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En este trabajo se caracteriza y evalúa una secuencia de enseñanza aprendizaje orientada al estudio de la Naturaleza de la Ciencia (NdC) en profesores de secundaria en formación, la cual se ha implementado en el Máster en Educación Secundaria de la Universidad de Cádiz en las especialidades de Física y Química y Biología y Geología. El diseño de la secuencia ha partido de la experiencia acumulada desde la implantación del MAES (2009-2010), teniendo en cuenta distintos principios de diseño entre los que se encuentra la adopción como referentes de aprendizajes de los acuerdos sobre NdC encontrados en la literatura. Un cuestionario abierto y una actividad final de reflexión metacognitiva han sido, entre otros, los instrumentos empleados para analizar la evolución en las visiones sobre la ciencia de los participantes. Un primer análisis cualitativo sugiere que la secuencia permite la progresión de las visiones de la ciencia de solo una parte de los alumnos, pero esta progresión se ve beneficiada por la actividad final reflexiva de autorregulación.

espanolEnsenar ciencias desde una vision constructivista implica atender las concepciones previas de quien aprende. En este sentido, en el presente trabajo se analizan las concepciones que mantienen estudiantes de los Programas en Educacion Primaria e Infantil sobre tres aspectos: la imagen de la ciencia, su aprendizaje y su ensenanza. Para explorarlas se utilizo el instrumento denominado Inventario de Creencias Pedagogicas y Cientificas de Profesores, de tipo Likert, constituido por 56 declaraciones y que fue completado por 142 estudiantes de dos universidades espanolas, ambos al inicio y al final de asignaturas cuatrimestrales disenadas desde una perspectiva constructivista y de promocion de la alfabetizacion cientifica. Los datos se analizaron estadisticamente, entre otros, mediante analisis multivariante Traza de Pillai, univariante, y correlacion de Pearson. Los resultados muestran que las concepciones iniciales de estos estudiantes evolucionaron hacia posiciones constructivistas tras implementar las propuestas didacticas, particularmente en los del Grado en Educacion Primaria, quienes partieron de posiciones mas tradicionales. Se evidencian ademas relaciones entre las distintas dimensiones consideradas, excepto entre la imagen de la ciencia y su aprendizaje. Se concluye que la implementacion de propuestas didacticas de corte constructivista y enfocadas a promover la alfabetizacion cientifica permite que los futuros docentes evolucionen hacia modelos de aprendizaje y ensenanza de las ciencias adecuados, a la vez que se diagnostica una mayor dificultad a la hora de abordar aspectos relacionados con la imagen de la ciencia. EnglishFrom a constructivist perspective, science teaching involves attending to learners’ misconceptions. In this regard, in the present work, we analyze misconceptions of preservice teachers of Preschool and Primary School Education on three aspects: the image of science, science learning, and science teaching. To explore them we used the Inventory on Pedagogical and Scientific Beliefs of Teachers (Inventario de Creencias Pedagogicas y Cientificas de Profesores), a quantitative Likert-type questionnaire constituted by 56 statements. A total of 142 students from two Spanish universities completed it, both at the beginning and at the end of subjects that had been specifically designed from a constructivist perspective and to promote scientific literacy. Data were statistically analyzed, among others, employing multivariate analyses, univariate analyses, and Pearson correlations. Results show that initial student misconceptions evolved towards constructivist positions after subjects’ implementations, particularly those of students of Degree in Primary Education, who departed from more traditional positions. Moreover, relationships among the three considered dimensions are evidenced, except between the image of science and science learning. It is concluded that implementation of constructivist didactic proposals aimed to promote scientific literacy facilitates that initial pre-service teachers’ beliefs evolve towards appropriate science teaching and learning models. Moreover, difficulties to approach images of science are diagnosed. portuguesEnsinar ciencias com perspectiva construtivista implica atender as preconcepcoes do aluno. Nesse sentido, o presente trabalho analisa as concepcoes que apresentam os alunos do curso de Educacao Infantil e Fundamental sobre tres aspectos: a imagem da ciencia, sua aprendizagem e seu ensino. Para estuda-los, foi utilizado o instrumento Inventario de Crencas Pedagogicas e Cientificas do Professor, tipo Likert, composto por 56 depoimentos e preenchido por 142 estudantes de duas universidades espanholas, tanto no inicio quanto no final de quatro meses de disciplinas planejadas sob uma perspectiva construtivista e de promover a alfabetizacao cientifica. Os dados foram analisados ​​estatisticamente, entre outros, por analise multivariada de tracos de Pillai, univariada e correlacao de Pearson. Os resultados mostram que as concepcoes iniciais desses estudantes evoluiram para posicoes construtivistas apos a implementacao das propostas didaticas, principalmente na Licenciatura em Educacao Primaria, que partiam de posicoes mais tradicionais. Os relacionamentos tambem sao evidentes entre as diferentes dimensoes consideradas, exceto entre a imagem da ciencia e seu aprendizado. Conclui-se que a implementacao de propostas didaticas de natureza construtivista e focada na promocao da alfabetizacao cientifica permite que futuros professores evoluam para modelos apropriados de aprendizagem e ensino de ciencias, diagnosticando uma maior dificuldade em abordar aspectos relacionados a imagem da ciencia.

