Influence of (extreme) radiation and optical characteristics in physical and biological features of a regulated lake

¹ University of Concepción, Environmental Sciences Center (EULA). Chile
² Planetary Science Laboratory, Universidad Central “Marta Abreu” de Las Villas, Santa Clara, Cuba
³ UFZ - Helmholtz Centre for Environmental Research, Brückstraße 3a, D-39114 Magdeburg, Germany
⁴ University of Concepción, Faculty of Engineering. Chile.

¹ Corresponding author: lrodriguezl@udec.cl

Abstract

Radiation plays an essential role in the establishment and proliferation of biota in natural environments. The photosynthetic process determines the existence of all life forms, since it supplies the energy that this photobiological process needs for the reaction, it is carried out by absorbing photons in the visible and infrared bands of the electromagnetic spectrum, while ultraviolet (UV) photons and ionizing radiation tends to inhibit it (decreasing, by various mechanisms, its quantum yield). The speed of photosynthesis, measured by the amount of O2 released in the unit of time (or CO2 absorbed) depends on the intensity of the incident light, in the last three decades this radiation has been increased by the decrease of stratospheric ozone in the South latitudes of our planet, for this reason the UV values in the aquatic ecosystems of Chile have been high as well as a considerable increase in the surface temperature of the bodies of water, having possible implications in the primary biological productivity of the ecosystems lakes, especially in Andean lakes. This increase in radiation could be related to the abundance of the different algal groups and the seasonal variability of them, creating favorable conditions for those dominant species considered invasive of these ecosystems. This paper shows the direct relationship between the concentration of ozone (O3) and ultraviolet radiation and how it influences the vertical distribution of the phytoplankton groups in the water column. For the first time it was found in this lake the appearance of a bloom of toxic cyanobacteria.