Researchers warned of a "domino effect" related to overfishing.
If too many fish of a certain species are harvested from a specific area it could affect other animals in the ecosystem more dramatically than many would expect, a Florida State University news release reported.
"You don't realize how interdependent species are until it all unravels," Felicia Coleman, director of the Florida State University Coastal and Marine Laboratory and a co-author on the study said in the news release.
The researchers looked at marine ecosystems that had been severely distressed in the past.
In the Northern Benguela ecosystem off Namibia during the 1970s the sardine and anchovy populations were almost wiped out as a result of overfishing; the species was replaced by hoards of bearded goby and jellyfish. The population replacement turned out to be bad news for local predators such as "penguins, gannets and hake" since bearded goby and jellyfish do not have as high of a nutritional content as sardines and anchovies.
The loss of nutritious prey resulted in a 77 percent decline in African penguins population and 94 percent drop in Cape gannets.
Both Cape hake and deep-water hake's production fell from 725,000 metric tons in 1972 to 110,000 metric tons in 1990. Cape fur seals have also been influenced by the ecosystem changes.
"When you put all these examples together, you realize there really is something important going on in the world's ecosystems," FSU biological science Professor Joseph Travis said. "It's easy to write off one case study. But, when you string them all together as this paper does, I think you come away with a compelling case that tipping points are real, we've crossed them in many ecosystems, and we'll cross more of them unless we can get this problem under control."
The researchers hope their findings will encourage fisheries to quickly address the problem and implement changes.
"It's a lot easier to back up to avoid a tipping point before you get to it than it is to find a way to return once you've crossed it," Travis said.
