Effects of mining chemicals on fish: exposure to tailings containing Lilaflot D817M induces CYP1A transcription in Atlantic salmon smolt

Functional and molecular characterization of the Atlantic salmon gill epithelium cell line ASG-10; a tool for in vitro gill research

Fish gills are not only the respiratory organ, but also essential for ion-regulation, acid-base control, detoxification, waste excretion and host defense. Multifactorial gill diseases are common in farmed Atlantic salmon, and still poorly understood. Understanding gill pathophysiology is of paramount importance, but the sacrifice of large numbers of experimental animals for this purpose should be avoided. Therefore, in vitro models, such as cell lines, are urgently required to replace fish trials. An Atlantic salmon gill epithelial cell line, ASG-10, was established at the Norwegian Veterinary institute in 2018. This cell line forms a monolayer expressing cytokeratin, e-cadherin and desmosomes, hallmarks of a functional epithelial barrier. To determine the value of ASG-10 for comparative studies of gill functions, the characterization of ASG-10 was taken one step further by performing functional assays and comparing the cell proteome and transcriptome with those of gills from juvenile freshwater Atlantic salmon. The ASG-10 cell line appear to be a homogenous cell line consisting of epithelial cells, which express tight junction proteins. We demonstrated that ASG-10 forms a barrier, both alone and in co-culture with the Atlantic salmon gill fibroblast cell line ASG-13. ASG-10 cells can phagocytose and express several ATP-binding cassette transport proteins. Additionally, ASG-10 expresses genes involved in biotransformation of xenobiotics and immune responses. Taken together, this study provides an overview of functions that can be studied using ASG-10, which will be an important contribution to in vitro gill epithelial research of Atlantic salmon.

Effects of mine tailing exposure on early life stages of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus)

Mining and processing of minerals produce large quantities of tailings as waste. Some countries, including Norway, allow disposal of mine tailings in the sea. In this study we investigated the impacts of tailings from a calcium carbonate (CaCO₃) processing plant on early live stages of haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua). Fish eggs (3 days post fertilisation; dpf) were exposed for 48 h to three concentrations of tailings, nominally 1 mg L^-1 (low, L); 10 mg L^-1 (medium, M) and 100 mg L^-1 (high, H); with L and M representing concentrations occurring at tailing release points. Results show that tailings rapidly adhered to eggs of both species, causing negative buoyancy (sinking of eggs) in M and H exposures. While tailings remained on egg surfaces in both species also after exposure termination, adhesion seemed more pronounced in cod, leading to larger impacts on buoyancy even after exposure. Tailing exposure further induced early hatching and significantly reduced survival in M and H exposed embryos in both fish species, and in cod from the L exposure group. Moreover, tailing exposure caused reduced survival and malformations in larvae, potentially related to premature hatching. This study shows that mineral particles adhere to haddock and cod eggs, affecting egg buoyancy, survival and development.

Pre-closure assessment of elevated arsenic and other potential environmental constraints to developing aquaculture and fisheries: The case of the Mae Moh mine and power plant, Lampang, Thailand

Our assessment of 30 water bodies in the vicinity of the Mae Moh coal mine and power station in northern Thailand does not indicate substantial water quality management challenges to developing fisheries/aquaculture in peripheral reservoirs and streams. Negative water quality issues such as high concentrations of arsenic (2-17 μg/L) and ions including sulfate (868-2605 mg/L), sodium (217-552 mg/L), and total ammonia (<1-5 mg/L) were associated with groundwater and surface water resources on the facility, as well as the stream network draining from it. Total dissolved solids were also very high, ranging from 658 to 3610 mg/L. Six of seven ponds tested had As concentrations in the range of 5-17 μg/L. Although these levels are less than the Thai regulation for industrial effluent, they are elevated over background surface water concentrations. The highest concentration in a contaminated stream was 10.54 μg/L As, which is only slightly above the WHO (2017) regulation of 10 μg/L for drinking water. Ponds, contaminated streams, and deep subsurface water should not be used for fisheries/aquaculture without extensive remediation/treatment. Concentrations of these water parameters in peripheral streams and reservoirs were not of environmental concern. High water hardness (161-397 mg/L CaCO₃ and potential ionic imbalances may be the greatest hindrances to developing sustainable fisheries and aquaculture in reservoirs in the study area. Routine monitoring of inorganic As species and other contaminants in water is needed to assess the full extent of arsenic risk at the site following closure.

