Answer:
The answer is the dropping pH of the ocean
Explanation:
The ocean absorbs tons of carbon dioxide (Co2) from the atmosphere which changes the chemistry of the water. The ocean is naturally Alkaline but, as the oceans absorb Co2 it turns into carbolic acid. This doesn't make the ocean's immediately acidic but it is causing them to be gradually less alkaline. Since the direction of change is near the acid end of the scale, the process is known as ocean acidification. The coral reefs need the alkaline environment and can feel when the environment changes and when the ocean becomes to acidic for them it kills off the coral.
The food web (in contrast to the food chain) means that there may be more than one organisms competing for the same prey or food or they may be one organism that preys on many kinds of food etc. It is more complex than the food chain. If the food source of a certain animal was added to the food web, meaning there will be other organisms competing for that food source, then the population of that certain animal will either decrease (if the animal is not fit for the competition of food), or become constant or even rise (if the animal is well suited for the competition).
Because everybody thinks scientifically by making observations and testing them
