Recovery potential of periphytic communities in a river impacted by a vineyard watershed

Abstract

8Vineyard areas are important causes of water contamination, especially by pesticides 9 and residues. These compounds can markedly disturb aquatic communities particularly 10 photosynthetic organisms that are targeted by herbicides. Biofilms and diatoms were used as 11 bioindicators for quality assessment in the Morcille watershed, an area impacted by 12Beaujolais vineyards (SE France), during the pesticide spreading period (April-May 2008). 13Biofilms were allowed to settle on glass slides for 4 or 8 weeks at three sites along a 7-km 14 long gradient of trophic (mainly orthophosphate) and pesticide pollution. After a 4-week 15 colonisation, samples from the two contaminated downstream sites were transferred upstream 16 to the clean site for four weeks while others were left in the same place. 17In vivo fluorescence measurements indicated that the periphytic communities were 18 dominated by diatoms. Going downstream, biofilm biomass and diatom species richness 19 decreased; normalized diatom indices (including the French standard BDI) expressed the 20 increase in trophic status quite well. The species composition of the assemblages was used to 21 discriminate between the effects of nutrients and toxicants, which increased simultaneously as 22 the river continued downstream. 23The way in which the biofilm samples transferred upstream recovered was quite 24 different depending on the location of the original site in the contamination gradient. Most of 25 the quantitative descriptors reached a level comparable to that of the reference communities, 26 Manuscript Click here to view linked ReferencesRecovery potential of periphytic communities in a river impacted by a vineyard watershed. Morin, S. etal. 2010. Ecological Indicators, vol. 10, n° 2. p. 419-426. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6W87-4X30C60-1&_user=5403746&_rdoc=1&_fmt=&_orig=search&_sort=d&_docan but the diatom assemblages (cell density per surface unit, taxonomic composition) varied 27 between dates and along the gradient. These communities did not entirely recover a reference 28 structure but the increase in diversity, associated with the settlement of sensitive species, 29 suggested an elevated recovery potential. 30 31 Keywords 32 River biofilms; diatoms; pesticides; Biological Diatom Index; community analysis; diuron; 33 recovery 34 35Recovery potential of periphytic communities in a river impacted by a vineyard watershed. Morin, S. etal.

Freshwater sediment pesticide biodegradation potential as an ecological indicator of microbial recovery following a decrease in chronic pesticide exposure: A case study with the herbicide diuron

“…The upstream section of the Morcille river was proposed as a reference site, because of repeated reports over the years showing a marked pollution gradient for the herbicide diuron from up-to downstream (e.g. Montuelle et al, 2010 andMorin et al, 2010). To validate this proposal, diuron concentration and diuron mineralization potential were monitored respectively in water and sediment samples collected upstream in the Morcille river over the four-year survey.…”

Variations of periphytic diatom sensitivity to the herbicide diuron and relation to species distribution in a contamination gradient: implications for biomonitoring

“…In the upstream site neither diuron nor any other pesticide is usually detected. 2,19 Only 7 kilometres separate the two sites.…”

“…7,8 The presence of diuron has been reported in many freshwater systems all over the world and is the herbicide most often detected in French rivers. 9 To date, the toxicity of diuron towards diatoms has been assessed in two different ways: (1) via short monospecific tests or (2) by the use of contaminated experimental channels and exposure of natural biofilm samples usually over a longer time scale. The first method allows the standard determination of toxicity parameters such as the 50% effect concentration (EC50) from the inhibition of growth or photosynthesis.…”

“…It was suggested that diatom community variations may also reflect the presence of toxic stressors such as pesticides. [2][3][4][5] As plants, diatoms may be particularly sensitive to herbicides which are commonly found in rivers draining agricultural areas with peak concentrations in spring after field application and rain events. 6 Diuron (3,4-dichlorophenyl)-1,1-dimethylurea is a herbicide which belongs to the phenylurea class.…”

Dynamics of Bacterial Aggregates in Microflows

“…Recent attempts to engineer devices out of biofilms successfully produced electrooptical devices [2]. The advancement of synthetic biology is paving the way for the use of biofilms as bioindicators or biosensors in the environment [11]. There are efforts to use biofilms emitting optic signals as microsensors in microdevices.…”