The sudden disappearance of great white sharks from South Africa’s False Bay is causing major changes in the ocean ecosystem, according to a new study published in Frontiers in Marine Science.
These top predators, famous for their dramatic leaps out of the water while hunting, once played a critical role in keeping the ocean’s food web in balance.
Now, scientists are seeing how their absence is affecting nearly every level of marine life.
Researchers from the University of Miami’s Rosenstiel School spent over 20 years studying the waters of False Bay.
They found that great white sharks, once common in the area, have dramatically declined in recent years.
This may be due to long-term human impact, such as sharks being caught in protective nets, along with recent attacks on them by orcas.
With the great whites gone, other species have stepped in to fill the gap—but not without consequences. Cape fur seals and sevengill sharks have become more common, and this shift is creating a ripple effect.
The seals are now feeding more heavily on local fish populations, while sevengill sharks are preying on smaller sharks.
As a result, several fish and small shark species are declining. This kind of chain reaction, where changes at the top of the food web affect many other species, is known as a “trophic cascade.”
The research team used several methods to study these changes, including underwater video surveys, shark sighting records from boat trips, and data from citizen scientists observing seal behavior. These surveys, taken over a decade apart, offered a unique before-and-after view of the ecosystem.
Yakira Herskowitz, one of the study’s co-authors, explained that the number of animals caught on camera helped show not just how many were present, but also how they were behaving.
Animals that fear predators tend to hide more, so their sudden appearance—or increase—can reveal changes in who is at the top of the food chain.
Lead author Dr. Neil Hammerschlag said the study confirms what ecologists have long predicted: when an apex predator disappears, the balance of the ecosystem can shift in unexpected and harmful ways.
Without great white sharks keeping populations in check, other species multiply and overconsume their prey, throwing the entire system off balance.
The study highlights why it’s so important to protect sharks around the world. Healthy oceans depend on apex predators like the great white shark.
Without them, the delicate balance that supports marine biodiversity—and the human activities that depend on it—could be at risk for the long term.
Source:KSR.
