What impact does acid deposition have on aquatic organisms?

Acid deposition, often resulting from atmospheric pollutants like sulfur dioxide and nitrogen oxides, can lead to a decrease in pH levels in aquatic environments. This drop in pH can have several detrimental effects on aquatic organisms, particularly fish. When the water becomes more acidic, it can clog the gills of fish, which are crucial for their respiration and overall health. Clogged gills hinder their ability to breathe and can reduce their ability to absorb oxygen from the water.

Additionally, acid deposition can disrupt reproductive processes in fish, affecting spawning success. The overall impact on fish populations can be severely negative, with increased mortality rates and reduced recruitment of new individuals to the population. Therefore, this answer aptly captures the harmful effects of acid deposition on aquatic organisms, highlighting the physiological challenges they face in acidic environments.

The other options suggest outcomes that are generally beneficial to aquatic life, such as promotion of population growth, improved water quality, or increased biodiversity, which do not align with the known adverse effects of acid deposition.