If the amount of algae in the ocean decreases by 50%, the population of its consumers, goby fish, will

likely decrease as well. Goby fish are known to feed on algae, and a decrease in the amount of algae will lead to a decrease in the food supply for the goby fish. This can result in a decrease in the population of goby fish, as they may struggle to find enough food to survive and reproduce. Additionally, other predators that feed on goby fish may also be affected by the decrease in their population, leading to further ecological impacts.