Macrozoobenthos (small animals at the bottom of the water) Biodiversity of small waterbodies

In the 2024 status report, large differences in the macrozoobenthos biodiversity of small water bodies were generally reported. On average, a Shannon diversity of 1.8, a total number of 32.1 taxa and 3.9 taxa of particularly sensitive species were found per body of water. A status update will be provided in 2028.

Due to a limited database, the status indicator “macrozoobenthos (aquatic insects)” could so far only be applied to the small water body type “Sölle of the North German Plain” without a temporal comparison or a distinction between agricultural areas. The results of the application showed large differences in Shannon diversity, number of taxa found and number of particularly sensitive species (EPT taxa) in the small water bodies examined. A comparison between different types of agricultural areas and further interpretation and classification of the state of biodiversity is currently being carried out using newly collected data.

The data basis is the water-specific taxonomic composition of macrozoobenthos with the number of individuals per taxon. The indicator values calculated using representative samples within the small water body (>0.15 ha to <1.0 ha) are reported at national level. Where the spatial coverage of the samples allows, the national reporting level can be supplemented with agricultural area-specific statements. With the start of implementation of regular monitoring, the first results will be available from 2023; the indicator should be completely reported every 5 years. Since no generally valid evaluation system can be created due to the natural spread of the data, a qualitative classification is not possible, but only a comparison with other small water bodies (or groups of small water bodies).