[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA | International audience | This study evaluates the combined effects of two contaminants (copper and a herbicide S-metolachlor) and temperature on the early life stages of the Pacific oyster Crasssotrea gigas,which is native to Arcachon Bay (southwest France). The responses of D-larvae, obtained fromwild and cultivated oysters,were investigated for one year during the oyster breeding period at different sampling sites and compared with the response of D-larvae from a commercial hatchery. Embryotoxicity was measured by considering the percentage of abnormal D-shaped larvae. Normal development of embryos occurred only from 22 °C to 26 °C. There were synergistic effects of copper at low and high temperatures. Native oysters appear particularly sensitive to an increase in water temperature, suggesting a future increase in the percentage of larval abnormalities as a result of global climate change. Hatchery oysters represent a good alternative model for studying the effects of both pollutants and climate change stressors.

This study evaluates the combined effects of two contaminants (copper and a herbicide S-metolachlor) and temperature on the early life stages of the Pacific oyster Crasssotrea gigas, which is native to Arcachon Bay (southwest France). The responses of D-larvae, obtained from wild and cultivated oysters, were investigated for one year during the oyster breeding period at different sampling sites and compared with the response of D-larvae from a commercial hatchery. Embryotoxicity was measured by considering the percentage of abnormal D-shaped larvae. Normal development of embryos occurred only from 22°C to 26°C. There were synergistic effects of copper at low and high temperatures. Native oysters appear particularly sensitive to an increase in water temperature, suggesting a future increase in the percentage of larval abnormalities as a result of global climate change. Hatchery oysters represent a good alternative model for studying the effects of both pollutants and climate change stressors.

International audience | Abstract Nanomaterials are increasingly being used to improve the properties and functions of common building materials. A new type of self-cleaning cement incorporating TiO2 nanomaterials (TiO2-NMs) with photocatalytic properties is now marketed. This promising cement might provide air pollution-reducing properties but its environmental impact must be validated. During cement use and aging, an altered surface layer is formed that exhibits increased porosity. The surface layer thickness alteration and porosity increase with the cement degradation rate. The hardened cement paste leaching behavior has been fully documented, but the fate of incorporated TiO2-NMs and their state during/after potential release is currently unknown. In this study, photocatalytic cement pastes with increasing initial porosity were leached at a lab-scale to produce a range of degradation rates concerning the altered layer porosity and thickness. No dissolved Ti was released during leaching, only particulate TiO2-NM release was detected. The extent of release from this batch test simulating accelerated worst-case scenario was limited and ranged from 18.7 ± 2.1 to 33.5 ± 5.1 mg of Ti/m2 of cement after 168 h of leaching. TiO2-NMs released into neutral aquatic media (simulate pH of surface water) were not associated or coated by cement minerals. The TiO2-NM release mechanism is suspected to start from freeing of TiO2-NMs in the altered layer pore network due to partial cement paste dissolution followed by diffusion into the bulk pore solution to the surface. The extent of TiO2-NM release was not solely related to the cement degradation rate.

Nanomaterials are increasingly being used to improve the properties and functions of common building materials. A new type of self-cleaning cement incorporating TiO2 nanomaterials (TiO2-NMs) with photocatalytic properties is now marketed. This promising cement might provide air pollution-reducing properties but its environmental impact must be validated. During cement use and aging, an altered surface layer is formed that exhibits increased porosity. The surface layer thickness alteration and porosity increase with the cement degradation rate. The hardened cement paste leaching behavior has been fully documented, but the fate of incorporated TiO2-NMs and their state during/after potential release is currently unknown. In this study, photocatalytic cement pastes with increasing initial porosity were leached at a lab-scale to produce a range of degradation rates concerning the altered layer porosity and thickness. No dissolved Ti was released during leaching, only particulate TiO2-NM release was detected. The extent of release from this batch test simulating accelerated worst-case scenario was limited and ranged from 18.7 ± 2.1 to 33.5 ± 5.1 mg of Ti/m2 of cement after 168 h of leaching. TiO2-NMs released into neutral aquatic media (simulate pH of surface water) were not associated or coated by cement minerals. The TiO2-NM release mechanism is suspected to start from freeing of TiO2-NMs in the altered layer pore network due to partial cement paste dissolution followed by diffusion into the bulk pore solution to the surface. The extent of TiO2-NM release was not solely related to the cement degradation rate.

