The dreaded shark teeth “are created to cut meat, not to resist acidity,” summarizes the statement about the study, published Wednesday in the magazine Frontiers in Marine Sciencewhich concluded that the “deadly” shark teeth may not resist the effects of ocean acidification – which is increasing due to increasing concentration on seawater from the main gas with greenhousethe dioxide of carbon (CO2).
The team of scientists collected more than 600 discarded teeth of an aquarium that housed sharks and submitted them to tests to observe the effect of the predictable increase in ocean acidification. The teeth exposed to the most acidic water, because they have larger amounts of CO2 emitted by human activity, have become significantly more damaged. In living fabric and with increasing acidification damage can be much more serious, they warn.
“Shark teeth, despite being composed of highly mineralized phosphates, are vulnerable to corrosion in future ocean acidification scenarios,” says the first author of the article by Frontiers in Marine ScienceMaximilian Baum, Biologist at Düsseldorf (HHU) Heine University in Germany, quoted in the press release on the study. “They are highly developed weapons made to cut meat, not to resist the acidity of the ocean. Our results show how vulnerable even the sharp weapons in nature can be.”
In response to blue by e-mailBaum said that experiences with teeth of black-black shark were carried out that naturally fell. “We found that the teeth exposed to lower pH values had more visible damage, such as cracks, root corrosion, and changes in the surface structure,” he summarizes. This indicates that ocean acidification can affect not only coral or shells, but also the tools of the main predators, adds the investigator.
In the article, the authors remember that the change in ecological factors represents a challenge for many organisms. “Global changes and associated environmental changes have a significant impact on marine organisms and threaten biodiversity of marine ecosystems. Previous experimental studies have shown that the acidification of oceans caused by the anthropogenic liberation of CO2 [dióxido de carbono] In the atmosphere and the subsequent dissolution on seawater will have a significant impact on various marine organisms, “they write.
An ocean ten times more acidic
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In this investigation, scientists investigated “the corrosive effects of acidification on isolated shark morphology in an incubation of eight weeks to a pH of 7.3, the expected pH of seawater in 2300”. The pH of ocean water was 8.2 in the pre-industrial era (which made it alkaline). But today, it will have already reduced to about 8.1, due to the absorption of excess CO₂ in the atmosphere, which is the process through which ocean acidification is happening. This decrease in pH may seem insignificant, but it represents an increase of approximately 30% in acidity and threatens marine life.
In 2300, it is expected to fall to 7.3, making the ocean almost ten times more acidic than it is currently. At that time, the ocean is still alkaline, but it will be very close to becoming an acid – which happens with pH value below 7.
“Sharks are famous for replacing their teeth, with new teeth growing whenever the current ones wear out. As sharks depend on teeth to capture prey, they are vital to the survival of one of the main ocean predators,” the press release contextualizes.
To blue, Baum clarifies, however, that “although sharks can replace their teeth, the energy costs of doing so in increasingly acidic conditions can become a true disadvantage.” “This shows how human impacts on oceans can be complex and multifaceted.”
Thus, scientists warn, these powerful tools may not resist the pressures of a warm -up world, and according to this work, specifically ocean acidification can make shark teeth more fragile and weak.
Max Baum
In the study, the researchers collected more than 600 discarded teeth from an aquarium that houses sharks. And note: “16 teeth – those that were completely intact and without damage – were used for the pH experience, while another 36 teeth were used to measure the circumference before and after.” The teeth were incubated for eight weeks in separate 20 -liter tanks, with a pH -submerged part of 8.1 and another at 7.3 pH.
Compared to the teeth incubated at a pH of 8.1, the teeth exposed to the most acidic water became significantly more damaged. “We observed visible surface damage such as cracks and holes, increased root corrosion and structural degradation,” describes Sebastian Fraune, which runs the HHU Institute of Zoology and Organic Interactions, quoted in the statement.
Teeth looked bigger, but they got weaker
There were other changes. “Tooth circumference was higher at higher pH levels. However, teeth did not really grow. The surface structure became more irregular, making them look longer in 2D images,” reports the article, stressing that “although a altered dental surface can improve cutting efficiency, it can also make teeth structurally weaker and more likely.”
Scientists, however, recognize an obvious limitation of their study. The work analyzed only discarded teeth of non -alive mineralized fabric. What can happen in living organisms? Can there be any adaptation that triggers repair processes of these damage?
Sebastian Fraune risks an answer: “In living sharks, the situation may be more complex. Potentially, teeth could be remunerated, or those damaged could be replaced faster. But the energy costs of this would probably be higher in acidified water.”
“The next steps of our investigation will be to examine these processes in living sharks, rather than just lost teeth. This will help us understand if how can sharks can compensate for damage. We also want to investigate how different species are affected, which have different dental replacement rates,” he adds to Maximilian Baum.
The black-black sharks(Carcharhinus melanopterus), Which served for this study need to swim with a permanently open mouth to breathe, which means that the teeth are constantly exposed to water. “If it is very acidic, the teeth suffers damage automatically, especially if acidification intensifies,” scientists predict.
Road-black sharks are often maintained in exposure aquariums under controlled conditions. Therefore it was used in this study. These conditions greatly facilitate the minimally invasive sampling for investigation on-sitejustify the authors in the article.
Corrosive effects
“The teeth of this species Shark are orthodontic, have a strong serial in the upper jaw, ”they describe. Using electronic microscopy, it was possible to observe“ the corrosive effects of acidification in different dental structures such as the root, primary and secondary serials and the crown of black-ponta-shark teeth ”.
Stephen Frink/GettyImages
“Our results show that ocean acidification will have significant effects on the morphological properties of the teeth, including visible corrosion in the crown, the degradation of root structures and the loss of thin details of the seril in low pH conditions. This may lead to changes in food demand, energy absorption and ultimately the physical fitness of elasmobraneums. [uma subclasse de peixes cartilagíneos] In the oceans of the future, ”scientists write.
Maximilian Baum gives more details on the predictable negative effect: “Even moderate pH falls can affect more sensitive species, with slow tooth replication cycles, or have cumulative impacts over time.”
Solution? Reduce CO2 emissions
How to avoid this scenario? The answer is simple: “Keeping the pH of the ocean close to the current average of 8.1 can be fundamental to the physical integrity of predators tools.”
Solution? “Addressing this problem means, first of all, to combat the main cause, which is the continuous increase in CO2 emissions and the consequent acidification of the oceans,” Baum responds to the blue.
“At the same time, there is a greater awareness than climate change They even affect the smallest structures of marine life. Reducing emissions and supporting marine conservation are therefore essential steps if we want to protect ecosystems, from coral to sharks, “said the scientist.
Despite all that was left out of this investigation, and that the effects of acidification on living tissues have not been tested, the authors point out that work shows that “microscopic damage may be sufficient to represent a serious problem for animals that depend on teeth to survive.”
“It’s a reminder that climate change has a chain impact throughout the food chain and ecosystems,” concluded Maximilian Baum.
