Coastal Ecosystems

Coastal waters and estuaries represent some of our nation's most ecologically important areas. They provide over 75% of the total commercial landings and 80-90% of the recreational catch of fish and shellfish in the U.S. These commercial fisheries produce $2 billion in revenue to fishermen and generate $25 billion in economic activity. Recreational fishing is pursued by 17 million Americans and generates an additional estimated $18 billion in economic activity.

Increasing coastal populations and the cumulative effects of human activities are the primary threat to the future health and productivity of coastal ecosystems. Today over half of our total population lives on the 10% of the land area defined as "coastal." At the same time coastal recreation and tourism are growing rapidly in many coastal areas. However, these recreational activities are threatened by declining environmental quality. In 1992, U.S. coastal beaches were closed or advisories issued against swimming on almost 3,000 occasions. These closings represent an underestimate of the true problem because only four states monitor the entire length of their shorelines.

Increasingly, nature is signaling that coastal ecosystems are being stressed beyond their limits. For example, red tides and other harmful plankton blooms are occurring with increasing frequency and severity. Habitat loss and the introduction of non-indigenous species threaten to drastically diminish the diversity of our rich marine ecosystems. These events can have serious impacts on commercial fisheries, tourism and human health, or may alter the food webs of coastal ecosystems. The causes of these incidents are not well known, making preventive management difficult. The National Research Council has identified the following issues as posing significant threats to the integrity of coastal ecosystems:

• Eutrophication
• Habitat modification
• Hydrologic and hydrodynamic disruption
• Over exploitation of resources
• Toxic effects
• Introduction of non-indigenous species
• Global climate change and variability
• Shoreline erosion and hazardous storms
• Pathogens and toxins affecting human health

Problems associated with changes in the quantity and quality of inputs to coastal environments from runoff and atmospheric deposition are considered especially important. These problems include increases in nutrient loading from agriculture, habitat losses due to eutrophication, widespread contamination by toxic materials, changes in the supply of riverborne sediment, and alteration of coastal and estuarine hydrodynamics.