Paralytic Shellfish Poisoning refers to a kind of life threatening illness. It is one of the most common types of shellfish poisoning through contaminated seafood such as mussels, oysters, geoduck and scallops which contain harmful toxin to human.

 Cause:

Paralytic Shellfish Poisoning is caused by the in take of contaminated seafood, which, as an example, when algae increase in a huge numbers, it would cause the formation of harmful algal Bloom. Algal blooms happened in marine environments which an algal species reproduces rapidly a large number of algal cells in a short period of time. An Algal Bloom would normally kill aquatic life by blocking the sunlight to the water and or using up all of the oxygen in the water, but a harmful algal bloom would even produces detrimental toxins called saxitoxin. It could cause poison within 30 minutes, faster than most of the others toxins. When the shellfish fed by those multiple, toxic microorganisms, they would pass the toxin though the food chain, and eventually, transfer to human.

 The Affection of Human Activities:

Although harmful algae blooms are not directly caused by human activities, some events like runoff from agricultural fields would lead into algae blooms indirectly. Due to the fact that when wash fertilizers into the water, it can provide nutrient loading that create a favorable conditions for the growth of algae. Other events such as the incidence of The Pacific Ocean, an algal bloom produced due to the rise of water temperature from storm events, as an example, El Nino.