A marine ecosystem is a complex community of living organisms and their physical environment in oceans and seas. It includes various habitats such as coral reefs, mangroves, and open ocean areas. These ecosystems support a wide range of species, including fish, marine mammals, and invertebrates, all interacting with each other and their surroundings. The health of marine ecosystems is crucial for the planet, as they provide essential services like oxygen production, carbon storage, and food resources. Human activities, such as overfishing and pollution, can threaten these ecosystems, making conservation efforts vital for their sustainability and the overall health of the Earth.