Cyanobacteria

Definition

Cyanobacteria, also known as blue-green algae, are a phylum of bacteria that obtain their energy through photosynthesis. They play a critical role in aquatic ecosystems as primary producers, influencing the food web and contributing to oxygen production. Their ability to fix atmospheric nitrogen makes them vital in nutrient cycling, impacting both microbial metabolism and phytoplankton diversity.

5 Must Know Facts For Your Next Test

1. Cyanobacteria are unique among bacteria because they possess chlorophyll a and conduct photosynthesis similar to plants.
2. They can exist in various forms including unicellular, filamentous, or colonial structures, allowing them to adapt to different aquatic environments.
3. Cyanobacteria can produce toxins that affect aquatic life and human health during harmful algal blooms.
4. They significantly contribute to the carbon cycle by converting CO2 into organic matter, which serves as food for other organisms in the ecosystem.
5. Factors like light availability, temperature, and nutrient concentrations can dramatically influence the growth rates and bloom occurrences of cyanobacteria.

Review Questions

• How do cyanobacteria contribute to the nitrogen cycle and what is their importance in aquatic ecosystems?
  • Cyanobacteria are crucial in the nitrogen cycle due to their ability to fix atmospheric nitrogen into ammonia through the process of nitrogen fixation. This transformation makes nitrogen available for other organisms, supporting plant growth and overall productivity in aquatic ecosystems. As primary producers, they form the foundation of the food web and play a significant role in oxygen production, impacting both biodiversity and ecosystem health.
• Discuss the role of cyanobacteria in phytoplankton diversity and how they interact with other phytoplankton species.
  • Cyanobacteria contribute to phytoplankton diversity as they represent a significant group within this category. Their ability to perform photosynthesis allows them to compete effectively for light and nutrients. They often coexist with other phytoplankton species, enhancing overall productivity. However, under certain conditions like nutrient enrichment, cyanobacterial blooms can dominate, outcompeting other species and leading to shifts in community structure.
• Evaluate the impact of environmental factors on cyanobacterial growth and their implications for freshwater systems.
  • Environmental factors such as nutrient levels, light availability, and temperature significantly influence cyanobacterial growth. For instance, eutrophication from nutrient runoff can lead to excessive cyanobacterial blooms, which may deplete oxygen levels in water bodies, harming fish and other aquatic life. This shift can disrupt entire freshwater ecosystems, leading to loss of biodiversity and altering food web dynamics. Understanding these impacts is crucial for managing water quality and ecosystem health.

Related terms

Nitrogen fixation:

The process by which certain microorganisms, including cyanobacteria, convert atmospheric nitrogen into ammonia, which can then be utilized by plants and other organisms.

Phytoplankton:

Microscopic organisms that live in aquatic environments and perform photosynthesis; they form the base of the aquatic food web and are significantly influenced by cyanobacteria.

Eutrophication:

A process where water bodies receive excess nutrients, leading to algal blooms and oxygen depletion; cyanobacteria can thrive under these conditions, sometimes causing harmful algal blooms.