Polybrominated diphenyl ethers (PBDEs) have been commonly used as flame retardants and now become ubiquitous in the global environment. Using zebrafish as a model, we tested the hypothesis that PBDEs may affect the reproduction and development of fish. Zebrafish were exposed to environmentally relevant concentrations of DE-71 (a congener of PBDE commonly found in the environment) throughout their whole life cycle, and the effects of DE-71 on gonadal development, gamete quality, fertilization success, hatching success, embryonic development and sex ratio were investigated. Despite gonadal development was enhanced, reductions in spawning, fertilization success, hatching success and larval survival rate were evident, while significant increases in malformation and percentage of male were also observed in the F1 generation. Our laboratory results suggest that PBDEs may pose a risk to reproductive success and alter the sex ratio of fish in environments highly contaminated with PBDEs.

Embryo toxicity of particles generated by combustion processes is of special concern for human health. A significant part of these toxic effects is linked to the binding of some pollutants (like polycyclic aromatic hydrocarbons or PAHs) to the Aryl hydrocarbon Receptor (AhR) and the activation of target genes, like the cytochrome P4501A. This activity was analyzed for ambient air and coal-combustion particle extracts in zebrafish embryos (the cyp1aDarT assay) and in two single-cell bioassays: the yeast-based YCM-RYA and the DR-luc (rat cells) assay. Observed AhR ligand activity of samples generally correlated to the predicted toxic effect according to their PAH composition, except for one of the coal combustion samples with an anomalously high activity in the cyp1aDarT assay. This sample induced deformities in zebrafish embryos. We concluded that the combination of morphological and molecular assays may detect embryonic toxic effects that cannot be predicted from chemical analyses or single-cell bioassays.

Little knowledge is available on impact of microplastics (MPs) on the bivalve larvae at different developmental stages throughout their life history, especially for metamorphic stage. Therefore, this study aims to evaluate the toxic responses of carboxylated (PS-COOH) and amino (PS-NH2) polystyrene MPs on the developing clam larvae at three key life stages, i.e., fertilized eggs, D-veliger larvae, and umbo larvae. PS-COOH and PS-NH2 significantly decreased the hatching rates by 5.79–39.5% and developmental rates by 4.78–7.86% of the clam larvae relative to the unexposed clam larvae. The toxicity of MPs followed the order: hatching stage > metamorphosis > D-veliger larvae stage, showing stage-dependent toxic effects. Moreover, PS-NH2 with a smaller hydrodynamic diameter showed a greater toxicity to the developing larvae compared to PS-COOH. Our study highlighted the stage-dependent toxic effects of MPs on the developing clam larvae, thus posing ecological risks to population succession of marine bivalves and aquatic ecosystems.

Hypoxia likely compromises the reproductive success of those marine organisms carrying out external fertilization because their gametes and embryos are inevitably exposed to the external environment. Hydroides elegans, a dominant serpulid polychaete in Hong Kong waters, can spawn throughout the year but the number of recruits drops during summer when hypoxia commonly occurs. This study attempted to explain such observation by investigating the gamete quality, including sperm motility, egg size, complexity and viability, after 1-h hypoxic exposure (1mg O2l−1). In addition, how gamete quality affects fertilization success and embryonic development was examined. After 1-h hypoxic exposure, sperm motility was significantly reduced, compromising fertilization success. Although the eggs remained viable, more malformed embryos and retarded embryonic development were observed. We interpreted that the harmful effect of hypoxia on embryonic development was attributed to the teratogenicity and induced oxidative stress, ultimately causing the reduction in recruitment during summer.

It is well known that mussels are exposed to microplastics but ingestion and potential effects on mussel larvae are not well understood. We quantified ingestion and egestion of 100 nm and 2 μm polystyrene beads in blue mussel larvae after 4 h exposure and 16 h depuration using different plastic-to-microalgae ratios. Effects on growth and development of mussel larvae were investigated at 0.42, 28.2 and 282 μgL−1 within 15 days of exposure. We found that, on a mass basis, larvae ingested a higher amount of 2 μm than 100 nm beads, while egestion was independent of particle size and the plastics-to-algae ratio. Although particle egestion occurred readily, microplastics remained inside the larvae. Larval growth was not affected but abnormally developed larvae increased after exposure to polystyrene beads. Malformations were more pronounced for 100 nm beads, at higher concentration and after longer exposure time.

