There is a concern over the increase in harmful algal blooms in the seawater of India. What could be the causative factors for this phenomenon?
- Discharge of nutrients from the estuaries.
- Run-off from the land during the monsoon.
- Upwelling in the seas.
Select the correct answer from the code given below:
- 1 only
- 1 and 2 only
- 2 and 3 only
- 1, 2 and 3
Explanation
All are correct
- Discharge of nutrients from the estuaries – Estuaries act as transition zones between rivers and the sea and often receive large quantities of nutrients from upstream sources. These nutrients, primarily nitrogen and phosphorus from agricultural runoff, sewage discharge, and industrial effluents, are carried into the sea. The influx of these nutrients into coastal waters fuels algal growth, especially when water movement is relatively slow and allows algae to accumulate.
- Run-off from land during the monsoon – During the monsoon season, heavy rains increase the surface runoff from agricultural fields, urban landscapes, and industrial zones. This runoff often contains high concentrations of fertilizers, pesticides, organic matter, and other pollutants, which eventually enter rivers and coastal waters. The sudden spike in nutrient availability in marine waters during the monsoon creates ideal conditions for algal blooms to develop and spread.
- Upwelling in the seas – Upwelling is a natural oceanographic process in which cold, nutrient-rich water from the deep sea rises to the surface. This process enhances nutrient concentrations in the photic zone (sunlit upper layer of the sea), where algae can photosynthesize and multiply rapidly. Although upwelling is a natural phenomenon, it can exacerbate algal blooms when combined with human-induced nutrient loading.
