio of 1:1; and almost all adults breeding annually. The straight carapace length (SCL) at which 50% of the population had matured to adult status was used to define size at first breeding and was 18.9cm for males and 21.1cm for females. Mean of all adults was SCL = 22.9cm for males and 25.1cm for females. Length/weight analyses measure health and body condition for each sex. Elseya sp. was uncommon in the area and was mostly concentrated in a single pool. Elseya sp. has a well-developed cloacal gill system. Its population structure indicated that the population was not performing well. Captured turtles comprised large adults and a group of immature turtles born in about 1990-1991. Recruitment of young appears to be limited. Chelodina expansa and Elseya latisternum occurred at very low density in the study area. A set of parameters to describe population performance of chelid turtles and suitable for short-term studies is identified: size class distribution by sex and maturity; and size at first breeding, mean size of adults, annual breeding rate, and length/weight condition curves for each sex

Freshwater turtle population in the area to be flooded by the Walla Weir, Burnett River, Queensland: baseline study

A baseline turtle study was requested in a review of impacts of changed water levels to follow construction of the Walla Weir on the Burnett River (25o02'S, 152o04'E) at Wallaville, Queensland. Four species of freshwater turtle occur in the area. Emydura krefftii was abundant throughout most of the Walla Weir area. This population's characteristics indicate poor recruitment or survivorship of young turtles, even though adults breed at a very high rate; a size class distribution skewed towards adults; a sex ratio of 1:1; and almost all adults breeding annually. The straight carapace length (SCL) at which 50% of the population had matured to adult status was used to define size at first breeding and was 18.9cm for males and 21.1cm for females. Mean of all adults was SCL = 22.9cm for males and 25.1cm for females. Length/weight analyses measure health and body condition for each sex. Elseya sp. was uncommon in the area and was mostly concentrated in a single pool. Elseya sp. has a well-developed cloacal gill system. Its population structure indicated that the population was not performing well. Captured turtles comprised large adults and a group of immature turtles born in about 1990-1991. Recruitment of young appears to be limited. Chelodina expansa and Elseya latisternum occurred at very low density in the study area. A set of parameters to describe population performance of chelid turtles and suitable for short-term studies is identified: size class distribution by sex and maturity; and size at first breeding, mean size of adults, annual breeding rate, and length/weight condition curves for each sex