In this study, we analyzed the descriptive knowledge and mental models of the phenomenon of tides manifested by 111 preservice primary teachers. The instrument employed is an open-ended questionnaire, analyzed by means of an approach that explores the descriptions, explanations, and predictions in respect of this phenomenon by our subjects. First, we made a descriptive study of the kinds of ideas applied across different dimensions of analysis, and, subsequently, a cluster analysis was performed to check how those ideas were articulated and modeled. By means of this analysis, we were able to identify the mental models underlying the responses of preservice primary teachers. Furthermore, the results showed that the models they did have were not used when it came to making predictions in local situations. Instead, they employed heuristic rules based on everyday assumptions, not always consistent with tidal cycles of approximately 12 h. However, faced with situations that required thinking on a global scale, they did use their models, normally based on alternative conceptions. Lastly, from the results obtained, we consider some of the possible difficulties that preservice primary teachers may have in learning about the phenomenon of tides, and the implications for future teaching-learning designs aimed at overcoming those difficulties., Contract grant sponsor: Spanish Ministry of Science, Innovation, and Universities. R&D EDU2017-82518-P.

[Resumen] La argumentación es una competencia que se debería trabajar de manera explícita y con profundidad en los procesos de enseñanza-aprendizaje de las ciencias. El propósito de este trabajo es evaluar la calidad de los argumentos que presentan futuros maestros de primaria en una actividad de una propuesta didáctica de corte argumentativa. La actividad fue un debate y la controversia sociocientífica trabajada “¿son las telefonías móviles perjudiciales para la salud?”. La información recogida procedió de la argumentación individual. Éstas se analizaron utilizando el método de cluster, basado en el modelo de análisis s de argumentación de Toulmin. Los resultados muestran que la mayoría del alumnado se encuentra en niveles medios de argumentación. Un documento técnico sobre el pensamiento crítico y un blog fueron las fuentes más útiles para formar la opinión del alumnado. Consideramos la necesidad de seguir avanzando desde el ámbito universitario el desarrollo de propuestas en esta dirección. [Abstract] To be able to expose an argument is a task that should be deeply covered during the teachinglearning process. The purpose of this paper is to evaluate the quality of the arguments presented by future primary school teachers in a socio-scientific debate activity. The proposed activity object of the experimentation was based on the question: ‘are the mobile telephone antennas tower a risk for your health?’. The information was collected through individual reports that were analyzed using a cluster method applying the Toulmin’s argument pattern. The results show us a level medium most of the students. A technical paper on critical thinking and a blog were the most useful sources for forming student opinion. We consider the necessity to continue reinforcing the development of experiences in the direction of the proposed activity in graduate programs.

