Due to the ecological importance of estuaries, it is necessary to understand the biological effects that potentially toxic contaminants induce in bioindicator species. A key aspect is whether effects at lower levels of biological organisation transfer through the system to higher levels. In understanding such processes, characterising multivariate relationships between contaminants, sediment toxicities and detoxification processes are important. Worms (Hediste diversicolor) and sediments were collected along the Humber Estuary, England, and inorganic and organic contaminants were quantified. Sediment toxicities and glutathione S-transferases (GSTs) activity in the ragworm were analysed. Concentrations of metals were highest near urban and industrial areas, whereas organic contaminants appeared at upstream locations. GST activity correlated with heavy metals. The genotoxicity, estrogenicity, dioxin and dioxin-like activity were higher at upstream locations. Estrogenicity correlated with alkylphenols and some organochlorines, whilst genotoxicity correlated with organochlorines and heavy metals. Despite this, higher level biological responses could not be predicted, indicating that homeostasis is operating.

Changes in the structure and dynamics of sandy beach macrofaunal populations result from the simultaneous action of local and regional factors acting synergistically. This is particularly noticeable in transitional interfaces between freshwater and marine ecosystems, where large-scale gradients affect local beach morphodynamics and resident fauna. The wedge clam Donax hanleyanus occurs on beaches with contrasting morphodynamics along the salinity gradient generated by the Rio de la Plata estuary. We conducted sampling surveys to determine a fine-grained comprehensive coverage of the species’ distribution in Uruguay to assess the concurrent effects of large-scale variations in salinity and local beach morphodynamics on wedge clam populations along 400 km (16 sandy beaches) over 2 yr. The main factor controlling wedge clam occurrence was salinity, overriding the effects of local habitat features. On beaches where the species was present, total abundance was higher on oceanic dissipative shores, which also harbored a higher abundance and relative representation of recruits. Recruitment was almost lacking in reflective beaches. However, biomass of adults with larger body sizes prevailed on reflective beaches, suggesting a scaling of abundance to body size and potential density-dependent effects. In this metapopulation, estuarine beaches are sinks, whereas oceanic beaches act as source habitats. We concluded that large-scale gradients generated by salinity variations translated into local population patterns (distribution, abundance and population structure) and processes (recruitment), which were secondarily driven by local morphodynamics. The relative importance of pre- and post-settlement processes across the morphodynamic spectrum from reflective to dissipative beaches has yet to be elucidated.

Integrated step-selection analyses(ISSAs) are frequently used to study animal movement and habitat selection. Methods for incorporating random effects in ISSAs have been developed, making it possible to quantify variability among animals in their space-use patterns. Although it is possible to model variability in both habitat selection and movement parameters, applications to date have focused on the former despite the widely acknowledged and important role that movement plays in determining ecological processes from the individual to ecosystem level. One potential explanation for this omission is the absence of readily-available software or examples demonstrating methods for estimating movement parameters in ISSAs with random effects.To demonstrate methods for characterizing among-individual variability in both movement and habitatselection parameters, we fit two models to an acoustic telemetry data set involving locations of 35 red snapper (Lutjanus campechanus). In the first model, the distribution of snapper step lengths and turn angles were assumed to depend on a categorical habitat variable indicating the type of benthic habitat the fish was located in at the start of the movement step. In the second model, step lengths and turn angles were assumed to depend on a continuous variable measuring the distance between the fishes’ current location and nearest edge habitat. In both models, we also quantified habitat selection for different benthic habitat classes and distance to edge habitat at the end of the movement step.There was substantial among-individual variability in both habitat selection and movement parameters. Nonetheless, most red snapper selected for high-relief hardbottom habitat and for locations nearer to edge habitat. They also moved less when in high-relief hardbottom habitat or when they were close to reef edges. Turn angles were frequently near ±π, but were more dispersed when fish were far away from edge habitat.We provide code templates and functions for quantifying variability in movement and habitat-selection parameters when implementing ISSAs with random effects. In doing so, we hope to encourage ecologists conducting ISSAs to take full advantage of their ability to model among-individual variability in both habitat-selection and movement patterns.

Resumen: las acciones y omisiones del presente en materia de política forestal pueden clarificarse si se revisan los antecedentes históricos. Por ello, el objetivo de esta investigación fue analizar la influencia del contexto internacional sobre las políticas forestales implementadas durante el régimen de Porfirio Díaz. Se amplía el panorama sobre las de uso y conservación de los bosques, así como sus repercusiones en San Luis Potosí. Para contextualizar los procesos mencionados, se realizó una consulta exhaustiva de documentos históricos y bibliográficos, y se encontró que el entorno internacional incentivó la creación de leyes e instituciones federales y locales para regular la explotación, el manejo y la conservación de los bosques. A pesar de ello, en esta entidad hubo una reducción importante en sus superficies boscosas; además, el gobierno federal y estatal no evidenció un interés por preservarlas.Palabras clave: conservación de bosques; políticas forestales; explotación forestal; conservación del medio ambiente; deforestación; porfiriato; San Luis Potosí. Forest policies in the state of San Luis Potosi in the PorfiriatoAbstract: current actions and omissions in forest policy can be clarified if the historical background is reviewed. Therefore, the objective of this research is to analyze the influence of the international context on forest policies implemented during the regime of Porfirio Diaz (1876-1911). In particular, it aims to broaden the outlook on government policies created for the management, use and conservation of forests and their impacts on San Luis Potosí. A thorough consultation of historical and bibliographical documents was made to understand the historical processes. It was found that the international environment encouraged the creation of laws, regulations and federal and local institutions for the purpose of regulating the exploitation, management and conservation of forests. However, the state of San Luis Potosi experienced a significant reduction in their forest areas; in addition, the federal and state governments showed no interest in applying conservation of forests in Potosi territory.Key words: conservation of forests; forest policies; forest exploitation; environmental conservation; deforestation; Porfiriato period; San Luis Potosi.

Environmental gradients and wastewater discharges produce aggregated effects on marine populations, obscuring the detection of human impact. Classical assessment methods do not include environmental effects in toxicity tests designs, which could lead to incorrect conclusions. We proposed a modified Whole Effluent Toxicity test (mWET) that includes environmental gradients in addition to effluent dilutions, together with the application of Generalized Linear Mixed Models (GLMM) to assess and decouple those effects. We tested this approach, analyzing the lethal effects of wastewater on a marine sandy beach bivalve affected by an artificial canal freshwater discharge used for rice crops irrigation. To this end, we compared bivalve mortality between canal water dilutions (CWd) and salinity controls (SC: without canal water). CWd were prepared by diluting the water effluent (sampled during the pesticide application period) with artificial marine water. The salinity gradient was included in the design by achieving the same final salinities in both CWd and SC, allowing us to account for the effects of salinity by including this variable as a random factor in the GLMM. Our approach detected significantly higher mortalities in CWd, indicating potential toxic effects of the effluent discharge. mWET represents an improvement over the internationally standardized WET tests, since it considers environmental variability and uses appropriate statistical analyses.