Human activities have been directly responsible for a number of developments that have damaged or destroyed local ecosystems in almost every region of the country. Living on Lake Superior, one of the two largest fresh-water lakes in the world, one can easily view or experience the ramifications of human activity for the local ecosystems in and around that particular body of water.
Lake Superior, of course, is part of the “Great Lakes,” which are connected through a series of channels. Mining activity, a major economic factor in this region, is integrally linked to the shipping industry, as the iron ore and other minerals mined near here must be transported to market via large cargo ships that regularly ply these waters. Because ships’ maintenance crews for many years neglected the inspection of their vessels for signs of species of plants and animals in their bilge tanks or attached to their rudders and propellers, predatory species like zebra mussels and sea lamprey have been inadvertently transported from one region where they are native to other regions, where they are not. The problem of foreign or invasive species being brought into Lake Superior has been costly both in financial terms and in the decimation of native species by the unwanted interlopers. In fact, the damage to local ecosystems has been so bad, especially with regard to the introduction into Lake Superior of zebra mussels and sea lampreys, that local, state and federal agencies have been forced to spend thousands of dollars and untold man-hours developing ways to reverse the damage.
Another manner in which local ecosystems are adversely affected by human activity is through pollution of previously pristine waters through the careless dumping of industrial race and the contamination of water supplies through the continuous introduction of toxic chemicals into the local waterways through sewage systems. Homeowners for decades routinely disposed of paints, automotive fluids, cleaning chemicals, and other toxic substances by pouring them down household drains. The result has been destruction of maritime ecosystems, especially fragile coral reefs that cannot be easily replaced. The U.S. Navy has deliberately sunk decommissioned ships in the ocean so that the hulls can be used as the foundations for new coral reefs, but this is a poor, and potentially damaging, substitute for the naturally-forming reefs that provide sustenance to many species of marine life.
These are just two ways in which local ecosystems are damaged through human activity. Unfortunately, there are many more examples, including damage to wetlands caused by human activity, and overhunting of certain species of animals.
Population increase results in many human activities that can have an effect on the local ecosystem. An ecosystem consists of the environment and its constituents (such as the organisms – plants, animals, microbes – and nutrients) that live in or cycle through it.
An increase in population requires an increase in housing. Land must typically be cleared to accomplish this. Trees are cut down, soil is moved, rivers or streams may be dammed to provide land to build on. This decreases habitat for organisms that once lived in that area. It can also alter the cycling of nutrients. Dams, for example, can prevent the natural flow of silt from the mountains to the ocean.
More human activity means there is more human waste that enters the environment. Humans create waste just by eating and drinking (think: sewage), not to mention garbage generated by every day living. This waste has to be disposed of or treated in some manner. Improperly disposed chemicals can enter the water table and affect the viability of other organisms living in the ecosystem.