Resumen En este trabajo se demarcan, en primer lugar, distintos elementos característicos de los enfoques de enseñanza mediante modelización a partir de una revisión de la bibliografía existente. En segundo lugar, se analiza mediante los mismos una propuesta didáctica constituida por un total de 29 actividades y planteada para el estudio del sistema Sol-Tierra, concretamente del fenómeno de las estaciones, con maestros de educación primaria en formación inicial. Se trataba de comprobar en qué medida el diseño seguido podría situarse dentro del marco de enseñanza por modelización, y extraer de ahí sus fortalezas y debilidades que permitan una mejora del contenido y la estructura. Abstract This paper presents, first a different characteristic elements based on the approach of educational modelling throughout a bibliography review. Secondly, a didactic proposal consisting of a total of 29 activities was analyzed. This proposal was proposed for the study of Sun and Earth but specially in the seasons phenomenon, with teachers in starting level from primary school. The experience tried to demonstrate, how the following design would be integrated in to the education by modelling, and in consequence extract the weaknesses and strength to improve the contents and its structure. Resumo Neste trabalho distinguimos, em primeiro lugar, distintos elementos característicos das abordagens de ensino através da modelagem de acordo com uma revisão da bibliografia existente. Em segundo lugar, é analisada uma proposta didática composta por um total de 29 atividades e criadas para o estudo do sistema Sol-Terra, mais especificamente do fenômeno das estações, com professores do ensino primário em formação inicial. O objetivo era verificar em que medida a proposta seguida poderia ser colocada no quadro do ensino por modelagem e extrair pontos fortes e fracos que permitam uma melhoria no conteúdo e estrutura do mesmo.

Se presenta una investigación sobre las experiencias de aprendizaje de las ciencias de los maestros/as en formación inicial de dos universidades españolas. Se recogieron 263 relatos de vida entre estudiantes de Grado en Educación Infantil y Primaria -a partes iguales en que narraban sus vivencias en las etapas de Infantil, Primaria y Secundaria, y también en entornos no académicos. Estos relatos se analizaron cualitativamente, mediante la definición de categorías y subcategorías de contenido, y cuantitativamente, mediante el recuento de la frecuencia de aparición de fragmentos clasificados en ellas. Se presentan resultados respecto a contenidos, recursos, aproximaciones metodológicas, aspectos subjetivos y aprendizaje en entornos no académicos. Estos evidencian la necesidad de promover, desde la formación inicial de maestros/as, experiencias de aprendizaje de las ciencias enmarcadas en un modelo constructivista, que impliquen un papel protagonista del estudiante, el uso de metodologías activas y de contextos de aprendizaje distintos al aula. We present a research on science learning experiences of initial teacher training students at two Spanish universities. We collected 263 life-stories among students of Degree in Preschool and Primary Education -equal halves-, where students explained their experiences at Preschool, Primary and Secondary Education, and at non-academic contexts. These life-stories were qualitatively analyzed, by defining content categories and subcategories, and also quantitatively analyzed, by counting the frequency of appearance of fragments classified within them. We present results regarding contents, didactic resources, methodological approaches, subjective aspects, and learning at non-academic contexts. These clearly show the need to promote, from initial teacher training, science learning experiences framed in a constructivist model involving a leading role of students, and the use of active methodologies and learning contexts other than the classroom.

En este artículo se analizan, en primer lugar, algunas de las principales bases teóricas sobre las que se sustentan los enfoques de enseñanza de las ciencias centrados en los modelos, desde tres planos distintos: el epistemológico, el cognitivo y el didáctico. A partir de dichas bases, se caracterizan, en segundo lugar, los enfoques de enseñanza mediante modelización, los cuales vienen convirtiéndose hoy día en referentes importantes en la enseñanza de las ciencias, tanto desde el punto de vista del desarrollo de nuevas estrategias didácticas, como desde la perspectiva de líneas de investigación emergentes en didáctica de las ciencias.This article analyses in the first place, some of the main theoretical bases on which, approaches of science teaching focussed models, are sustained. These theoretical bases are considered from three different dimensions: epistemological, psychological and educational. From these bases, secondly, teaching approaches by modelling, which are becoming today in important reference in science teaching, are characterized not only as the point of view of the development of new didactic strategies, but also the perspective of emerging research lines in science education.

