Multiannual variations in Microcystis bloom episodes - Temperature drives shift in species composition

Area of Science:

• Environmental Microbiology
• Aquatic Ecology
• Phycology

Background:

• Cyanobacteria, particularly Microcystis species, cause harmful algal blooms.
• These blooms produce microcystins (MCs), potent hepatotoxins impacting water quality and ecosystems.
• Toxic blooms are a growing global concern for drinking water and aquatic health.

Purpose of the Study:

• To analyze the long-term population dynamics of Microcystis in Lake Kinneret.
• To investigate the influence of environmental factors on the shift between toxic and non-toxic Microcystis strains.
• To understand the genetic and chemotypic diversity within Microcystis blooms.

Main Methods:

• Retrospective analysis of seasonal Microcystis blooms over decades.
• Monitoring of biotic and abiotic environmental parameters.
• Laboratory experiments to assess the impact of temperature and salinity.

Main Results:

• Lake Kinneret Microcystis population comprises at least 25 genotypes and two chemotypes.
• Relative abundance of these genotypes and chemotypes has varied over decades.
• Minor increases in water temperature, not salinity, correlated with shifts from toxic to less or non-toxic Microcystis strains.

Conclusions:

• Water temperature is a key factor influencing Microcystis community structure and toxicity.
• Environmental shifts can alter the balance between toxic and non-toxic cyanobacterial strains.
• Understanding these dynamics is crucial for managing harmful algal blooms and water quality.