Plankton

Definition

Plankton refers to the tiny organisms that drift or float in the water column of oceans, seas, and freshwater bodies. This diverse group includes phytoplankton, which are microscopic plants, and zooplankton, which are small animals and larval forms of larger organisms. Plankton plays a crucial role in aquatic ecosystems as the base of the food web and is heavily impacted by changes in environmental conditions such as ocean acidification.

5 Must Know Facts For Your Next Test

1. Plankton is responsible for about half of the Earth's oxygen production through photosynthesis, primarily via phytoplankton.
2. Ocean acidification can directly affect plankton populations by altering their growth rates, reproductive success, and physiological processes.
3. Changes in plankton communities can have cascading effects on the entire marine food web, impacting fish populations and overall ocean health.
4. Plankton serve as indicators of ocean health, with shifts in their composition often signaling changes in environmental conditions.
5. Phytoplankton are sensitive to nutrient levels; an increase in nutrients from runoff can lead to harmful algal blooms, which disrupt marine ecosystems.

Review Questions

• How do changes in plankton populations influence marine ecosystems?
  • Changes in plankton populations can significantly influence marine ecosystems as they form the foundation of the food web. Phytoplankton serves as primary producers, converting sunlight into energy, while zooplankton are key consumers that feed on these primary producers. A decline in plankton due to factors like ocean acidification can lead to reduced food availability for fish and other marine organisms, ultimately disrupting the entire ecosystem.
• Discuss the impact of ocean acidification on phytoplankton and how it might affect marine biodiversity.
  • Ocean acidification negatively impacts phytoplankton by altering their growth rates and reproductive success. As CO2 levels rise and pH levels drop, many phytoplankton species struggle to maintain their calcium carbonate structures or cope with stress, leading to changes in community composition. This decline can affect not only phytoplankton abundance but also the entire marine food web, resulting in reduced biodiversity as key species disappear or become less competitive.
• Evaluate the role of plankton as indicators of ocean health in the context of climate change.
  • Plankton play a vital role as indicators of ocean health, particularly under the stress of climate change. As conditions shift—such as temperature increases and altered nutrient flows—plankton communities respond rapidly, reflecting broader environmental changes. By monitoring shifts in plankton diversity and abundance, scientists can gauge the impacts of climate change on marine ecosystems. The response of plankton populations not only highlights immediate ecological shifts but also serves as a forecast for future changes within the ocean's biological and chemical systems.

Related terms

Phytoplankton:

Microscopic photosynthetic organisms that form the foundation of the aquatic food web and produce a significant portion of the Earth's oxygen.

Zooplankton: Tiny floating animals that feed on phytoplankton and are essential for transferring energy up the food chain.

Ocean Acidification:

The process whereby increased CO2 absorption by oceans leads to lower pH levels, affecting marine life, particularly organisms with calcium carbonate structures.