Jakarta Bay has become contaminated by both organic and inorganic pollutants, including heavy metals. This study aimed to examine the effect of heavy metal pollution on green mussels cultured in Muara Kamal Waters, Jakarta Bay over seven months. In this research, the water quality was assessed, through measuring the concentrations of the heavy metals, Hg, Pb, Cd, Cr, and Sn in the water, and in the tissue of green mussels that had been cultured there for seven months. The percentage of congenital abnormalities (malformations) in the green mussels was analyzed descriptively and the relationship between the water quality, heavy metals, and green mussel malformation was studied through principal component analysis (PCA). The result showed that the heavy metals concentrations in the water and sediment exceeded the quality standard at Muara Kamal but that in other respects the water quality was quite good. The green mussels cultured there for seven months had accumulated high concentrations of heavy metals, and ±60% of them had malformations of their shells. Based on the heavy metal concentrations in their bodies, the main cause of malformations in green mussels was suspected to be Pb, Hg, and Sn. However, the result of PCA showed it was the interaction between nitrogen compounds, phosphate, turbidity, salinity, pH, as well as the heavy metals in the water that determined the green mussel abnormality.

Due to hydrophobic and persistent properties, polycyclic aromatic hydrocarbons (PAHs) have a high capacity to accumulate in sediment. Sediment quality criteria, for the assessment of habitat quality and risk for aquatic life, include understanding the fate and effects of PAHs. In the context of European regulation (REACH and Water Framework Directive), the first objective was to assess the influence of sediment composition on the toxicity of two model PAHs, benzo[a]pyrene and fluoranthene using 10-day zebrafish embryo-larval assay. This procedure was undertaken with an artificial sediment in order to limit natural sediment variability. A suitable sediment composition might be then validated for zebrafish and proposed in a new OECD guideline for chemicals testing. Second, a comparative study of toxicity responses from this exposure protocol was then performed using another OECD species, the Japanese medaka. The potential toxicity of both PAHs was assessed through lethal (e.g., survival, hatching success) and sublethal endpoints (e.g., abnormalities, PMR, and EROD) measured at different developmental stages, adapted to the embryonic development time of both species. Regarding effects observed for both species, a suitable artificial sediment composition for PAH toxicity testing was set at 92.5 % dry weight (dw) silica of 0.2-0.5-mm grain size, 5 % dw kaolin clay without organic matter for zebrafish, and 2.5 % dw blond peat in more only for Japanese medaka. PAH bioavailability and toxicity were highly dependent on the fraction of organic matter in sediment and of the K ow coefficients of the tested compounds. The biological responses observed were also dependent of the species under consideration. Japanese medaka embryos appeared more robust than zebrafish embryos for understanding the toxicity of PAHs following a sediment contact test, due to the longer exposure duration and lower sensitivity of sediment physical properties.

Due to hydrophobic and persistent properties, polycyclic aromatic hydrocarbons (PAHs) have a high capacity to accumulate in sediment. Sediment quality criteria, for the assessment of habitat quality and risk for aquatic life, include understanding the fate and effects of PAHs. In the context of European regulation (REACH and Water Framework Directive), the first objective was to assess the influence of sediment composition on the toxicity of two model PAHs, benzo[a]pyrene and fluoranthene using 10-day zebrafish embryo-larval assay. This procedure was undertaken with an artificial sediment in order to limit natural sediment variability. A suitable sediment composition might be then validated for zebrafish and proposed in a new OECD guideline for chemicals testing. Second, a comparative study of toxicity responses from this exposure protocol was then performed using another OECD species, the Japanese medaka. The potential toxicity of both PAHs was assessed through lethal (e.g., survival, hatching success) and sublethal endpoints (e.g., abnormalities, PMR, and EROD) measured at different developmental stages, adapted to the embryonic development time of both species. Regarding effects observed for both species, a suitable artificial sediment composition for PAH toxicity testing was set at 92.5 % dry weight (dw) silica of 0.2-0.5-mm grain size, 5 % dw kaolin clay without organic matter for zebrafish, and 2.5 % dw blond peat in more only for Japanese medaka. PAH bioavailability and toxicity were highly dependent on the fraction of organic matter in sediment and of the K ow coefficients of the tested compounds. The biological responses observed were also dependent of the species under consideration. Japanese medaka embryos appeared more robust than zebrafish embryos for understanding the toxicity of PAHs following a sediment contact test, due to the longer exposure duration and lower sensitivity of sediment physical properties.