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Dryad

Lake Sanabria ecosystem regime shift (1986-2019)

Abstract

This dataset has been used to study the ecosystem regime shifts of Lake Sanabria, the largest natural glacial lake in Spain, in a situation of climate change that may affect compliance with ecological quality objectives, even with no significant water quality pressures. It comprises basic data from long-term (1986-2017) and intensive short-term (2015-2017) limnological monitoring of a few relevant state variables related to nutrients balance, primary production of phytoplankton and thermal structure of the water column. Data about recent history of the lake productivity, reconstructed by high-resolution palaeolimnological analysis of a surface sediment core, is provided. Time series analysis over several decades has detected significant conditional heteroscedasticity in the concentrations of parameters such as chlorophyll and oxygen in recent years in relation to lake turnover rates, coinciding with exceptional episodic single-species blooms of some planktonic diatoms. We include precipitation data, inflow measurements and land use modeling data that indicate how external nutrient loadings have declined during the last decades, with reduced precipitation and progressive afforestation of the catchment, but the lake is shifting to a more productive regime enhancing the relevance of internal loading and processes.