Assessing the chronic toxicity of copper and aluminium to the tropical sea anemone Exaiptasia pallida

A comprehensive review of the effects of salinity, dissolved organic carbon, pH, and temperature on copper biotoxicity: Implications for setting the copper marine water quality criteria

In recent years, there has been a growing concern about the ecological hazards associated with copper, which has sparked increased interest in copper water quality criteria (WQC). The crucial factors affecting the bioavailability of copper in seawater are now acknowledged to be salinity, dissolved organic carbon (DOC), pH, and temperature. Research on the influence of these four water quality parameters on copper toxicity is rapidly expanding. However, a comprehensive and clear understanding of the relevant mechanisms is currently lacking, hindering the development of a consistent international method to establish the seawater WQC value for copper. As a response to this knowledge gap, this study presents a comprehensive summary with two key focuses: (1) It meticulously analyzes the effects of salinity, DOC, pH, and temperature on copper toxicity to marine organisms. It takes into account the adaptability of different species to salinity, pH and temperature. (2) Additionally, the study delves into the impact of these four water parameters on the acute toxicity values of copper on marine organisms while also reviewing the methods used in establishing the marine WQC value of copper. The study proposed a two-step process: initially zoning based on the difference of salinity and DOC, followed by the establishment of Cu WQC values for different zones during various seasons, considering the impacts of water quality parameters on copper toxicity. By providing fundamental scientific insights, this research not only enhances our understanding and predictive capabilities concerning water quality parameter-dependent Cu toxicity in marine organisms but also contributes to the development of copper seawater WQC values. Ultimately, this valuable information facilitates more informed decision-making in marine water quality management efforts.

A broad-taxa approach as an important concept in ecotoxicological studies and pollution monitoring

Aquatic invertebrates play a pivotal role in (eco)toxicological assessments because they offer ethical, cost-effective and repeatable testing options. Additionally, their significance in the food chain and their ability to represent diverse aquatic ecosystems make them valuable subjects for (eco)toxicological studies. To ensure consistency and comparability across studies, international (eco)toxicology guidelines have been used to establish standardised methods and protocols for data collection, analysis and interpretation. However, the current standardised protocols primarily focus on a limited number of aquatic invertebrate species, mainly from Arthropoda, Mollusca and Annelida. These protocols are suitable for basic toxicity screening, effectively assessing the immediate and severe effects of toxic substances on organisms. For more comprehensive and ecologically relevant assessments, particularly those addressing long-term effects and ecosystem-wide impacts, we recommended the use of a broader diversity of species, since the present choice of taxa exacerbates the limited scope of basic ecotoxicological studies. This review provides a comprehensive overview of (eco)toxicological studies, focusing on major aquatic invertebrate taxa and how they are used to assess the impact of chemicals in diverse aquatic environments. The present work supports the use of a broad-taxa approach in basic environmental assessments, as it better represents the natural populations inhabiting various ecosystems. Advances in omics and other biochemical and computational techniques make the broad-taxa approach more feasible, enabling mechanistic studies on non-model organisms. By combining these approaches with in vitro techniques together with the broad-taxa approach, researchers can gain insights into less-explored impacts of pollution, such as changes in population diversity, the development of tolerance and transgenerational inheritance of pollution responses, the impact on organism phenotypic plasticity, biological invasion outcomes, social behaviour changes, metabolome changes, regeneration phenomena, disease susceptibility and tissue pathologies. This review also emphasises the need for harmonised data-reporting standards and minimum annotation checklists to ensure that research results are findable, accessible, interoperable and reusable (FAIR), maximising the use and reusability of data. The ultimate goal is to encourage integrated and holistic problem-focused collaboration between diverse scientific disciplines, international standardisation organisations and decision-making bodies, with a focus on transdisciplinary knowledge co-production for the One-Health approach.

