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The high levels of contamination in aquatic ecosystems caused by pesticides and the organisms' consequent continuous exposure to it has made them vulnerable to damage. However, mobile organisms can avoid this continued exposure to contaminants by moving to less disturbed habitats. Therefore, through the use of the Heterogenous Multi-Habitat Assay System (HeMHAS), our objective was to evaluate the ability of Daphnia magna to detect and avoid habitats contaminated by fipronil and 2,4-D, in a spatially connected landscape. Further, the role of contamination by these pesticides, isolated and in mixtures, concerning the colonization of habitats by daphnids was also evaluated. Given that not all organisms successfully escape contamination, the chronic toxicity of the same pesticides using different parameters for D. magna (maternal survival, fecundity and maternal body length) was also evaluated. When evaluating the avoidance response by D. magna exposed to pesticides, there was no preference for the less contaminated areas for both compounds. However, organisms did not move to contaminated zones in the colonization experiments, with no immigration of daphnids to the zones with intermediate and the highest levels of fipronil, nor to the highest concentration of 2,4-D. Finally, the colonization by daphnids was significantly prevented when exposed to a mixture of the pesticides, in which the areas with the highest combinations of pesticide concentrations were not colonized by D. magna. Regarding the long-term chronic effects, negative consequences were observed, particularly for maternal body length, fecundity and maternal survival, due to the exposure to fipronil. Considering that pesticides can limit the areas colonized by organisms by making them unattractive, the risk of local population extinction may be underestimated if only standard endpoints involving forced exposure are studied.

As the exposure of organisms to contaminants can provoke harmful effects, some organisms try to avoid a continuous exposure by using different strategies. The aim of the current study was to assess the ability of the shrimp Palaemon varians to detect a triclosan gradient and escape to less contaminated areas. Two multi-compartmented exposure systems (the linear system and the HeMHAS-Heterogeneous Multi-Habitat Assay System) were used and then results were compared. Finally, it was aimed how sensitive the avoidance response is by comparing it with other endpoints through a sensitivity profile by biological groups and the species sensitive distribution. The distribution of the shrimps along the triclosan gradient was dependent on the concentrations, not exceeding 3% for 54 μg/L in the linear system and 7% for 81 μg/L in the HeMHAS; 25% of organisms preferred the compartment with the lowest concentrations in both systems. Half of the population seems to avoid concentrations around 40–50 μg/L. The triclosan concentration that might start (threshold) to trigger an important avoidance (around 20%) was estimated to be of 18 μg/L. The profile of sensitivity to triclosan showed that avoidance by shrimps was less sensitive than microalgae growth and avoidance by guppy; however, it might occur even at concentrations considered safe for more than 95% of the species. In summary, (i) the HeMHAS proved to be a suitable system to simulate heterogeneous contamination scenarios, (ii) triclosan triggered the avoidance response in P. varians, and (iii) the avoidance was very sensitive compared to other ecotoxicological responses., C.V.M. Araújo is grateful to the Spanish Ministry of Science, Innovation and Universities for the Juan de la Cierva (IJCI-2014-19318) and Ramón and Cajal (RYC-2017-22324) contracts. M. Hampel benefits from a Ramón and Cajal contract (RYC-2012-12217) from the Spanish Ministry for Economy and Competitiveness. This study was funded by the Spanish Ministry of Science, Innovation and Universities, Spain (Explora Project: #CGL2017-92160-EXP) and the Ministry for Economy and Competitiveness in the framework of the project HORACIO (CTM2015-70731-R).

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). Dissolution processes affect the form and concentration of AgNPs in both environments. Dissolution of Ag from AgNPs was around 25 times higher in marine water. Nevertheless, dissolution of AgNPs in both culture media seems to be related to the small size and higher surface area of NPs. In marine water, the main chemical species were AgCl2− (53.7%) and AgCl3−2 (45.2%). In contrast, for freshwater, the main chemical species were Ag+ (26.7%) and AgCl− (4.3%). The assessment of toxicological responses, specifically growth, cell size, cell complexity, chlorophyll a, reactive oxygen species, cell membrane damage and effective quantum yield of PSII, corroborated the existence of different toxicity mechanisms for microalgae. Indirect effects, notably dissolved Ag ions, seem to control toxicity to freshwater microalgae, whereas direct effects, notably attachment onto the cell surface and the internalization of AgNPs inside cells, seem to determine toxicity to the marine species studied. This research contributes to knowledge on the role of intrinsic and extrinsic factors in determining the behavior of NPs in different aquatic environments and the interaction with microalgae., This research has been funded by the Junta de Andalucía (PE2011-RNM-7812 project and FQM-110 group) and the Spanish National Research Plan (CTM2012-38720-C03-03 and Project MINECO/FEDER MAT2013-40823-R).

