Hobbies And Interests
Impact on Predators
If an important food species becomes extinct, the animals that eat the species also suffer. If a fish species disappears, for example, this affects all the larger fish, birds and mammals that depend upon it for sustenance. These species often include humans. The collapse of the cod fisheries off Canada, for instance, had a devastating social and economic impact on onshore and near-shore communities in those provinces.
Impact on Food Species
In the food web, each species also affects the ones it eats. The loss of a grazing species transforms grassland. The loss of a predator sometimes lets the prey species multiply unchecked. The loss of large carnivores, such as wolves, from areas of Europe and the United States has led to problems with too many deer. The deer often go hungry, overgraze their habitat or cause problems for local farmers.
Ecosystem Services
Aside from their role in the food web, animals also contribute to their environment in less obvious ways. Pollination is a key example. Many flowering plants depend upon animals, including insects, birds and mammals, to pollinate their flowers, allowing them to produce seeds. Some plants are adapted to just one or a few species of pollinator. If the pollinating animal becomes extinct, the plant might struggle to survive or might even disappear as well. Pollination services are crucial to agriculture as well as natural habitats. The decline of bees has impacted farmers throughout the world. Other important ecosystem services include the distribution of seeds and the supply of nutrients, for example through droppings.
The Physical Environment
Animals alter their environment and if a species is extinct, the environment changes. For example, before large-scale whaling occurred, the huge numbers of great whales helped sustain their ecosystems. They did this partly through the movement of water. A diving and surfacing whale creates turbulence, which brings nutrients to the surface. Some species also eat at depth and defecate near the surface, which has a similar effect. According to Steven Nicol, a researcher at the Australian Antarctic Division, the near eradication of whales has appeared to reduce plankton and, in turn, fish populations.