Drowned river valleys also known as coastal plain estuaries. In place where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross- section) in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m (100 ft). Examples of this type of estuary in the U.S. are the Hudson River, Chesapeake Bay, and Delaware Bay along the Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast. San Francisco Bay is another good example of a drowned river valley. 2.Indo pacific region has greater coral reef diversity than the caribbean region. There are two likely reasons for the far higher biodiversity found on Indo-Pacific coral reefs than their Caribbean counterparts. First, the sheer size of the region occupied by Indo-Pacific coral reefs - as well as the length of coastline where corals can successfully grow - is much greater than in the Caribbean. This allows more room and opportunities for species diversification. Secondly, most Indo-Pacific coral reefs did not experience the severe temperature changes the Caribbean region suffered during the Pleistocene ice ages. This likely resulted in more species of coral, fishes, and other types of reef life surviving into the current post-glacial epoch. Because of the sheer size and remoteness of portions of this region, many Indo-Pacific reefs remain largely unexplored and new species of fishes and other reef life are continually being discovered. Salinity: The amount of dissolved salts in the water is referred to as salinity and is measured in parts per thousand (ppt). Corals can tolerate a narrow range of salinities, between 30 and 40 ppts. Solution Drowned river valleys also known as coastal plain estuaries. In place where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross- section) in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m (100 ft). Examples of this type of estuary in the U.S. are the Hudson River, Chesapeake Bay, and Delaware Bay along the Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast. San Francisco Bay is another good example of a drowned river valley. 2.Indo pacific region has greater coral reef diversity than the caribbean region. There are two likely reasons for the far higher biodiversity found on Indo-Pacific coral reefs than their Caribbean counterparts. First, the sheer size of the region occupied by Indo-Pacific coral reefs - as .