A biodiversity monitoring program for macroinvertebrates inhabiting streams and rivers of South Tyrol (Italy): aims, methodologies, and publicly accessible dataset

Despite very limited in their extension - about 1% of the total surface of our planet – freshwater habitats greatly contribute to the biodiversity of Earth, since 10% of the known species and 33% of the vertebrates inhabit freshwaters. However, continuous monitoring of habitats and biodiversity – not only aquatic – is considered as a complex task due to the long-term perspective these monitoring programs should have, and the connected required financial needs. Here, within the framework of a regional-scale program of biodiversity monitoring started in the mountainous region of the Autonomous Province of Bolzano/Bozen (Italy) – including terrestrial and aquatic habitats – we present a dataset covering the first year of the fieldwork campaign aiming at sampling and identifying the benthic macroinvertebrates inhabiting the running-waters of the region. First, we developed a GIS model with the aim of classifying all the running-waters of the region on the base of their water origin, elevation, mean discharge, slope, and geology of the catchment. After having identified a final set of 12 different stream types, 10 sampling points per each type were selected throughout the region, 2 of which – defined as “reference points” – were scheduled to be sampled each year, in order to keep a “year-by-year” temporal resolution in addition to a long-term one. Thus, every year, 48 points are sampled: 24 “reference points” (2 sites x 12 stream types), and 24 additional sites whose re-sampling is scheduled to happen every 4 years. In summary, in a 4 year-period all the 120 sites are sampled, and the same sampling campaign is planned to be repeated every 4 years, in order to build an ecological time series in a long-term perspective. At each site, we collect benthic macroinvertebrates through a kick-net sampler (mesh size 500 µm), following a detailed protocol involving, among other aspects, characterization and quantification of the habitats present in the stretch selected for the sampling, as well as measurement of the water velocity associated to each habitat. The benthic samples are then sorted in the lab – with no application of sub-sampling – and identified mostly to family or genus level using appropriate literature. In addition, at each site, water samples are collected and analyzed within the same day, through a spectrophotometer, looking for a set of chemical species of nitrogen and phosphorous.