Integrated multivariate approach of ecological and ecotoxicological parameters in coastal environmental monitoring studies

The coastal ecosystems are recognized worldwide by their ecological an economic importance. In these ecosystems, aquatic life is governed by the abiotic variations, therefore, the interactions between natural stressors and anthropogenic pollution (multiple stressors) may represent an additional threat. Thus, considering these combined effects with the climate change scenarios, it is urgent to develop cost-effective tools to assess the impact of pollution on sensitive and important ecosystems, such as estuaries and coastal lagoons, and implement mitigation plans to prevent the environmental and human health degradation. In order to contribute to this crucial issue, the central objective of this study was to validate and propose an integrated methodology, including ecological and ecotoxicological parameters, to evaluate the effects of natural stressors and pollution on key estuarine fish in real scenarios, using the common goby Pomatoschistus microps (Kroyer, 1838), an important estuarine intermediary predator, as a bioindicator and a North Atlantic coastal lagoon (the Aveiro lagoon; NW coast of Portugal) as a case study area. The methodology included fourteen water quality variables, sediment characteristics, the concentrations of nine metals in sediments and in the fish body, fish condition indexes, eight biomarkers and multivariate statistics (Redundancy (RDA) and Principal Response Curves analysis (PRC)) to integrate the information provided by different parameters. The study was conducted over one year with seasonal sampling (winter, spring, summer and autumn) at four sampling sites with different contamination histories. The integrated approach suggested significant differences between the reference site and the remaining ones, both in biological and environmental descriptors. Bioaccumulation factors suggested that fish bioaccumulated some metals, especially Zn. The overall integration of all selected parameters and methods discriminated locations with different contaminated levels and associated health status of the selected species with multiple stressors. The present work represented a case-study, highlighting the use of biomarkers as early warning indicators of ecosystems health and stressing the importance of using an integration approach through multivariate analysis in biomonitoring studies, providing an important baseline and integrated information that may be used as scientific support for conservation and management and ecological models of estuarine and coastal lagoon systems.