Effect of Weather-Related Episodic Events over Chlorophyll-a in a Shallow Lake: an Analysis Based on High-Frequency Data

Abstract

With conventional monitoring at low-frequency, biological responses to weather-related events are missed. In this paper, we examine the chlorophyll-a concentrations in a shallow lake using high-frequency data from an in situ buoy. Also, we used monthly data of phytoplankton to relation high and low-frequency data. This is the first study about chlorophyll-a in high-frequency from a buoy in situ in South America. Significant minimums of chlorophyll-a concentration were detected, associated with episodic weather events in La Salada shallow lake. We present the data obtained from October 2012 to April 2015, and as an example analyzed some occasions in which these events of a significant minimum of Chlorophyll-a were detected. Extreme minimum values prevailed during winter months. We can conclude, the predominance of western winds registered, which (given the small size of the predominant species) could generate a spatial displace-ment (patches) of phytoplankton. Also, the high transparency conditions could affect phytoplankton by photo-inhibition. Chlorophyll-a concentrations returned to previous conditions after two days. This study suggests that the duration of western wind events and photo-inhibition with high water transparency could explain the spatial changes of phytoplankton communities. These results emphasize the importance of the analysis of high-frequency measurements in conjunction with meteorological variables to understand phyto-plankton dynamics and sampling planning.