|IDEAL - Insecticides, DEtritivores and ALiens: Combined effects of invasive species and insecticides along detritus based stream food webs|
João Luís Teixeira Pestana
Programme - PTDC/AAC-AMB/119433/2010
Execution dates - 2012-05-01 - 2015-04-30 (36 Months)
Funding Entity - FCT
Funding for CESAM - 150000 €
Total Funding - 150000 €
Proponent Institution - Universidade de Aveiro
Institute of Environmental Assessment and Water Research - Department of Environmental Chemistry (IDÆA), CSIC Barcelona, Spain
The ecological integrity of natural ecosystems is more often evaluated in terms of species occurrence and composition rather than in terms of changes in trophic interactions and ecosystem processes. As a result, our mechanistic understanding of ecosystems is not substantially advancing. Approaches such as mesocosm experiments and powerful statistical approaches allow nowadays for a more integrative investigation of the ecological consequences of anthropogenic chemicals that continue to pollute freshwater systems. Progress in this research field is urgent since investigations using a combination of organismal, population and community responses will contribute for a comprehensive understanding of the direct and indirect effects of stressors and thus to reliable prediction of anthropogenic impacts on natural ecosystems.In agricultural areas, stream ecosystems face ever increasing pressures not only by pesticide and nutrient load but also by environmental changes (habitat alteration, hydrological constraints, and climate change). Anthropogenic chemicals like insecticides entering surface waters are often associated with other stressors and there is frequently the presence of invasive alien species. This presence of new species, many of which outcompete the native ones and become dominant in a particular ecosystem can have profound effects on communities and ecosystem functions. It is thus critical to investigate the ecological consequences of biotic invasions to different natural ecosystems. To our knowledge, integrative studies investigating mechanistic links between biotic invasions and responses of communities to contamination are scarce. The IDEAL project intends to tackle this by studying the effects of insecticides on detritivore aquatic communities. This will be achieved with standard and mesocosms experiments enclosing simplified detritivore based stream trophic chains and structural equation modeling approaches to evaluate the complete set of direct and indirect effects of selected insecticides on these communities and on ecosystem functions. Detritus processing is vital for river ecosystems with shredders contributing for the decomposition of coarse particulate organic matter into fine particulated matter and for recycling of nutrients that can be transported along the stream and used by collector organisms. Monitoring studies of the ecological quality of river ecosystems need to incorporate toxic effects along these processing chains. This monitoring should include the community responses to anthropogenic stressors in the presence of invasive species.This project will address three main questions:
- What are the bottom-up (resource identity) and top down (predator identity) effects of alien invasive species in detritus processing chains?
- Does environmental relevant concentrations of insecticides disrupt shredder-collector interactions and the processing of detritus in streams?
- What are the ecological consequences of invasive species in freshwater ecosystems under pesticide contamination?
Investigating the effects of the selected insecticides and alien species on trophic interactions will include a series of parameters in different levels of biological organization (from energetic biomarkers to macroinvertebrate’s individual growth and feeding rates to organic matter decomposition and ecosystem respiration). Experiments with natural and more complex macroinvertebrate communities will also be conducted in the mesocosms to validate the results obtained with the model detritus based food web. Understanding how invasive species mediate detritivore trophic interactions and ecosystem processes such as organic matter processing will be of indispensable value for an improved interpretation of the ecological effects of pesticides. At the same time these ecotoxicological experiments can provide important cues related to the mechanisms and processes of biological invasiveness and consequent ecological consequences of alien species. The study of the effects of anthropogenic pollutants on community composition, species interactions and ecological processes, termed ‘‘community ecotoxicology”, offers the scientific concepts, approaches and techniques needed to address these important issues. We are convinced that the results from this project can help to speed up this research field, with significant contributions in several areas of environmental science.