Final answer:
An algal bloom is a rapid increase of algae due to excess nutrients, which can lead to dead zones in the aquatic ecosystem, produce toxins, and cause economic and health problems.
Step-by-step explanation:
What is an Algal Bloom?
An algal bloom is a rapid increase in the population of algae in an aquatic system, typically driven by an excess of nutrients such as nitrogen and phosphorus. These nutrients often come from sources like sewage, agricultural runoff, or fertilized lawns entering lakes and ponds. Algal blooms can produce harmful effects on ecosystems by blocking light penetration, releasing toxins and eventually leading to severe oxygen depletion when the algae decompose.
Impact on Aquatic Ecosystems
When an algal bloom occurs, it can create a dead zone where the level of dissolved oxygen is so low that most marine life cannot survive. Depletion of oxygen occurs due to the overgrowth and subsequent decay of algae, which consumes the oxygen needed by other organisms. Some algae, such as those responsible for red tides, produce toxins that can kill marine life and contaminate shellfish, leading to economic impacts and health risks for humans.