espanolEl proposito del presente articulo es utilizar la fotografia como herramienta didactica que propicie el analisis y reflexion hacia actitudes, destrezas y nociones medioambientales en la etapa de infantil. Para ello elaboramos una propuesta didactica en base a la estrategia de resolucion de problemas socioambientales; utilizamos la deforestacion como eje central para mas adelante tratar aspectos mas concretos que puedan llevarse al aula como es el consumo de papel. Una cuestion a tener en cuenta en el uso de fotografias es la importancia de emplear imagenes cercanas al nino ya que son las que van a producir un mayor interes e implicacion en el tema que se este tratando. Por tanto, la fotografia puede utilizarse como recurso educativo por presentar un potente componente motivador, fundamental en todo proceso de ensenanza-aprendizaje. Ademas, la etapa de infantil se trata de un momento idoneo para iniciar la educacion ambiental, de manera que los ninos y ninas empiecen a tomar conciencia de que sus actos conllevan unas repercusiones en el medio donde viven, reflexionen sobre el consumo de los recursos naturales y propongan posibles soluciones. EnglishThe proposal of this article is to use photography as a didactical tool that promotes both analysis and reflection towards attitudes, skills and environmental knowledge in the primary school phase. We have thus elaborated a didactical proposal based upon the strategy of resolving socio-environmental problems. We shall use deforestation as a central theme so as to later treat more specific themes applicable to the classroom such as the use of paper. One question to keep in mind with the use of photography is the importance of using images that are close to the child’s personal experience as these will cause a greater implication in the themes to be treated. For this reason, photography can be used as an educative resource in that it is a potential motivator, fundamental in all educative processes. Also, the first years of primary school are ideal moments to initiate an environmental education, so that children can begin to be aware of how their acts have consequences upon their own environment. This will cause them to reflect on how they consume natural resources and make them think about new solutions.

En este artículo se investigan las opiniones de 169 alumnos del Grado de Educación Primaria sobre la utilidad de varios modelos analógicos empleados en su formación sobre el fenómeno de las estaciones. Para ello, al finalizar la experiencia de aprendizaje sobre dicho tópico, se les administró un cuestionario al objeto de valorar sus percepciones al respecto. En él, se contemplaron dos variables: el modelo concreto evaluado y la población a la que va dirigido (maestros frente a alumnos de primaria). Los resultados obtenidos mostraron niveles de valoración que iban de moderados a altos. Además, la variabilidad de las respuestas se explicaba mejor a partir de la idiosincrasia del modelo evaluado que en función del tipo de sujeto destinatario. No obstante, no siempre la intencionalidad didáctica depositada por el docente en cada recurso fue adecuadamente percibida por los participantes., In this paper the opinions of 169 students of the Degree of Primary Education, about the usefulness of various analogic models used in their training in the phenomenon of the seasons, has been investigated. With this purpose, a test was used in order to evaluate the perceptions of the participants just to finalize a curricular unit on that topic that used analogic models. Two factors were considered for the data reported. One being, the specific model evaluated and if this learning process is centred on teachers or primary students. The results showed scores ranging from moderate to high. In addition, the variability of responses was better explained due to the analogy models’ characteristics rather than the subjects to which the models are targeted. However, the didactic intention of each resource was not always properly perceived by the participants., En aquest article s'investiguen les opinions de 169 alumnes del Grau d'Educació Primària sobre la utilitat de diversos models analògics empleats en la seva formació sobre el fenomen de les estacions. Per a això, en finalitzar l'experiència d'aprenentatge sobre dita tòpica, se'ls va administrar un qüestionari a fi de valorar les seves percepcions sobre aquest tema. En ell, es van contemplar dues variables: el model concret avaluat i la població a la qual va dirigit (mestres enfront d'alumnes de primària). Els resultats obtinguts van mostrar nivells de valoració que anaven de moderats a alts. A més, la variabilitat de les respostes s'explicava millor a partir de la idiosincràsia del model avaluat que en funció del tipus de subjecte destinatari. No obstant això, no sempre la intencionalitat didàctica dipositada pel docent en cada recurs va ser adequadament percebuda pels participants.

