(CN) — Without drastic changes, humanity is headed for a much warmer future, and some creatures won't make it there with us. According to a new study, sharks might be one animal to get wiped out by the warmer climate we could experience 80 years from now.
Research presented at the Society for Experimental Biology Annual Conference in Prague this week found that shark eggs are much less likely to hatch successfully if global warming goes unchecked.
It's more than just warmer temperatures that ocean life will have to contend with. Higher temperatures mean that more carbon dioxide will dissolve into the ocean, making it acidic and hostile to life.
"The embryos of egg-laying species are especially sensitive to environmental conditions,” Noémie Coulon, a PhD student at the Laboratoire de Biologie des Organismes et des Écosystèmes Aquatiques, France said in a press release. “The hatching success of embryos is a crucial factor for population dynamics. In the case of skates and sharks, which have a slow pace of life, low hatching rates could be critical for population renewal.”
The study, conducted over the course of 10 months, examined embryo growth, yolk consumption, and survival rates of small-spotted catshark eggs under three separate conditions.
There was a control group, with temperatures and water pH matching the oceans from 1995 to 2014.
Then there was a group referred to as SSP2, or the "Middle of the Road" scenario, where temperatures rise by 2.7°C and the pH drops by 0.2. This group is meant to simulate what would happen in 2100 if humans reduce fossil fuel use but don't stop using it completely.
In another group, called SSP5, or the "Fossil-fueled Development" scenario, temperatures rise by 4.4°C and pH drops by 0.4. This group simulates what would happen if humans continue to increase their usage of fossil fuels through 2100.
The shark embryos showed a high survival rate in groups one and two — 81% and 83%, respectively. Group 3, which models the projected ocean conditions if humanity continues to use more and more fossil fuels, had a disastrously low survival rate: just 11%.
“We were shocked by the low survival rate observed in the SSP5 scenario, with only 11% of embryos hatching,” Coulon said. “This mortality was most pronounced in August, coinciding with the highest temperatures (reaching 23.1°C), and during a stage of development where embryos undergo gill reabsorption."
According to the study, the surviving sharks in the third group had a different growth pattern from other sharks. The surviving sharks were slimmer than those from other groups but had a faster growth rate after hatching.
The researchers theorize that sharks may need to develop abnormally in order to survive a major change in climate.
“What makes these individuals special remains unclear," Coulon said. "But by acknowledging the inter-individual variation among young marine organisms, we could better evaluate the future ecological success of species.”
Despite the catastrophic results for the sharks in the third group, the researchers say the study revealed something positive. The high survival rate of sharks in the second group shows that, even if we don't completely stop climate change, humanity could still prevent a complete environmental catastrophe.
"Our findings demonstrate that the more moderate SSP2 scenario can limit the damage inflicted on species like the small-spotted catshark, which gives us a positive incentive to reduce our greenhouse gas emissions," Coulon explained.
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