高中二年级英语(人教版)下册 Unit 13 Integrating Skills 1

　　NATURE'S NURSERY: ESTUARIES

　　As the oceans are the source of life on earth, the estuaries are our planet's nurseries. An estuary is the body of water where a river meets the ocean. Salt water from the ocean and fresh water from the river mix together in an estuary. This mixing of fresh and salt water creates a unique environment filled with life of all kinds -- a zone between the land and the sea. Estuaries are the homes of thousands of animals and plants. Many cities and towns are built near estuaries, and a lot offish are caught in estuaries.

　　Estuaries are great places for nature's young ones. Here, animals can enjoy all the benefits of the oceans without having to face many of the dangers. Tides provide energy for the ecosystems, but estuaries are protected from waves and storms by islands, mud or sand. Nutrients arrive in estuaries from both the land and the ocean. The density of living creatures is higher than in any other habitat on earth. The diversity of life in estuaries is incredible -- birds, fish, marine mammals, shellfish and other species all come here to live, feed and reproduce.

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