Which term describes a bloom harmful to marine life and can threaten human health?

• A. Red tide
• B. Harmful algal bloom
• C. Base of the food web
• D. Shellfish poisoning

Answer: (B)

A rapid overgrowth of algae that harms marine life and can threaten human health is called a harmful algal bloom. This term covers blooms that release toxins or create low-oxygen conditions, which can kill fish and other wildlife and contaminate seafood humans rely on. Red tide is a common example of a harmful algal bloom, recognizable by the water’s color, but not all HABs are red, and not all red-tide events occur every time a HAB happens. The idea isn’t about the influence in the food web or a health outcome by itself; it’s about the bloom phenomenon itself. Shellfish poisoning describes a health effect from HAB toxins, and the base of the food web is a trophic level description, not a bloom term.