Paul A Butcher

Geochemistry and mercury contamination in receiving environments of artisanal mining wastes and identified concerns for food safety

Abstract Artisanal small‐scale gold mining (ASGM) using mercury (Hg) amalgamation has been occurring on Buru Island, Indonesia since early 2012, and has caused rapid accumulation of high Hg concentrations in river, estuary and marine sediments. In this study, sediment samples were collected from several sites downstream of the Mount Botak ASGM site, as well as in the vicinity of the more recently established site at Gogrea where no sampling had previously been completed. All sediment samples had total Hg (THg) concentrations exceeding Indonesian sediment quality guidelines and were up to 82 times this limit at one estuary site. The geochemistry of sediments in receiving environments indicates the potential for Hg‐methylation to form highly bioavailable Hg species. To assess the current contamination threat from consumption of local seafood, samples of fish, molluscs and crustaceans were collected from the Namlea fish market and analysed for THg concentrations. The majority of edible tissue samples had elevated THg concentrations, which raises concerns for food safety. This study shows that river, estuary and marine ecosystems downstream of ASGM operations on Buru Island are exposed to dangerously high Hg concentrations, which are impacting aquatic food chains, and fisheries resources. Considering the high dietary dependence on marine protein in the associated community and across the Mollucas Province, and the short time period since ASGM operations commenced in this region, the results warrant urgent further investigation, risk mitigation, and community education. HighlightsMercury contamination of sediments and seafood due to artisanal gold mining.Considerable risks to human and ecosystem health are identified.Results emphasise the urgent need for risk mitigation and community education.

Effects of salinity and anatomical hook location on the mortality and physiological response of angled-and-released sand whiting Sillago ciliata

Three experiments were done with sand whiting Sillago ciliata: the first two assessed the short-term mortality and physiological response of individuals after being mouth hooked and then subjected to rapid changes in salinity, while the third experiment investigated their longer-term fate after ingesting hooks (independent of salinity changes). In experiment one, 48 tanks containing a single S. ciliata were randomly assigned as either one of three treatments or a control. The fish in treatments one and two were exposed to salinity changes during their angling and subsequent release while those in treatment three were only subjected to angling and air exposure. Control fish remained untouched. Fish were then monitored for up to 6 days for mortalities before blood samples were taken to determine concentrations of plasma cortisol and glucose. Blood samples were also taken from five wild-caught fish to provide baseline estimates of the above variables. None of the treatment or control fish died over the 6 days, and there were no significant differences in blood cortisol or glucose between treatment, control and wild fish. In experiment two, 102 S. ciliata and 52 experimental tanks were used. The treatments were repeated as above, however, six individuals from each treatment and control group were removed and sampled for blood (and then glucose and cortisol) at 0, 24, 48 and 72 h post release. Some changes in behaviour due to the salinity changes occurred as well as a significant main effect of time for cortisol, with all fish having significantly elevated acute stress at the first sample time. In experiment three, 52 S. ciliata were placed into individual tanks. Twenty-six of these fish were allowed to ingest baited J-hooks, played for 60 s, removed from their tanks, and then released after their lines were cut (50 mm from their mouths). Control fish were not touched. All fish were then monitored over 21 days. Six of the treatment fish died (between 3 h and 14 days), while the remaining hooked fish resumed feeding within 5 days and 25% ejected their hooks (between 1 and 19 days). It was concluded that (1) salinity and mouth hooking had few independent or interactive effects on the mortality or physiological response of angled-and-released S. ciliata and (2) while hook ingestion caused some mortalities, the protracted physiological effects were limited, with all surviving fish resuming feeding and some eventually ejecting their hooks.

Metal and metalloid concentrations in the tissues of dusky Carcharhinus obscurus, sandbar C. plumbeus and white Carcharodon carcharias sharks from south-eastern Australian waters, and the implications for human consumption.

Shark fisheries have expanded due to increased demand for shark products. As long-lived apex predators, sharks are susceptible to bioaccumulation of metals and metalloids, and biomagnification of some such as Hg, primarily through diet. This may have negative health implications for human consumers. Concentrations of Hg, As, Cd, Cu, Fe, Se and Zn were analysed in muscle, liver and fin fibres (ceratotrichia) from dusky Carcharhinus obscurus, sandbar Carcharhinus plumbeus, and white Carcharodon carcharias sharks from south-eastern Australian waters. Concentrations of analytes were generally higher in liver than in muscle and lowest in fin fibres. Muscle tissue concentrations of Hg were significantly correlated with total length, and >50% of sampled individuals had concentrations above Food Standards Australia New Zealands maximum limit (1 mg kg(-1) ww). Arsenic concentrations were also of concern, particularly in fins. Results warrant further investigation to accurately assess health risks for regular consumption of shark products.

