Temporal coherence of physical, chemical and biological variables in four tropical lakes (Minas Gerais, Brazil)

Abstract

Abstract Aim: The main objective of this study was to evaluate the presence of temporal coherence of limnological variables and pairs of lakes considering four tropical lakes of the Rio Doce State Park, using monthly data from the Long-Term Ecological Research Program (LTER) between the years of 2004 to 2009. Methods Subsurface data (0.5 meters) from the Carioca, Dom Helvécio, Gambazinho, and Jacaré Lakes were used in the analysis. We estimated the temporal coherence from the creation of time series for each of the variables. Through these series, we calculated the Pearson correlation coefficient between all pairs of lakes (N=6) and performed the average. We also analyzed the correlation between the temporal coherence found for the different pairs of lakes and two predictors of spatial patterns: proximity and exposure to climatic factors. The spatial proximity of the lake pairs was calculated in kilometers, and the exposure to climatic factors was estimated using two metrics: surface area and surface area/mean depth ratio. Results The largest temporal coherence levels were recorded for water temperature (0.97), pH (0.78), and dissolved organic carbon (DOC) (0.74). The lowest levels were found for chlorophyll-a (0.25) and phytoplankton richness (-0.02). The average temporal coherence was 0.58. Different from other studies, no significant correlation was found between the synchronicity of the lake pairs and the differences in their exposure to climatic factors. Also, no relation was found with the spatial proximity. Conclusions Our results demonstrate the existence of temporal coherence in tropical lakes to compatible levels with those found in temperate regions. Our work contributes to the knowledge of how synchronicity works at different set of lakes and climatic regions.