LAUSR

This study investigated the biodiversity and hydrochemistry of seven unconfined aquifers located in two hydrogeological complexes in the north-western region of Algeria. The aim of the study was to: (1) contribute new data on the biodiversity and distribution patterns of groundwater fauna in groundwater bodies in North Africa, (2) assess whether the current biodiversity patterns of groundwater taxa reflect the difference in aquifer type, hydrogeological conditions and hydrochemistry, and (3) evaluate the role of hydrogeological, geographical and physicochemical variables in determining the distribution pattern of groundwater invertebrates. Sixty-three wells were investigated between August 2010 and June 2013. In total, 41,297 specimens belonging to 51 taxa, 10 of which were crustaceans, were collected during the survey. Taxa abundances varied significantly between aquifer types, but not between the two hydrogeological complexes (continental and littoral). The groundwater assemblages collected in seven aquifers in northwest Algeria differed significantly between aquifer types in this region. The distribution of groundwater fauna across the whole study area was primarily affected by distance to streams, the geological period and electrical conductivity. Overall, the assemblages showed a spatial distribution that to some extent mirrored the hydrogeological and hydrochemical conditions of groundwater in the north-western part of Algeria. These findings suggest that groundwater biota, and crustaceans in particular, may play a key role in distinguishing between the typologies of the investigated aquifers. This study contributes to knowledge of current groundwater biodiversity in northwest Algeria and demonstrates that this knowledge is still far from being complete.