Bioaccumulation of PCBs in liver tissue of dusky Carcharhinus obscurus, sandbar C. plumbeus and white Carcharodon carcharias sharks from south-eastern Australian waters.

Polychlorinated biphenyls (PCBs) are ubiquitous pollutants in the marine environment that are known to accumulate in apex predators such as sharks. Liver samples from dusky Carcharhinus obscurus, sandbar Carcharhinus plumbeus, and white Carcharodon carcharias sharks from south-eastern Australian waters were analysed for the seven indicator PCBs 28, 52, 101, 118, 138, 153 and 180. Median ∑PCBs were significantly higher in white than sandbar sharks (3.35 and 0.36 μg g(-1) lipid, respectively, p=0.05) but there were no significant differences between dusky sharks (1.31 μg g(-1) lipid) and the other two species. Congener concentrations were also significantly higher in white sharks. Significant differences in PCB concentrations between mature and immature dusky (3.78 and 0.76 μg g(-1) lipid, respectively) and sandbar (1.94 and 0.18 μg g(-1) lipid, respectively) sharks indicated that PCB concentrations in these species increased with age/growth. Higher-chlorinated congeners (hexa and heptachlorobiphenyls) dominated results, accounting for ~90% of ∑PCBs.

The potential for unmanned aerial vehicles (UAVs) to conduct marine fauna surveys in place of manned aircraft

Unmanned aerial vehicles (UAVs) are increasingly used in marine wildlife research. As technological developments rapidly advance the versatility and functionality of affordable UAVs, their potential as a marine aerial survey tool is quickly gaining attention. Currently, there is significant interest in whether cost-effective UAVs can outperform manned aircraft in aerial surveys of marine fauna at sea, although few empirical studies have compared relative sampling efficiency, accuracy and precision. Civil aviation restrictions, and subsequent available civilian technologies, make it unlikely that UAVs will currently be more effective than manned aircraft for large area marine surveys. UAVs do, however, have the capacity to fill a niche for intensive smaller spatial scale sampling and for undertaking aerial surveys in isolated locations. Improvements in UAV sensor resolutions and alternative sensor types, such as multispectral cameras, may increase area coverage, reduce perception error, and increase water penetration for sightability. Additionally, the further development of auto-detection software will rapidly improve image processing and further reduce human observer error inherent in manned aerial surveys. As UAV technologies and associated methodology is further developed and becomes more affordable, these aircraft will be increasingly adopted as a marine aerial survey tool in place of traditional methods using manned aircraft.

Age and growth of mangrove red snapper Lutjanus argentimaculatus at its cool-water-range limits

This study investigates the age and growth of Lutjanus argentimaculatus at its southern (cooler) range limits in eastern Australia. Specimens were collected from New South Wales and southern Queensland between November 2011 and December 2013. Fork lengths (LF ) ranged from 190 to 1019 mm, and ages ranged from 2+ to 57+ years. Growth was described by the von Bertalanffy growth function with coefficients L∞ = 874·92 mm, K = 0·087 year(-1) and t0 = -2·76 years. Estimates of the instantaneous natural mortality rate (M) ranged from 0·072 to 0·25. The LF (mm) and mass (W; g) relationship was represented by the equation: W=2·647×10-5LF2·92. The maximum age of 57+ years is the oldest reported for any lutjanid and comparisons with tropical studies suggest that the age-based demography of L. argentimaculatus follows a latitudinal gradient. High maximum ages and low natural mortality rates indicate considerable vulnerability to overexploitation at the species cool-water-range limits. These results demonstrate the need to identify underlying processes driving latitudinal gradients in fish demography.

Absorption of metals in mulloway (Argyrosomus japonicus) after ingesting nickel-plated carbon-steel hooks

Previous research has alluded to the potential of metals being absorbed by fish after ingesting fishing hooks, which may have adverse effects on fish health and the organisms that consume them. Subsequently, this study aimed to quantify the potential of mulloway (Argyrosomus japonicus) to absorb metals during the decay of ingested nickel-plated carbon-steel hooks. Twenty-five treatment fish were allowed to ingest nickel-plated carbon-steel hooks during angling and then monitored with 25 controls (untreated fish) for up to 42 days for hook ejection and mortality. Blood, liver and muscle samples were collected from treatment, control and 14 wild-caught individuals to determine the concentrations of chromium, cobalt, copper, iron, manganese and nickel. The results showed that increased oxidation influenced hook ejection, and that hook-ingested fish had significantly elevated concentrations of nickel in their liver and blood, but not muscle. This research has shown that there is an avenue for metal absorption from ingested hooks.

