In most animals, high concentrations of heavy metals in the bloodstream could be a death sentence.
But somehow, great white sharks’ bodies seem unfazed by the toxins.
Scientists analyzing blood samples from sharks in the waters off
Though the sharks’ blood samples revealed concentrations of heavy metals that the researchers say would be considered toxic to many other animals, their immune systems appeared to be functioning just fine. File photo
While the sharks’ health thus may not be of immediate concern in this case, researchers say the discovery highlights the worrying presence of toxic elements in the food they eat – including fish that humans consume.
Researchers Ocearch and the University of Miami collected blood samples from 43 great white sharks.
All of the sharks in the study were also tagged and released.
Though the blood samples revealed concentrations of heavy metals that the researchers say would be considered toxic to many other animals, their immune systems appeared to be functioning just fine.
The team noted body condition, total leukocytes, and granulocyte to lymphocyte ratios all appeared normal.
‘The results suggest that sharks may have an inherent physiological protective mechanism that mitigates the harmful effects of heavy metal exposure,’ said lead author Liza Merly, a senior lecturer at the University of Miami Rosenstiel School of Marine and Atmospheric Science.
Researchers screened the sharks’ blood for concentrations of 12 trace elements and 14 heavy metals, revealing the presence of mercury, arsenic, and lead.
The work provides important new insight to the living conditions of great whites in South Africa, and could help to create a baseline for the levels of different elements in their blood.
It could also help researchers better understand harmful elements that could be appearing in food that ends up on our dinner tables.
In most animals, high concentrations of heavy metals in the bloodstream could be a death sentence. But somehow, great white sharks’ bodies seem unfazed by the toxins. File photo
‘As top predators, sharks bio-accumulate toxins in their tissues via the food web from the prey they eat,’ said Neil Hammerschlag, study co-author and research associate professor at UM’s Rosenstiel School and Abess Center for Ecosystem Science & Policy.
‘So by measuring concentrations of toxins, such as mercury and arsenic, in the blood of white sharks, they can act as “ecosystem indicators” for the health of the ecosystem, with implications for humans.
‘Basically, if the sharks have high levels of toxins in their tissues, it is likely that species they eat below them will also have toxins, including fishes that humans eat.’
WHAT DOES THE GREAT WHITE SHARK’S DNA TELL US?
The genome of the great white shark has finally been decoded, and it may hold the key to discovering a cure for cancer.
The genome is far bigger than that of a human and contains a plethora of mutations that protect against cancer and other age-related diseases.
It contains an estimated 4.63 billion ‘base pairs’, the chemical units of DNA, making it one-and-a-half times bigger than its human counterpart.
Within the great white’s DNA is evidence of around 24,500 protein-encoding genes, compared with 19,000 to 20,000 in the average human.
Great white sharks, which measure up to 20 feet long (six metres) and weigh as much as three tonnes, are ancient giants that have been on Earth for at least 16 million years.
The animal’s genetic code also gives them enhanced wound healing which allows them to recover from severe ailments.
Experts believe the great white genome evolved to be stable and disease resistant and could be key in developing future treatments.