Comparison of Environmental Signals Between Contemporary and Subfossil Cladocera (Crustacea) Assemblages: A Case Study of Shallow Urban Ponds

ABSTRACT Cladocera are an important component of freshwater zooplankton and serve as proxies in paleoecological reconstructions. However, the similarity of environmental signals reflected in the dominant species structure of contemporary (CC) and subfossil (SC) cladoceran communities remains an open question. 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, through intermediate depths, to the deepest part of each pond. During sampling, the following parameters were measured: depth (DEPTH), temperature, 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; 23 species were identified in the CC samples and 38 species were identified in the SC samples. Although the SC samples contained a greater number of species, several significant taxa from the CC samples were either rarely detected or completely absent from 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. Further analysis revealed synchronous changes in species structure in both CC and SC communities along the COND and DEPTH, which aligns with the established ecological preferences of the taxa. That suggest the structure of CC and SC communities in artificial water bodies—even of small size—mirrors specific patterns, resulting the formation of distinct species assemblages. Shifts in dominant species structure within CC and SC may be useful for reconstructing DEPTH, while COND can only be roughly estimated based on the presence of certain subdominant species. The study also discusses the implications of cladoceran species preservation for reconstructing environmental variables.