International audience

peer reviewed | Anthropogenic particles (APs), including microplastics, are ingested by a wide variety of marine organisms. Exposure of Clupeiformes (e.g. herrings, anchovies, sardines) is poorly studied despite their economic and ecological importance. This study aims to describe the morphology of the filtration apparatus of three wild-caught Clupeiformes (Sardina pilchardus, Clupea harengus and Engraulis encrasicolus) and to relate the results to ingested APs. Consequently, the species with the more efficient filtration apparatus will be more likely to ingest APs. We hypothesized that sardines were the most exposed species. The filtration area and particle retention threshold were determined in the three species, with sardines displaying the highest filtration area and the closest gill rakers. Sardines ingested more fibers and smaller fragments, confirming that it is the most efficient filtering species. These two results lead to the conclusion that, among the three studied, the sardine is the species most exposed to APs.

International audience | The replenishment and persistence of marine species is contingent on dispersing larvae locating suitable habitat and surviving to a reproductive stage. Pelagic larvae rely on environmental cues to make behavioural decisions with chemical information being important for habitat selection at settlement. We explored the sensory world of crustaceans and fishes focusing on the impact anthropogenic alterations (ocean acidification, red soil, pesticide) have on conspecific chemical signals used by larvae for habitat selection. Crustacean (Stenopus hispidus) and fish (Chromis viridis) larvae recognized their conspecifics via chemical signals under control conditions. In the presence of acidified water, red soil or pesticide, the ability of larvae to chemically recognize conspecific cues was altered. Our study highlights that recruitment potential on coral reefs may decrease due to anthropogenic stressors. If so, populations of fishes and crustaceans will continue their rapid decline; larval recruitment will not replace and sustain the adult populations on degraded reefs.

peer reviewed | The replenishment and persistence of marine species is contingent on dispersing larvae locating suitable habitat and surviving to a reproductive stage. Pelagic larvae rely on environmental cues to make behavioural decisions with chemical information being important for habitat selection at settlement. We explored the sensory world of crustaceans and fishes focusing on the impact anthropogenic alterations (ocean acidification, red soil, pesticide) have on conspecific chemical signals used by larvae for habitat selection. Crustacean (Stenopus hispidus) and fish (Chromis viridis) larvae recognized their conspecifics via chemical signals under control conditions. In the presence of acidified water, red soil or pesticide, the ability of larvae to chemically recognize conspecific cues was altered. Our study highlights that recruitment potential on coral reefs may decrease due to anthropogenic stressors. If so, populations of fishes and crustaceans will continue their rapid decline; larval recruitment will not replace and sustain the adult populations on degraded reefs.

The replenishment and persistence of marine species is contingent on dispersing larvae locating suitable habitat and surviving to a reproductive stage. Pelagic larvae rely on environmental cues to make behavioural decisions with chemical information being important for habitat selection at settlement. We explored the sensory world of crustaceans and fishes focusing on the impact anthropogenic alterations (ocean acidification, red soil, pesticide) have on conspecific chemical signals used by larvae for habitat selection. Crustacean (Stenopus hispidus) and fish (Chromis viridis) larvae recognized their conspecifics via chemical signals under control conditions. In the presence of acidified water, red soil or pesticide, the ability of larvae to chemically recognize conspecific cues was altered. Our study highlights that recruitment potential on coral reefs may decrease due to anthropogenic stressors. If so, populations of fishes and crustaceans will continue their rapid decline; larval recruitment will not replace and sustain the adult populations on degraded reefs.