Rediscovery and redescription of Niphargus enslini Karaman, 1932 (Amphipoda, Niphargidae) in southern Germany

Niphargus enslini Karaman, 1932 was collected only once in 1905 from the Falkensteiner Höhle (Baden-Württemberg, Germany). Two years after its description, the species was synonymized with Niphargus virei and not studied any more. During recent surveys on German niphargids, further samples collected in this cave did not yield N. enslini specimens, but this species was collected in the Blätterteighöhle and in the Schwarzer Brunnen, two caves located in Baden-Württemberg and intercepting the same karstic aquifer feeding Falkensteiner Höhle. In an integrative taxonomic approach, we carefully studied the morphology of the newly collected specimens and sequenced two molecular markers (fragments of the cytochrome c oxidase subunit I (COI) and of the nuclear 28S rRNA gene) to test for possible conspecificity of N. enslini with N. virei. Morphological analysis confirmed that N. enslini is distinct from the N. virei species complex. We provide a redescription of newly collected material, together with new drawings of a more than 100 years old topotypic female. We briefly discuss the putative origin of N. enslini and the age of its split from the N. virei species complex.

Status and codification of karst aquifer systems in Greece

Karst groundwater is an important natural resource for the water supply. The karst aquifer systems of Greece are developed within carbonate sedimentary (limestone, dolomite) and metamorphic rocks (marbles) and contribute significantly to water supply for domestic and irrigation use. They are discharged through springs: submarine, coastal brackish and inland freshwater springs. This review presents the general characteristics of karst aquifers focusing on hydraulic properties. Evaluation of the results shows that the hydraulic parameters of the karstic aquifer systems range within a large scale of values depending on karstification, tectonics and stratigraphy. High values of transmissivity and specific capacity are recorded in the upper stratigraphically levels of the karstic aquifer systems. In addition, a total of 229 different karst systems were classified according to five criteria: 1) Lithology, 2) Position, 3) Quality status, 4) Exploitation and quantitative status and 5) Discharge of springs. The majority (80%) of karst systems is developed in sedimentary rocks (limestones) and is of good water quality and quantitative status. Poor water quality status is recorded in coastal karst aquifers (mainly on islands) due to seawater intrusion phenomena. Finally, this work summarizes the characteristics of the karst aquifers in Greece in order to ensure the sustainable management of groundwater resources.

Characterization of karstic aquifer complexity using fractal dimensions

The present study analyzes fractal dimensions for the daily discharge data series of 12 karstic springs registered over two decades in Northeast Hungary. Fluctuation in the observed data is frequent and irregular, producing rough time series. The level of roughness is measured by the fractal dimension defined in different ways and corresponds to the intensity of fluctuation. That, in turn, results from the structure of the karstic aquifer, its conduits’ geometry, and the water migration in them. In the given case of springs, p-variogram based fractal dimensions reflect the karstification level primarily. On the other hand, box-count and information dimensions are associated with mixing karstic and hydrothermal components when the latter is present. Therefore, the analysis of fractal dimensions of spring discharges may provide a way to obtain information on the complexity of the hidden subsurface conduits and the water flows in them in an exploratory and comprehensive way.

Feasibility of repurposing existing and abandoned hydrocarbon wells in the form of a geothermal well-triplet system

There are various types of extraction and utilization possibilities of geothermal energy, of which a large group is energy recovery. The development of this sector is slow mainly due to its high initial investment demand and the long planning phase. The overall goal of the present research is cutting the cost of the drilling phase as the most expensive part of the establishment by repurposing unused and abandoned hydrocarbon wells. The article assesses the feasibility of a geothermal well-triplet system chosen to be the most promising technique amongst several utilization possibilities depending on the characteristics of both the geological media and the method itself. From the 14 examined abandoned wells three were found to be suitable based on their current condition and distance from each other. The mentioned technique requires an adequately porous and permeable media which was not provided by the initial depth of the wells, thus the considerable option left was to overdrill the existing wells till they reach the target geology, the known fractured karstic aquifer below. The current study summarizes the final results of a long going research, from the geographical-, lithological surveys till the potential heat-transport modeling. This article supports the final aspirations of a further going research project as an integral part of it carried out by the University of Miskolc.

Tethysbaena ledoyeri n. sp., a new thermosbaenacean species (Thermosbaenacea) from the Port-Miou karstic aquifer in southern France

A new species of the thermosbaenacean genus Tethysbaena Wagner,1994 is described as T. ledoyeri n. sp. Together with an as yet undescribed amphipod (Niphargus sp.) it is an inhabitant of the brackish water of an aquifer that flows through the Basse-Provence Urgonian karstic system and reaches the Mediterranean Sea, 15 km east of Marseille, in the “Calanques” coast. The new taxon, being part of the T. argentarii-group, is compared with its closest allies in this group. Preliminary DNA data obtained from two specimens of the new species provide confirmation of its close ties to T. argentarii but also to T. scabra, the two geographically closest described species.