the study of aquifers from an ecosystemic perspective that focus on their invertebrate communities is relatively recent. particularly, the invertebrates living in low permeability loessic aquifers have not been studied. the objective of this work was to evaluate the influence of environmental variables on the invertebrate communities in the loessic phreatic aquifer of la colacha basin (córdoba). seven perforations were selected according to the thickness of the vadose zone and the surrounding land use. also a superficial water body was selected as a reference. the perforations were sampled twice during a hydrological year. the samples corresponded to fresh water, with the exception of one perforation (brackish water). nitrate was detected in all samples. as expected, the superficial water body showed higher invertebrate abundance than the wells. invertebrate density ranged between 1.6 and 23.7 individuals/l, which is in the range of densities of other aquifers of the world. the dominant taxon was crustacea, in particular copepoda, followed by acari, collembola, insecta, oligochaeta, pauropoda and nematoda. invertebrate abundance diminished with vadose zone depth, associated with a decrease of the flow of oxygen and organic matter to the groundwater. land use surrounding the wells significantly affected the aquifer invertebrates through the contribution of organic matter.