Modelling diatom life forms and ecological guilds for river biomonitoring

Abstract

-Biomonitoring is central to the European Union's Water Framework Directive (WFD) and to the French water and aquatic environmental law, but most diatom indices do not separate different anthropogenic impacts. To address this gap, the effect of water chemistry on diatom ecological guilds and life forms was assessed in order to indicate stream perturbations. Generalised additive models (GAMs) were built on a large-scale data set of 1571 samples from the French monitoring network. The relationships between diatom ecological guild and life form metrics were investigated by Principal components analysis and the results predicted by GAMs. The models characterised eight chemical parameters that modified adaptive strategies (ecological guilds) and growth morphology (life forms). Total phosphorus, conductivity, nitrate and pH are the main influencing factors, followed by temperature, dissolved oxygen and organic matter. The findings confirm three groups of diatoms with different adaptive strategies: 1 -fast moving species, 2 -species growing close to the substrate and 3 -species extending to the surface layers of the biofilm. Thirteen diatom metrics displayed a variety of responses to different ranges of the eight chemical parameters. These metrics could be used to help to identify and quantify which chemical alterations are caused by polluted effluents in rivers.Keywords: benthic diatoms / ecological guilds / biological traits / biomonitoring / generalised additive model Résumé -Modélisation des formes de vie et guildes écologiques des diatomées pour la bioindication en rivières. La bioindication est centrale dans la directive cadre européenne sur l'eau et la loi française sur l'eau, mais la plupart des indices diatomiques ne séparent pas les différents impacts anthropiques. Pour combler ce manque, l'effet de la physico-chimie de l'eau sur les guildes écologiques et formes de vies des diatomées a été étudié pour indiquer des perturbations des cours d'eau. Des modèles additifs généralisés (GAMs) ont été construits sur un jeu de données de 1571 échantillons des réseaux de suivi des cours d'eau français. Les relations entre les métriques de guildes écologiques et formes de vie des diatomées ont été étudiées par une ACP et les résultats prédits par des GAMs. Les modèles ont caractérisé huit paramètres physico-chimiques qui modifient les stratégies adaptatives (guildes écologiques) et morphologies de croissance (formes de vie). Le phosphore total, la conductivité, les nitrates et le pH sont les facteurs les plus influents, suivis par la température, l'oxygène dissous et la matière organique. Les résultats confirment trois groupes de diatomées avec des stratégies adaptatives différentes : 1 -les espèces se déplaçant rapidement, 2 -les espèces proches du substrat et 3 -les espèces s'étendant vers la surface du biofilm. Quatorze métriques diatomiques ont montré une variété de réponses à différentes gammes de valeurs des huit paramètres physico-chimiques. Ces métriques pourraient être utilisées pour aider à identifier ...

Niche dimensionality and herbivory control stream algal biomass via shifts in guild composition, richness, and evenness

“…, Marcel et al. ) and we too show here distinct responses of algal guilds to nutrient additions. However, we caution that the overriding effect of herbivory on guild composition may hamper bioassessment efforts and future biomonitoring programs should develop metrics that are based on guild richness, which may be less sensitive to grazing.…”

“…exhibit differential sensitivity to disturbance, as originally proposed (Passy 2007). Diatom guilds have gained popularity in biomonitoring of water pollution (Berthon et al 2011, Marcel et al 2017) and we too show here distinct responses of algal guilds to nutrient additions. However, we caution that the overriding effect of herbivory on guild composition may hamper bioassessment efforts and future biomonitoring programs should develop metrics that are based on guild richness, which may be less sensitive to grazing.…”

A new diatom index to assess ecological quality of running waters: a case study of water bodies in western Anatolia

“…C. excisa Ku¨tzing has been considered to be dominant in I-II water quality (less polluted) (Go´mez and Licursi, 2001). F. capucina Desmazie`res and C. excisa Ku¨tzing are high profile species that dislike high TSS (Marcel et al, 2017) and are good competitors for nutrients (Rimet et al, 2016). S. radiosum (Ku¨tzing) Kuntze has been reported as a sensitivity indicator species (Wang et al, 2014).…”

Colonisation processes in benthic algal communities are well reflected by functional groups

“…Recent studies demonstrated that both single traits and functional groups of benthic diatoms or other benthic algal assemblages may be useful indicators of environmental changes in watercourses (Berthon et al, 2011;Stenger-Kovács et al, 2013;Kókai et al, 2015;B-Béres et al, 2014B-Béres et al, , 2016B-Béres et al, , 2017Lange et al, 2016;Marcel et al, 2017). Single traits or functional groups alone could indicate some physical and chemical changes in water courses (Kókai et al, 2015;Lengyel et al, 2015).…”

“…Although a coherent benthic life form classification was developed for diatoms (Rimet & Bouchez, 2012 based on Round et al, 1990; Table 1), the use of this classification for nondiatoms is also feasible (Law et al, 2014;Lange et al, 2016). While some studies reported a strong relationship between life forms and environmental factors (Berthon et al, 2011;Lange et al, 2016, Marcel et al, 2017, others have not found any relationship between these variables (Law et al, 2014). However, Law et al (2014) demonstrated that a higher functional resolution can be achieved by combining life forms with other traits (maximum linear dimension, surface area to volume ratio), and the created groups have strong significant relation to environmental factors.…”