Changing Habitats

A view of New York City from the Statue of Liberty

Every creature, humans included, needs a place to live. Ecologists call those places habitats. Humans change natural habitats and sometimes the local residents—plants and animals—can’t adapt.

Altered Habitats: Where Is It Safe To Live?

Many of us live in coastal habitats, which we have learned to modify for our use and benefit. In coastal wetlands and estuaries (where freshwater and seawater mingle), which are often shallow and flooded, we dredge deep channels, harbors, and marinas. We fill low marshes and seagrass beds to protect homes, warehouses, and other infrastructure from flooding and storms. Many of the mangrove forests that once lined and protected shorelines and produced food and shelter for coastal ecosystems have been removed to build aquaculture ponds that help feed growing human populations. Much of the oil and gas that powers modern societies comes from offshore platforms, places that require humans and wildlife to share habitats. In fact, more than 90% of coastal wetlands, marshes, and estuaries in many areas of the U.S. have been converted to human habitat at the expense of the ecosystems that occupy the coast. We need to recognize the real cost of such coastal development and habitat alteration as our populations grow and we continue to build.

Extraction: Taking Out More Than Nature Can Replace

Coastal sediment is an important feature of lakeshore and seashore ecosystems. Sediments like sand, gravel, clay, and silt form shore habitats, provide protection from extreme weather, and even transport important nutrients. These sediments are brought downstream by rivers to the coast, where wind, ocean currents, and waves then circulate the sediment along the shore and into the ocean.

Human activities can disrupt the natural processes needed to transport sediment to the coast and beyond. Dams and other diversions divert the natural flow of the rivers that carry sediment to the lake and seashore. Structures built to stabilize dynamic coastal features, like jetties and harbors, trap sand and prevent it from spreading along the coast, while other structures meant to reduce cliff and bluff erosion inadvertently reduce the amount of sediment that reaches and replenishes the shoreline. Sand dredged at harbors and other coastal areas is often not relocated to places that need it the most, but rather to the most convenient location. This impairment of natural sediment movement results in too much sediment in some areas—eroding beaches and wetlands and destroying habitats, and too little sediment in others—decreasing coastal water quality.

Last updated: March 28, 2016


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