Pelli Louise Howe

Development of a chronic, early life-stage sub-lethal toxicity test and recovery assessment for the tropical zooxanthellate sea anemone Aiptasia pulchella

There is an urgent need to identify additional tropical marine species and develop sensitive sub-lethal and chronic toxicity test methods for routine ecotoxicology. The tropical symbiotic sea anemone Aiptasia pulchella is a suitable species for use in ecotoxicology and here we have assessed the effects of trace metal exposures on the development of asexually produced A. pulchella pedal lacerates to a juvenile stage. Concentrations of 55 µg/L for cadmium, 262 µg/L for cobalt, 5 µg/L for copper, and 269 µg/L for zinc were estimated to inhibit normal development by 50 percent after 8-d exposures, and are among the most sensitive available toxicity estimates for marine organisms. This work illustrates the potential value of this species and sub-lethal toxicological endpoint for routine ecotoxicology in tropical marine environments.

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.

Toxicity of raw and neutralized bauxite refinery residue liquors to the freshwater cladoceran Ceriodaphnia dubia and the marine amphipod Paracalliope australis

The extraction of alumina from bauxite produces a highly toxic residue, termed bauxite refinery residue (BRR) or red mud. The toxicity of this material is due to chemical and biological effects of high pH, alkalinity, electrical conductivity (EC), and Na(+) and Al(3+) concentrations. Several neutralization techniques may allow BRR to be used for environmental remediation. The present study investigated standardized 48-h acute toxicity tests with a freshwater cladoceran, Ceriodaphnia dubia, and a marine amphipod, Paracalliope australis, against raw supernatant BRR liquor (RL) versus liquors neutralized with acid (ANL), CO(2) (CNL), seawater (SNL), and a hybrid method (HNL). Based on 48-h LC50 values, the toxicity of the liquors to C. dubia increased in the following order; HNL ≤ SNL< ANL ≤ CNL < RL, with comparable responses from P. australis. The high toxicity of RL likely is due to high pH (≈ 12), alkalinity, and Al concentration. Toxicity of CNL likely is due to high EC and alkalinity. Sulfate and Na(+) concentrations are considered sources of toxicity in ANL. Seawater-neutralized liquor and HNL were considerably less toxic to both test species. These data provide evidence of the acute lethal toxicity of raw supernatant liquor from BRR and four neutralized supernatant liquors to the freshwater cladoceran C. dubia and the marine amphipod P. australis, providing valuable baselines for further ecotoxicological investigations of BRR materials in aquatic environments.

Investigating lethal and sublethal effects of the trace metals cadmium, cobalt, lead, nickel and zinc on the anemone Aiptasia pulchella, a cnidarian representative for ecotoxicology in tropical marine environments

The zooxanthellate sea anemone Aiptasia pulchella is found throughout the tropical and subtropical oceans of the Indo-Pacific and is easily maintained in aquaria, posing potential suitability as a standard tropical marine test organism for use in ecotoxicology. To gain an understanding of the sensitivity of A. pulchella to trace metals, 96-h static-renewal toxicity tests were conducted. Values of 96-h LC50 between 946 and 1196 µg L–1 were estimated for cadmium, between 595 and 1146 µg L–1 for zinc, 8060 and 12 352 µg L–1 for lead and 2209 and 5751 µg L–1 for nickel. In addition, preliminary assessment of rapid tentacle retraction was made. Six-hour EC50 values of 355 and 979 µg L–1 for cadmium, between 384 and 493 µg L–1 for zinc, between 2340 and 2584 µg L–1 for nickel, and 2610 µg L–1 for lead, were estimated for ‘severe’ tentacle retraction. Cobalt concentrations up to 1547 µg L–1 caused extreme zooxanthellae loss, but no more than 10% mortality and no rapid ‘severe’ tentacle retraction. The present study has provided important baseline information, enabling comparison of the acute sensitivity of A. pulchella to trace metals with other marine invertebrates, and guiding the development of sublethal endpoints.

Toxicity estimates for diuron and atrazine for the tropical marine cnidarian Exaiptasia pallida and in-hospite Symbiodinium spp. using PAM chlorophyll-a fluorometry

Effective ecotoxicological risk assessments for herbicides in tropical marine environments are restricted by a lack of toxicity data, sensitive test methods and endpoints for relevant species, and this requires rectification. The symbiotic sea anemone Exaiptasia pallida is a suitable test species, representing the phylum Cnidaria and allowing for assessments of toxicological responses of both the animal host and in-hospite Symbiodinium spp. Pulse amplitude modulated (PAM) chlorophyll-a fluorometry is recognised as a valuable ecotoxicological tool, and here newly-developed test methods are presented using PAM fluorometry to measure herbicide effects on photosynthetic efficiency of in-hospite Symbiodinium spp. Additionally, measurements on healthy laboratory-reared E. pallida provide baseline data demonstrating the normal effective quantum yield (EQY) and the maximum electron transport rate (ETRm) for Symbiodinium spp. in the absence of herbicide stress. Concentration-dependant reductions in the EQY and ETRm occurred during diuron and atrazine exposures; a mean 48-h EC50 (effective concentration; 50%) of 8μg/L of diuron was estimated, however atrazine elicited a much lower toxicity. Twelve-day exposures to 10-200μg/L diuron showed that the greatest EQY effect occurred during the first 48h, with little subsequent change. However, longer exposures to the lowest diuron treatment (1μg/L) showed the lowest EQYs after 96h followed by recovery to control levels within 12d. Furthermore, asexual reproduction was inhibited during 12-d exposures to diuron, and 12-d EC50 values of 100 and 132μg/L were estimated to inhibit successful reproduction of pedal lacerates and juveniles by 50% respectively. This study provides much needed data contributions to species sensitivity curves for development of diuron and atrazine water quality guidelines in tropical marine environments.

Toxicity of manganese to various life stages of selected marine cnidarian species

Manganese (Mn) pollution in marine waters is increasing and sensitivities to this metal vary widely among marine species. The aims of this study were to characterise Mn chemistry in seawater, and evaluate the toxic effects of Mn on various life stages of two scleractinian corals - the branching sp. Acropora spathulata and massive sp. Platygyra daedalea, and the anemone Exaiptasia pallida. Analytical and theoretical characterisation experiments showed that 97-100% of Mn (II) additions ≤ 200 mg/L in seawater were soluble over 72 h and largely assumed labile complexes. Concentrations estimated to reduce coral fertilisation success by 50% (5.5-h EC50) were 237 mg/L for A. spathulata and 164 mg/L for P. daedalea. A relatively low 72-h LC50 of 7 mg/L was calculated for A. spathulata larvae. In a pilot test using fragments of adult A. spathulata, intact coral tissue rapidly sloughed away from the underlying skeleton at very low concentrations with a 48-h EC50 of just 0.7 mg/L. For E. pallida, survival, tentacle retraction and reproduction were unaffected by prolonged high exposures (12-d NOEC 54 mg/L). This study provides important data supporting the derivation of separate water quality guidelines for Mn in systems with and without coral - a decision recently considered by Australian and New Zealand authorities. It demonstrates the high sensitivity of coral larvae and adult colonies to Mn and the potential risks associated with relying on other early life stage tests and/or E. pallida as ecotoxicological representatives of critically important scleractinian corals.