INFLUENCE OF TEMPERATURE ON BIOMASS AND GROWTH RATE OF BENTHIC DIATOMS

Sammanfattning: Temperature has a significant impact on structure and abundance of microalgal community as well as on physiology (Sheehan et al., 2020). Given the anticipated temperature fluctuations and likely rise in temperature during summer seasons in the greenhouse at Swedish Algae Factory (SAF), it is essential to comprehend the response of diatoms to temperature, in order to sustain growth and microalgal biomass production. In this study, the influence of three different temperature scenarios on biomass and growth rate of two species of benthic diatoms (Nitzschia sp. and Diatoma sp.) along with the algal community cultivated at SAF, were examined. Treatments were carried out in 100ml flasks, and nutrient levels, chlorophyll a fluorescence parameter (Fv’/Fm’), cell density, growth rates, and photosynthetic pigments (through HPLC) were measured. Pigments were calculated as concentrations (µg L-1) and as ratios relative to chlorophyll a. The results showed an increase in biomass and growth rate at ambient temperature (11-16°C) and 20°C for the two species and the algal community, while a decline in biomass and growth rate was observed at 30°C. Moreover, results revealed that an increase in temperature to 30°C generated an increase in green algae and cyanobacteria within the algal community. Additionally, Diatoma sp. also exhibited green algae and cyanobacteria at 30°C, whereas Nitzschia sp. did not, even at high temperatures, indicating its suitability for SAF cultivations. Overall, these findings illustrate the variation in thermal performance among benthic diatoms and emphasize the importance of studying species-specific responses to temperature change.