Wildfires, which are an increasing problem in Europe and other regions, can have significant environmental effects beyond their immediate impact on air quality. These less visible consequences include the triggering of algal blooms in oceans and lakes.
Algal blooms involve the rapid growth of algae and other plant-like microorganisms. While many are harmless, some can produce dangerous toxins. When these blooms decompose, they deplete oxygen in the water, leading to the formation of 'dead zones'.
Smoke and ash from wildfires can fuel these blooms when they settle on water. This material contains iron, which is scarce in marine environments, and even small amounts can stimulate algal growth. This phenomenon was observed during Australia's 2019-20 bushfires, where iron-rich ash plumes led to an algal bloom in the Southern Ocean that covered an area larger than Australia.
The overall effects are complex, as smoke can also contain toxins that inhibit algal growth, and dense smoke clouds may reduce the sunlight needed for photosynthesis. However, it is clear that wildfires can have environmental consequences that extend far beyond the immediate destruction of local vegetation.