Pseudo-nitzschia can release domoic acid, a neurotoxin that can cause amnesiac shellfish poisoning, which has been found to accumulate in the tissue of certain shellfish. If ingested by humans, domoic acid will attack tissue in the brain that humans use for memory and learning. This is an example of what?

harmful algal bloom (HAB)

Explanation:

Harmful algal bloom (HAB) -

It refers to the combination of various organisms , that reduces the level of oxygen in natural water , and which can make the survival of the marine organisms difficult , is referred to as harmful algal bloom (HAB) .

These blooms can live for some days to months , as they die , the microbes decomposes them and consume even more amount of oxygen , making the survival of the marine organisms , near to impossible .

Hence , from the given scenario of the question ,

The correct answer is  harmful algal bloom (HAB) .

they need it to survive

explanation: