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.
Our results are the first insight into groundwater copepods of the Polish Lowland. The sampling was conducted in 28 wells in north-eastern Poland, and Copepoda were present in 16 wells. We have ...identified six Copepoda species and one Cladocera. We have classified four species as stygophiles—Eucyclops serrulatus, Diacyclops bisetosus, Diacyclops crassicaudis, and Cyclops furcifer. These species were frequently found in studied wells of different regions of north-eastern Poland, often in high numbers, and females with egg sacs were observed. We present a detailed morphological description of these species, together with molecular characteristics based on mitochondrial DNA markers (COI gene) for E. serrulatus, D. bisetosus, and D. crassicaudis, and 12S ribosomal RNA for C. furcifer. We also present the development of abnormal structures in one specimen of D. crassicaudis, where the upper part of furcal rami was fused to form a single plate.
Our research provides valuable insights into the uneven distribution of groundwater copepods in the lowland river valley ecosystem using an integrative taxonomy approach. The study was conducted in ...101 wells in the Biebrza River Valley (northeastern Poland), which is one of the largest and best-preserved lowland rivers in Europe. It stands out for its exceptional biodiversity and pristine natural landscapes. Groundwater copepods were found in 49 of the 101 analyzed wells. We identified ten species of Copepoda and eight species of Cladocera. The most frequent copepods were Diacyclops bicuspidatus, Diacyclops crassicaudis, Canthocamptus staphylinus, Paracyclops cf. fimbriatus, Diacyclops bisetosus, and Eucyclops serrulatus. The aforementioned species were categorized as stygophiles, and no stygobionts were detected. Our findings suggest that the groundwater Copepoda community in this region is relatively stable and composed mostly of stygophiles along with stygoxenes. We did not find any significant impact of environmental parameters or different aquifers on the distribution of copepods, suggesting a patchy distribution of groundwater copepods in the lowland river valley. The relatively high presence of stygoxenes suggests that the exchange of organisms between surface water and groundwater plays a vital role in maintaining the diversity of microcrustaceans in lowland river valleys. Our study contributes to filling the knowledge gap regarding groundwater fauna in lowland Europe, particularly in areas affected by Pleistocene glaciations.
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