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The coast of Chañaral Bay in northern Chile has been affected by copper mine wastes for decades. This sustained perturbation has disrupted the intertidal community in several ways, but the mechanisms behind the observed shifts in local biodiversity remain poorly understood. Our main goal was to identify the species (lumped into trophic groups) belonging to the Chañaral intertidal community that, being directly affected by copper pollution, contributed primarily to the generation of the observed changes in community structure. These groups of species were called initiators. We applied a qualitative modelling approach based only on the sign and direction of effects among species, and present a formula for predicting changes in equilibrium abundances considering stress on multiple variables simultaneously. We then applied this technique retrospectively to identify the most likely set of initiators. Our analyses allowed identification of a unique set of four initiators in the studied intertidal system (a group of algae, sessile invertebrates, a group of herbivores and starfish), which were hypothesized to be the primary drivers of the observed changes in community structure. In addition, a hypothesis was derived about how the perturbation affected these initiators. The hypothesis is that pollution affected negatively the population growth rate of both algae and sessile invertebrates and suppressed the interaction between herbivores and starfish. Our analytic approach, focused on identifying initiators, constitutes an advance towards understanding the mechanisms underlying human-driven ecosystem disruption and permits identifying species that may serve as a focal point for community management and restoration.

The study presented here searched for the level of taxonomic resolution required to detect the effects of low-level chronic pollution on estuarine meiobenthic communities. Meiofauna from two sites, with special attention to harpacticoid copepods, was analysed at different taxonomic levels of aggregation using uni- and multivariate methods. Adaptation processes that could buffer biodiversity disruptions were also considered through the analysis of fitness-related and tolerance traits in the harpacticoid copepod Paronychocamptus nanus. Results showed that uni- and multivariate analyses could be inadequate when assessing subtle anthropogenic contamination. Instead, the assessment of inter-population differences in tolerance to the main source of stress rises as a required procedure if potential effects of this type of contamination are being investigated. Specifically, a 96 h acute toxicity test performed with populations from the affected site appears as a faster and reliable general tool to assess impacts of low-level chronic pollution in estuaries.

Environmental gradients are common in nature, and geographically widespread species must cope with environmental differences between habitats. Environmental differences produce bio- geographic patterns that can involve morphological, physiological, and life-history traits. The Bergmann's rule has been described as one of these ecological and evolutionary patterns, predicting an increase in body size towards colder climates. Human-induced polluting events could impair the performance and/or fitness of exposed individuals and populations. Thus, we hypothesized that spe- cies undergoing exposure to pollutants will show a breakage of the natural biogeographical variation of their fitness-related life-history traits. In northern Chile, copper mine tailings have been dumped continuously for more than 60 yr. Because the snapping shrimp Betaeus emarginatus is commonly found in intertidal pools near this dumping site, it was used as a study model. This shrimp has a pelagic larva and a wide distribution along the Chilean coast. Different life-history traits were stud- ied in 5 populations over a range of 19 degrees of latitude along the Chilean coast. Population mean values for female body mass, egg volume, and reproductive output were positively correlated with latitude. In contrast, egg number was negatively correlated with latitude and positively correlated with temperature. Shrimps from the dumping site showed life-history trait values significantly lower than the range observed in areas with no copper enrichment, breaking the biogeographical patterns predicted by the Bergmann's rule. Such studies emphasize the need for integrating different concepts of organism and population ecology and life-history theory in the assessment of anthropogenic pollution.

Although physiological and genetic adaptation to toxic stress has been the focus of recent research, the role of lifestyle in pollution tolerance has received less attention. In this study, copper tolerance of benthic and epi-benthic species of harpacticoid copepods was investigated. Concentration-response curves were generated for populations of both species but collected at contaminated and uncontaminated estuaries. The population of the benthic species from the contaminated site showed higher tolerance than its population from the uncontaminated site. The epi-benthic species showed no inter-specific differences in tolerance. The comparison of tolerance between field collected animals of the benthic species and animals from the same population but reared in the laboratory for two generations suggested the existence of a genetic inherited tolerance. Results revealed the importance that lifestyle may have on the generation of tolerance to toxic substances and highlight a potential unforeseen role of it in maintenance of biodiversity on contaminated habitats.

La relacion bidireccional de influencia que la acuicultura establece con el ambiente en el cual se desarrolla determina limites al crecimiento de esta actividad economica en Chile. Esto se ha traducido tanto en restricciones tecnicas, como en conflictos ambientales y sociales. La creciente demanda de nuevos productos quimioterapeuticos y su consecuente vertido en ambientes acuaticos es considerado uno de los principales problemas ambientales que enfrenta la industria del salmon en Chile. Sin embargo, poco se sabe acerca de los efectos que ejercen estas sustancias sobre especies no objetivo y, en general, sobre la estructura y funcion de los ecosistemas expuestos. Mediante la aplicacion de teoria y metodos de ecologia contemporanea, el trabajo aqui presentado busca contribuir oportunamente al desarrollo de una metodologia que permita reducir el nivel de incertidumbre asociado a la evaluacion de riesgo ambiental de productos veterinarios utilizados en acuicultura. Se revisa el estado actual de la evaluacion de riesgo ambiental en Chile y se identifican aspectos criticos y factibles de corregir en el marco de los procedimientos utilizados. Finalmente, se entrega una propuesta metodologica general que contempla extender de un modo coherente las pruebas ecotoxicologicas estandar, combinando experimentacion a niveles comunitario, poblacional e individual, junto a la modelizacion matematica de sistemas ecologicos.

