Why does the increased level of nutrients in the water affect the survival of aquatic organisms?
An increase in the level of nutrients in a water body leads to an excessive increase in the population of algae in the water body. When these algae die, they serve as food for decomposers. A lot of oxygen is utilised in this process, consequently leading to a decrease in the level of oxygen dissolved in the water body. This in turn causes fishes and other aquatic organisms to die.
The increased level of nutrients in the water can lead to a phenomenon called eutrophication. This occurs when excessive amounts of nutrients, such as nitrogen and phosphorus, enter a body of water. While these nutrients are necessary for plant growth, an excess of them can have detrimental effects on aquatic organisms.
Initially, the increased nutrients stimulate the growth of algae and other aquatic plants in the water, resulting in excessive plant biomass. This excessive growth can lead to a process called algal bloom. During an algal bloom, the water becomes densely populated with algae, causing the water to turn green or brown.
As the algae grow and eventually die, they sink to the bottom of the water body, and bacteria begin to decompose them. This decomposition process consumes a large amount of oxygen, leading to a significant decrease in the dissolved oxygen levels in the water. Lower oxygen levels can make it difficult for aquatic organisms to survive, especially those that require oxygen to breathe, such as fish, insects, and other organisms.
Additionally, the excessive growth of algae can block sunlight from penetrating the water. Reduced sunlight limits the photosynthetic activities of other aquatic plants and algae, further degrading the overall ecosystem health. This can disrupt the food chain and negatively impact organisms that rely on plants for food, including herbivores and primary consumers.
Furthermore, when the excessive growth of algae and aquatic plants eventually begin to die, their decomposition releases toxic substances and can lead to the formation of harmful algal blooms. These blooms can produce toxins that are harmful to both aquatic organisms and humans, leading to a variety of health problems.
Therefore, the increased level of nutrients in the water can have cascading effects on the survival of aquatic organisms, disrupting the balance of the ecosystem and potentially causing long-term harm.