Toxic Bloom Turns Sea Lions Aggressive | 14 Apr 2025

Source: DTE 

A toxic algal bloom off California’s coast has led to unprecedented aggression in sea lions, causing them to attack humans. 

• Domoic acid, a neurotoxin produced by the diatom Pseudo-nitzschia, is responsible for altering the brain function of sea lions. 
  • It causes stress, muscle spasms, brain damage, and aggressive behavior in marine mammals. 
• Domoic acid enters the food chain, harming marine life and posing a deadly risk to humans through contaminated seafood. 
• Stronger winds (from global warming) cause upwelling and bring nutrient-rich water to the surface, fueling algal growth. 
  • Pollutant discharge and wildfire runoff (e.g., from Los Angeles wildfires) add nutrients that further feed the algae. 
• Sea Lions: Sea lions (along with Seals and walruses) belong to a group of marine mammals called pinniped group (fin-footed marine mammals).
  • They are found in large groups and known for their loud barking sounds. 
  • Spend most of their time in the ocean but come ashore for resting, mating, and pupping. 
  • They live mostly in Pacific waters.