Thallium toxicity to temperate and tropical marine organisms: Derivation of water quality guidelines to protect marine life

A lack of thallium (Tl) toxicity data for marine organisms has hampered the development of water quality guidelines for protecting marine life and assessing ecological hazard/risk. This study assessed the toxicity (EC10/EC50) of Tl in natural seawater (salinity 34 psu and pH 8.05) to 26 functionally diverse marine organisms (19 phyla from five trophic levels) from a variety of temperate and tropical coastal marine habitats. EC10 values ranged from 3.0 μg/L (copepod, Acartia tranteri) to 489 μg/L (cyanobacterium, Cyanobium sp.), while EC50 values ranged from 9.7 μg/L to 1550 μg/L. Thallium(I) was the dominant (86-99 %) oxidation state in test waters across the range of EC10 and EC50 values. Thallium toxicity (EC10/EC50) did not differ between temperate and tropical marine organisms. New, reliable, long-term Tl water quality guidelines were derived using species sensitivity distributions (with model-averaging) to protect marine life in Australia (e.g., 3.9 μg/L for 95 % species protection).

Application of a behavioural and biochemical endpoint in ecotoxicity testing with Exaiptasia pallida

Exaiptasia pallida has been applied as a cnidarian model to assess the toxicity of various contaminants using endpoints related to growth, reproduction and mortality. However, increasingly accepted behavioural and biochemical endpoints are underrepresented in ecotoxicity testing with cnidarian species. The aim of this study was to assess the suitability of tentacle retraction and superoxide dismutase activity as behavioural and biochemical endpoints for ecotoxicity testing with E. pallida. A concentration-dependent, tentacle retraction response was found in sub-lethal toxicity testing for anemones exposed to 1-65 μg L^-1 Cu and 2-630 μg L^-1 Zn for 24 and 96 h. Semi-quantitative and quantitative approaches to tentacle retraction analysis showed a difference in response sensitivity, however, both methods resulted in similar 24- and 96-h EC50 values for Cu and Zn. Additionally, tentacle retraction analysis provided the benefit of identifying recovery in anemones previously exposed to 359 μg L^-1 Zn following a 96-h recovery period. Conversely, no significant difference in superoxide dismutase activity was detected in anemones exposed to the Cu and Zn solutions compared with controls, after either 24- or 96-h exposures. These findings support the ease of application and sensitivity of tentacle retraction as an endpoint in ecotoxicity testing with E. pallida and recommend its suitability for use in acute, sub-lethal toxicity testing. Moreover, evidence of recovery in E. pallida following exposure suggests that recovery should be incorporated into future toxicity assessments.

Developing a Multi-Dose Computational Model for Drug-Induced Hepatotoxicity Prediction Based on Toxicogenomics Data

Drug-induced hepatotoxicity may cause acute and chronic liver disease, leading to great concern for patient safety. It is also one of the main reasons for drug withdrawal from the market. Toxicogenomics data has been widely used in hepatotoxicity prediction. In our study, we proposed a multi-dose computational model to predict the drug-induced hepatotoxicity based on gene expression and toxicity data. The dose/concentration information after drug treatment is fully utilized in our study based on the dose-response curve, thus a more informative representative of the dose-response relationship is considered. We also proposed a new feature selection method, named MEMO, which is also one important aspect of our multi-dose model in our study, to deal with the high-dimensional toxicogenomics data. We validated the proposed model using the TG-GATEs, which is a large database recording toxicogenomics data from multiple views. The experimental results show that the drug-induced hepatotoxicity can be predicted with high accuracy and efficiency using the proposed predictive model.

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.

