Primary productivity maintenance through chlorophyll a changes in Elodea potamogeton during an annual cycle

Abstract

Measurements of the photosynthetic rate (oxygen exchange) and concentration of chlorophyll a (Chl a) were conducted, during an annual light cycle, in Elodea potamogeton (Bert.) Espinosa, a submerged limnic plant with vegetative growth, found in Peru, Bolivia and Chile. In temperate Chile (Peñaflor), this plant grows abundantly in a lotic system whose waters have constant physical and chemical conditions and non-limiting nutrients during the year. The results showed that E. potamogeton is able to maintain, with a two-fold variation, a similar photosynthetic rate (P) all year round, with a mean and S.E. of 21.4 ± 0.6 mg O2 per g dry weight h-1. In contrast, the Chl a concentrations increased during winter, to between three and seven times of those observed at the end of spring. Plants exposed to similar irradiance variations showed an inverse relationship between their concentrations of Chl a and the total solar daily radiation (I) available 3 days prior to their collection. The light re