Removal of Physical Materials from Systems

Abstract

The wide spatial distribution of wetlands (e.g., swamps, bogs, marshes, and mires) across different latitudes and geomorphological settings reflects their complex biotic and abiotic interactions that define their ecological function and high economic value. As space becomes more limited, and landscape fragmentation increases, competition over land area for development and related human activities will certainly limit management options/decisions related to the conservation and rehabilitation/restoration of wetland ecosystems, especially at large spatial scales. In this chapter, we draw information from multiple sources and experiences to compile a series of case studies to focus our attention on characterizing the direct and indirect causes of wetland degradation and loss, particularly in coastal regions. The examples used in this chapter include deltaic regions (Mississippi River Delta, Louisiana, USA; Grijalva–Mezcalapa–Usumacinta, Mexico; and Central Coast, Netherlands), islands (Puerto Rico), and karstic platforms (Everglades, FL, USA). Current estimates of global wetland area range from 6.8 to 10.1 million km 2 , which represents 5–8% of the Earth (56% in tropical and subtropical regions). Loss of approximately 50% of wetlands around the world indicates the significant effect of human activities. Practices such as excessive harvesting, hydrological modifications and seawall constructions, coastal development, and pollution are some of the most pressing causes of wetland loss. Similarly, inland wetlands have been impacted by constant hydrologic modification and agriculture and urban development. The examples presented in this chapter underline the dynamic interaction between human actions and wetland habitat reduction at local and global scales. These issues define well the scope of ‘human use and abuses’ of productive ecosystems vital for the sustainability of both poor and rich nations. However, present political, social, and economic structures in most of the coastal regions around the world are disconnected from the actual functioning of the natural environment in which they reside, hindering conservation of productive wetland ecosystems.