Habitat alteration and disturbance occur from natural processes and human activities, and can be placed into three categories:
- permanent loss;
- degradation; and
- periodic disturbance
Permanent loss of habitat can result from activities such as wetland filling, coastal development, harbor dredging, and offshore mining operations. Habitat degradation may be caused by physical changes, such as increased suspended sediment loading, overshadowing from new piers and wharves, as well as introduction of chemical contamination from land-based human activities. Periodic disturbances are created by activities such as trawling and dredging for fish and shellfish and maintenance dredging of navigation channels.
Generally, activities that lead to a permanent loss of habitat reduce the quantity of habitat, whereas habitat degradation and periodic disturbances result in a loss of habitat quality. The reduced quality of habitat (e.g., siltation, eutrophication, and alteration of salinity and food webs) may be equally damaging to the biological community as a loss in habitat quantity. The physical structure of the habitat does not need to be directly altered for negative consequences to occur. For example, reductions in water quality can impair and limit the ability of aquatic organisms to grow, feed, and reproduce. The end point of gradual declines in the quality of habitat can be the complete loss of habitat structure and function. Losses of habitat quantity and quality may reduce the ability of a region to support healthy and productive fish populations. From the population perspective, the loss of habitat quantity and quality creates stresses on a population. Populations that are stressed by one or more factors can be more susceptible to stresses caused by other factors, resulting in cumulative effects.
In 2010, 39 percent of the nation's population lived along the coast, representing less than 10 percent of the contiguous U.S land area. Although the amount of loss of coastal wetlands to development has decreased in the last several decades, the percentual rate of loss has remained similar to that of the 1920-1950 periods. The construction of urban, suburban, commercial, and industrial centers and corresponding infrastructure results in land use conversions that typically remove vegetation and create additional impervious surface. Runoff from impervious surfaces and storm sewers is the most widespread source of pollution into the nation’s waterways.
Impacts from coastal development involve numerous activities occurring within the broad coastal region. The geographic scope of these activities occur from freshwater rivers and streams that flow towards the ocean, in coastal uplands and wetlands, estuaries and bays, and out to the open ocean including the Exclusive Economic Zone. There are many types of activities occurring within the coastal zone which can have an adverse effect on fishery habitat. Although not exhaustive by any measure, those activities listed below are some the most well-known and described:
- Discharge of Nonpoint Source Pollution and Urban Runoff
- Road Construction and Operation
- Flood Control/Shoreline Protection
- Beach Nourishment
- Wetland Dredging and Filling
- Docks, Piers, and Floats
- Pile Driving and Removal
- Marine Debris
- Offshore Petroleum and Liquefied Natural Gas Exploration, Production, and Transportation
- Offshore Wind, Wave, and Tidal Energy Facilities
- Cables and Pipelines
- Dam Construction and Operation
- Stream Crossings
- Water Withdrawal and Diversion
- Construction, Maintenance, and Expansion of Ports and Marinas
- Navigation Dredging
- Offshore Dredging and Disposal Activities
- Offshore Mineral Mining
- Vessel Disposal
- Sewage and Industrial Discharge Facilities and Combined Sewer Overflows
- Water Intake and Discharge Facilities
- Croplands, Rangelands, Livestock, and Nursery Operations
- Silviculture and Timber Harvest Activities
- Timber and Paper Mill Processing Activities
- Introduced/Nuisance Species
- Fishing Activities
- Climate Change
- Ocean Noise
The Habitat Conservation Division conducts technical reviews for coastal development projects proposed, licensed, or funded by federal agencies. The reviews include requests for permits to fill wetlands and waterways, deepen federal navigation channels for commercial and recreational boats, license applications for building and removing dams, and constructing offshore natural gas pipelines and facilities. In recent years, these reviews have included licenses applications for offshore renewable energy facilities such as wind farms and tidal energy devices. Technical reviews assess the biological effects of these human activities and the value of coastal habitats, and include recommendations for reducing habitat loss and degradation.
For further information:
Impacts to Marine Fisheries Habitat from Nonfishing Activities in the Northeastern United States, NOAA Technical Memorandum NMFS-NE-209, 2008.
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