Behavioural and biochemical alterations in Penaeus monodon post-larvae diet-exposed to inorganic mercury

Mercury is a metal naturally present in the environment with concentrations in aquatic systems increasing annually due to human activities. This represents a great concern mainly due to its high toxicity to organisms and consequences for human health. Most studies regarding the toxic effect of mercury have focussed on freshwater species using water as the exposure and uptake pathway. In contrast, the present study investigated the effects of dietary exposure of mercury to the marine crustacean Penaeus monodon post-larvae during 96xa0h to evaluate changes in behaviour (swimming activity and risk taken) and in biochemical biomarkers [acetylcholinesterase (AChE) and glutathione S-transferase (GST)]. Results showed a decrease in swimming activity with an increase in mercury exposure, but no changes were observed regarding the behavioural response risk taken. Prawns from medium (0.56xa0μgxa0g-1) and high (1.18xa0μgxa0g-1) treatments had their GST activity reduced in relation to the beginning of experiment (time 0), while AChE activity was increased in the low (0.15xa0μgxa0g-1) treatment in relation to time 0. In the present study, behaviour analysis were clearer than biochemical biomarkers and results might indicate P. monodon populations from a mercury contaminated environment might be at risk, since the behavioural alterations observed increases the risk of predation.

Angling-induced barotrauma in snapper Chrysophrys auratus: are there consequences for reproduction?

In response to concerns regarding the potential for sub-lethal impacts of barotrauma on reproductively active Chrysophrys auratus during catch and release, 90 males and 90 females representing five reproductive stages (immature or resting-28%, developing-8%, developed-7%, ripe or spawning-23% and spent-34%) were angled from 8–70 m and macroscopically assessed (on-board and then in a laboratory). Irrespective of sex, all fish exhibited various clinical signs of barotrauma, including a prolapsed cloaca (60% of fish); gastric herniation (46%); ruptured swim bladder (73%); organ displacement (48%); and kidney (3%), liver (73%) and coloemic-cavity haemorrhaging (33%);with the frequency of nearly all positively associated with capture depth. Reproductive stage was also an important barotrauma predictor (reflecting related morphological changes) with a general trend towards spent fish least likely to incur the various clinical signs—especially for a prolapsed cloaca (also common among immature or resting fish and significantly affected by food in the digestive tract) and a ruptured swim bladder (common among ripe or spawning fish). The only macroscopically visible gonad damage was haemorrhaging, which was least common among immature or resting and spent fish and, irrespective of reproductive stage, temporally reduced in frequency, and more quickly among males than females. While further research is required to accurately describe the effects of angling at each stage of the reproductive cycle and the physiological consequences of barotrauma on the gonads of C. auratus, given the observed influences of reproductive stage and depth on barotrauma found in this study, any adverse effects might be partially managed by regulating either temporal or spatial fishing effort.

Ingestion of inorganic mercury by juvenile black tiger prawns (Penaeus monodon) alters biochemical markers

There is a lack of information regarding the effects on biochemical markers in invertebrates diet-exposed to inorganic mercury. In the present study, juvenile black tiger prawn (Penaeus monodon) were fed with food dosed with mercuric chloride (low: 0.2u2009mgu2009kg−1; medium: 0.77u2009mgu2009kg−1; high: 1.41u2009mgu2009kg−1; higher: 2.52u2009mgu2009kg−1) and control (0.03u2009mgu2009kg−1) over 12 days. At the end of exposure periods, ventral nerve cord, compound eyes and muscle were dissected for biochemical marker analyses (acetylcholinesterase – AChE; lipoperoxidation – LPO; glutathione S-transferase – GST; catalase – CAT). Prawn muscle showed an increase in total mercury concentration over time for low and high treatments, but did not show an accumulation in comparison to controls. AChE activity tended to decrease over time in all tissues. CAT activity increased over time in controls and lower dose treatments but was suppressed in the higher treatment relative to controls on day 12; indicating that inorganic mercury is impacting the normal stress response by reducing the capacity to degrade hydrogen peroxide. In contrast, no effect was observed in LPO and GST activity. A depuration treatment was performed and compared to medium treatment; only AChE and GST activities from muscle showed significant difference, with AChE activity from depuration treatment lower than medium treatment, while the opposite was observed in GST activity. Overall, the low mercury accumulation observed over 12 days of exposure may have limited the biochemical stress responses, which could also have limited the detection of differences in the depuration treatment relative to medium treatment.