[FPU2019] Evaluación de la Calidad Ambiental

Contamination: A worldwide problem that might affect the distribution pattern of species. Toxicity vs avoidance behavior

The spatial distribution of aquatic organisms and the differences in the index of biodiversity is commonly attributed to environmental conditions that favor or prevent the presence of species. Those conditions are related to elements that can present risks (presence of predators and competitors…) or represent unfavorable factors (lack of food, changes in salinity and temperature patterns…) to the survival of the species. In studies about the effects of contamination on organisms, the focus of those effects is, generally, on toxicity, that means:  how organisms suffer when in contact with contamination. The simulation of the contact with contamination is by a continuous and mandatory exposure. Under the condition in which organisms are immobile and the contamination scenario is spatially homogeneous, that forced exposure approach is undoubtedly relevant, because the continuous exposure to contamination will lead to some kind of suffering. This traditional approach used in ecotoxicology is crucial to understand how contaminants might cause damage, from subcellular levels to physiological homeostasis, and even behavioral alterations. However, from a wider conceptually perspective, ecosystems and ecological relations are very complex and sometimes hard to predict; therefore, some particularities that can condition the responses of organisms to contamination should be considered: (i) are organisms able to escape from contaminants thus avoiding their toxic effects? (ii) what is the role of contamination in organisms’ habitat selection processes?
This project brings a new perspective to the question of how risky contaminants are by changing the perspective from toxicity, at the individual level, to avoidance/preference behaviors. Here, avoidance and preference (habitat selection response) are considered as the ability of organisms to detect and escape from a potentially toxic environment, thus avoiding its toxic effects and selecting the most favorable habitat. The main goal is to study how contamination might affect species’ spatial distribution and how important contamination is for the habitat selection processes in comparison with other environmental factors like food, protection (refuges), predation and presence of competitors. This new focus on the effects of contamination supposes a change from the traditional forced method of exposure to contamination (mandatory exposure), to a non-forced multi-compartmented exposure system. The main difference between both approaches consists in the fact that the multi-compartmented system allows organisms to move freely among many compartments with different characteristics (such as levels of contamination) and avoid the less favorable compartments. The approach proposed for the PhD Thesis brings two new scientific challenges: a change of the conceptual paradigm of the effects of the contaminants by including new concepts (habitat selection, habitat connectivity, chemical fragmentation of habitat, colonization and meta-ecosystem) to ecotoxicology and an improvement of the exposure systems to assess the contamination-driven environmental risk.
The student will be provided with training based on the three pillars of environmental risk assessment: ecology, chemistry and ecotoxicology. Regarding the ecological concepts, the student will have to apply study methods related to population dynamics, the functioning of ecosystems and habitat selection mechanisms used by organisms from the perspective of environmental stress. The student involved in this project will learn to perform ecotoxicological assays in a new multi-compartmented exposure system (HeMHAS–Hetrogeneous Multi-Habitat Assays System; a system that has been created by our group) and to create different linear multi-compartmented systems. Further to this, ecotoxicological experiments with different aquatic organisms (cladocerans, mysids, shrimps and fish) are to be performed to verify how contaminants drive the spatial distribution of species by triggering spatial avoidance or preventing colonization processes. The final goal of the PhD Thesis project is to provide a novel and ecologicall relevant tool that is able to improve the understanding of the potential and real consequences of the contamination for the aquatic biota.