Microplastics do not affect standard ecotoxicological endpoints in marine unicellular organisms.

In this study, the acute toxicity of microplastics (MPs) on unicellular organisms as marine decomposers and microalgae was assessed, by evaluating standards endpoints included in International Standard Organization (ISO) protocols. The bacteria Vibrio fischeri and the diatom Phaeodactylum tricornutum were exposed to different sizes (1-500 μm) of polyethylene MPs in order to evaluate bioluminescence inhibition and microalgal growth. No acute toxicity was found on bacteria or microalgae in an order of magnitude above environmentally relevant concentrations, suggesting that tested MPs did not affect the investigated biological processes.

Might the interspecies interaction between fish and shrimps change the pattern of their avoidance response to contamination?

Contamination seems to exert a crucial role in the spatial distribution of some organisms, such as shrimps and fish. Both, especially the freshwater fish Danio rerio and the shrimp Atyaephyra desmarestii, have been tested experimentally for their avoidance response and have showed the ability to escape from toxic effects. As the behavior of avoiding or not the contamination might be altered in the presence of other factors, the aim of the current study was to verify whether the avoidance response of both species, when exposed jointly (multispecies tests), to a copper gradient is different from the avoidance response observed in monospecies tests.

Biochemical response of the clam Ruditapes philippinarum to silver (AgD and AgNPs) exposure and application of an integrated biomarker response approach.

Silver is a ubiquitous metal in the marine environment which can be accumulated by marine organisms. In order to assess the effect of dissolved silver (AgD) and AgNPs in R. philippinarum, the organisms were exposed to 20 μg L of AgD and AgNPs (15 nm) over 7 days.

Does the previous exposure to copper alter the pattern of avoidance by zebrafish in a copper gradient scenario? Hypothesis of time-delayed avoidance due to pre-acclimation.

The traditional ecotoxicity assays (forced exposure) tend to use organisms that are cultured under controlled conditions or that come from undisturbed ecosystems, with no (or negligible) previous contact with contamination. The same occurs in the non-forced approach, in which organisms are exposed to a contamination gradient and can move between different concentrations choosing the less toxic one. Considering that organisms inhabiting contaminated ecosystems tend to be gradually exposed to contamination, an abrupt exposure from uncontaminated conditions to a contaminated environment might present two problems: lack of ecological relevance to a scenario where the contamination occurs gradually and a magnification of the toxicity due to the sudden change in the environmental conditions.

Avoidance behaviour of the shrimp Palaemon varians regarding a contaminant gradient of galaxolide and tonalide in seawater.

The musk fragrances galaxolide (HHCB) and tonalide (AHTN) are compounds of emerging concern that have been found in various environmental compartments. The present study addressed the ability of HHCB and AHTN to elicit the avoidance response in the estuarine shrimp Palaemon varians and to predict the population immediate decline (PID) of P. varians when exposed to HHCB and AHTN by integrating both avoidance (non-forced exposure) and lethality (forced exposure) responses.

Are the primary characteristics of polystyrene nanoplastics responsible for toxicity and ad/absorption in the marine diatom Phaeodactylum tricornutum?

Nowadays, the occurrence of a large volume of plastic litter in oceanic and coastal zones has increased concern about its impacts on marine organisms. The degradation of plastic polymers leads to the formation of smaller fragments at both micro and nano scale (<5 mm and <1 μm respectively). Nanoplastics (NPs), due to their smaller size and high specific surface area can establish colloidal interactions with marine microalgae, therefore potential toxicity can be led.

Disturbance of ecological habitat distribution driven by a chemical barrier of domestic and agricultural discharges: An experimental approach to test habitat fragmentation.

Contamination is an important factor for determining the pattern of habitat selection by organisms. Since many organisms are able to move from contaminated to more favorable habitats, we aimed to: (i) verify if the contamination along the river Guadalete (Spain) could generate a chemical barrier, restricting the displacement of freshwater shrimps (Atyaephyra desmarestii) and (ii) discriminate the role of the contaminants concerning the preference response by the shrimps. A.

Spatial avoidance, inhibition of recolonization and population isolation in zebrafish (Danio rerio) caused by copper exposure under a non-forced approach.

