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IBGN [id:]

Method: Global biological normalized index [Indice Biologique Global Normalisé]

1. General information

1.01 GIG: Alpine, Central-Baltic, Mediterranean
Relevant intercalibration types: n.a.
1.02 Category: Rivers
1.03 BQE: Benthic Invertebrates
1.04 Country: France
1.05 Specification: none
1.06 Method name: Global biological normalized index
1.07 Original name: Indice Biologique Global Normalisé
1.08 Status: Method is/will be used in First RBMP (2009)
1.09 Detected pressure(s):
Catchment land use, Eutrophication, General degradation, Pollution by organic matter Specification of pressure-impact-relationship:
Large-scale model (PLS regression) linking IBGN index to river basin and riparian land cover were developed using national monitoring networks (3662 sites and 12682 samples covering the period 1992-2002). Land cover explained 18% of IBGN index variability. This model showed significant negative effect of urbanization and agriculture.
Yes, with quantitative data (e.g. against range of sites reflecting continuous gradient of pressure).
1.10 Internet reference:
1.11 Pertinent literature of mandatory character:
Norme AFNOR NF T 90 350 (1992;2004) and circular MEDD/DE 05 no 14 (july 05).
1.12 Scientific literature:
Terrasson, I., 2004. The IBGN- its history, sampling and future. Technical synthese. ENGREF Centre de Montpellier.
1.13 Method developed by: Jean Verneaux
Email of developer: n.a.
Institute of developer: Laboratoire de biologie Faculté des Sciences de Besançon
1.14 Method reported by: Andrè Chandesris & Virginie Archaimbault
Email of person reporting the method:,
Email of institute reporting the method: CEMAGREF
IBGN is the French historical assessment method applied since 1992 in our national monitoring network. This methodology was not entirely compliant with the WFD requirements therefore we are improving it by modifying the sampling design and by creating a new Multimetric assessment index. Our objectives are 1/ to collect information allowing the calculation of the metrics required by the WFD; 2/ to integrate these metrics into a multimetric index, 3/ to be compliant with the AQEM methodology and 4/ to allow a recalculation of the IBGN index. Until the finalization of this new assessment tool, the IBGN index and associated metrics are still in use.

2. Data acquisition

Field sampling/surveying

2.01 Sampling/Survey guidelines:
Until 2005 Norme AFNOR NF T 90 350 (1992; 2004)
since 205 Circulaire DE/ MAGE/ BEMA 04/ no 18 ( 23 décembre 2004) modified by Circulaire DE/ MAGE/ BEMA 07/ no 4 (11 avril 2007) (Environment Ministry) ; now normalized Norme AFNOR XP T 90 333 (sept 2009).
2.02 Short description:
Before 2005: multi-habitat sampling designed for sampling the 8 most biogenous habitats is carried out
After 2005: multi-habitat sampling designed is carried out for sampling :
1/ minor habitats (<= 5%) according to their habitability
2/ major habitats (> 5%) in proportion to their presence within a sampling reach.
A sample consists of 12 ?sampling units? taken from all habitat types at the sampling site according to above rules.
A ?sampling unit" is a stationary sampling performed by positioning the net and disturbing the substrate in an area that equals the frame-size upstream of the net (0.20 x 0.25 m).
Sediments must be disturbed to a depth of 5 cm (where possible).
2.03 Method to select the sampling/survey site or area: Expert knowledge, Stratified sampling/surveying
2.04 Sampling/survey device: Hand net, Surber or Hess sampler
2.05 Specification: surber sampler 1/20 m2
2.06 Sampled/surveyed habitat:
Sampled habitat: All available habitats per site (Multi-habitat)
2.07 Sampled/surveyed zones in areas with tidal influence: not relevant
2.08 Sampling/survey month(s):
During low water level (June to September in lowlands, Februar to March in high mountains)
2.09 Number of sampling/survey occasions (in time) to classify site or area: One occasion per year
2.10 Number of spatial replicates per sampling/survey occasion to classify site or area:
8 replicates (according to their habitability) until 2005, 12 replicates (4 for substrates <=5% coverage and 8 for subtrates >5% coverage in proportion to their presence) since 2005.
2.11 Total sampled/surveyed area or volume or total sampling duration to classify site or area:
8/20= 0.4 m2 until 2005, 12/20= 0.6 m2 since 2005

Sample processing

2.12 Minimum size of organisms sampled and processed: 500 µm
2.13 Sample treatment:
Organisms of the complete sample are identified.
2.14 Level of taxonomical identification:
Level: Family, Genus, Other
Specification of level of determination:
Before 2005, family or other levels;
after 2005: Plecoptera, Ephemeroptera, Trichoptera (without Limnephilidae), Coleoptera (without Dytiscidae, Hydrophilidae and Curculionidae), Megaloptera, Planipennia, Odonata (without Coenagrionidae), Hymenoptera, Crustacea (without Asellidae), Bivalvia, Gastropoda (without Planorbidae): Genus level
Diptera, Heteroptera (without Corixinae), Lepidoptera, Hirudinea et Branchiobdellida, Turbellaria: Family level
(Hydracarina), Oligochaeta, Bryozoa, Nematoda, Gordiacea, Hydrozoa, Porifera
Nemertea: Group level
2.15 Record of abundance:
Determination of abundance: Abundance classes, Individual counts
Abundance is related to: Area
Unit of the record of abundance: number of individuals per effort sampling
Other relation of abundance: before 2005 : abundance classes
after 2005 : individual counts
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: Richness, sensitive taxa, abundance classes
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: Aggregated data from multiple spatial replicates

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
3.07 Reference site characterisation:
Number of sites: 305
Geographical coverage:
all over the territory of France, but more sites on the medium and small streams
Location of sites: all over the territory
Data time period: historical datas since 1992 until 2003
1/ qualitative criteria's list at the basin, reach, site scale evaluated by local experts
2/ GIS criterias based on Corine Land Cover's datas (artificial, intensive agriculture, agriculture in the watershed)
3.08 Reference community description: not available with the IBGN protocol, in progress with the new one
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: n.a.
3.12 "Good status" community: n.a.


3.13 Consideration of uncertainty: No (to be done)
3.14 Comments: uncertainty results expected for the end of 2012

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