Wildfires Trigger Massive Ocean Algae Blooms
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- Wildfires release iron-rich smoke and ash that settle on water bodies, providing nutrients that can trigger rapid algal growth in oceans and lakes
- Algal blooms can become so extensive they change water color and are visible from space, as seen after Australia’s 2019-20 bushfires
- Australia’s 2019-20 'black summer' bushfires spread vast plumes of ash across the Southern Ocean, sparking an algal bloom larger than the continent itself
- Dead zones form when algal blooms die and decompose, consuming oxygen in the water and harming aquatic life
- Iron from wildfire ash acts as a key catalyst for algal growth, especially in iron-poor marine environments where even small inputs have outsized effects
- Smoke can both promote and inhibit algal growth—iron fuels blooms, while toxins and sunlight-blocking clouds may suppress photosynthesis, creating complex ecological impacts
Why it matters: Marine ecosystems gain no benefit from wildfire-driven blooms, while fisheries and coastal communities face increased risks from toxic algae and oxygen-depleted waters. The scale of the Southern Ocean bloom—larger than Australia—shows how regional fires can drive basin-scale biological shifts with little warning or control.
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