Assessing chronic toxicity of aluminium, gallium and molybdenum in tropical marine waters using a novel bioassay for larvae of the hermit crab Coenobita variabilis

A novel bioassay is presented that allows for the estimation of the chronic toxicity of contaminants in receiving tropical marine environments. Relevant procedures to identify contaminants of concern and evaluate hazards associated with contamination in these environments have long remained inadequate. The 6-day bioassay is conducted using freshly hatched planktonic larvae of the hermit crab Coenobita variabilis and is targeted at generating environmentally relevant, chronic toxicity data. The developmental endpoint demonstrated consistently high control performance and was validated through the use of copper as a reference toxicant. In addition, the biological effects of aluminium, gallium and molybdenum were assessed. The endpoint expressed high sensitivity to copper (EC₁₀ = 24 µg L^-1) and moderate sensitivity to aluminium (EC₁₀ = 312 µg L^-1), whereas gallium and molybdenum elicited no obvious effects, even at high concentrations (EC₁₀ > 6000 µg L^-1), providing valuable information on the toxicity of these elements in tropical marine waters for derivation of water quality guidelines or testing of compliance limits.

Water quality guideline values for aluminium, gallium and molybdenum in marine environments

Revised water quality guideline values (WQGVs) are presented for the metals aluminium (Al), gallium (Ga) and molybdenum (Mo) in receiving marine environments. These elements are commonly found in elevated concentrations in alumina refinery waste streams, yet current WQGVs fail to accurately assess the environmental risk. Here, chronic biological effects data we have generated over the course of several years were combined with toxicity data from the open literature to construct species sensitivity distributions (SSDs) which enabled the computation of revised WQGVs for Al, Ga and Mo in marine environments. These procedures are in accordance with internationally recommended derivation procedures, and newly computed WQGVs may be incorporated in regulatory frameworks aimed at sustainable exploitation of environmental resources and ongoing protection of the marine estate. Where the available datasets allowed such distinction, separate SSDs were constructed for temperate and tropical environments and zone-specific WQGVs derived. Extrapolated from the SSDs, WQGVs of 56 μg Al L^-1, 800 μg Ga L^-1 and 3.88 mg Mo L^-1 (in the 0.45-μm filtered fraction) for 95% species protection were recommended for implementation in both temperate and tropical receiving environments. Currently, there is insufficient validation to separate the tropical from the temperate data and in most cases, application of the generic WQGVs is recommended.

Floc behavior and removal mechanisms of cross-linked Durio zibethinus seed starch as a natural flocculant for landfill leachate coagulation-flocculation treatment

This study investigated the behavior and mechanisms of cross-linked Durio zibethinus seed starch (CDSS) flocculants for landfill leachate treatment. A physical-chemical treatment method of coagulation-flocculation process and starch modification were implemented in treating stabilized leachate from Matang Landfill, Perak, Malaysia. In practical, the removal performance of color, COD, suspended solid and turbidity for CDSS flocculants were evaluated by combining with primary coagulant of polyaluminium chloride (PAC). In this study, the application of crosslinking modification for Durio zibethinus seed waste starch flocculants showed good improvement. The impurities removal for colour, COD, suspended solid and turbidity were increased by the addition of CDSS flocculants. Furthermore, the average size of the floc was also increased from 60.24 µm to 89.5 µm. Despite, the addition of CDSS flocculants produced a reduction of PAC coagulant from 2700 mg/L to 2200 mg/L, with 500 mg/L reduction on the PAC dosage dependency. Therefore, these results affirmed the potentials of crosslinked modification for Durio zibethinus seed waste starch flocculants in landfill leachate treatment.

Threat of plastic ageing in marine environment. Adsorption/desorption of micropollutants

Ageing of various plastics in marine environment was monitored after immersion of two synthetic (polyvinylchloride, PVC, and polyethylene terephthalate, PET) and one biodegradable (poly(butylene adipate co-terephtalate), PBAT) plastics for 502days in the bay of Lorient (Brittany, France). Data analysis indicates that aged PVC rapidly releases estrogenic compounds in seawater with a later adsorption of heavy metals; PET undergoes a low weakening of the surface whereas no estrogenic activity is detected; PBAT ages faster in marine environment than PVC. Aged PBAT exhibits heterogeneous surface with some cavities likely containing clay minerals from the chlorite group. Besides, this degraded material occasionally shows a high estrogenic activity. Overall, this study reports, for the first time, that some aged plastics, without being cytotoxic, can release estrogenic compounds in marine environment.