The capture and storage of CO2 in sub-seabed geological formations has been proposed as one of the potential options to decrease atmospheric CO2 concentrations in order to mitigate the abrupt and irreversible consequences of climate change. However, it is possible that CO2 leakages could occur during the injection and sequestration procedure, with significant repercussions for the marine environment. We investigate the effects of acidification derived from possible CO2 leakage events on the European green crab, Carcinus maenas. To this end, a lab-scale experiment involving direct release of CO2 was conducted at pH values between 7.7 and 6.15. Female crabs were exposed for 10 days to sediment collected from two different coastal areas, one with relatively uncontaminated sediment (RSP) and the other with known contaminated sediment (MZ and ML), under the pre-established seawater pH conditions. Survival rate, histopathological damage and metal (Fe, Mn, Cu, Zn, Cr, Cd and Pb) and As accumulation in gills and hepatopancreas tissue were employed as endpoints. In addition, the obtained results were compared with the results of the physico-chemical characterization of the sediments, which included the determination of the metals Fe, Mn, Cu, Zn, Cr, Pb and Cd, the metalloid As, certain polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), as well as nonchemical sediment properties (grain size, organic carbon and total organic matter). Significant associations were observed between pH and the histological damage. Concentrations of Fe, Mn, Cr, Pb, Cd and PAHs in sediment, presented significant negative correlations with the damage to gills and hepatopancreas, and positive correlations with metal accumulation in both tissues. The results obtained in this study reveal the importance of sediment properties in the biological effects caused by possible CO2 leakage. However, a clear pattern was not observed between metal accumulation in tissues and pH reduction. Animals' avoidance behavior and degree of tolerance to acidification are confounding factors for assessing metal bioaccumulation. Further research is required to find a suitable assay that would allow us to predict the risk to environmental health of possible negative side effects of metal mobility derived from CO2 leakage during its injection and storage in sub-seabed formations., This work was supported by grants from Spanish Ministerio de Economía y Competitividad under grant reference CTM 2011-2843-CO2-02 and Andalusian Regional Government under grant reference RNM-3924 and Andalusian Research Plan (Ecotoxicology, Ecophysiology, and Biodiversity of Aquatic Systems Group, RNM306 EEBAS).

In November 2002, the oil spill from the tanker Prestige in the Galician Coast caused an ecological catastrophe in Spain. The adverse effects associated with the contaminants bound to sediments were tested using juveniles of the fish Sparus aurata (seabream). The approach evaluates sediment quality by using an integrated assessment including chemical and ecotoxicological data. Sediment samples were physicochemically characterized, and the concentration of contaminants (polycyclic aromatic hydrocarbons-(PAHs) and metals) was measured. Different biomarkers of exposure (metallothioneins and ethoxyresorufin O-deethylase activity (EROD)) and biomarkers of effect (histopathology) were analyzed along the time. A multivariate analysis approach was used to correlate concentration of contaminants and sublethal effects measured in individuals of fish. Results show that increasing concentrations of PAHs in sediments were related to increased EROD activities and histopathological lesions. This is the first evidence showing adverse effects associated with petroleum contamination of PAHs in sediments after this spill, and it demonstrates the utility of the sublethal toxicity tests for monitoring the impact of petroleum spills.

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.

The urgent need to minimize the potential harm deriving from global climate change and ocean acidification has led governmental decision-makers and scientists to explore and study new strategies for reducing the levels of anthropogenic CO2. One of the mitigation measures proposed for reducing the concentration of atmospheric CO2 is the capture and storage of this gas in subseabed geological formations; this proposal is generating considerable international interest. The main risk associated with this option is the leakage of retained CO2, which could cause serious environmental perturbations, particularly acidification, in marine ecosystems. The study reported is aimed at quantifying the effects of acidification derived from CO2 leakage on marine organisms. To this end, a lab-scale experiment involving direct release of CO2 through marine sediment was conducted using Ruditapes philippinarum as a model benthic organism. For 10 days bivalves were exposed to 3 sediment samples with different physicochemical characteristics and at pre-established pH conditions (8.0–6.1). End points measured were: survival, burrowing activity, histopathological lesions, and metal accumulation (Fe, Al, Mn, Cu, and Zn) in whole body. Correlations analyses indicated highly significant associations (P < 0.01) between pH and the biological effects measured in R philippinarum, except for metal concentrations in tissues. Further research to understand and predict the biological and economic implications for coastal ecosystems deriving from acidification by CO2 leakages is urgently needed., This work was funded by the Junta de Andalucı́a (Regional Government) under grant reference RNM-3924, and by the Spanish Ministerio de Economı́a y Competitividad under grant reference CTM 2011-2843-CO2-02.

