Human Population Growth: Consequences for Coastal Ecosystems

Earth has a total of 1,643,701 km of coastline, a distance that could wrap around the planet 402 times (5). Approximately 41% of the world’s population lives within 100 km of this coastline, and 21 of the world’s 33 mega-cities are on the coast (6, 5). Coastal counties (excluding Alaska) make up only 11 percent of the land in the United States, but they are home to more than half of the country’s population (4). Through population increase and redistribution through migration, the U.S. coastal population is predicted to reach 165 million people by 2015 (4). This is an increase of 3,600 people every day. Human population living within 100 km of the coast around the earth has increased from 2 billion in 1990 to 2.2 billion in 1995, representing 39 percent of global population (4). This population pressure has dramatic effects on coastal environments and the organisms that live in them. Human dependence on the resources and services provided by coastal ecosystems makes it even more critical that we control the damage we inflict on these already vulnerable habitats.

Coastal systems are made up of a wide variety of ecosystem types, including coral reefs, mangroves, wetlands, sea-grass beds, barrier islands, estuaries, and peat swamps (4). The biota in coastal ecosystems is highly diverse, both taxonomically and genetically. Ecosystems on the coastline also perform several natural functions important to human welfare, such as storing and cycling nutrients, filtering pollution, and protecting land from storms and erosion. Coastal aquatic ecosystems regulate ocean hydrology and climate, sequester carbon, and provide oxygen through phytoplankton photosynthesis. (4)

Coastal ecosystems are also among some of the most fragile systems, and rising populations in coastal areas cause vegetation, habitat, and biodiversity loss. Human activity can also reduce beach elevation and alter soil pH and temperature (4). These environmental changes can negatively affect ecosystem health and sustainability. Human population growth on the coast increases the need for resources and services, such as clean water, waste treatment and disposal, public health, food, and protection from natural disasters. It also causes destruction of wetlands and coastal forests to build roads and buildings; an estimated 800,000 or more new housing units are built on U.S. coasts every year (6). Currently, half of the planet’s wetlands are destroyed, 60 percent of coral reefs are damaged, and extensive areas of mangrove systems are gone (6). Development and the dumping of waste into and coastal waters wipe out and contaminate coastal ecosystems. Rivers and streams empty into coastal waters, carrying with them the pollution, sediment and nutrients from across the land. (6)

Even though they are sustaining great amounts of damage, aquatic habitats along the coast are some of the most productive marine areas of the world. They supply seafood to humans and a multitude of other aquatic organisms, and often serve as nesting grounds on which other marine life depends. However, a large portion of the world’s coastal fisheries are severely exploited, especially in Asia, where coastal fish stock has declined to only 10-30 percent of what it was 30 years ago (6). Existing fish populations are dominated by smaller species that grow more quickly and are worth less due to over-harvesting of larger, more valuable species.

Despite the threatened state of many coastal environments, humans are moving closer and closer to the sea (4). Why are human populations concentrating in coastal areas? The reasons are not fully understood, but a possible explanation is the coast’s accessibility, which attracts ports, industries, cities, and other economic benefits. In addition, coastal lands and waters are often very productive ecologically, have high biodiversity, and are aesthetically pleasing, drawing farmers, fishermen, and tourists (6). Coastal ecosystems provide the bulk of the world’s fish, shellfish, and seaweed, and also are harvested for fertilizer, pharmaceuticals, cosmetics, household products, and construction materials (4).

We still have much to learn about the relationships among human populations, coastal areas, and destructive human activities, and more understanding is needed to inform management and policy decisions regarding these issues. Specifically, we need more knowledge about who is living on the coasts, which resources they use, and how population growth, redistribution and fertility influence consumption and damage to coastal environments. There is a lack of data on global coastal ecosystems and their functioning, and some parts of the world have a particularly miniscule amount of information (4). Research on coastal management practices have concentrated on institutional, environmental, economic, and resource use issues, but have devoted little attention to questions of population growth and redistribution (6). Despite these gaps in our knowledge, at today’s demographic trends, population changes will substantially worsen anthropogenic pressures on coastal ecosystems through habitat development, pollution, and resource utilization (5).

The pattern of human usage of coastal resources and destruction of coastal habitats comes at no surprise; humans have been exploiting their surrounding environments throughout history. Unchecked population growth and migration to the coast, however, exacerbate this exploitation and its consequences on coastal ecosystems. There is recognition of these problems and efforts to mitigate them among agencies working in the coastal zone, such as governmental and non-governmental organizations (4). However, it is likely that the average coastal dwellers have little more than a basic awareness of the fragility and threatened status of the coastal ecosystems that provide them with a multitude of benefits and services. It is human nature to selectively react to sudden, obvious threats to our livelihood and future, but recognizing the risk of gradual and less visible dangers is more difficult (3). If only we could portray the consequences of coastal ecosystem destruction as more overt and immediate, like a jaguar jumping out of a tree. We then might pay more attention and make greater efforts to reduce our environmental impacts, and both our future and that of the coasts would have a better outlook.

References

1) Burke, L., Kura, Y., Kassem, K., Revenga, C., Spalding, M., and D. McAllister. (2000). Pilot analysis of global ecosystems: Coastal ecosystems: Executive Summary. World Resources Institute. Available at http://www.wri.org/publication/content/8839.

3) Ehrlich, Paul R. (2000). Human Natures: Genes Cultures, and the Human Prospect. Washington, D.C.: Island Press.

5) Martínez, M. L., Intralawan, A., Vázquez, G., Pérez-Maqueo, O., Sutton, P. and R. Landgrave. (2007). The coasts of our world: Ecological, economic and social importance. Ecological Economics 63(2-3): 254-272.