Lability of toxic elements in Submarine Tailings Disposal: The relationship between metal fractionation and metal uptake by sandworms (Alitta virens)

Mine tailings from the iron ore mine Sydvaranger Gruve have been deposited in Bøkfjorden, Northern Norway, for >40 years. This study investigates the environmental impacts of submarine tailings disposal one year after the cessation of the mine by combining analyses of total metal concentrations (nitric acid digestion) and metal fractionation patterns (sequential extraction procedure) of sediments with the metal uptake (bioassays) by sandworms (Alitta virens) exposed to Bøkfjorden sediment. The analyses focused on metals (As, Cd, Cr, Cu, Fe, Ni, Pb, Zn) in sediment cores retrieved from a horizontal transect of the fjord. High concentrations of the target metal iron was found in the fjord (>13,000 mg/kg). According to Norwegian sediment quality guidelines (SQG), cadmium (2.55 mg/kg) and lead (174 mg/kg) were the only metals to exceed good sediment quality at the source area of mine tailings discharge. Despite general low total metal concentrations, labile (summarized exchangeable, acid soluble, reducible fractions) and potentially labile (summarized labile and oxidisable fractions) pools of mine tailings-related metals of cadmium (10-82%), copper (25-88%) and lead (10-67%) were detected while iron were characterized as inert (residual fraction: 89-97%). Despite spatial trends in total metal concentrations presumed to originate from mine tailings (Cd, Cu, Fe, Pb), there were no correlations between total and labile fractions. This can be explained by the high concentrations of iron, which under oxidised forms are suggested to inhibit a high lability of other metals. The metal uptake of sandworms was generally high compared to similar studies and exceeded moderate contamination classes for all metals compared to Norwegian standard values. Both labile metal fractions (cadmium, copper and iron) and total metal concentrations (copper, iron) showed positive correlations (r > 0.6) with metal uptake. Thus, both the total and labile metal fractions can pose an environmental risk.

Effects of mine tailings exposure on early life stages of atlantic cod

In Norway, mine tailings waste can be deposited by coastal submarine dispersal. Mine tailings slurry includes fine particles <10 µm with elevated levels of metals (e.g., copper, iron) from residual mineral ore. Prolonged suspension of small particles in the water column may bring them into contact with locally spawned pelagic fish eggs, including Atlantic cod, Gadus morhua. Newly fertilized cod embryos were exposed to suspended mine tailings particles up to 3.2 mg/L in flow-through aquaria for a total of 21 d. Significantly more particles adhered to the surface of the chorion from the high treatment after 11-d exposure, and dissolved Cu concentrations increased in the water (up to 0.36 ± 0.06 µg/L). There was no adverse effect on embryo mortality but an 8% elevation in larval mortality. There were no differences with treatment on timing of hatching, embryo and larva morphometrics, abnormalities, or cardiac activity. There was a treatment-dependent up-regulation of stress marker genes (hspa8, cyp1c1) but no indication of metal-induced activation of metallothionien (mt gene transcription). Transcription markers for DNA and histone methyltransferases did show treatment-related up-regulation, indicative of altered methylation in larvae when developmental methylation patterns are determined, indicating some level of chronic toxicity that may have longer-term effects. Environ Toxicol Chem 2019;38:1446-1454. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Chemical contaminants entering the marine environment from sea-based sources: A review with a focus on European seas

Anthropogenic contaminants reach the marine environment mostly directly from land-based sources, but there are cases in which they are emitted or re-mobilized in the marine environment itself. This paper reviews the literature, with a predominant focus on the European environment, to compile a list of contaminants potentially released into the sea from sea-based sources and provide an overview of their consideration under existing EU regulatory frameworks. The resulting list contains 276 substances and for some of them (22 antifouling biocides, 32 aquaculture medicinal products and 34 warfare agents) concentrations and toxicity data are additionally provided. The EU Marine Strategy Framework Directive Descriptor 8, together with the Water Framework Directive and the Regional Sea Conventions, provides the provisions against pollution of marine waters by chemical substances. This literature review should inform about the current state of knowledge regarding marine contaminant sources and provide support for setting-up of monitoring approaches, including hotspots screening.

High mobility group protein DSP1 negatively regulates HSP70 transcription in Crassostrea hongkongensis

HSP70 acts mostly as a molecular chaperone and plays important roles in facilitating the folding of nascent peptides as well as the refolding or degradation of the denatured proteins. Under stressed conditions, the expression level of HSP70 is upregulated significantly and rapidly, as is known to be achieved by various regulatory factors controlling the transcriptional level. In this study, a high mobility group protein DSP1 was identified by DNA-affinity purification from the nuclear extracts of Crassostrea hongkongensis using the ChHSP70 promoter as a bait. The specific interaction between the prokaryotically expressed ChDSP1 and the FITC-labeled ChHSP70 promoter was confirmed by EMSA analysis. ChDSP1 was shown to negatively regulate ChHSP70 promoter expression by Luciferase Reporter Assay in the heterologous HEK293T cells. Both ChHSP70 and ChDSP1 transcriptions were induced by either thermal or CdCl2 stress, while the accumulated expression peaks of ChDSP1 were always slightly delayed when compared with that of ChHSP70. This indicates that ChDSP1 is involved, very likely to exert its suppressive role, in the recovery of the ChHSP70 expression from the induced level to its original state. This study is the first to report negative regulator of HSP70 gene transcription, and provides novel insights into the mechanisms controlling heat shock protein expression.