Final answer:
Algal blooms disrupt aquatic ecosystems by depleting dissolved oxygen, creating dead zones, and releasing toxins, which can kill marine life and affect human health. They occur due to excess nutrients from sources like fertilizer runoff and sewage.
Step-by-step explanation:
The role of algal blooms in disrupting the equilibrium of an aquatic ecosystem is multifaceted and often detrimental. Algal blooms occur when there is an overabundance of nutrients, particularly nitrogen and phosphorus, which enter water bodies from sources like fertilizer runoff or sewage. The surplus of nutrients accelerates algae growth, leading to a substantial increase in algae known as an algal boom.
Once the algae die off, their decomposition by bacteria consumes vast amounts of oxygen, creating hypoxic conditions or 'dead zones' where aquatic life cannot survive. This loss of dissolved oxygen can lead to massive fish kills and disrupt the food webs within these ecosystems. Additionally, certain algal blooms can produce toxins that harm or kill marine organisms and may pose health risks to humans if contaminated shellfish are consumed.
Beyond the immediate effects, algal booms can also affect the clarity and quality of water, reducing light penetration and outcompeting other photosynthetic organisms, like sea grasses, that are crucial for marine life. The consequences of altering the salinity and other physical properties of the water can further disrupt the delicate balance of the ecosystem. Consequently, there is a need for responsible agricultural practices, regulation of nutrient runoff, and ecosystem restoration efforts.