Zimbabwe News Update
africahotspot
2 min read
the claim that sharks contribute half of the planet’s oxygen is a widely circulated, but scientifically unfounded, myth. while sharks are vital to ocean health, they are consumers of oxygen, not producers. like all fish, sharks require oxygen for respiration, which they extract from the water using their gills.the vast majority of oxygen produced in the ocean—which accounts for an estimated 50% of the earth’s total oxygen—comes from microscopic photosynthetic organisms called phytoplankton . these tiny drifting plants, algae, and cyanobacteria perform photosynthesis, converting carbon dioxide and sunlight into energy and releasing oxygen as a byproduct.
a key contributor, the bacteria prochlorococcus, is estimated to produce up to 20% of the oxygen in the biosphere, more than all of the tropical rainforests combined. though sharks don’t produce oxygen, their role as apex predators is crucial for maintaining the healthy balance of the marine ecosystem where oxygen production occurs. this is known as a trophic cascade. sharks keep populations of their prey (e.g., smaller predators and herbivores) in check. by preventing the overconsumption of primary producers like seagrasses and kelp forests, they indirectly protect these carbon-absorbing, oxygen-producing habitats . studies suggest that in some areas, the mere presence of sharks can alter the grazing behavior of herbivores, allowing vital vegetation to flourish.
for example, the presence of tiger sharks can deter sea turtles from overgrazing seagrass meadows. these meadows are significant in sequestering “blue carbon.”in conclusion, there are no proven statistics that show sharks contribute to planetary oxygen production. all scientific evidence indicates they are oxygen consumers. their invaluable contribution to the planet is in maintaining the ecological integrity of the ocean, which, in turn, allows the true oxygen producers—the phytoplankton—to thrive. the loss of shark populations would not immediately reduce atmospheric oxygen, but it would have severe, cascading negative effects on the marine food web, jeopardizing the long-term health and stability of the ocean ecosystem. source: africa hotspot
