Development and Sensitivity of a 12-h Laboratory Test with Daphnia magna Straus Based on Avoidance of Pulp Mill Effluents

Abstract-Natural populations exposed to pollutants are predicted to experience a loss of genetic diversity, especially through genetic drift, gene flow (emigration), and/or selection (as sensitive genotypes may be lost). In the present study, the authors discuss the use of selectable markers and neutral markers to evaluate a contaminant-driven loss of genetic diversity and possible implications of genetic erosion on populations' viability. Viability could be reduced by altering life history parameters, especially due to fitness costs associated with the acquisition of resistance and/or by compromising the resilience and adaptation to future environmental changes. This discussion aims at an integrated and critical analysis of this topic; it is illustrated by several independent studies (each with its own specific objectives) that were carried out at the same location with Daphnia longispina populations. To the best of the authors' knowledge, this is the most extensively documented case study on genetic erosion of a natural zooplankton population. Directional selection has been found to be a main factor of microevolution; therefore, genetic erosion was detected by monitoring suitable phenotypic markers. Genetic drift was found to be probably irrelevant or masked by other factors, especially gene flow. Although the acquisition of resistance apparently did not entail genetically determined fitness costs under uncontaminated conditions, the present case study suggests the possibility of a further loss of genotypes due to some negative linkages between the sensitivity to potential ulterior toxicants. Environ. Toxicol. Chem. 2012;31:977-982. # 2012 SETAC

Section: The Genetic Erosion Hypothesismentioning

confidence: 95%

Contaminant driven genetic erosion: A case study with Daphnia longispina

Ribeiro

Baird

Soares

et al. 2012

“…Because the forced approach focuses on toxicity and the nonforced, multicompartmented method focuses on spatial displacement, integration of both approaches provides a wider vision of the health conditions (toxicity) of the organisms and the spatial distribution of the populations. In the studies by Rosa et al (, ), an interesting approach was described to demonstrate how both forced and nonforced exposure methods could complement each other to assess the risk linked to contamination: the responses obtained might help us to understand population decline on a local scale. For instance, in terms of avoidance and mortality, it is possible to predict population immediate decline from the number of organisms that escaped toward other areas and the number of nonavoiders (remainers) that might die.…”

Section: Integrating Ecological Concepts To Improve Erasmentioning

confidence: 99%

Spatial avoidance as a response to contamination by aquatic organisms in nonforced, multicompartmented exposure systems: A complementary approach to the behavioral response

Araújo¹,

Blasco²

2018

The idea that the hazard of contaminants is exclusively related to their toxic effects does not consider the fact that some organisms can avoid contamination, preventing toxicity. Although inferences about avoidance are made in most behavioral ecotoxicology studies, assessment of the real spatial displacement (organisms moving toward another habitat to escape contamination) is difficult due to the type of exposure (confined and mandatory) used in the bioassays: a forced exposure approach. A complementary approach using nonforced exposure systems to assess how contaminants affect the spatial distribution of organisms in a bicompartmented (toxic or nontoxic) environment has long been described. Recently, this nonforced approach has been developed to include a multi compartmented system in which different samples can be simultaneously tested. The aim of the present review was to describe the importance of the nonforced, multicompartmented exposure approach to simulate a gradient or patches of contamination, to describe the 2 main exposure systems, and to highlight the ecological relevance of including spatial avoidance and habitat preference in ecotoxicological studies. The multicompartmentalization of the system makes it possible to simulate more complex scenarios and therefore include new ecological concepts in bioassays. We also contrasted spatial avoidance in the nonforced exposure systems with the behavioral endpoints measured under other exposure systems. Finally, we showed that the nonforced, multicompartmented exposure approach makes it possible 1) to improve environmental risk assessments by adding the dispersion pattern of organisms in a multihabitat scenario, and 2) to integrate ecological concepts such as recolonization of recovering habitats, loss of habitat connectivity, habitat fragmentation, and contamination-driven metapopulation, which have received limited attention in ecotoxicological studies. Environ Toxicol Chem 2019;38:312-320. C 2018 SETAC

“…Obviously, over the long term, if contamination is stopped and the ecosystem recovers, the avoiding organisms could recolonize it. Moreover, avoidance may be considered highly sensitive, because it can be evidenced in concentrations lower than conventional sublethal effects .…”

Section: Introductionmentioning

confidence: 99%

“…Avoidance assays using a nonforced exposure system have had prominence in recent years, and a number of studies have taken place with different freshwater species and contaminants: cladocerans exposed to Cu , atrazine , and pulp mill effluent , copepods exposed to polycyclic aromatic hydrocarbon , amphibians exposed to Cu and fungicide pyrimethanil , and fish exposed to Cu, acid mine drainage effluent , and pyrimethanil . All of the studies using nonforced exposure systems have been exclusively carried out with freshwater species, in spite of the fact that a spatial distribution, influenced by the presence of contamination gradients, also can be observed in marine and estuarine ecosystems.…”

Section: Introductionmentioning

confidence: 99%

Predicting the effects of copper on local population decline of 2 marine organisms, cobia fish and whiteleg shrimp, based on avoidance response

Araújo

Cedeño-Macías

Vera-Vera

et al. 2016

The present study focuses on avoidance response to predict population decline of the marine fish Rachycentron canadum (cobia) and larvae of the estuarine shrimp Litopenaeus vannamei (whiteleg shrimp). Avoidance of approximately 60% was recorded for the cobia fry exposed to 1.0 mg Cu/L, 1.60 mg Cu/L, and 1.80 mg Cu/L. For the shrimp larvae, avoidance was approximately 80% for all Cu concentrations. The population decline of cobia fry was conditioned by avoidance in lower concentrations. However, in higher concentrations mortality begins to play an important role. The displacement toward uncontaminated habitats might determine shrimp population decline. A Cu-contaminated environment can determine the habitat selection of both species and, therefore, their local population decline.