A major weakness in evaluating the suitability of a biomonitor organism is the poor ability to predict the variability of the bioavailability of metals from measured environmental concentrations. In this study, the intertidal gastropod Hydrobia ulvae was used to evaluate its suitability as a test organism for assessing sediment metal toxicity. Toxicity tests were run with sediments spiked with copper, cadmium and zinc applied both as single metal and as a mixture to investigate toxicological interactions evaluating different lethal and sublethal effects. Dose-response relationships were constructed based both on tissue residue approach and particulate metal concentrations. Because metal-spiked sediments used in routine toxicity tests often do not exhibit the same adsorption/desorption kinetics as the natural sediments, the laboratory results were compared to 10-d bioassays conducted with natural field sediments collected from the Guadalete estuary (SW Spain). Highly significant correlations between tissue residue concentrations and particulate metal concentrations were found for all metal-spiked or field-collected and demonstrated that: (i) H. ulvae readily accumulated copper and cadmium in response to contamination and (ii) dietary uptake was determined to be the most significant route of metal exposure. The comparison of the modeled tissue residue-response curve developed from the mixture tests was in good agreement with the results from the bioassay conducted with field sediments and strongly demonstrated that H. ulvae is also a suitable test organism for assessing copper sediment toxicity. In contrast, the dose-response curve expressed as a function of total particulate metal concentrations would fail in predicting effect, erroneously assessing higher metal toxicity. © 2013 Elsevier Ltd., This research was partially funded by the Junta de Andalucia but this Agency was not involved in the research design, analysis or interpretation of data, writing process or in the decision to submit the paper for publication.

The individual and combined toxicities of acetaminophen, carbamazepine, diclofenac and ibuprofen have been examined in neonate nauplii (, This research was funded by the Spanish National Research Plan (MINECO)CTM2012-38720-C03-03.

7 páginas, 2 figuras, 3 tablas., Cylindrotheca closterium cells were maintained at low temperature (4 ± 1 °C) and dark conditions up to 21 weeks to assess the effect on survival and physiological status. From a control culture under standard conditions, three densities were prepared: (A) 2 × 104, (B) 10 × 104, and (C) 25 × 104 cells ml−1. Weekly, inoculums of each stored density were exposed to continuous light and at 20 ± 1 °C. Sensitivity to copper for microalgal cultures was evaluated in order to assess possible changes in cells sensitivity due to storage. Concurrently, assays with a control culture were carried out in order to assess the sensitivity of C. closterium to copper and to be able to generate a standard sensitivity control chart with a mean value of EC50-72 h ± 2SD (standard deviation). Density-C presented higher cell yield values, between 40% and 80% relative to control culture. Cell density showed to be important feature that may be taken into account in cell storage experiments. There was an increase in sensitivity of cells submitted to storage; however results always kept in the range established as standard sensitivity with no statistically significant difference with regards to control culture. EC50-72 h mean value for the control culture was 29 ± 10 μg Cu l−1, while for densities-A, B and C were 22 ± 7; 23 ± 9 and 23 ± 8 μg Cu l−1, respectively. In spite of drastic changes in the environmental conditions due to storage, it is concluded that C. closterium cells stored during 5 months remained metabolically active and with no significant change in its sensitivity., This work has been funded by the Spanish Ministry of Science and Education (project MECASEC: CTM2006-01437/MAR).

The relationship between bioaccumulation of heavy metals (Zn, Cd, Pb and Cu) and histological lesions in different tissues of organisms is assessed in three different areas located in the southwest of Spain in the Gulf of Cadiz (Ria of Huelva, Guadalquivir estuary and Bay of Cadiz) affected and non-affected by mining activities. Data included in these relationships were obtained along the years 2000 and 2001 to address the impact of the Aznalcollar mining spill on the Guadalquivir estuary. The bioaccumulation and the histological lesions measured in this seasonal study in the Gudalquivir estuary were linked to derive tissue quality guidelines (TQGs) by means of a multivariate analysis approach (MAA). Sediments collected in the same areas of study were used to expose organisms during the survey carried out in autumn 2001 and to address the relationship between bioaccumulation and histological lesions under laboratory conditions and related to chemicals bound to sediments. Lesions show that the organisms collected in the ria of Huelva and exposed to their sediments were severe, intermediate in the Guadalquivir estuary and absent in the Bay of Cadiz. Results show that the Guadalquivir estuary trends to recover its initial status quo previous to the mining spill. The link between chemical concentration and the lesions measured in the same tissues using MAA permits to derive tissue quality guidelines for two organisms, oysters (Crassostrea angulata) and clams (Scrobicularia plana) collected in the Guadalquivir estuary and associated with the heavy metals from the mining spill (Zn and Cd). The TQG values expressed as concentrations (mg kg−1––dry weight) not associated with biological effects are for oysters, Zn, 8603, Cd, 3.42; and for clams Zn, 800, Cd, 2.6.

The bioaccumulation of six metals (Fe, Mn, Zn, Cd, Pb and Cu) was studied as part of the monitoring of the Aznalcóllar mining spill (April 1998) on the Guadalquivir estuary and in other estuaries located in the Gulf of Cádiz. Fish, clams and oysters were collected during different seasonal periods along the years 2000 and 2001 in the Guadalquivir estuary to determine the bioaccumulation of the metals originated by the mining spill. Results were compared to the bioaccumulation of the same metals in fish and clams exposed in the laboratory to sediments collected in the same areas during autumn 2001. The bioaccumulation of these metals was compared to the concentration of metals measured in tissues of same taxas collected in the areas of the ria of Huelva and the Bay of Cádiz. Results show that the bioaccumulation of Zn and Cd in the organisms sampled in the Guadalquivir estuary was associated with the enrichment of these metals in the estuary from the mining spill and decreased along the time reaching the lowest values in autumn 2001. The metal Cu show different trends that are associated with other sources of contamination than the spill and related to the transport of this metal from Huelva to Guadalquivir estuary and/or to the use of this metal as plaguicide in the rice fields located in the area. The comparison between bioaccumulation results under field and laboratory conditions obtained in the different areas of study shows that these data can be used to discriminate between acute and chronic impacts associated with mining activities.