Investigation of ecological and hydrogeochemical conditions for aquatic invertebrates by multivariate statistical analysis

This research paper investigates the subterranean fauna distribution and diversity, and it determines the environmental variables that influence them in a study area two mountainous areas. The sampling sites are distributed in two regions, Baumberge and Schöppinger Berg in Münsterland, North-Rhine Westphalia (NW Germany). Groundwater invertebrates are collected and analyzed from eight springs in three sampling occasions between 2018 and 2019, 24 hours for 2-4 consecutive days each. Physiochemical parameters of groundwater, chemical analyses, isotopes, microbial analysis (biomass and activity), and groundwater discharge and rainfall are the data used in the investigation.

Groundwater in both areas is of the type of Ca-HCO₃, and it is influenced mainly by rock-water interactions. Stable Isotopes of water indicate meteoric origin with little evaporation effect before infiltration or in the unsaturated zone. The stable isotopes of nitrate and sulfate confirm an anthropogenic contamination through manure and natural pollution by mineralization of soil organic nitrogen and sulfide oxidation in the deeper groundwater.  Spearman correlation (n=12, p < 0.01) shows that invertebrates do not correlate significantly with most abiotic variables in both BB and SB. In Baumberge, they are significantly positively correlated with groundwater table and negatively with precipitation, Mg and Sr. In Schöppinger Berg, invertebrates are influenced by detritus. Factor analysis, multidimensional scaling and hierarchical clustering confirmed that chemical composition does not affect the invertebrates in Baumberge. The invertebrates are not affected much by other factors, e.g. biological indicator especially Groundwater Fauna Index (GFI), biomass (TCC) and activity (ATP).