The biology, growth and reproduction of the axillary seabream, Pagellus acarne, was studied based on data obtained from the catches of the Andalusia commercial fleet operating off the coasts of southern Spain from October 2003 to September 2004. The axillary seabream had a very wide depth distribution, appearing from the surface down to 500 m depth. The length–weight relationship was given by TW = 0.0048 TL3.3207 (R2 = 0.98) (TW = total weight; TL = total length) for all fish from the Gulf of Cadiz and TW = 0.0093 TL3.1132 (R2 = 0.94) for all fish from the Alboran Sea. The proportion of females to males increases as length increases in both populations and the species is characterized by protandric hermaphroditism. Spawning males were present almost throughout the year although higher percentages were observed in spring and early summer. In females, the spawning period occurred mainly in spring. In both areas, the mean size at first maturity for males was smaller than for females. The mean lengths at first maturity were 18.04 cm for males and 21.7 cm for females from the Gulf of Cadiz, and 17.7 cm and 20.1 cm for males and females from the Alboran Sea, respectively. The average total fecundity was estimated at 290,070 and 173,509 oocytes for Atlantic and Mediterranean individuals, respectively. The parameters of the von Bertalanffy growth model were estimated by age readings of the 247 sagitta collected. Two rings, one opaque and one hyaline, were laid down each year on the otoliths. The opaque zone was formed during spring and summer and the hyaline one during the remaining months of the year. The relationship between otolith radius and total length of the fish was described by the equation: TL = 27.7 OR – 1.8 (r = 0.96) (where OR = otolith radius). The parameters of the fitted Von Bertalanffy growth equation were L∞ = 31.65 cm, k = 0.21 yr−1 in the Gulf of Cadiz and L∞ = 32.14 cm, k = 0.17 yr−1 in the Alboran Sea., Sí

A chronic bioassay was carried out under laboratory conditions using juvenile Solea senegalensis to determine the toxicity of contaminants from an oil spill(Prestige). Also, the repair processes in fish affected by contaminants due to oil exposure were evaluated. Over 30 days individuals were exposed to clean sediment (control) and to sediment contaminated by a mixture of polyaromatic hydrocarbons (PAHs) and other substances. The physicochemical parameters of the tanks (salinity, temperature, pH and dissolved oxygen) were controlled during the exposure period. Clean sediment from the Bay of Cadiz (Spain) was used as negative control and was mixed with fuel oil to prepare the dilution (0.5% w:w dry-weight). After the exposure period, fish were labeled and transferred to "clean tanks" (tanks without sediment) in order to study the recovery and the repair processes in the exposed organisms. A biomarker of exposure (ethoxyresorufin-O-deethylase activity - EROD activity) and a biomarker of effect (histopathology) were analyzed during the exposure and recovery period. After 10, 20 and 30 days of exposure, individuals showed significant induction (P0.05) of the EROD activity and also presented diverse histopathological damages. The analysis of both the biomarkers of exposure and effect, after the 5th and 10th day of recovery in the "clean tank", enabled a first evaluation of the repair process of the induced damages due to the fuel oil exposure. After the recovery phase, control individuals showed a more significant decrease (P0.05) of the alteration of the measured biomarkers than in the oil-exposed fish. While in the oil-exposed fish the EROD activity showed some recovery, the histopathological damages did hardly improve. According to our results, tissue repair processes probably need longer recovery periods to observe significant improvement of the affected organs. This will be further investigated in the future.

