Washington: The loss of large predators at the top of the food chain has hit ecosystems across the world.
An analysis of research from a wide range of terrestrial, freshwater and marine ecosystems show "the loss of apex consumers is arguably humankind`s most pervasive influence on the natural world".
Large animals were once common across the globe. They shaped the structure and dynamics of ecosystems, said marine ecologist James Estes of the University of California, Santa Cruz.
Plummeting numbers of apex consumers are most pronounced among the big predators, such as wolves, sharks and large fish in freshwater ecosystems, journal Science quoted Estes as saying.
There also are dramatic declines in populations of elephants and bison, according to a California university statement.
Their decline, largely caused by humans through hunting and habitat fragmentation, has far-reaching and often surprising consequences, including changes in vegetation, wildfire frequency, infectious diseases, invasive species, water quality and nutrient cycles.