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IBD 2006 [id:]

Method: Biological Diatom Index 2006 [Indice Biologique Diatomées 2006]

1. General information

1.01 GIG: Alpine, Central-Baltic, Mediterranean
Relevant intercalibration types: R-A1, R-A2, R-M1, R-M2, R-M4, R-C1, R-C2, R-C3, R-C4, R-C6
1.02 Category: Rivers
1.03 BQE: Benthic Diatoms
1.04 Country: France
1.05 Specification: none
1.06 Method name: Biological Diatom Index 2006
1.07 Original name: Indice Biologique Diatomées 2006
1.08 Status: Method is/will be used in First RBMP (2009), Second RBMP (2015)
1.09 Detected pressure(s):
Eutrophication, General degradation, Pollution by organic matter Specification of pressure-impact-relationship:
Correlation with NH4 and PO4 has been studied through 2556 samples. The relationships between IBD2006 and those two parameters were significant: R2 (IBD2006/NH4) = 0.45 and R2 (IBD2006/PO4) = 0.46.
Yes, with quantitative data (e.g. against range of sites reflecting continuous gradient of pressure).
1.10 Internet reference: n.a.
1.11 Pertinent literature of mandatory character:
Norme AFNOR NF T90-354, December 2007.
Qualité de l'eau - Détermination de l'Indice Biologique Diatomées (IBD).
1.12 Scientific literature:
Coste, M., S. Boutry, J. Tison-Rosebery & F. Delmas, 2009. Improvements of the Biological Diatom Index (BDI): Description and efficiency of the new version (BDI-2006). Ecological Indicator 9 (4): 621-650.
1.13 Method developed by:
Michel Coste, Sébastien Boutry, Juliette Rosevery, François Delmas
Email of developer:
Institute of developer: CEMAGREF groupement Bordeaux
1.14 Method reported by: Juliette Rosebery
Email of person reporting the method:
Email of institute reporting the method: CEMAGREF groupement de Bordeaux
1.15 Comments: none

2. Data acquisition

Field sampling/surveying

2.01 Sampling/Survey guidelines:
Norme AFNOR NF T90-354, December 2007.
Qualite de l'eau - Determination de l'Indice Biologique Diatomees (IBD).
2.02 Short description:
Samples are collected on stones (100cm2, >= 5 stones) on a sunny and running site of the river, thanks to a brush or a scraper. The biofilm collected is fixed with a 10% formaldehyde solution.
2.03 Method to select the sampling/survey site or area: Expert knowledge
2.04 Sampling/survey device: Brush, Scraper
2.05 Specification: scraper or brush
2.06 Sampled/surveyed habitat:
Specification of sampled habitat: Stones
Sampled habitat: Single habitat(s)
2.07 Sampled/surveyed zones in areas with tidal influence: not relevant
2.08 Sampling/survey month(s): Summer low flow period
2.09 Number of sampling/survey occasions (in time) to classify site or area: One / year
2.10 Number of spatial replicates per sampling/survey occasion to classify site or area: 1
2.11 Total sampled/surveyed area or volume or total sampling duration to classify site or area:
100 cm2 (>= 5 stones)

Sample processing

2.12 Minimum size of organisms sampled and processed: About 100 cm2 biofilm sampled on stones
2.13 Sample treatment:
Organisms of the complete sample are identified.
2.14 Level of taxonomical identification:
Level: Species/species groups
Specification of level of determination:
The level of taxonomical identification is the species, or the variety when existing.
2.15 Record of abundance:
Determination of abundance: Individual counts, Relative abundance
Abundance is related to: n.a.
Unit of the record of abundance: per thousand
Other record of abundance:
relative abundance is calculated for a total of 400 individuals counted / slide minimum
2.16 Quantification of biomass: n.a.
2.17 Other biological data: none
2.18 Special cases, exceptions, additions: none
2.19 Comments: none

3. Data evaluation


3.01 List of biological metrics:
Relative abundance of key taxa (Ax), with pollution sensitivity (Pxi) and valence values (Vx) (=F(i)=B = 1x F(1) + 2x F(2) + 3x F(3) + 4x F(4) + 5x F(5) + 6x F(6) + 7x F(7)
B is transformed into a /20 note.
3.02 Does the metric selection differ between types of water bodies: No
3.03 Combination rule for multi-metrics: Not relevant
3.04 From which biological data are the metrics calculated:
List of biological metrics: Data from single sampling/survey occasion in time

Reference conditions

3.05 Scope of reference conditions: Surface water type-specific
3.06 Key source(s) to derive reference conditions:
Scope of reference conditions:
Existing near-natural reference sites, Expert knowledge, Least Disturbed Conditions
3.07 Reference site characterisation:
Number of sites: 234
Geographical coverage: Whole French hydrosystem
Location of sites: Whole French hydrosystem
Data time period: From 1977 to 2007
The national dataset has been analysed with an unsupervised neural network, the self-organizing-map, a well accepted method for community ordination. 11 different communities were identified, 5 corresponding to non-impacted or slightly impacted conditions and representing the diatom natural variability of our dataset. These 5 natural communities corresponded to 5 different types of hydro-ecoregions, i.e. 5 river types with similar geological context and range in altitude.
All the stations corresponding to those 5 reference community types were checked according to REFCOND criteria (land use criteria and physico-chemical parameters values) or from expert knowledge when chemical values were not available (samples from the national reference stations network).
3.08 Reference community description:
According to the river type, 5 different reference communities have been described.
See: TISON, J., Y. S. PARK, M. COSTE, J.G. WASSON, L. ECTOR, F. RIMET, F. DELMAS (2005) ? Diatom community variability and hydro-ecoregions: a French assessment. Water Research, 39: 3177-3188.
3.09 Results expressed as EQR: Yes

Boundary setting

3.10 Setting of ecological status boundaries:
High-good boundary derived from metric variability at near-natural reference sites
3.11 Boundary setting procedure:
The good/moderate boundary was calculated using a two step procedures (this procedure based on diatom-derived biotypes to define the provisional threshold values of the good ecological status of French river (ministerial circular DE/MAGE/BEMA 05 n14 of the 28th July 2005):
1: For each type, the remaining range below the H/G boundary and the IBD minimum value was split into 4 equal classes to derive a preliminary G/M boundary, following a procedure proposed in the REFCOND guidance.
2: This preliminary boundary was then increased by 1 point on the IBD scale for all national types.
This procedure of boundaries calculation was chosen to be congruent with the French macroinvertebrates approach.
Then the IBD values obtained were checked to verify their compliance with normative definitions: a graph (not displayed here) shows the percentage of sensitive species (?oligotraphent? + ?mesotraphent? species: van Dam et al., 1994) in reference conditions and along the ecological status gradient.
This graph shows:
- no significant difference in sensitive species % between reference conditions and high status;
- a very slight but significant decrease of sensitive species between high and good status;
- a drop in the percentage of sensitive species between good and moderate status.
3.12 "Good status" community: n.a.


3.13 Consideration of uncertainty: No (to be done)
3.14 Comments: First results of uncertainty will be available at the end 2010.

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