Global Warming and the Interactions Between Cyanobacteria and Chlorophyta: Exploring Population Dynamics and Cyanotoxin Production

• Grant number: 25/00842-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Biological Sciences - Microbiology - Biology and Physiology of Microorganisms
• Principal Investigator: Ana Teresa Lombardi
• Grantee: Sara dos Santos Guimaraes
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The imbalance of CO2 and other gases in the atmosphere intensifies the greenhouse effect and has led to a global warming that the planet has never experienced before. Heatwaves have been occurring more frequently and intensely each year, possibly affecting biodiversity. Microalgae and Cyanobacteria are primary producers in aquatic ecosystems and play a crucial role in the food web and global photosynthesis. However, the interaction of these microorganisms in the natural environment, considering the effect of heatwaves, is still poorly understood. Moreover, most of the literature prioritizes monocultures, resulting in a limited approach when considering natural ecological interactions. The aim of this research is to investigate the effect of heatwaves, situations likely to promote the dominance of the cyanobacteria, on the interaction between two cosmopolitan photosynthetic microorganisms: a green alga (Scenedesmus quadricauda) and a toxic cyanobacterium (Microcystis aeruginosa). The focus of the interactions will be on cyanotoxin production and the population dynamics of the organisms. Population densities of each microorganism in culture will be monitored through absorbance at distinct wavelengths and the number of cells per coenobium (S. quadricauda). Cyanotoxins will be determined before and after the treatment that consists of 2 heatwaves with 48 h each and applied with 72 h interval. Meteorological data from São Carlos (2024) will be used to simulate temperature variations, and experiments will be conducted under controlled conditions in a temperature-regulated water bath. This project has the collaboration of Prof. Dr. Sandra Maria Feliciano de Oliveira e Azevedo (UFRJ), an expert in the Cyanobacteria and their toxins. The results obtained will provide a deeper understanding of population dynamics and cyanotoxin production under extreme climatic conditions and may contribute to decision-making regarding the sustainability of the planet in present and future scenarios.