The effects of light availability in shallow, turbid waters: a mesocosm study

Author： Llames M. E. Lagomarsino L. Diovisalvi N. Fermani P. Torremorell A. M. Perez G. Unrein F. Bustingorry J. Escaray R. Ferraro M. Zagarese H. E.

Publisher： Oxford University Press

ISSN： 1464-3774

Source： Journal of Plankton Research, Vol.31, Iss.12, 2009-12, pp. : 1517-1529

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

Seasonal patterns of water transparency in turbid Pampean lakes suggest that the amount of seston is strongly influenced by incident solar radiation. However, the unequivocal identification of light as the major forcing variable is precluded due its co-variation with several potentially confounding variables. In order to specifically investigate the role of light, we performed a mesocosm (3000 L) experiment aimed at investigating the effects of different degrees of light availability on planktonic community structure and metabolism. The experimental setup successfully mimicked the light limiting conditions prevailing in Pampean turbid lakes. We used neutral density filters to create four light treatments, approximately covering the natural annual range of incident irradiance. Our results are consistent with field patterns and light-limitation theory: (i) light attenuation and (ii) primary production increased with light availability. In contrast, the abundance of most grazers displayed negative relationships with light availability. The decreases in the density of grazers could have resulted from changes in the nutritional value of the food. This possibility is also supported by (iii) decreases in seston P-content and (iv) increases in community respiration with increasing light availability.