The toxicity produced by fuel pollutants was evaluated through bioassays using the Senegalese sole Solea senegalensis. Juveniles were exposed for 21 days to different dilutions obtained by mixing fuel extracted from the Prestige oil tanker and sediment from a clean area of Cadiz Bay. After the exposure period, three biomarkers were analyzed (7-ethoxyresorufin-Odeethylase [EROD], glutathione S-transferase [GST], and glutathione reductase [GR] enzymatic activity), as well as the histopathology of two of the main target organs (gills and liver). Significant (P < 0.05) biomarker inductions were observed in the exposed fish analyzed on day 21 relative to the control group (day zero). Lesions were detected in both organs studied, but the liver was the most affected. The frequency of appearance of the lesions was greater in the samples containing higher concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals. The results showed significant correlations between the total PAH concentrations and GST, GR, and EROD enzymatic activity, with correlation coefficients of R = 0.96 for GST, R = 0.82 for GR, and R = 0.60 for EROD. Se evaluo la toxicidad que producen los contaminantes presentes en un fuel mediante un bioensayo con el pez plano Solea senegalensis (lenguado). Se expusieron juveniles de esta especie durante 21 dias a distintas diluciones realizadas mezclando fuel extraido del buque Prestige y un sedimento procedente de una zona limpia de la Bahia de Cadiz. Tras la exposicion se analizaron tres biomarcadores de exposicion (actividad enzimatica de 7-etoxiresorufin-O-deetilasa [EROD], glutation S-transferasa [GST] y glutation reductasa [GR]) junto a la histopatologia de dos de los principales organos diana (branquias e higado). Los resultados obtenidos mostraron inducciones significativas (P < 0.05) en los biomarcadores de exposicion analizados en los peces el dia 21 respecto del control del dia 0 en los peces. Asimismo, se detectaron lesiones en los dos organos estudiados. El organo mas afectado fue el higado. La frecuencia de aparicion de lesiones fue mayor en las muestras con mayores concentraciones de hidrocarburos aromaticos policiclicos (PAHs, por sus siglas en ingles) y metales. Los resultados obtenidos en este trabajo mostraron correlaciones significativas entre las concentraciones de PAHs totales y la actividad enzimatica EROD, GST y GR, obteniendose coeficientes de correlacion de R = 0.60 para EROD, R = 0.96 para GST y R = 0.82 para GR. Palabras clave: bioensayo, biomarcadores, ecotoxicologia, fuel, lenguado, sedimento.

More and more, the coastal regions of the world suffer from the contamination of petroleum hydrocarbon [principally polycyclic aromatic hydrocarbons (PAHs)]. This contamination can be acute, as it happened in the Coast of Galicia (NW, Spain) by the oil spill from a tanker, or chronic by the existence of high maritime traffic and a lot of industries as it is the case of the Bay of Algeciras (BA) (SW, Spain). It is of a great concern due to the toxicity, especially in sediments and ecosystem associated to it. The objective of this study is to assess, through chronic bioassay, sediment toxicity in samples collected in different littoral areas of Spain and to compare the damage caused in benthic fish, Solea senegalensis, according to that which suffers acute spill (Coast of Galicia) or chronic spill (the BA) by means of histopathology methods and enzymatic activities studies. Organisms were exposed to different sediments from Galician Coast and the BA during 42 days and every sample was analyzed by triplicate in glass aquaria. At the end of the bioassay, histopathological diseases were analyzed in the gills, target organ. Likewise, stress parameters as ethoxyresorufin-O-deethylase (EROD) and the glutathione S-transferases (GSTs) activities were determined in the liver. Results showed a significant positive correlation between the biomarkers of exposure (EROD and GST), biomarkers of effect (histopathology), and PAHs concentrations in the sediments.

