Harmful algal bloom



We can see sometimes the ocean, river and lakes change colour from blue to red, brown and green. This phenomenon is caused by an algae bloom.

Algae is a microorganism which will grow and proliferate when there are abundant nutrients in the water. It will rapidly multiply and changes the water colour depending on the species.This phenomenon might look fascinating but it can be harmful to animals and humans. While most algae in the water is harmless, the harmful algal bloom (HAB) can secrete or contain phycotoxin that can accumulate in the fish, crab or bivalve filter feeder (shellfish).

In shellfish, the toxin will accumulate in the digestive glands without causing any adverse effect on the shellfish itself. However, when substantial amount of contaminated shellfish is consumed by humans, it can cause severe intoxification of various kinds of shellfish poisoning that may lead to severe effect to health and even death. The toxins don’t go away even when shellfish are cooked or frozen. Here are some of the shellfish poisoning that is caused by HABs that occur around the world.