|ECOAPPROACH - Bridging the gap between metal contamination and ecologically significant effects on macrobenthic communities: a multidisciplinary approach from gene to community|
Susana Isabel Almeida Alves Carvalho
CESAM Responsible researcher - Mário Guilherme Garcês Pacheco
Programme - Concurso de Projectos de Investigação FCT 2010
Execution dates - 2012-03-01 - 2015-02-28 (36 Months)
Funding Entity - FCT
Funding for CESAM - 57.776 €
Total Funding - 160000 €
Proponent Institution - Instituto Nacional de Recursos Biológicos, I.P. (INRB/MADRP)
Universidade de AveiroCentro de Ciências do Mar (CCMar/CIMAR)
Three main factors have been contributing to the occurrence of inconsistent patterns between macrobenthic communities and metal levels in sediment: i) metals from natural and anthropogenic origin coexist in marine sediments; ii) measurable quantities of metals alone do not indicate they are bioavailable; and iii) tolerance mechanisms in aquatic organisms activated with exposure to metals are known to occur. Moreover, guidelines for sediment quality have been usually proposed based on laboratory dose-response experiments. However, the effects of contaminants are known to vary depending on species density and diversity, as well as on biological interactions and habitat features. Consequently, in contamination impact studies significant ecological changes in community structure and function are usually identified below the values obtained from ecotoxicological experiments. In order to overcome these gaps, field studies integrating several disciplines are crucial to enhance the knowledge on the ecologically significant effects of metal contamination on estuaries, since i) they allow assessing the effects on a large number of species with different functional attributes; and ii) account for real environmental conditions. The present research will be conducted in the Tagus estuary that was chosen has it presents a major contaminated area where concentrations of mercury in sediments reach 100 times values found in other areas of the estuary. High levels of other metals like arsenic and lead are also found in confined areas.
The main objectives of the present research are:
1) to evaluate the effectiveness of a battery of endpoints for the detection of ecologically significant effects of metal contamination;
2) to assess the most sensitive endpoints to the early detection of ecologically significant effects of metal contamination;
3) to assess the ecologically significant thresholds for macrobenthic organisms of the Tagus estuary;
4) to assess potential impacts on ecosystem functioning resulting from metal contamination.
Along a well defined metal contamination gradient, samples will be collected for determination of i) metals in sediments, as well as other descriptive environmental parameters; ii) macrobenthic communities and population patterns; iii) metals accumulated in macrobenthic organisms; iv) ecogenotoxicological endpoints (e.g. oxidative stress, aneuploidy rate, nuclear abnormalities and chromosomal structural aberrations, metallothionein gene expression levels). Therefore, the present strategy not only involves a multidisciplinary approach but the identification of potential ecological effects at different biological organization levels (gene, chromosome, cell, individual, population and community). In what concerns the community level, analysis will also take into consideration the functional attributes of the species (morphological, physiological and behavioural). These attributes can reflect their role in the ecosystem, allowing to infer on the consequences of metal contamination on the overall ecosystem functioning. On the other hand, at the gene level, the analysis of the expression levels of MT genes will contribute to a better knowledge of the physiological role of different MTs isoforms, whereas suppression subtractive hybridization (SSH) technique will provide information on new genes responding to metal exposure in local species. Through data mining and statistical modelling, deterministic relationships between metal contamination settings and biological responses will be explored in a holistic approach. Endpoints will not be used as environmental indicators separately but integrated by numerical tools, allowing the clarification of the choice of indicators based on their effectiveness. The advances in numerical tools will expand the effective use of data mining in environmental impact studies as a basis for improved decision making and increased understanding of species-habitat relationships. To our knowledge a multidisciplinary approach connecting these disciplines was never applied in the marine environment.
The outcome of this proposal will be: 1) the identification of the most sensitive endpoints of ecologically significant effects of metal contamination on benthic communities; 2) the indication of real thresholds for macrobenthic communities from the Tagus estuary; and 3) the evaluation of metal contamination effects on ecosystem functioning. With this holistic research we expect to go forward on the knowledge of adaptive responses of macrobenthic organisms to metal contamination.