Coastal ecosystems change naturally, but external stressors can influence the types and rates of those changes and pose risks to the ecosystems.
Naturally occurring stressors and those resulting from human activities fall into five general categories–climate change, extreme events, pollution, invasive species, and land and resource use. Any one of these five stressors can cause ecosystem damage, but often they occur in combination and have cumulative impacts. NCCOS scientists are learning about the impacts of each individual stressor, and working to understand the combined effects of multiple stressors, which is more difficult.
Climate change and climate variability can influence sea level, water temperature and currents, and stratification (layering) of water bodies. These conditions influence freshwater delivery, sedimentation, and pollution of an ecosystem. Salinity, tidal patterns, erosion, and coastal flooding also are affected, rendering coastal ecosystems and communities more vulnerable to adverse conditions. Learn more ›
Extreme events such as hurricanes, coastal storms, floods, and droughts affect coastal ecosystems and people living along the coasts. Storms can cause major geographic changes and lead to more pollution in coastal ecosystems. The frequency, severity, and extent of harmful algal blooms can increase, which can lead to costly closures of shellfish beds and curtail recreational opportunities. Emergency planners and responders benefit from advances in forecasting the effects of these events. They can develop preventive measures that will protect human and ecosystem health Learn more ›
Invasive species - plants and animals brought to the U.S. from other countries or relcoated to inappropriate habitats within the U.S. – can threaten economically and environmentally important native plants and animals. These non-native species often outcompete the native populations for finite ecosystem resources, and change the general ecological structure, thereby affecting communities with economies that depend on native species. Learn more ›
Land and resource use associated with heavily populated coastlines and development pressures pose serious risks to the nation's coastal ecosystems. Urbanization, dredging, and commercial and residential construction can lead to habitat changes, increased sediment runoff, and depleted fish populations. These activities can also damage habitats critical to ensuring ecosystem vitality. Learn more ›
Pollution directly affects marine ecosystems. Over the past 30 years, the nation has made great progress in controlling water pollution from point source discharges (i.e., those with a clearly identifiable source like an effluent discharge pipe). Nonpoint source pollution, such as urban runoff from cities, roads and highways, and agricultural fields, has become more problematic. Air pollution and excess nitrogen runoff resulting from agricultural operations continue to stress fragile marine ecosystems. Coastal managers need better forecasts on the effects of these pollution sources to prioritize management actions. Learn more ›
