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The hyporheic (phreatic) zone connects groundwater and surface water and hosts a diverse community of organisms that are adapted to its unique conditions. In order to investigate the hitherto poorly understood biotic connections between the hyporheic zone and temporary ponds, we analyzed changes in the community of Copepoda in a small and shallow ephemeral puddle in a meadow for one year, with comparison to the groundwater fauna of the surrounding region in northeastern Poland. In the puddle, three species of Cyclopoida (Acanthocyclops vernalis, Diacyclops bisetosus, and Cyclops furcifer) were present in large numbers throughout the year. These species were also common components of the region's groundwater fauna, but in much lower densities in the groundwater than in the puddle. These results suggest that temporary puddles can be a convenient place for copepods to feed and reproduce, while groundwater may serve as an important corridor for their dispersal. This study contributes to a more comprehensive understanding of copepod ecology and the functioning of ephemeral aquatic habitats. [ABSTRACT FROM AUTHOR]

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Asymmetric, pendant cements are considered good indicators for early lithification in the vadose zone. In the present study, asymmetric cements are recorded in thin-sections of a Lower Jurassic limestone from the Traras Mountains (northwest Algeria). Geopetal fabrics, however, indicate that these seemingly "pendant cements" are, in some places, oriented upwards, i.e., they have grown in the opposite direction from that expected, or they grew from grains towards the pore centers. These observations disprove their origin as gravitational cements precipitated from pendant water droplets on the undersides of grains as in the vadose zone. In contrast, a formation in the marine phreatic zone seems more probable. Under high-energy conditions, and after an early lithification stage with isopachous cements in the subtidal zone, strong tidally driven horizontal pore-water flow allowed sufficient seawater to pass through the slightly cemented but still highly permeable rock. Those grain sides, which were oriented towards the pore center, where faster flowing water prevailed, were more exposed to CaCO3-supersaturated percolating seawater and therefore the cements precipitated here show their greatest thickness. In relatively more protected areas around the margins of the pores, asymmetric cements are rarely developed. The resulting rock exhibits an unusual, heterogeneous cementation with preferential centripetal nucleation areas. [ABSTRACT FROM AUTHOR]