The degree of contamination and toxicity in sediment from four Spanish ports (Cadiz, Huelva, Pasajes and Bilbao) was assessed in the present study. Two marine invertebrate species, the shore crab Carcinus maenas and the clam Ruditapes philippinarum, were exposed to the different sediments under laboratory conditions for 28 days. Relationships were developed among metal contamination (As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn) in sediments, metal accumulation in gill tissues and histopathological lesions in different biological tissues to assess sediment toxicity. A multivariate analysis approach was used to calculate sediment quality guidelines (SQGs) by linking metal concentration in sediments with histopathological lesions measured in the exposed organisms. The results showed significant contaminant accumulation and histopathological lesions due to As, Pb and Zn in sediments at the port of Huelva; As, Cr, Cu, Hg and Ni at the ports of Pasajes and Cadiz; and Cr and Hg at the port of Bilbao. The link between chemical concentration in sediments and histopathological lesions allowed the determination of SQGs for the chemicals As, Cd, Cu, Cr, Hg, Ni and Zn.

10 páginas, 4 figuras, 1 tabla., Sediments in the National Park of the Atlantic Islands (Galicia, Spain) were affected by the spill of the tanker Prestige (November, 2002) and still present high levels of Polycyclic aromatic hydrocarbons. The adverse effects associated with the contaminants in sediments were tested using a chronic bioassay, exposing juveniles of the fish Sparus aurata (seabream). A toxicokinetic approach is proposed to evaluate sediment quality by linking chemical and ecotoxicological data along the time. Sediment samples were physicochemically characterized and the concentration of contaminants (Polycyclic aromatic hydrocarbons – PAHs – and metals) was measured. Fishes were exposed to contaminated sediments, and samples from different tissues were collected every 15 days throughout the 60 days that lasted the experiment. A biomarker of exposure (ethoxyresorufin O-deethylase activity – EROD activity) and a biomarker of effect (histopathology) were analyzed during the exposure period. Results show a relationship between the biomarkers and the concentrations in sediments of polycyclic aromatic hydrocarbons—PAHs. Besides, the toxicokinetic approach links biomarkers response providing information about the relationship between the detoxification process and the damages observed in the different tissues. The frequency of the histological damage is highest when the EROD activity slightly decreases in accordance with the mechanism of detoxification of this enzymatic system against PAHs and other organic contaminants., The described work was partially supported by Grant funded by the Ministry of Education and Science VEM2003-20563. Carmen Morales Caselles was funded by the Ministerio de Ciencia y Tecnología (FPU) of Spain.

7 páginas, 4 figuras, 3 tablas., Sediment quality assessments for regulatory purposes (i.e. dredged material disposal) are characterized by linking chemical and acute ecotoxicological data. The design of chronic bioassays that incorporate more sensible endpoints than acute tests is discussed to address sediment quality for environmental quality assessment and regulatory proposes. The chronic tests use juveniles of commercial species of fish Sparus aurata and Solea senegalensis, to assess sediment toxicity in samples collected along different littoral areas in the North and the South of Spain. The organisms were exposed during 60 days and sublethal endpoints were selected including biomarkers of exposure to metals (metallothioneins — MTs) and to organic contaminants (ethoxyresorufin-O-deethylase activity — EROD activity) and biomarkers of effect (histopathology in different tissues, gill and liver). A Multivariate Analysis Approach was conducted in order to associate these biological responses with sediment metal concentration from the ports and with chemical residues in biological tissues exposed to sediments under laboratory conditions., The work was partially funded by the Spanish ministry for Development (BOE 13/12/2002) and Ministry for Science and Education (CTM2005-07282-C03-01/TECNO). Maria Jose Salamanca thanks the i3p program for her fellowship. Carmen Morales thanks MEC for her FPU fellowship.

The use of the histopathological alterations as a biomarker of effect in marine invertebrates has been widely included in the assessment of the quality of the marine environment. This biomarker may link the bioavailability of different compounds with the effect at target tissues and it has been successfully included in major national monitoring programmes. Nevertheless, this biomarker is still under a experimental stage. The present work critically reviews the advantages and limitations of the use of this biomarker: the methodology for its determination and its inclusion as a complementary tool for the marine pollution assessment in a Weight of Evidence (WOE) approach. Keywords: biomarkers; toxicity; weight of evidence; invertebrate diseases