Write a detailed report on one of the following topics: 1- Different types of beaches, their characteristics, and human control on coastal erosion. 2- Different types of saltmarshes, their characteristics, importance and human impacts on them. 3- Mangrove ecosystems, their characteristics, importance and natural and human impacts on them. 4- Coral reef ecosystems, their characteristics, importance and natural and human impacts on them. 5- Seagrasses and seaweeds ecosystems, their characteristics, and importance. .