Exploring the distribution of groundwater Crustacea (Copepoda and Ostracoda) to disentangle aquifer type features – a case study in the upper Tajo Basin (central Spain)
One of the most challenging questions in the assessment of groundwater ecosystem health is whethe... more One of the most challenging questions in the assessment of groundwater ecosystem health is whether assemblages of groundwater biota can be used reliably as biomarkers. In the present study, we aimed to: (i) explore the diversity, distribution and ecological composition of groundwater Crustacea Copepoda and Ostracoda communities from six aquifers in central Spain; and (ii) relate the structure of the species assemblages to the aquifers’ hydrogeological conditions, habitat features and hydrochemistry. The data sets were simultaneously collected from 24 boreholes drilled in six unconfined aquifers from the upper part of the Tajo catchment. Our results show that the assemblages are primarily influenced by the specific hydrogeological conditions of the aquifer, determined by groundwater flow, supply of organic matter from the surface and habitat features, whereas the aquifer’s hydrochemistry has only a marginal effect. The assemblages from the Tertiary detrital aquifer were the most diverse, containing a mixture of stygobiont and non stygobiont species distributed preferentially in the recharge area of the aquifer, characterized by medium hydraulic conductivity, high surface input and relatively high water renewal. The Quaternary alluvial aquifer type was found to have a moderate richness with several hyporheic dwellers, indicating an active surface/groundwater 32 exchange with the adjacent stream channel. In contrast, the carbonate aquifer type was less diverse, but markedly distinct owing to the high occurrence of stygobionts. Our results provide a step forward in exploring the groundwater biodiversity of aquifers in Spain and towards incorporating an ecological perspective into overall assessments of groundwater status.
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Papers by Sanda Iepure
patchy discontinuity on a longitudinal transect and induces changes in the structure and functioning of biotic communities.
Nevertheless, the factors that influence biotic communities along spatial and temporal gradients remain poorly understood.
This study aimed to characterise the diversity and spatial pattern distribution of Cyclopoida and Ostracoda from the hyporheic
zone in relation to the riverbed sediment structure and the quantity of organic matter in two second-order rivers in central
Spain, whose alluvium is derived from materials of contrasting geology (siliceous vs. carbonates). Both streams were found
to be characterised by marked habitat heterogeneity along the hyporheic flow path, as reflected by the different lithology,
riverbed permeability and distinct hyporheic biota assemblages. The results indicate that the alluvium riverbeds dominated
by carbonates rocks and associated with high permeable riverbeds had slightly diverse hyporheic assemblages (25 species in
all) with species of mixed ecology (stygobites/stygophiles/stygoxenes). Conversely, the siliceous alluvium riverbeds with
low mineralised waters, associated with reduced permeability and relatively less active surface/ground water exchanges,
displayed slightly lower diversity (23 species) with assemblages exclusively composed of stygophiles/stygoxenes. The results
highlight the role of the riverbed substratum for the hyporheic biota and provide forthcoming approaches for depicting surfacesubsurface
hydrological exchanges.