Compared to the control (red line), in which both sea urchins and limpets are present, removing limpets alone (blue line) did not have much effect. This might suggest that limpets have little effect on seaweed distribution. However, seaweed cover increased much more when both urchins and limpets were removed (purple line) than when only urchins were removed (green line). How might you explain this result?

a) Both limpets and urchins eat seaweed, so both species have to be removed in order for seaweed cover to increase.

b) When only urchins were removed, limpets increased in abundance and reduced seaweed cover.

c) Both limpets and urchins eat seaweed, so removing either species has the same effect on seaweed cover.

d) If only limpets are removed, more time is needed for seaweed cover to increase.

b) When only urchins were removed, limpets increased in abundance and reduced seaweed cover.

Explanation:

The accumulation of seaweed in aquatic bodies can kill the biodiversity of these environments. This problem occurs when there is an excessive proliferation of algae that, finding more food, reproduce ferociously, and end up polluting. And where there is pollution life can die. In this scenario, the hedgehogs and limpets can be very important, because by using seaweed as food, they reduce the problem of their excessive proliferation.

Much research has been done to evaluate the relevance of these two animals in combating pollution caused by the proliferation of seaweed. In the case of the research shown in the question above, seaweed cover increased much more when the sea urchins and limpets were removed than when only the sea urchins were removed. This probably happened because when only the hedgehogs were removed, the limpets increased in abundance and reduced the coverage of seaweed.