IUCN list of species is also called the threatened species red list and these are put into nine categories of as NE <u>Not evaluated, Extinct, Extinct in the wild, Critically endangered, Vulnerable, Endangered, then Least concern, Near threatened, and Data deficient types.</u>
The EN species has a high risk of extinction in the wild, for Endangered and comes under the threatened and at-risk category. The main reason for a species to be endangered is the nearness to its extinction in the near future if proper conservatory steps are not taken.
About 3,079 animals and 2,655 plant species are on a verge of extinction by the process of hunting and landscape development. The US defines a species recovery plan that aims to access their status in the wild and then keeping them in captive breeding hubs for recovery purposes.
Thus at large scale, national parks and reserves ad sanctuary have been built in the US for there protection and preservation of habitats of these species as they can grow and develop in wild.
Low dissolved oxygen concentrations that occur in many bodies of water when nutrients stimulate the growth of algae that subsequently die and are decomposed by oxygen-using bacteria.