Aquatic ecosystems receive run-off and discharges from different sources that lead to the accumulation of contaminants such as copper. Besides producing lethal and sub-lethal effects, copper has shown to be aversive to zebrafish (Danio rerio) by triggering avoidance response. The primary aim of the present study was to evaluate how a copper gradient could affect the spatial distribution of D.

Erythromycin sensitivity across different taxa of marine phytoplankton. A novel approach to sensitivity of microalgae and the evolutionary history of the 23S gene.

Erythromycin has been recorded in coastal waters and could pose a severe threat to marine microbial life. Macrolides such as erythromycin may affect microalgae by inhibiting the pathways involved in protein synthesis. Toxicological testing of microalgae has proven to be a useful tool for the risk assessment of a substance affecting phytoplankton.

Effect of erythromycin and modulating effect of CeO NPs on the toxicity exerted by the antibiotic on the microalgae Chlamydomonas reinhardtii and Phaeodactylum tricornutum.

Erythromycin is an antibiotic employed in the treatment of infections caused by Gram positive microorganisms and the increasing use has made it a contaminant of emerging concern in aqueous ecosystems. Cerium oxide nanoparticles (CeO NPs), which are known to have catalytic and antioxidant properties, have also become contaminants of emerging concern. Due to the high reactivity of CeO NPs, they can interact with erythromycin magnifying their effects or on the other hand, considering the redox potential of CeO NPs, it can alleviate the toxicity of erythromycin.

Stress-driven emigration in complex field scenarios of habitat disturbance: The heterogeneous multi-habitat assay system (HeMHAS).

Lines of evidence used in ecological risk assessment (ERA) are essentially three: chemistry, biology and ecotoxicology. Until now, the fundamental assumption made when measuring ecological risks is that organisms are forcedly exposed to stressors. However, when organisms can avoid disturbed habitats by escaping to less stressful areas, the assumption that exposure is mandatory to pose risk may not match field disturbance scenarios.

Stressor-driven emigration and recolonisation patterns in disturbed habitats.

Although essential to conservation, little is known about how stress intensity can provoke emigration from disturbed habitats and allow recolonisation of those same environments. To demonstrate the applicability of laboratory experiments, we tested two hypotheses empirically using zebrafish response to artificially polluted environments that exhibited a linear gradient of stressor (acid mine drainage) levels. We hypothesized that emigration is distance-independent but time-correlated (spacelessness hypothesis).

Influence of interspecific interactions on avoidance response to contamination.

An increasing number of studies have shown the ability of organisms to escape from toxic effects due to contamination, by moving spatially towards less contaminated habitats. However, this issue has been investigated in monospecific scenarios, without considering possible interactions between species during the contamination avoidance process. It is widely known that the spatial distribution of one species can be affected by another one, in different ways.

A novel approach to assessing environmental disturbance based on habitat selection by zebra fish as a model organism.

Aquatic ecotoxicity assays used to assess ecological risk assume that organisms living in a contaminated habitat are forcedly exposed to the contamination. This assumption neglects the ability of organisms to detect and avoid contamination by moving towards less disturbed habitats, as long as connectivity exists. In fluvial systems, many environmental parameters vary spatially and thus condition organisms' habitat selection.

Cytotoxicity of CeO nanoparticles using in vitro assay with Mytilus galloprovincialis hemocytes: Relevance of zeta potential, shape and biocorona formation.

Over the last decades, the growth in nanotechnology has provoked an increase in the number of its applications and consumer products that incorporate nanomaterials in their formulation. Metal nanoparticles are released to the marine environment and they can interact with cells by colloids forces establish a nano-bio interface. This interface can be compatible or generate bioadverse effects to cells.

Bisphenol risk in fish exposed to a contamination gradient: Triggering of spatial avoidance.

Bisphenol A (BPA) is an emerging contaminant widely used in various industrial products. Sublethal toxicity of BPA on aquatic organisms is expected to occur at a concentration of around 500 μg L, which is much higher than environmentally realistic concentrations found in water bodies (up to 0.41 μg L).

Habitat fragmentation caused by contaminants: Atrazine as a chemical barrier isolating fish populations.

