Sharks without teeth might sound like the stuff of dreams to swimmers and surfers. Now a new study has found that ocean acidification could leave the apex predators without their critical survival weapon.<\/p>\n
Shark jaws carry several rows of teeth and new ones quickly push forward to replace losses. However, rapidly acidifying oceans are damaging shark teeth<\/a> and could speed losses past replacement rates. Sharks with bad teeth could struggle to feed themselves efficiently, \u201cpotentially affecting shark populations and marine ecosystem stability\u201d, the study said.<\/p>\n Ocean acidification is caused by rapid carbon dioxide absorption<\/a> creating a chain reaction that lowers pH levels. Projections suggest oceans could be far more acidic by the year 2300, falling from a current average pH of about 8.1 to 7.3, a change that will have \u201cprofound implications for marine organisms\u201d, the study said.<\/p>\n To test acidification effects, researchers kept 60 freshly fallen shark teeth in artificial seawater tanks, one matching the current ocean average pH of 8.1, another with the projected 7.3 pH. The teeth, safely collected from a German aquarium, had already been naturally discarded by six male and four female blacktip reef sharks.<\/p>\n Maximilian Baum, who conducted the study, with a blacktip reef shark jaw. He found increased root corrosion and altered serration. Photograph: Roman M\u00fcller-B\u00f6hm<\/p>\n After eight weeks, teeth in the more acidic tank suffered about twice as much damage, said Maximilian Baum, the study\u2019s lead author and a researcher working with Germany\u2019s Heinrich Heine University\u2019s Institute for Zoology and Organismic Interactions. Effects included \u201cincreased root corrosion \u2026 and altered serration\u201d, he said.<\/p>\n Dental stress would add to sharks\u2019 other problems, which include prey shortages caused by overfishing.<\/p>\n Reducing human-caused CO2 emissions is vital to mitigate ocean acidification<\/a>. Previous research has found acidification damages denticles<\/a>, a toothy scale on sharks\u2019 skin.<\/p>\n Even moderate drops could affect more sensitive shark species, such as those that use fewer rows of teeth<\/a> or have slower replacement rates<\/a>, said Baum.<\/p>\n \u201cI think there will be effects on the teeth of ocean predators in general when they are highly mineralised structures like we have in sharks,\u201d he said.<\/p>\n