What is the key concept for this section? What major ecosystem and economic services are provided by marine systems? What are the three major life zones in an ocean? Define coastal zone. Distinguish...

What is the key concept for this section? What major ecosystem and economic services are provided by marine systems? What are the three major life zones in an ocean? Define coastal zone. Distinguish between an estuary and a coastal wetland and explain why each has high net primary productivity. Explain the ecological and economic importance of coastal marshes, mangrove forests, and seagrass beds.