Loss of habitats and disturbance
Habitat loss is caused by natural disasters (hurricanes, fires, flooding, etc) and human activity (clearing land for agricultural, industrial, and residential development; clear-cut harvesting of timber; oil spills; and war).
The coastal bays watershed has lost nearly three quarters of its historic forest and wetland habitat since colonial times. Although the rate has slowed considerably in recent years, new development resulting from tourist and residential growth projections is still increasing rapidly causing the loss of valuable coastal bays’ habitat.
Although some impacts may be irreversible, natural processes such as forest re growth, reestablishment of sea grass beds, and succession of vegetation in wetland areas have partially reduced the environmental consequences of some habitat loss. While recovery of some bay bottom habitats may take a year or two, recovery of forested wetlands may take decades.
Habitat loss and alteration have direct and indirect effects on the coastal bays’ ecology. While habitat loss reduces the availability of useful lands, food, and other resources available to plants, fish, and wildlife, destruction of certain habitats may have disproportionate effects. For example, destruction of wetlands and salt marshes decreases their ability to filter nutrients and sediment from surface runoff and groundwater, and deprives waterfowl and shorebirds of important foraging and resting areas. Loss of sea grass beds not only deprives marine species of habitat and food sources, but also exacerbates sediment resuspension problems and increases shoreline erosion from wave action.
A number of activities is the cause to habitat loss including residential and commercial development, marina and boat slip construction, dredging, draining and clearing of wetlands and forest for agriculture and development, shellfish harvesting, bulkheading, boating, erosion and overwash of the north end of Assateague Island . Even the Assateague ponies contribute their share by grazing in the salt marshes.
Do you know that what we do inour countries can affect other countries no matter how far they are? Take for example,
The Arctic's climate is changing, with a noticeable warming trend that is affecting polar bears. The region is experiencing the warmest air temperatures in four centuries. The Intergovernmental Panel on Climate Change, the U.S. EPA, and the Arctic Climate Impact Assessment all report on the effect of this climatic change on sea-ice patterns. A recent report notes that there has been a 7% reduction in ice cover in just 25 years and a 40% loss of ice thickness. It also predicts a mostly ice-free arctic summer by 2080 if present trends continue. Many scientists believe that the Arctic will continue to grow warmer as a result of human activity, namely, the introduction into the atmosphere of increasing quantities of carbon dioxide and other “greenhouse gases”. While there is no consensus on whether human activity is the most significant factor, the Arctic has in fact been warming, whatever the cause.
Polar bears depend on a frozen platform from which to hunt seals, the mainstay of their diet. Without ice, the bears are unable to reach their prey. If the reduced ice coverage results in more open water, cubs and young bears may also not be able to swim the distances required to reach solid ice.
Because polar bears are a top predator in the Arctic, changes in their distribution of numbers could affect the entire arctic ecosystem. There is little doubt that ice-dependent animals such as polar bears will be adversely affected by continued warming in the Arctic. It is therefore crucial that all factors which may affect the well-being of polar bears be carefully analyzed. Conservative precautionary decisions can only be made with a full understanding of the living systems involved.
How can animals in the Arctic be contaminated by pollutants entering the air and water elsewhere in the world? It happens because everything is connected to everything else. Dust from storms in the Sahara Desert, soot from the cooking fires of India and Africa, and chemical fumes from third-world industries rise in the sky and travel around the world to settle onto the snow and ice of the Arctic.
Likewise, contaminants entering rivers and seas from agricultural run-off, untreated sewage, and chemical-laden discharge from ships and factories become entrained in globe-girdling ocean streams to enter environments far from their source.
As wind and water have always affected everything, the presence of so-called pollutants in the Arctic is nothing new. But the addition of modern synthetic chemicals is new. The best studied example is the synthetic organic chemical compound known as PCB, short for Polychlorinated Biphenyl. Used in hundreds of industrial and commercial applications throughout the world, the manufacture of PCBs was banned when it was learned that they persist in the environment and are injurious to wildlife. Entering the oceans, trace amounts of PCBs eventually make their way to the Arctic, are gradually concentrated as they rise up the food chain, and are ingested by polar bears through their prey base of seals.
Studies indicate that high levels of PCBs in the blubber of polar bears appear to hamper their immune systems. This can lead to greater susceptibility to parasites and disease. High PCB levels in bears have also been linked to reproduction failure and malformed organs.
Studies show that all polar bears carry significant pollution loads, although the exact levels at which such pollutants lead to biological problems is unknown. In addition, multiple pollutants sometimes have synergistic effects.