Humans have mined resources from the remote and rocky coast of Peru and Chile for more than a century and a half, gathering the guano deposits of seabirds for fertilizer and gunpowder. Those seabirds flourished on anchoveta in the coastal waters, while Peruvians in the highlands ate the same fish as dried snacks.

Now fishing vessels haul 7.5 million tons of the small silvery fish out of the water every year. Almost all the catch is reduced to fish oil and fish meal, which is fed to pigs, poultry and salmon being raised thousands of miles away to satisfy demand in the industrialized and rapidly-growing developing world.

The Peruvian seabird population that used to number in the tens of millions has dropped to 2 million.

“These fish are an important source of food, and the basis of the ecosystem,” said Peruvian conservation biologist Patricia Majluf. “It’s part of the global syndrome of misuse of resources.”

As the global population reaches the 7-billion mark, these sort of ecological distortions are becoming more pronounced and widespread. Sometimes local needs are depleting water, fish and forests; other times food and fuel needs in one region of the world are transforming ecosystems in another. Under either scenario, however, expanding human demands are placing pressure on resources, particularly on world water supply and fisheries.

Robert Engelman, executive director of the Worldwatch Institute, noted that societies have repeated this pattern of depleting one natural resource and then turning to another, whether it’s the whale oil that gave way to fossil fuels or the guano that has been substituted by chemical fertilizer. But the current scale of exploitation has become so vast, Engelman said, that it now exacts even larger consequences.

“When you have China out roaming the seas looking for anything they can get for its population of 1.3 billion people, that’s increasingly affecting any local resource anywhere in the world, which is at risk of getting depleted for a distant populous power,” Engelman said.

These extractive activities are not just a simple function of adding people to the planet: They are driven as well by the rising economic aspirations and lifestyle choices humans are making around the globe.

Robert Glennon, the University of Arizona’s Morris K. Udall professor of law and public policy, said water supplies are under pressure because they meet so many needs. About 70 percent of the world’s fresh water is used for irrigation, 22 percent for industry and 8 percent for domestic use, according to the U.N. World Water Assessment Programme.

Climate change is reducing the fresh water people get from glaciers and springs in South and Central America, as well as in the Himalayas. At the same time, aquifers are becoming contaminated in countries such as India and Bangladesh as industrialized activities and population expand.

“It’s the most critical resource issue, partly for itself, partly for its contribution to producing energy and growing food” said Glennon, author of the book, “Unquenchable: America’s Water Crisis and What to Do About It.”

By 2025, according to the U.N. Food and Agriculture Organization, two-thirds of the world’s population could be living in areas where the fresh water supply is under stress. And according to the U.N.’s 2006 Human Development Report, more than 1.4 billion people live in river basins where their water use exceeds the amount of water that is naturally replenished, thereby depleting rivers and groundwater.

“If you look around the world, water quality is deteriorating, water quantity is declining,” said Ned Breslin, who heads the nonprofit organization Water for People.

A number of private-sector groups have started projects to address global water supply. Breslin’s organization has experimented with a number of initiatives, including training specialists in India who can maintain communities’ water supplies and have a financial incentive to keep them operating. Coca-Cola has launched 385 projects in 90 countries, including some that protect watersheds and others that allow small farmers to irrigate more efficiently.

Manish Bapna, interim president at the World Resources Institute, said emerging economies will have to manage their growth differently than industrialized nations if they hope to achieve sustainability.

“It’s only going to be achieved if we find a way to decouple natural resources from improvements in lifestyle,” Bapna said.

In many cases, business and political leaders in these countries are just beginning to confront the challenge. Alibaba Group chief executive Jack Ma, a Chinese Internet entrepreneur who serves on the Nature Conservancy’s global board of directors, said he began to recognize the impact of his country’s economic gains once he started traveling outside his country. “I was shocked,” he recalled. “I thought, ‘The economy’s good, but the environment’s terrible.’ ”

Forests — which provide critical habitat for many species, protect local water supplies and store carbon that otherwise would accelerate climate change — are another resource under stress. Several nations and regions with relatively stable or declining populations, such as the United States and Europe, have seen the acreage and density of their temperate forests rise in the past few decades, but a number of developing nations with biologically diverse tropical forests have lost ground.

“When you look at Central America and Southeast Asia, the hot spots of deforestation, a large amount of that is being driven by global demand for food and, increasingly, fuel,” said Glenn Hurowitz, a consultant for the group Climate Advisers.

Jason Clay, senior vice president for market transformation at the World Wildlife Fund, noted that in the past decade land conversion to farmland worldwide has grown at a pace of 0.6 percent a year; by 2050 that would mean another 24 percent of the Earth would be devoted to agriculture, on top of the 33 percent used now.

“There just isn’t enough land out there, so we’ve got to intensify,” Clay said.

Babatunde Osotimehin, executive director of the U.N. Population Fund, said people need to recognize how human needs are transforming the planet.

“People can’t talk about the environment without talking about population,” he said. “Many of the environmental issues you talk about, whether it’s climate change or something else with the environment, people are in the center of it.”

In the end, according to National Geographic fellow Barton Seaver, the world’s growing population will have to learn how to live better within its means.

“We’re not going to find more fish; we’re not going to plow more rain forest to create more calories,” Seaver said. “I would rather have my anchoveta in all its briny, delicious, shiny glory than through a pork chop on my plate.”