( CNN ) -- The world 's wildlife has declined by 27 percent since 1970 because of the human impact on the environment , the World Wildlife Fund said Friday . These two adult frilled-neck lizards are threatened species and are bred in captivity in Australia . The WWF 's latest Living Planet Index shows terrestrial , freshwater and marine species all suffered declines in their populations between 1970 and 2005 , with freshwater species experiencing the biggest drop . The index is included in a report called `` 2010 and Beyond : Rising to the Biodiversity Challenge , '' which the WWF prepared for an international biodiversity conference in Germany later this month . `` No one can escape the impact of biodiversity loss because reduced global diversity translates quite clearly into fewer new medicines , greater vulnerability to natural disasters , and greater effects from global warming , '' said James Leape , director-general of WWF International . The Living Planet Index measured 4,000 populations of 1,477 vertebrate species , which the WWF says is a good indicator of overall biodiversity trends . Terrestrial species in both temperate and tropical areas fell by an average of 25 percent during the 35-year period , the WWF said . Marine species fell by 28 percent in the same period , with a dramatic decline between 1995 and 2005 , the WWF said . `` Many marine ecosystems are changing rapidly under human influence , and one recent study estimates that more than 40 percent of the world 's ocean area is strongly affected by human activities while few areas remain untouched , '' the WWF report said . Freshwater species in both temperate and tropical regions fell by 29 percent between 1970 and 2003 . The WWF said that is especially significant because despite covering only about 1 percent of the total land surface of the planet , inland waters are home to more than 40,000 vertebrate species . In tropical regions , freshwater species were especially hard-hit ; the index shows they suffered a 35-percent drop between 1970 and 2000 . The WWF said it had insufficient data to chart tropical freshwater species beyond 2000 and temperate freshwater species beyond 2003 . The causes of the declines are varied but ultimately stem from human demands on the biosphere , such as consumption of natural resources or the displacement of ecosystems , the WWF said . The dominant threat to marine life is overexploitation -- harvesting or killing animals or plants beyond the species ' capacity to replace itself , the WWF said . Overfishing is one example . Overexploitation is also a threat to terrestrial species , according to the report , which cites the hunting of tropical forest mammals . Overharvesting of timber is also a major factor , it said . Invasive species , whether introduced deliberately or not , are another threat , especially in freshwater ecosystems , where they are thought to be the main cause of extinction among endemic species , the WWF said . Pollution and overall climate change are other factors causing a loss of biodiversity , it said . The WWF called on governments attending this month 's conference to take urgent action to reduce the rate of loss by 2010 . It wants governments to establish protected areas , particularly those areas important for food security , water supply , medicine , and disaster mitigation , and to commit to zero deforestation by 2020 .
The world 's wildlife has declined by 27 percent since 1970 because of pollution . WWF : Terrestrial , terrestrial , marine species all under threat . Agriculture and overall climate change are other factors causing loss of biodiversity .