Estuaries are areas where fresh water from rivers meets salt water. As the river drains, it carries much nutrient-rich sediment. Many animal species depend on this food source to provide for their young.
The species was a keystone species.
Keystone species are the species that ''hold the ecosystem together''.
They have an important role in the trophic networks (food chains) and often they can even afflict changes in the abiotic part of the ecosystem (change the composition of soil, purify the water, lower the effect of the wind etc)
Therefore, when a keystone species is removed it affects greatly the whole ecosystem.
Answer:
Gravity.
Explanation:
Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun.
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