10 pages, 2 figures, 1 table.-- PMID: 17267012 [PubMed].-- Printed version published May 2007., Polluting events can change community structure and ecosystem functioning. Selection of genetically inherited tolerance on exposed populations, here referred as micro-evolution due to pollution, has been recognized as one of the causes of these changes. However, there is a gap between studies addressing this process and those assessing effects at higher levels of biological organization. In this review we attempt to address these evolutionary considerations into the ecological risk assessment (ERA) of polluting events and to trigger the discussion about the consequences of this process for the ecosystem response to toxic stress. We provide clear evidence that pollution drives micro-evolutionary processes in several species. When this process occurs, populations inhabiting environments that become polluted may persist. However, due to the existence of ecological costs derived from the loss of genetic variability, negative pleiotropy with fitness traits and/or from physiological alterations, micro-evolution due to pollution may alter different properties of the affected populations. Despite the existence of empirical evidence showing that safety margins currently applied in the ERA process may account for pollution-induced genetic changes in tolerance, information regarding long-term ecological consequences at higher levels of biological organization due to ecological costs is not explicitly considered in these procedures. In relation to this, we present four testable hypotheses considering that micro-evolution due to pollution acts upon the variability of functional response traits of the exposed populations and generates changes on their functional effect traits, therefore, modifying the way species exploit their ecological niches and participate in the overall ecosystem functioning., This study is part of the Portuguese Research Project POCI/BIA-BDE/59037/2004 funded by Fundação para a Ciência e a Tecnologia (FCT) and FEDER. J.A. Correa is founded by ICA and FONDAP-FONDECYT 15010001 Program No. 7) research grants (Chile) and C. Barata by a Ramón y Cajal Contract from the Ministerio de Educación y Ciencia (Spain). We thank Agnès Marhadour for reviewing a final version of the manuscript.

Copper effects on the early developmental gametophytic and sporophytic stages of the kelp Lessonia nigrescens were tested in gradients of increasing concentrations of ASV-labile copper. The results demonstrated a high sensitivity to copper of all life-history stages of the alga, where even the lowest tested concentration affected spore release as well as their subsequent settlement. More significant, concentrations higher than 7.87 μg L −1 totally interrupted the development of the spores after they settle. This effect led to a failure in the formation of male and female gametophytes and, as a consequence, to a complete disruption of the normal life cycle of the kelp. Thus, we suggest that the absence of L. nigrescens from copper-enriched environments results from the high sensitivity of its early life cycle stages, which limits growth and maturation of the gametophytic microscopic phase and, as a consequence, prevents development of the macroscopic sporophytic phase.

In earlier single-species toxicity tests we showed the negative effects on the calanoid copepod Acartia tonsa upon exposure to cypermethrin, a pesticide used in treatment for sea lice in salmon farming. In the present study we assessed effects at a higher level of biological organization and under a more realistic exposure scenario using mesocosms. The results showed that simulated field studies (SFSs) could be conducted with the mesocosms designed here. When cypermethrin was applied inside these mesocosms, its concentration decreased exponentially following a first-order kinetics model. The pesticide immediately reduced zooplankton density and biodiversity not only directly, by killing copepods, but also indirectly, by increasing the numbers of rotifers. Zooplankton density recovered after treatment, but zooplankton biodiversity remained altered. In an open environment, however, the rapid dissipation of the pesticide, coupled with population processes of compensation, migration, and immigration, may lead to recovery of the affected zooplankton communities.

A short-term Tisbe battagliai toxicity test design was used to assess the potential eco- logical effects of pollutants in coastal marine communities. By exposing nauplii and reproductive females over 4 and 6 d, respectively, to 3 toxic substances (fluoranthene, cypermethin and delta- methrin), the bioassay was seen to successfully measure survival effects on egg, nauplii and adults and sublethal effects on food acquisition and clutch size. Predictive consequences of toxic exposure at population level was estimated in terms of reproductive success, by integrating effects on adult survival and reproductive performance over the studied exposure period. Fluoranthene exposure reduced feeding rate and clutch size at concentrations below those affecting survival and population responses. For cypermethrin, survival, sublethal and reproductive success concentration effects were of a similar magnitude. For deltamethrin adult and nauplii survival, clutch size and reproductive suc- cess were equally affected at concentrations which were lower than those affecting feeding and egg survival. Responses to contaminated algae showed a different pattern, with toxicant effects only on nauplii survival and reproductive success, and under exposure to pyrethroid insecticides. Thus, dif- ferences in the dominant ecotoxicological modes of action, in terms of the balance between survival and sublethal responses with potential effects at the population level, could be successfully assessed using this short-term bioassay. These results have important implications for risk assessment in estu- arine and coastal waters because with relatively short-term, and thus cost-effective tests, the func- tional relationship between effects on survival, feeding and reproduction rates and concentration can be determined.