Monitoring the health of green turtles in northern Queensland post catastrophic events

Between 2014 and 2017, the Rivers to Reef to Turtles (RRT) project examined the health of green turtles at two coastal sites impacted by urban and agricultural human activities (Cleveland and Upstart Bays) and one proposed pristine site (Howick Group of Reefs) in northern Queensland, Australia, through blood biochemistry and haematology, plasma protein electrophoresis, and clinical assessments including body condition and barnacle counts. Furthermore, cases of mortality were subjected to comprehensive postmortem examination. In an attempt to advance diagnostics, associations between specific contaminants and health of turtles in this region were tested. No comprehensive health assessments had been conducted at these sites prior to this study. The coastal Cleveland and Upstart Bays both demonstrated effects likely to be in response to stressors suspected to be anthropogenic in origin (elevated total white cell counts and creatinine kinase levels across the populations, respectively). This was associated with a suite of trace elements, in particular cobalt. While these indicators of stress resolved by the final year of the study, a chronic stressor was suspected to be persisting with ongoing low albumin: globulin. Necropsies did not elucidate any specific diseases. Although body condition index did not closely correlate with site health, barnacle counts in juvenile turtles may prove a reliable indicator of site health. Based on previously established indicators of poor health, barnacle counts showed that 10% of the population was in poor health at Upstart Bay and nearly 20% of the population at Cleveland Bay. This is above what would be expected for a normal population. Overall, the health component of this study suggested that the pristine turtle population was healthy and the coastal turtle populations were under active stressors, possibly caused by anthropogenic effectors such as chemical pollutants, when initially examined in 2014. These stressors resolved by the conclusion of the study in 2017; but chronic stressors remained absent in the pristine site and present within each of the studied coastal populations.

Green turtle (Chelonia mydas) population demographics at three chemically distinct foraging areas in the northern Great Barrier Reef

The catchments of the Great Barrier Reef (GBR) have experienced significant modifications in recent decades, leading to increases in sources of pollutants and declines in coastal water quality. As coastal waters of the GBR support some of the highest density green turtle (Chelonia mydas) foraging populations in the western Pacific Ocean, understanding the effects of contaminants on GBR green turtle populations is a priority. In 2012, elevated strandings of green turtles in the Upstart Bay region instigated the WWF's collaborative Rivers to Reef to Turtles (RRT) project to investigate if coastal pollutants are compromising green turtle health. Important to interpreting these investigations into toxicology and health is understanding the demographics of the green turtle populations being investigated. In three green turtle foraging grounds, Cleveland Bay (CLV), Upstart Bay (UPB) and the Howick Group of Reefs (HWK), this study explored population size, age class structure, sex ratio, growth rates, body condition and diet, as well as indices of turtle health, such as plastron barnacle loads and eye lesions. The three foraging populations had similar age class structure and adult sex ratios to other green turtle foraging populations in the GBR. Somatic growth rate was nonlinear, peaking in immature turtles, and was much slower in turtles foraging at HWK compared to the other two sites. This may have been due to differences in food source, which was supported by the observed dietary shifts between seagrass and algae in HWK turtles, compared to a consistently seagrass diet in CLV and UPB turtles. There were also small differences in body condition between sites, as well as differences in barnacle loads, eye lesions and occurrence of fibropapilloma tumors. This study provides important information on green turtle foraging ground population dynamics in the northern GBR, and context for the other papers in this special issue.

Phylogeography, Genetic Diversity, and Management Units of Hawksbill Turtles in the Indo-Pacific

Hawksbill turtle (Eretmochelys imbricata) populations have experienced global decline because of a history of intense commercial exploitation for shell and stuffed taxidermied whole animals, and harvest for eggs and meat. Improved understanding of genetic diversity and phylogeography is needed to aid conservation. In this study, we analyzed the most geographically comprehensive sample of hawksbill turtles from the Indo-Pacific Ocean, sequencing 766 bp of the mitochondrial control region from 13 locations (plus Aldabra, n = 4) spanning over 13500 km. Our analysis of 492 samples revealed 52 haplotypes distributed in 5 divergent clades. Diversification times differed between the Indo-Pacific and Atlantic lineages and appear to be related to the sea-level changes that occurred during the Last Glacial Maximum. We found signals of demographic expansion only for turtles from the Persian Gulf region, which can be tied to a more recent colonization event. Our analyses revealed evidence of transoceanic migration, including connections between feeding grounds from the Atlantic Ocean and Indo-Pacific rookeries. Hawksbill turtles appear to have a complex pattern of phylogeography, showing a weak isolation by distance and evidence of multiple colonization events. Our novel dataset will allow mixed-stock analyses of hawksbill turtle feeding grounds in the Indo-Pacific by providing baseline data needed for conservation efforts in the region. Eight management units are proposed in our study for the Indo-Pacific region that can be incorporated in conservation plans of this critically endangered species.

Public health aspects of food fortification: a question of balance

Micronutrient malnutrition is widespread throughout the world, with important health and economic consequences. Tools to address this situation include food fortification, supplementation and dietary diversification, each having different and complementary roles. Fortification (mandatory and voluntary) has been practised over several decades in Western countries as well as in developing countries. Iodised salt was introduced in the USA in 1924 to reduce severe I deficiency. In 1938 voluntary enrichment of flours and breads with niacin and Fe was initiated to reduce the incidence of pellagra and Fe-deficiency anaemia respectively. Micronutrient intakes in European countries appear to be generally adequate for most nutrients. However, a number of population subgroups are at higher risk of suboptimal intakes (below the lower reference nutrient intake) for some micronutrients, e.g. folate, Fe, Zn and Ca in children, adolescents and young women. Dietary surveys indicate that fortified foods play a role in mitigating such risks for several important nutrients. The number of foods suited to fortification are considerably limited by several factors, including technological properties (notably moisture, pH and O2 permeability), leading to unacceptable taste and appearance, as well as cost and consumer expectations. In countries in which voluntary fortification is widely practised micronutrient intakes are considerably below tolerable upper intake levels. Concerns about safety are addressed in relation to the potentially increased level or proportion of fortified foods (e.g. following potential EU legislation), for nutrients with relatively low tolerable upper intake levels and where the potential benefit and risks are in different subpopulations (e.g. folic acid). Recent models for assessing these issues are discussed.

The distribution and abundance of the estuarine crocodile, Crocodylus porosus, in Queensland

A total of 6444 Crocodylus porosus (4303 non-hatchlings and 2141 hatchlings) were recorded during 196 vessel-based surveys of 103 waterways to determine the distribution and abundance of Crocodylus porosus in Queensland. The surveys, conducted from January 1994 to December 2000, covered 4174.3 km of waterway. Population structure was biased towards immature crocodiles, with 91% of all animals sighted being less than the minimum breeding size for individuals in the Northern Territory. The mean relative density of non-hatchling C. porosus was highest in waterways of north-western Cape York Peninsula and Lakefield National Park, and lowest for waterways along the populated east coast of Queensland. The highest numbers of hatchlings were recorded from waterways of north-western Cape York Peninsula, where nearly 74% of all hatchlings were recorded during the seven-year survey period. The C. porosus population in northern Queensland appears to be undergoing a limited recovery, with marginal increases in the mean relative density of non-hatchlings in seven of the eight crocodile biogeographic regions. On the basis of the distribution and abundance of hatchling and non-hatchling crocodiles, the north-western Cape York Peninsula region contains the best habitat for C. porosus in Queensland, particularly in the Wenlock River and Tentpole Creek area.