A multicompartment approach--diatoms, macrophytes, benthic macroinvertebrates and fish--to assess the impact of toxic industrial releases on a small French river.

Manon Lainé,Soizic Morin,Juliette Tison-Rosebery,Jose Luis Balcazar

doi:10.1371/journal.pone.0102358

Manon Lainé, Soizic Morin + Show 2 more

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https://doi.org/10.1371/journal.pone.0102358

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Abstract

The River Luzou flows through a sandy substrate in the South West of France. According to the results of two assessment surveys, the Water Agency appraised that this river may not achieve the good ecological status by 2015 as required by the Water Framework Directive (2000/60/EC). This ecosystem is impacted by industrial effluents (organic matter, metals and aromatic compounds). In order to assess and characterize the impact, this study aimed to combine a set of taxonomic and non-taxonomic metrics for diatoms, macrophytes, macroinvertebrates and fish along the up- to downstream gradient of the river. Diversity metrics, biological indices, biological and ecological traits were determined for the four biological quality elements (BQE). Various quantitative metrics (biomass estimates) were also calculated for diatom communities. The results were compared to physicochemical analysis. Biological measurements were more informative than physicochemical analysis, in the context of the study. Biological responses indicated both the contamination of water and its intensity. Diversity metrics and biological indices strongly decreased with pollution for all BQE but diatoms. Convergent trait selection with pollution was observed among BQE: reproduction, colonization strategies, or trophic regime were clearly modified at impaired sites. Taxon size and relation to the substrate diverged among biological compartments. Multiple anthropogenic pollution calls for alternate assessment methods of rivers' health. Our study exemplifies the fact that, in the case of complex contaminations, biological indicators can be more informative for environmental risk, than a wide screening of contaminants by chemical analysis alone. The combination of diverse biological compartments provided a refined diagnostic about the nature (general mode of action) and intensity of the contamination.

Highlights

Rivers are a key component for the development of civilizations and, human-induced impacts on these ecosystems are diverse and always increasing
From the results of two assessment surveys (2004 and 2006), the Water Agency appraised that this river may not achieve the good ecological status by 2015 [2]
Three sampling sites publicly accessible were selected along the study reach: a site called ‘‘upstream site (Up)’’ situated upstream of the factory (Lambert 93 coordinates: X385686, Y6312556) was considered as the reference station; sites ‘‘Down 1’’ (X387414, Y6312572) and ‘‘Down 2’’ (X389923, Y6310416) were situated about 500 m and 4500 m downstream of the factory, respectively

Summary

Introduction

Rivers are a key component for the development of civilizations and, human-induced impacts on these ecosystems are diverse and always increasing. Since 2000 in Europe, the Water Framework Directive [1] requires water bodies to achieve good ecological status by 2015, and consider biology as the central element of the assessment. This Directive recommends using four biological quality elements (BQEs) – diatoms, macrophytes, benthic macroinvertebrates and fish – to assess the rivers’ ecological status. The ecosystem is impacted by the effluent of an industrial plant producing rubber: the pollution is very diverse (mainly organic matter, metals and aromatic compounds including aniline), variable in composition over the year, and released in pulses (51 releases in 2010)

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