Ocean acidification associated with damage on shark skin
Recently, the effects of ocean acidification conditions were investigated on the puffadder shyshark (Haploblepharus edwarsii) over different periods of time. The study included chronic exposure of the sharks to elevated CO₂ conditions corresponding to lower pH for several weeks. One of the parameters studied was the effect on denticles – the small scales that cover the skin of sharks.
The results showed corrosion of the denticles under ocean acidification conditions. The authors attributed this effect to chemical dissolution. The observed damage could increase the turnover of these structures, and negatively affect the hydrodynamics and skin protection of sharks. As denticles and shark teeth are constructed in a similar manner, it can also be expected that the teeth will be affected, which would compromise feeding.
The puffadder shyshark is a small, endemic species in South African shallow waters. In these waters, CO₂ levels fluctuate naturally due to upwellings. Nevertheless, the results suggest that with increased ocean acidification, this and other endemic species in the area could be threatened due to the corrosive effects.
The shark species under study is bottom-dwelling, and does not need to swim in order to breathe. However, larger shark species in open waters that do need to be in constant motion, could be highly susceptible to reduced swimming speed, which would be one of the negative effects of impaired hydrodynamics. The effects of corrosion on teeth would also affect all shark species. These and other observations in the study indicate that ocean acidification is a threat to a group of animals that is already vulnerable.
The article: “Acid-base adjustments and first evidence of denticle corrosion caused by ocean acidification conditions in a demersal shark species”