South Australia Algal Bloom

Source: TH

Context: A massive bloom of toxic algae Karenia mikimotoi has killed over 200 species of marine life off the southern coast of Australia, affecting biodiversity and coastal tourism.

About South Australia Algal Bloom:

• What It Is?

• Karenia mikimotoi is a species of toxic dinoflagellate algae that forms harmful algal blooms (HABs), commonly referred to as red tides.

• Classification:

• Kingdom: Protista Phylum: Dinoflagellata It contains photosynthetic pigments but lacks protective thecal plates.

• Kingdom: Protista

• Phylum: Dinoflagellata

• It contains photosynthetic pigments but lacks protective thecal plates.

• Historical Occurrence:

• First identified in Japan in 1935. Since then, detected in Norway, China, USA (east coast), English Channel, and Australia. March 2025 marks the largest bloom in South Australia to date, spanning 4,400 sq. km.

• First identified in Japan in 1935.

• Since then, detected in Norway, China, USA (east coast), English Channel, and Australia.

• March 2025 marks the largest bloom in South Australia to date, spanning 4,400 sq. km.

• Recent 2025 Bloom:

• Coastline of South Australia, affecting: Kangaroo Island, Fleurieu Peninsula, and Yorke Peninsula

• Key Features:

• Appears as discoloured, foamy water during warmer months. Produces toxins (like gymnocin A & B) with low known toxicity but causes large-scale deaths. Creates oxygen-depleted (anoxic) zones and blocks fish gills. Affects marine life directly through contact and indirectly through water chemistry alteration. Associated with skin irritation, breathing issues, sore eyes in humans near affected beaches.

• Appears as discoloured, foamy water during warmer months.

• Produces toxins (like gymnocin A & B) with low known toxicity but causes large-scale deaths.

• Creates oxygen-depleted (anoxic) zones and blocks fish gills.

• Affects marine life directly through contact and indirectly through water chemistry alteration.

• Associated with skin irritation, breathing issues, sore eyes in humans near affected beaches.

• Impacts:

• Marine Life Deaths: Over 200 species, including sharks, rays, octopuses, and crabs perished. Ecological Damage: Long-term damage to coastal food chains and biodiversity. Economic Disruption: Affects fisheries, tourism, and local livelihoods. Public Health Risk: Causes respiratory and skin problems in beachgoers. Climate Linkage: Triggered by marine heatwaves, intensified by climate change and calm sea conditions.

• Marine Life Deaths: Over 200 species, including sharks, rays, octopuses, and crabs perished.

• Ecological Damage: Long-term damage to coastal food chains and biodiversity.

• Economic Disruption: Affects fisheries, tourism, and local livelihoods.

• Public Health Risk: Causes respiratory and skin problems in beachgoers.

• Climate Linkage: Triggered by marine heatwaves, intensified by climate change and calm sea conditions.