UVR Radiation as a Potential Driving Force for Zooplankton Community Structure in Patagonian Lakes

MARINONE, M. C., S. MENU MARQUE, D. AÑÓN SUÁREZ, M. C. DIÉGUEZ, A. P. PÉREZ, P. DE LOS RÍOS, D. SOTO AND H. E. ZAGARESE

PHOTOCHEMISTRY AND PHOTOBIOLOGY

Allen Press

Año: 2006

0031-8655

This paper explores the potential role of UVR to influence zooplankton communities. In the first section, we provide a general overview of UVR effects on freshwater zooplankton, with emphasis in Argentine and Chilean environments. In the second section, we present the results of a survey of 53 temperate lakes across a gradient of UVR exposure, looking for patterns of species richness and specific diversity. These community parameters decreased at high potential UVR exposure (i.e., high mean water column irradiance or low lake OD). A threshold value of mean water column irradiance of about 10% of surface level seems to limit both richness and diversity to minimum values. From the collected evidence it is not possible to definitely conclude that UVR, and not some other co-varying parameter, is responsible for the decrease in specific diversity observed at the lowest end of lake optical depth, but regardless of the mechanism, lakes above the previous threshold values are likely to exhibit highly depauperate zooplankton communities. As a cautionary note, we suggest that changes in the optical characteristics (i.e., due to changes in atmospheric conditions, precipitation patterns, or vertical displacement of the tree line) may result in sudden shifts in zooplankton community structure. Key words: UV radiation, Patagonia, community structure, freshwater zooplankton