EFFECT OF SILICA CHANGES IN THE DEVELOPMENT OF DIATOMACEOUS MICROALGAE Thalassiosira fluviatilis

Abstract

Microalgae are important to the environment because they constitute an important link in the aquatic food chain and can still be used as bioindicators of water quality and regulators of nutrients level in the water column. This study aimed to evaluate the development of diatom microalgae Thalassiosira fluviatilis in culture media Conway and Guilard f / 2, with different concentrations of sodium silicate and its influence on cultures of diatoms. The cultures were monitored by direct cell counts in a Neubauer chamber and the culture absorbance at 700 nm using a spectrophotometer. The best result was obtained with the Conway medium, using a low concentration of sodium silicate, followed by the Guilard medium, with the same silicate concentration. The cultures performed with twice the concentration of sodium silicate, showed a very short and lethargic development, resulting in excessive formation of precipitated material and depigmented cells, leading to the death of cultures. Thus, high concentrations of sodium silicate inhibit algal growth in cultures of T. fluviatilis.

Keywords: diatoms, sodium silicate, Thalassiosira fluviatilis.