Reconstruction of past lake environmental variables using variability in diatom concentration and accumulation rates in sediment from selected lakes (Türkiye): A quantitative approach in paleolimnology

This study aims to reconstruct dataset related to paleo-salinity, paleo-alkalinity, paleo-acidification, paleo-nutrient, paleo-trophic status, and paleo-conductivity variables from five lakes with different origins (Beymelek/Lagoon, Beyşehir/Tectonic, Ercek/Lava Dam, Gölcük/Crater, and Iodürge/Karstic). In the initial phase of the research, calibration sets were established, and in the subsequent phase, data reconstruction was performed. Although 50 lakes were initially investigated to create calibration datasets, statistically significant dataset was produced in 35 lakes. The calibration set 1 consists of 35 lakes, 14 environmental parameters, and 64 diatom taxa. Environmental parameters were reconstructed using the weighted average (WA) and weighted average partial least squares (WA-PLS) methods. Significant model performances were identified for conductivity, sulfate, potassium, magnesium, secchi depth, and calcium carbonate variables. For conductivity, R², rjack2, RMSE, and RMSEP values were 0,767, 0,476, 0,331 and 0,496, respectively. The diatom taxa with the highest and lowest optimum and tolerance values for conductivity were identified as Amphora commutata (1720,56-18,34 µS/cm) and Staurosira binodis (107,47-2,28 µS/ cm). Calibration set 2 includes 35 lakes, 12 environmental parameters, and 64 diatom taxa. Significant model performances were developed for salinity, sulfate, potassium, magnesium, pH, sodium, and chloride variables. For salinity, R², rjack2, RMSE, and RMSEP values were 0,694, 0,227, 0,140 and 0,225, respectively. The diatom taxa with the highest and lowest optimum and tolerance values for salinity were identified as Campylodiscus clypeus – Amphora pediculus (49,57-2,80) and Cyclotella atomus – Cymbopleura inaequalis (2,15-1,30). Calibration set 3 comprises 35 lakes, 15 environmental parameters, and 156 diatom taxa. For total phosphorus, R², rjack2, RMSE, and RMSEP values were 0,667, 0,311, 0,055 and 0,112, respectively. For total nitrogen, R², rjack2, RMSE, and RMSEP values were 0,715, 0,453, 0,109 and 0,168, respectively. The diatom taxa with the highest and lowest optimum and tolerance values for total nitrogen were Ctenophora pulchella – Hippodonta neglecta (3,83-1,27 mg/L) and Hantzschia amptaxys – Karaxevla clever (2,97-1,04 mg/L). For total phosphorus, the diatom taxa with the highest and lowest optimum and tolerance values were Hantzschia amphioxys – Cymbella parva (0,423-0,015 mg/L) and Hantzschia amphioxys – Mastogloia calcarea (0,308-0,008 mg/L).