Assessing pollution of toxic sediment in streams using bio‐ecological traits of benthic macroinvertebrates

Abstract

1. We examined the accuracy of a multimetric approach based on 22 biological and ecological traits of benthic macroinvertebrate communities to assess toxic sediment pollution in streams. 2. Faunal and chemical data from sites located on 150 medium-sized mountain streams in France were analysed. We used 18 additional sites, not included in the multimetric tool development as a test data set. A toxic quality class (from 'high' to 'poor ⁄ bad') was preassigned to each site using the French water quality assessment system (SEQ-Eau) based on toxic substances (metals, PAH and PCB) in sediment. 3. Each trait was described in multiple categories. The affinity of macroinvertebrate taxa for the different categories of a trait was described using a fuzzy coding procedure. The relative abundance of trait categories was calculated for communities at each site. 4. A nonparametric multiple comparison statistical procedure was used to compare relative abundances of trait categories between groups of sites assigned to different quality classes (e.g. high versus good; good versus moderate, etc.), to identify the combinations of trait categories that best separated sites between adjacent toxic quality classes. Based on such sets of trait categories, we propose a statistical procedure to allocate sites to toxic quality classes from the attributes of its benthic macroinvertebrate community. 5. Predictions from the trait-based functional tool achieved approximately 73% of correct site post-assignments to toxic quality classes pre-assigned using chemical criteria. All of the sites pre-assigned to the 'high' quality class, were post-classified into the same quality class using benthic community attributes. From 0-90% of sites from other quality classes were classified identically using both chemistry-and trait-based criteria, the observed biological impact being often lower than expected. We suggest that the rapid decline of sensitive species could lead to both low taxonomic richness and low diversity of adaptations, giving communities a less diverse range of potential functional responses to increasing toxic pressure. 6. Biological criteria based on macroinvertebrate traits could provide new methods for biological assessment. This study is the first step towards an in situ functional tool of stream sediment contamination assessment at community level. However, we need to increase the number of sites included in the development data set to improve the tool's precision, extend the procedure to additional stream types and validate the design at a larger spatial scale.

Benthic Invertebrate Bioturbation Activity Determines Species Specific Sensitivity to Sediment Contamination

“…Moreover, active bioturbators can hence promote release of sediment-associated contaminants across the benthic-pelagic ecosystem boundary, thereby stimulating delivery of contaminants from what is often the most polluted environmental compartment in freshwater ecosystems (Burton, 2013;Roig et al, 2015). Although research linking traits to toxicant sensitivity is still relatively rare, trait based ecotoxicology offers a possibly potent tool for predicting sensitivity of benthic invertebrates and the benthic community to sediment-associated contaminants (Baird et al, 2008;Archaimbault et al, 2010). It is alarming though, that the paucity of sediment toxicity data still poses the largest obstacle to deriving reliable SQGs.…”

Biomonitoring of lake sediments using benthic macroinvertebrates

“…The resistance and the resilience characteristics adopted by taxa therefore determine the response of the community to disturbance events. The advantage of using functional traits instead of taxonomic composition of communities is bound to the a priori predictable response of traits to individual stressors [16,54,77]. Each trait is supposed to respond independently to a given pressure and each pressure affects different traits.…”

“…At present, fuzzy coding analysis has been successfully used to match species with individual traits [16,77], but other approaches may be more powerful {e.g., Giller et al [51] suggested the allocation of species into groups based on several relevant traits}.…”

“…This approach was adopted to study the effects of toxic contamination on invertebrate communities in running waters [15][16][17]. It was shown that tolerant taxa are characterized by resistance and resilience traits [e.g., high mobility (which permits avoidance of exposition and dispersion) and short life cycles (which allow rapid re-colonization after disturbance)].…”

“…Riverine invertebrate communities have been extensively studied in response to gradients of contamination, producing effective toxicity indices [15][16][17]. By contrast, benthic communities in lakes have still been rather neglected, since the ecological status of lentic ecosystems has for long been assessed on the basis of only chemical and physical parameters.…”