Cyanobacteria

Definition

Cyanobacteria, often referred to as blue-green algae, are a group of photosynthetic bacteria that play a crucial role in aquatic ecosystems. These microorganisms are capable of converting sunlight into energy through photosynthesis, releasing oxygen as a byproduct, which has significant implications for primary production and the overall health of marine environments.

5 Must Know Facts For Your Next Test

1. Cyanobacteria are considered one of the oldest living organisms on Earth, with fossil evidence dating back over 3 billion years.
2. They are capable of nitrogen fixation, allowing them to thrive in nutrient-poor environments and enhancing their ecological significance.
3. Cyanobacteria contribute to primary production in both freshwater and marine environments, serving as a food source for various aquatic organisms.
4. Some species of cyanobacteria can form harmful algal blooms that produce toxins, impacting water quality and marine life.
5. They have been instrumental in shaping Earth's atmosphere by increasing oxygen levels during the Great Oxidation Event approximately 2.4 billion years ago.

Review Questions

• How do cyanobacteria contribute to primary production in marine environments?
  • Cyanobacteria contribute significantly to primary production in marine environments through their ability to perform photosynthesis. By converting sunlight into chemical energy, they produce organic matter that serves as a food source for various marine organisms. Additionally, their role in nitrogen fixation allows them to thrive in nutrient-poor waters, further enhancing their contribution to the productivity of aquatic ecosystems.
• What are the potential ecological consequences of harmful algal blooms caused by cyanobacteria?
  • Harmful algal blooms caused by certain cyanobacteria can lead to severe ecological consequences, including oxygen depletion and the release of toxins that can harm aquatic life and disrupt food webs. These blooms can result in fish kills, reduced biodiversity, and compromised water quality. Furthermore, when these toxins enter the food chain, they pose health risks to humans and other animals that consume contaminated water or fish.
• Evaluate the importance of cyanobacteria in the context of Earth's historical atmospheric changes and their ongoing role in modern ecosystems.
  • Cyanobacteria have played a pivotal role in Earth's atmospheric changes throughout history, particularly during the Great Oxidation Event when they significantly increased oxygen levels, transforming the planet's atmosphere. This not only allowed for the evolution of aerobic organisms but also laid the foundation for complex life forms. In modern ecosystems, cyanobacteria continue to be vital as primary producers in both marine and freshwater environments, contributing to nutrient cycling and supporting diverse aquatic communities. Their ability to adapt to changing environmental conditions highlights their importance in maintaining ecosystem health amidst ongoing climate change.

Related terms

Photosynthesis: The process by which cyanobacteria and other plants convert light energy into chemical energy, using carbon dioxide and water to produce glucose and oxygen.

Phytoplankton: Microscopic organisms that live in aquatic environments, including cyanobacteria, which form the base of the aquatic food web and contribute significantly to primary production.

Nitrogen Fixation: The process by which certain cyanobacteria convert atmospheric nitrogen into ammonia, making it available for use by other organisms and contributing to nutrient cycling in marine ecosystems.