Much of wildlife is threatened by increasing pollution. With rapid growth of manufacturing sectors in developing nations, more wastes are excreted into the local environment. In many industrial processes, chemicals known as persistent organic pollutants (POPs) form and spread through air currents. Due to high toxicity, POPs often cause health concerns such as cancer, reproductive problems, and birth defects. This not only disrupts a single organism’s chances of survival, but also limits the success of future generations. If animals are incapable of producing fertile and healthy offsprings, entire species could be wiped out in a matter of decades.
The dumping of wastes also affects aquatic ecosystems. Agricultural practices have increased damages done to surface water. The use of nitrogen fertilizers, for instance, pollutes lakes and rivers, contributing to eutrophication, whereby aquatic ecosystems are depleted of oxygen as excessive plant and algae growths occur. Many marine species cannot tolerate low-oxygen environments and thus, die. The consequence is an increase in aquatic “deserts,” where levels of life are low. Pollution, in part is a result of increased urbanization. In 1996, Statistics Canada reported that 78 percent of Canadians lived in urban areas. Cities produce large amounts of wastes, especially with the increase of packaging goods. Plastic coverings that are sold with products are often tossed into the garbage, where they are mismanaged. According to Plastic Oceans, “more than 8 million tons of plastic is dumped into the oceans every year.” Oblivious marine species often suffer in cases of entanglement and ingestion where many are left vulnerable to predators and weak to health implications.
Although human activities are often indirect causes of animal extinctions, occasionally, they are directly harming species survival. Overexploitation is one of these activities. Commercial fishing around the globe is pushing all kinds of fish into the brink of extinction, if not already. The UN Food and Agriculture Organization estimated that world fishing had hauled in 122 million tonnes of fish in 1997. However, such intense practices are highly unsustainable. Collapses of many large fisheries, such as the Canadian Grand Banks cod fishery, are the results of overfishing. Many other marine species are harmed as well due to problems with bycatch. Together with sports fishing, commercial harvests critically reduce the number of native and economically important fish. As fish are at the bottom of the food chain, decreased numbers would also mean a reduction in predators like dolphins, seals, and penguins. Overall, marine biodiversity is lost. The mining of coral reefs is another example of excessive exploitation. In India and Sri Lanka, entire sections of reefs have been removed to make building materials such as cement. When large sections of reefs are damaged, regrowth is slow. This brings devastating effects as coral reefs provide one of the most diverse ecosystems. Often called “the tropical rainforest of the oceans,” reefs house about a quarter of all marine species, some of which live exclusively in reefs. As such, the loss of biodiversity is immeasurable.
Climate change further reduces biodiversity. With increased global temperatures, many areas are susceptible to drought conditions. Currently, about 40 percent of the world has climates dry enough for desertification to take place. Few organisms are specialized enough to thrive in arid areas; thus, many species will be threatened. In addition, sources of food will also decrease as lower rainfall reduces fruit-bearing plants and other vegetation. Among those affected, reptiles are one of the most vulnerable vertebrate classes. According to BBC report, 20 percent of the world’s lizard species could be wiped out by climate change. Researchers say that this is because many lizards live at the edge of their “thermal limits.” As lizards are cold-blooded, they lack internal regulators of body temperatures, relying on external sources of energy for heating and cooling instead. Consequently, rising temperatures mean that lizards must dedicate more time to finding shade, lowering their overall productivity. Fluctuations in temperatures also affect the geographical range of organisms, exposing about 20 to 30 percent of species to increased risks of extinction. A concern of this is that species of the same family that used to be physically isolated may now interact as geographical barriers are broken. In some cases, interbreeding may occur, resulting in hybrid animals that are biologically weak and/or sterile, lowering progeny numbers after each mating season. Even in better scenarios, viable offsprings that do survive and reproduce are still indicative of diversity loss as separate species slowly merge into one.