Abstract: Copper has a dual role for organisms, both as micronutrient and toxic element. Copper mining activities have an enormous ecological impact because of the extraction process and the consequent release of copper-containing waste materials to the environment. In northern Chile, mainly in the Chanaral coastal area, this phenomenon is clearly evident. The released waste material has caused a strong modification of the area, and copper enrichment of beaches and rocky shores has provoked a decrease in the richness and diversity of many species of macroorganisms. However, the effects that copper enrichment has on microbial (e.g. bacterial epilithic) communities associated with the rocky shore environment are poorly understood. Using a culture-independent molecular approach, field sampling and laboratory microcosm experiments, we determined the effects of copper enrichment on bacterial communities inhabiting the rocky shore environment. Field samples showed a strong effect of copper on the structure of the natural bacterial epilithic communities, and microcosm experiments demonstrated rapid changes in bacterial community when copper is added, and reversibility of this effect within 48 h after copper is removed.

Abstract: Geographically widely spread species can cope with environmental differences among habitats by genetic differentiation and/or phenotypic flexibility. In marine crustaceans, intraspecific variations in life-history traits are pervasive along latitudinal clines. Replicated latitudinal clines are of evolutionary interest because they provide evidence of the occurrence of natural selection. If the means of traits along the latitudinal gradient are expected to be the result of natural selection, there is no reason why variances and covariances will not also be subject to selection, since selection is essentially a multivariate phenomenon. We studied life-history changes in means, variances, and covariances (i.e. P matrix) in 6 populations of the endemic crab Cyclograpsus cinereus (Decapoda: Grapsidae) along a latitudinal gradient over 19 degrees on the Chilean coast. Trait means differed among localities for all traits analyzed (i.e. female size, number and size of eggs, and reproductive output), and the variation displayed a clinal pattern. In general, the main result that emerged from planned comparisons of P matrices is that, when detected, differences between localities mainly reflect differences in the magnitude of phenotypic variation (i.e. eigenvalues), rather than in the relationships between traits (i.e. eigenvectors). Sea-surface temperature was only correlated with the covariance between egg numbers and reproductive output. Matrices comparisons for Flury and jackknife methods were highly linked, with limits of biogeographic provinces described for the coast of Chile. Our study strongly highlights the importance of estimating the P matrix, not only mean values, in order to understand the evolution of life-history traits along a latitudinal gradient. Furthermore, the study of the variation in the P matrix might provide important insights into those evolutionary forces acting on it.

Abstract: Stability is a central property of complex systems and encompasses multiple dimensions such as resistance, resilience, recovery, and invariability. How these dimensions correlate among them is focus of recent ecological research, but empirical evidence at regional scales, at which conservation decisions are usually made, remains absent. Using a field-based manipulative experiment conducted in two marine intertidal regions, we analyze the correlations among different aspects of stability in functioning (community cover) and composition of local communities facing a press disturbance. The experiment involved the removal of the local space-dominant species for 35 months in eight sites under different environmental regimes in northern- and southern-central Chile (ca. 30 and 40 degrees S, respectively). After the disturbance, the magnitude of the initial responses and the recovery patterns were similar among communities dominated by different species, but varied between the functional and compositional response variables, and among four dimensions of stability. The recovery trajectories in function and composition remained mostly uncorrelated across the system. Yet, larger initial functional responses were associated with faster recovery trajectories-high functional resilience, in turn, was associated with both, high and low variability in the pattern of recovery. Finally, the compositional stability dimensions were independent from each other. The results suggest that varying community compositions can perform similar levels of functioning, which might be the result of strong compensatory dynamics among species competing for space in these communities. Knowledge of several, and sometimes independent, aspects of stability is mandatory to fully describe the stability of complex ecological systems.