An algal bloom is a sudden and dramatic increase in the population of certain microorganisms such as algae or cyanobacteria in a body of water. when there are high levels of nutrients in the water, microorganisms will reproduce rapidly until they have used all the available resources. at that point, the algae dies off in tremendous quantities, vastly reducing the amount of oxygen in the water as it dies and begins to decompose. what impact, if any, would an algal bloom be likely to have on its local ecosystem? a) it would have no effect on the ecosystem because ecosystems are self-balancing. b) it would have no significant effect on the ecosystem since the algae dies off by itself after a time c) it would the ecosystem by providing extra algae for primary consumers to eat. d) it would kill many other organisms in the ecosystem by removing oxygen and nutrients from the water.