key term - Diatoms

Definition

Diatoms are a type of microscopic algae characterized by their unique silica-based cell walls, called frustules, which exhibit intricate and beautiful patterns. These organisms are crucial players in aquatic ecosystems, contributing to primary production and serving as a food source for various marine organisms. They are a major component of phytoplankton, significantly influencing the ecology of both freshwater and marine environments.

5 Must Know Facts For Your Next Test

1. Diatoms can be found in both freshwater and marine environments and are responsible for about 20% of the world's oxygen production through photosynthesis.
2. They reproduce asexually by binary fission, resulting in two daughter cells that are often smaller than the parent cell, which can lead to size reduction over generations.
3. Diatoms play a vital role in the carbon cycle; their ability to sequester carbon dioxide contributes to global carbon storage when they sink to the ocean floor after dying.
4. Their unique silica frustules preserve well in sediment, making diatoms important indicators of past environmental conditions and changes in aquatic ecosystems.
5. Different species of diatoms have specific ecological niches, with some thriving in nutrient-rich waters while others prefer more oligotrophic conditions.

Review Questions

• How do diatoms contribute to primary production in aquatic ecosystems?
  • Diatoms are primary producers that perform photosynthesis, converting sunlight into energy and producing oxygen as a byproduct. They form a crucial part of the phytoplankton community, which is responsible for a significant portion of the primary productivity in both freshwater and marine ecosystems. This primary production supports higher trophic levels, making diatoms vital for maintaining the overall health and balance of aquatic food webs.
• What role do diatoms play in understanding ecological changes over time?
  • Diatoms have unique silica frustules that can be preserved in sediments for thousands of years. By analyzing fossilized diatom communities, scientists can infer historical changes in environmental conditions such as nutrient levels, water temperature, and salinity. This information helps researchers understand past climate changes and the impacts of human activities on aquatic ecosystems, providing insights into current ecological challenges.
• Evaluate the impact of eutrophication on diatom populations and aquatic ecosystems.
  • Eutrophication can significantly impact diatom populations by promoting excessive growth due to increased nutrient availability. While some diatom species thrive in nutrient-rich waters, rapid algal blooms can lead to decreased light penetration and oxygen depletion as decomposition occurs. This imbalance can harm other aquatic life forms and disrupt the overall ecosystem dynamics. The response of diatom communities to eutrophication can serve as an indicator of ecosystem health, highlighting the need for management strategies to prevent nutrient over-enrichment.

Related terms

Phytoplankton:

Microscopic plants that float in aquatic environments, forming the base of the food web and performing photosynthesis.

Frustule: The rigid cell wall of diatoms made of silica, which provides structural support and protection.

Eutrophication:

The process by which water bodies become enriched with nutrients, often leading to excessive growth of algae, including diatoms.