Ecological assessment of French Atlantic lakes based on phytoplankton, phytobenthos and macrophytes

Abstract

Biological elements, including phytoplankton, phytobenthos, macrophytes, benthic invertebrates and fish, are employed by the EU Water Framework Directive (WFD) 2000/60/EC as ecological indicators for the assessment of surface waters. The use of primary producers (phytoplankton, phytobenthos and macrophytes) for water quality assessment has a long history, and several methods have been developed worldwide. In this study, we used these three communities to assess the ecological status of five natural lakes located in the Aquitaine region (southwest France). Several biological indices used in lakes from other European countries or in French rivers were employed and compared among the three communities. Each primary producer provided complementary information about the ecological status of the lakes, including the invasiveness of exotic taxa. Regardless of the producer community used, the response to the environment, as reflected by the indices (adequate for each community), was similar: Lakes Cazaux, Lacanau and Hourtin showed the best ecological status and Parentis and Soustons the worst. Phytoplankton diagnosis reflected and integrated unambiguously the water quality of the lakes, as demonstrated by the strong relationships between the phytoplankton index and the trophic status criteria. This community appeared as the best indicator, especially when macrophytes were absent. The methods applied here represent a potential tool for the assessment of the ecological status in the context of WFD, but they need to be refined. We propose modifications for phytobenthos index initially tailored for running waters for adequate use in lentic ecosystems. Indices for the three primary producers should be modified to incorporate exotic species which may provide information on potential biodiversity losses.

Assessment of ecological status in UK lakes using benthic diatoms

“…Some authors have shown that diatom metrics developed for rivers are strongly correlated with pressure gradients in lakes (Blanco et al 2004, Bolla et al 2010, Cellamere et al 2012). This outcome leads to questions regarding the need for distinct lake-diatom assessment tools.…”

“…Because UK lakes have fewer point-source discharges of organic matter and their littoral regions have longer residence times compared with rivers, taxa strongly associated with organic pollution (e.g., Nitzschia palea, Fistulifera saprophila) are less likely to thrive. Blanco et al (2004), Bolla et al (2010), and Cellamere et al (2012) all used metrics developed for rivers, but many of their sites were compressed into the upper half of the scale of the metrics. The river TDI used in our study fared better, perhaps because of its origin as an index of inorganic, rather than organic, enrichment (Kelly and Whitton 1995).…”

Benthic diatom communities in high altitude lakes: a large scale study in the French Alps

“…More effort has been done to improve the monitoring using benthic diatoms in rivers than in lakes (Cantonati and Lowe, 2014). However, from several years things changed and some authors applied existing river diatoms indices to the littoral zone of lakes (Blanco et al, 2004;Bolla et al, 2010;Cellamare et al, 2011) while others developed new tools based on diatoms communities (Schaumburg et al, 2007;Stenger-Kovács et al, 2007;Marchetto et al, 2013;Bennion et al, 2014) to respond to the demands of lakes assessment. Indeed, whereas phytoplankton is considered as the main ecological indicator on lakes, and usually is used to assess the overall lake quality, littoral diatoms demonstrated their efficiency to assess point source pollution and to be early warning of lake's deterioration (Cantonati and Lowe, 2014;Rimet et al, 2016).…”

Responses of phytoplankton functional groups to environmental factors in the Maixi River, southwest China

“…Because the phytoplankton functional groups approach can be used without geographic limitations (Padisák et al, 2009;Crossetti and Bicudo, 2008b;Becker et al, 2009;Pasztaleniec and Poniewozik, 2010), and habitat requirements and phytoplankton are sensitive to changes in water quality (Çelekli and Öztürk, 2014), it is a potential monitoring tool for the assessment of ecological status in the context of the Water Framework Directive (Cellamare et al, 2012). For instance, phytoplankton functional groups estimated reliable water quality states between hypertrophic and oligotrophic conditions in a reservoir of Turkey (Çelik and Sevindik, 2015), indicated eutrophication due to human impacts along the river Loire in France (Abonyi et al, 2012), and allowed an ecological assessment of French Atlantic lakes (Cellamare et al, 2012).…”

“…For instance, phytoplankton functional groups estimated reliable water quality states between hypertrophic and oligotrophic conditions in a reservoir of Turkey (Çelik and Sevindik, 2015), indicated eutrophication due to human impacts along the river Loire in France (Abonyi et al, 2012), and allowed an ecological assessment of French Atlantic lakes (Cellamare et al, 2012).…”