Abstract Biomarkers of environmental contamination have been frequently used in the assessment of marine ecosystem quality because they provide quantitative measures of biological changes in organisms exposed to pollutants such as hydrocarbons from oil spills. Polychaetes have been tested as sentinel organisms of marine environmental health because they are abundant taxa of benthic assemblages and their sedentary lifestyle ensures chronic exposure to toxins in impacted areas. In this study, we evaluated whether the polychaete Scolelepis goodbodyi can be used as a reliable sentinel species for exposure to polycyclic aromatic hydrocarbons (PAHs) from an experimental diesel spill in a dissipative sand beach in the Southern Atlantic. The design used in this study comprised replicated control and diesel impact sites sampled four times (one, two, four and seven days) before and after the impact. Total PAH levels reached 114.0 ng g -1 in the impact site one day after the diesel spill; however, the pattern of biomarker responses in S. goodbodyi was primarily influenced by spatial variation rather than being attributed to the simulated diesel spill. The apparent absence of a contaminating effect may be linked to the low levels of the toxins retained in the sediment after the spill was simulated to elicit a response or to the presence of an efficient repair system within the organism. Furthermore, the sediments tested in this study, composed of sandy fractions, had a low capacity to concentrate PAHs after the simulated diesel spill, which may have contributed to the low significant changes in their biomarker activities. Based on our results, further studies testing other Polychaeta species and simulating oil spills in sedimentary environments composed of fine sediments such as salt marshes and mangroves may help produce evidence on more effective biomarker responses in these organisms. areas (PAHs Atlantic one, (one two days 1140 114 0 114. 1 - however S organism Furthermore fractions activities results 11

A protocol using the computer program Adobe Photoshop CS2 (version 9.0) is proposed for determining the level of herbivory on intact and consumed leaves, using mangroves as an example. The usual manual methods consist of drawing the leaf on graph paper, restoring the original shape in cases of damaged edges. The computerized methods are intended to accelerate the leaf measurement time with applications, digitalization equipment, and portable area measurers that are more efficient, faster, and more economically viable than the manual methods. The need to restore the edges of the consumed leaves is an obstacle to all methodologies. Nonetheless, the reconstruction of the consumed foliar edges is shown to be more realistic with Adobe Photoshop, as this allows a better fit to the original shape of the leaf. Moreover, this application allows the use of compacted files such as JPEG, permitting a simple, rapid, and precise method for determining the levels or rates of foliar herbivory

Se propone un protocolo de utilización del programa computacional Adobe Photoshop CS2, versión 9,0, para la determinación de los niveles de herbivoría en hojas intactas y consumidas, tomando como ejemplo árboles de manglar. Los métodos manuales usuales consisten en el dibujo de la forma de la hoja en papel milimetrado, restaurando el formato original en caso que tenga los márgenes damnificados. Los métodos computacionales tienen como objetivo acelerar el tiempo de medición de la hoja con aplicativos, digitalizadores y medidores de áreas portátiles, que son más eficientes, veloces y económicamente viables que los manuales. La necesidad de restaurar los bordes de las hojas ya consumidas es un obstáculo en todas las metodologías. Sin embargo, la reconstrucción de los márgenes foliares consumidos se mostró más realista en el Adobe Photoshop por posibilitar un mayor ajuste al formato original de la hoja. Además, esta aplicación soporta la utilización de archivos compactados, como el formato JPEG, posibilitando un método sencillo, rápido y preciso para la determinación de los niveles o tasas de herbivoría foliar