Reference community description. Pristine coastal lagoons are considered to be dominated by extensive xxxxxxx of perennial seagrass species, since in oligotrophic waters rhizophytes take advantage of nutrient supply from sediment (Figure 1). Then, a key criterion to select reference sites is: “A lagoon with low human pressures covered with extensive angiosperm¾ xxxxxxx” (Meeting of the WFD CIS MED-GIG MACROPHYTES - Technical report - Kavala)
Reference community description. With historical data has been calculated the function of distribution (Xxxxxxx'x algorithm R software) than was taken into account the 90°percentile of the H' and Richness distribution and was calculated the average of the values of those parameters > of 90° percentile, that was considered the reference condition. For AMBI has been taken into account the 10° percentile, so the average of the values of AMBI<10° was considered a reference condition.
Reference community description. Reference community of the oligohaline type is characterized by Cloeon sp., Corixidae Gen. sp., Daphnia sp., Dasyhelea sp., Herpetocypris sp., Hydrachnidia Gen. sp., Xxxxxxxx sp., Laccophilus sp., Libellulidae Gen. sp., Megacyclops sp., Physella sp., Plea sp., Psectrocladius sp., Sarscypridopsis sp. and Sigara sp. Reference community of the mesohaline type is characterized by Cyprideis sp., Gammarus sp., Hydrobia sp., Lekanesphaera sp., Loxoconcha sp. and Xxxxxx sp. Reference community of the mesohaline type is characterized by Cletocamptus sp., Corixidae Gen. sp., Halocladius sp., Heterocypris sp., Nemotelus sp. and Sigara sp.
Reference community description. (still in progress) Values derived from models for each fish metric. This reference metric' value is calculated per habitat i.e. salinity zone (and also season) Method 1 : Reference community corresponds to the value of each metric in the least disturbed conditions based on our pressure index. Method 2 : pressure index set to 0 and the corresponding value of each metric calculated from the models is used as reference community description.
Reference community description. Reference conditions are assumed to correspond to an EQR value of 1, which is associated with expert-based type-specific metric values reflecting high taxa richness, sensitivity and diversity.
Reference community description. The number of different natural habitats in the estuary should be high. Habitats should have coverages equal or higher than expected ones. There should be no loss of extension of natural habitats of the estuary.
Reference community description species number, structural composition and diversity of benthic invertebrate communities, the abundance and share of sensitive species
Reference community description. Three types of communities have been defined. Abra community is a high richnness assemblage characterized by Loripes lacteus, Nephtys hombergii, Melinna palmata, Cerastoderma edule, Nassarius reticulatus, Abra alba, etc. Scrobicularia (called Scrobicularia II) is a low richness and high dominance community, dominated by Hediste diversicolor, Srobicularia plana, Cyathura carinata and Carcinus maenas. A third community is described (called Scrobicularia I), with an intermediate richness, in which are present the dominant species of Scrobicularia II but other species are also important (Abra tenuis, Cerastoderma edule, Ruditapes decussatus).
Reference community description the assessment tool includes a tab labelled 'References' with a ‘historical frequency category’ for each species (1 rare – 6 very frequent, on a massive scale). This provides indications of how frequently the species was found in the estuaries at the reference time.
Reference community description estuary fish fauna characterized by strong seasonal dynamics, both in abundance and in composition. Vulnerable species to anthropogenic pressures are present in the system. The estuary is populated by resident species, diadromous species, marine seasonal species, marine juvenile species . Furthermore a general description is given (in Dutch) in: STOWA (2009) Referenties en maatlatten voor natuurlijke watertypen. report 2007-32
