In the United States, he added, shark-watching results in $314 million per year, directly supporting 10,000 jobs.
He and the other researchers say that human health, pollination, pest control, water quality, food availability and other critical factors are also dependent upon ecosystem stability.
Yet another paper in the latest issue of Science outlines controversial measures, beyond basic conservation efforts, to improve the current situation. These include re-wilding, meaning placement of underrepresented species back into the wild; human removal of invasive species; and, perhaps most controversial of all, de-extinction: bringing already extinct species back to life.
"People are currently grappling with the implications of de-extinction, including how to select the best candidate species," co-author Philip Seddon, a zoologist at the University of Otago, told Discovery News.
Rogers said that restoration and re-introduction have shown progress.
"The return of the bald eagle and the California condor to the skies and the wild turkey to the lands of the U.S. are great success stories," she said.
She and Tewksbury are also working on the island of Guam, where the invasive brown tree snake has rid the island of birds, causing the forests there to be without seed dispersers for 30 years. This, in turn, has contributed to financial challenges for locals.
It's a mistake, though, to limit the value of non-human animals to their economic value, the researchers believe.
"From the cave paintings that represent the dawn of art to the icons of culture and sport around the world today, wild animals are a part of our fabric, and in a very real, evolutionary sense, these animals have made us who we are," said Tewksbury.
"The loss of these animals from landscapes around the world is thus a loss for all of humanity."