Comparison of environmental signals between contemporary and subfossil Cladocera (Crustacea) assemblages: a case study of shallow urban ponds

The objective of this study is to assess how changes in the dominant species structure of SC correlate with those in CC and with corresponding environmental conditions in artificial ponds. The research was conducted in seven artificial urban ponds in Moscow experiencing various degrees of anthropogenic pressure. Samples of both CC and SC were collected simultaneously from the same locations along a depth gradient: from the littoral zone, the intermediate depths and from the deepest part of each pond. During sampling, the following variables were measured: depth (DEPTH), temperature (TEMP), dissolved oxygen concentration, pH, conductivity (COND), oxidation-reduction potential, blue-green algae phycoerythrin, blue-green algae phycocyanin, and chlorophyll a. In total, 22 CC and 26 SC samples were collected. A total of 23 species were identified in the CC samples, and 38 species were identified in the SC samples. Redundancy analysis (RDA) and k-means clustering revealed five clusters for CC and four for SC, which were distributed along gradients of Depth and COND. Ecological preferences of <i>Chidorus sphaericus, Bosmina longirostris </i>and <i>Ceriodaphnia pulchella r</i>evealed in artificial ponds were similar with those previously described in natural ponds. <i>Bosmina longirostris</i> reflect similar environmental signals in CC and CS. The dominance species structure of CC and SC communities in artificial ponds—even of small size—mirrors patterns observed in natural ecosystems, resulting the formation of distinct species assemblages. Shifts in dominant species structure within CC and SC were similar and may be explained by changes in DEPTH and COND. The study also discusses the implications of cladoceran species preservation for reconstructing environmental variables. These results suggest consistency of ecological preferences of studied species and may be usefull for palaeoreconstructions. .<br>