Wetlands have generally been viewed in the past as areas of little value, and have even been considered as a threat to human health. This idea, which persists in a large part of the population, has motivated the destruction of many wetland areas. Urban development, the installation of large industrial ports, and the construction of fish and shellfish farms are some of the causes of the disappearance of mangrove systems and salt marshes, argued to produce greater economic and social development. However, recent studies indicate the opposite. Coastal wetlands provide an important source of goods and services to society, the value of which exceeds US $25,000 billions per year. This book is a new contribution to our knowledge of mangrove and salt marsh soils and sediments.