Information on how atrazine can affect the spatial distribution of organisms is non-existent. As this effect has been observed for some other contaminants, we hypothesized that atrazine-containing leachates/discharges could trigger spatial avoidance by the fish Poecilia reticulata and form a chemical barrier isolating upstream and downstream populations. Firstly, guppies were exposed to an atrazine gradient in a non-forced exposure system, in which organisms moved freely among the concentrations, to assess their ability to avoid atrazine.

Are the TiO NPs a "Trojan horse" for personal care products (PCPs) in the clam Ruditapes philippinarum?

In recent years, increasing quantities of personal care products (PCPs) are being released into the environment. However, data about bioaccumulation and toxicity are scarce; and extraction and analytical approaches are not well developed. In this work, the marine clam Ruditapes philippinarum, selected as model organism, has been employed to investigate bioaccumulation, antioxidant enzyme activities and DNA damage due to exposure to TiO nanoparticles and bulk TiO (inorganic compounds that are frequent components of PCPs, plastics, paints and coatings, foods and disinfectant water treatments).

Potential effects of triclosan on spatial displacement and local population decline of the fish Poecilia reticulata using a non-forced system.

Triclosan (TCS) is an emerging contaminant of concern in environmental studies due to its potential adverse effects on fish behavior. Since avoidance has been shown to be a relevant behavioral endpoint, our aims were: (i) to determine if TCS is able to trigger an avoidance response in Poecilia reticulata; (ii) to predict the population immediate decline (PID) caused by TCS exposure, by integrating lethality and avoidance responses; and (iii) to verify the overestimation of risk when mortality is assessed under forced exposure. Fish were exposed to TCS in a forced exposure system, to assess mortality, and to a TCS gradient in a non-forced exposure (NFE) system.

Toxicity of TiO, in nanoparticle or bulk form to freshwater and marine microalgae under visible light and UV-A radiation.

Use of titanium dioxide nanoparticles (TiO NPs) has become a part of our daily life and the high environmental concentrations predicted to accumulate in aquatic ecosystems are cause for concern. Although TiO has only limited reactivity, at the nanoscale level its physico-chemical properties and toxicity are different compared with bulk material. Phytoplankton is a key trophic level in fresh and marine ecosystems, and the toxicity provoked by these nanoparticles can affect the structure and functioning of ecosystems.

Direct and indirect effects of silver nanoparticles on freshwater and marine microalgae (Chlamydomonas reinhardtii and Phaeodactylum tricornutum).

The last decade has seen a considerable increase in the use of silver nanoparticles (AgNPs), which are found in many every-day consumer products including textiles, plastics, cosmetics, household sprays and paints. The release of those AgNPs into aquatic environments could be causing ecological damage. In this study we assess the toxicity of AgNPs of different sizes to two species of microalgae, from freshwater and marine environment (Chlamydomonas reinhardtii and Phaeodactylum tricornutum respectively).

Homoagglomeration and heteroagglomeration of TiO, in nanoparticle and bulk form, onto freshwater and marine microalgae.

TiO nanoparticles (TiO NPs) are employed in many products (paints, personal care products, especially sunscreens, plastics, paper, water potabilization and food products) and are then released into the environment from these products. These nanoparticles present potential risk to freshwater and marine microalgae. The primary toxicity mechanism is adsorption between NPs and microalgae (heteroagglomeration); however, studies of interactions of this kind are scarce.

CeO NPs, toxic or protective to phytoplankton? Charge of nanoparticles and cell wall as factors which cause changes in cell complexity.

CeO nanoparticles (CeO NPs) are well-known for their catalytic properties and antioxidant potential. Recent uses in therapy are based on the Ce ions released by CeO NPs. Reactions involving redox cycles between Ce and Ce oxidation stage seem to promote scavenging of reactive oxygen species (ROS), thus protecting cells from oxygen damage.

Effects of TiO nanoparticles and sunscreens on coastal marine microalgae: Ultraviolet radiation is key variable for toxicity assessment.

Given the large numbers of sunbathers on beaches, sunscreen compounds are being released into the coastal aquatic environment in significant amounts. Until now the effect of these potential pollutants on microbiota has been not well-known. Phytoplankton is a key component of the microbiota community.