Tânia Vidal
University of Aveiro, Portugal
Title: Optimization of growth conditions for laboratory and field assessments using immobilized benthic diatoms
Biography
Biography: Tânia Vidal
Abstract
Benthic diatoms are key role players at lotic freshwater environments and the lack of availability of rapid and effective methodologies for assessing lotic systems are still quite scarce. The primary goal of this study was to optimize the growth conditions of the sensitive and ubiquous benthic diatom Navicula libonensis for laboratorial and field assessments. The first set of experiments started with testing the effect of different conditions of temperature, photoperiod, initial cell density, test duration and cell encapsulation into calcium alginate. Results showed growth profiles of free versus immobilized cells was fairly variable but a slight increase in growth was observed in free and immobilized cell densities at 23ºC, at lower initial cell densities and at the shortest experimental period (6 days). A second experimental trial involved the validation of selected conditions, applied to the eco-toxicological testing of N. libonensis to two reference chemicals - 3,5-dichlorophenol and potassium dichromate - and a natural stream water besides the synthetic medium. The sensitivity of N. libonensis to standard chemicals spiked in synthetic medium and natural plain stream water was similar for free and immobilized cells. This outcome suggests that N. libonensis may potentially provide reliable responses under direct in situ exposures.