1. Discharge of nutrients from the estuaries.
2. Run-off from the land during the monsoon.
3. Upwelling in the seas.
Select the correct answer from the codes given below:
Explanation
A rapid rise in the population of algae in an aquatic system is known as an algal bloom, marine bloom, or water bloom. Algal blooms can appear in both marine and freshwater habitats. "Harmful algal blooms (HAB)" are blooms that can affect wildlife or the environment. Harmful Algal Bloom can lead to fish die-offs, cities cutting off water to residents, or states having to close fisheries.
Statement 1 is correct: Estuaries receive nutrient-rich water from rivers which can include agricultural runoff, sewage, and industrial effluents. These nutrients, particularly nitrogen and phosphorus promote the growth of algae causing algal blooms.
Statement 2 is correct: Heavy rainfall during the monsoon season can cause significant runoff from agricultural fields, urban areas, and other land surfaces. This runoff can carry fertilizers, pesticides, and other nutrients into the sea, providing the necessary conditions for algal blooms
Statement 3 is correct: Water that rises to the surface as a result of upwelling is typically colder and is rich in nutrients, which again leads to algal blooms.