An algal bloom off the coast of California has caused sea lions to exhibit unprecedented aggression towards humans due to exposure to a marine neurotoxin (domoic acid)  from Pseudo-nitzschia algae. 

About Algal Blooms

• Algae are microscopic organisms found in salt water, fresh water, and brackish water, using photosynthesis to generate energy from sunlight.
• Toxin-Producing Algae: Certain types of algae can produce toxins that harm people, animals, fish, and other parts of the ecosystem.

What is a Harmful Algal Bloom (HAB)?:

A harmful algal bloom occurs when toxin-producing algae grow excessively, creating visible blooms in green, blue-green, red, or brown colors.

Causes of Algal Bloom

• Environmental Factors: Conditions like warmer water temperatures, high light intensity, salinity changes, and altered pH can stimulate excessive algal growth.
• Nutrient Overload: Runoff carrying fertilizers, sewage waste, and other pollutants provides excess nutrients that trigger algal blooms.
• Climate Change Impact: Rising global temperatures and changes in water currents have increased the frequency and intensity of HABs.

Types of Algal Blooms and Their Impact

Impact of Algal Blooms  On Ecological Balance

• Oxygen Depletion:  HABs deplete oxygen levels in water bodies, leading to fish and aquatic life deaths.
• Light Blockage: Dense blooms block sunlight, affecting photosynthesis for deeper aquatic plants.
• Marine Animal Deaths:  Toxins from HABs cause illness and death in fish, dolphins, sea lions, and other marine creatures.
• Food Chain Disruption: Accumulated toxins in marine organisms impact higher predators and overall marine biodiversity.

Impact On Human Health

• Toxin Exposure: Humans can be exposed by consuming contaminated seafood, swimming in, or breathing near affected waters.
• Severe Illnesses: Health issues include vomiting, diarrhea, memory loss, seizures, respiratory problems, and even paralysis.
• Vulnerable Populations: Children, the elderly, and communities relying heavily on seafood face higher health risks.
• Business Losses: Fisheries, recreational activities, and tourism sectors suffer major revenue losses due to waterway closures and health advisories.