Often, when reference is made to increased levels of acidification of the seas, reference is made, with regard to damage to the ecomarine environment, to living beings such as corals, those with shells and the like. A new study, published in Scientific Reports, shows that fish, and specifically sharks, may be the worst off.
Water acidity levels are rising due to higher levels of carbon dioxide in the oceans. According to Lutz Auerswald, biologist at Stellenbosch University, South Africa, this phenomenon could lead to corrosion of the teeth and scales of these animals, two of the most important characteristics they use for hunting and feeding.
Researchers have come to study this phenomenon starting from the high acidity that characterizes beer, one of the most popular drinks in the world, as well as many other carbonated drinks. These drinks, in fact, cause the erosion of human teeth and the scientist wondered if the same could happen in waters with a higher diacidification level against marine animals.
The scientist first began to discard previous studies regarding this possible link and found only one study conducted on cat sharks of limited size, according to which no significant impacts were found. However, as Auerswald himself notes, this study was limited by the fact that carbon dioxide levels in the areas studied were still relatively low compared to many other marine areas today where acidity levels are much higher.
The researcher, together with colleagues, therefore began to investigate the effects of sea acidification on sharks of the species Haploblepharus edwardsii, animals of the Scyliorhinidae family (also known as cat sharks) and endemic to marine areas off South Africa. After capturing some specimens, they placed them in different tanks with different pH levels and after several months they analysed under an electron microscope the concentrations of calcium and phosphate, two materials present both in the teeth and scales of the sharks.
The researchers noted that the amount of calcium and phosphate in the teeth of sharks in the more acidic tanks was significantly reduced and that 25% of shark scales in the more acidic tanks were damaged compared to 9% in the control group of sharks in tanks with lower levels of acidity.
The researchers themselves believe that this loss of calcium and phosphate could have different impacts depending on the species and hunting techniques used by shark species. This means that corrosion of teeth and scales in particular could have a more significant impact on some species than others.