What happens to fish gills when aluminium levels rise in water?

When aluminium levels rise in water, it can be highly detrimental to fish, leading to severe physiological impacts, particularly on their gills. High concentrations of aluminium can damage the gill structures, impair gas exchange, and hinder the fish's ability to breathe. This disruption can lead to reduced oxygen uptake, increased stress, and ultimately, mortality. The gills are critical for extracting oxygen from water, and their deterioration directly affects the fish's survival.

In environments with elevated aluminium levels, fish may experience gill lesions and mucus secretion that obstruct proper respiratory function. As a result, the harmful effects of aluminium toxicity become evident, often culminating in death if the exposure is significant. Thus, the link between high aluminium levels in water and fish mortality is well established in ecological studies, making this answer the most accurate in describing the outcome for fish under these conditions.