Red tide happen when microorganisms (dinoflagellates) which are naturally living in the sea undergo a population explosion. The numbers become so large and dense that sometimes they impart a brownish-red colour to the sea. The micro-organisms usually are not very numerous in the seas and thus do not represent a health threat. Only when they become many and are eaten in large numbers by filter-feeding sea organisms such as oysters, mussels and other bivalves that render these shellfish toxic because of accumulation in their guts. Some fishes, which eats these organisms or other larger sea life (which originally eat this dinoflagellates), can become toxic since there will be an accumulation of these organisms in their guts.
This become a public heath problem when people eat these toxic clams and suffer from Paralytic Shellfish Poisoning (PSP). In addition, these dinoflagellated organisms become so many in the sea that they deplete the oxygen in the water causing fish kills by means of suffocation.
mohamadhafidh 