Sedimentary cladoceran assemblages and their functional attributes record late Holocene climate variability in southern Finland

摘要: We examined long-term relationships between Cladocera and limnogeological climate variables in a late Holocene lake sediment sequence to assess cladoceran responses change reconstruct past variations southern Finland, near the Baltic Sea coast. Elemental composition, organic matter, inferred water quality were used constrain paleoenvironmental (until 4500 cal BP) conditions human impact. Fossil assemblages, ephippia, body size trends utilized estimate mean July air temperature (TJul) variability, open-water season length, water-temperature regimes. Results revealed stable communities, dominated by Eubosmina, until 500 BP, followed major assemblage changes including increases Chydorus cf. sphaericus, Alonella spp., Bosmina longirostris. Pb Cu concentrations associated temporally with increasing impact warming during few centuries, most significant factors explaining community changes, based on redundancy analysis. A Cladocera-based TJul reconstruction estimated elevated temperatures for end of Thermal Maximum, cooler period ~3000–2000 slightly increased 1200–800 BP corresponding Medieval Climate Anomaly (MCA), lower Little Ice Age (LIA), 800–200 BP. The also suggests that took place twentieth century. Cladocerans mostly warm periods included B. longirostris Pleuroxus uncinatus, whereas Alona affinis, A. quadrangularis, C. sphaericus colder climate. Compared reference Chironomidae-inferred from same region, discrepancies apparent amplitude change, as variability cladoceran-based record was muted ~200 During LIA, ephippia agreed reconstruction, but suggested severely shorter reduced compared preceding episodes, even though showed quite similar these periods. Our results suggest fossil morphological attributes respond sensitively fluctuations this reflects well events provides realistic paleoclimatic estimates maritime Finland.