Climate Change Could Potentially Prevent Shark Eggs from Hatching
New and Improved Version
holey moly, climate change might be kicking sand in the face of some sharks, according to fresh research. It turns out that eggs belonging to the small-spotted catshark could be in big trouble by 2100, with a substantial decrease in survival rates under the worst-case climate scenario. However, these sharks could still thrive under less catastrophic conditions.
The study was spearheaded by boffins from the Biology of Aquatic Organisms and Ecosystems (BOREA) Lab in France and published in the journal Marine Environmental Research earlier this April. These scientists will be presenting their findings this week at the annual conference of the Society for Experimental Biology.
The small-spotted catshark, also known as the sandy or lesser spotted dogfish, is currently doing alright, with plenty of them swimming about the northeast Atlantic Ocean near Europe. But despite their current good fortune, these chompers may be becoming more vulnerable in our ever-warming world.
"The small-spotted catshark is already experiencing habitat loss in coastal areas, particularly during the summer months when egg-laying is at its peak," said lead researcher, Noémie Coulon, a PhD student at BOREA, in a statement from the Society for Experimental Biology.
To figure out what the future holds for these sharks, Coulon and her team raised and monitored batches of their eggs under three different scenarios. These scenarios were based on the temperature and pH of the water the eggs were kept in, with the latter being crucial due to rising carbon dioxide emissions leading to ocean acidification. The scientists kept a close eye on these eggs for four months (catshark pups usually hatch after 5 to 11 months), and then tracked their progress for another six months.
The first scenario was a control, with eggs kept under conditions similar to today's. In the others, the team adjusted the water temperature and pH to match two climate projections developed by the United Nations called the shared socioeconomic pathways (SSPs): SSP2 and SSP5.
Under SSP2, the global temperature would rise by 2.7 degrees Celsius while the water pH would lower by 0.2 by 2100. Under SSP5, the temperature would rise by 4.4 degrees Celsius, and the water pH would lower by 0.4.
In the worst-case scenario, only 11% of the small-spotted shark eggs hatched, compared to the 81% and 83% survival rate seen under the control and SSP2 conditions, respectively. The embryos inside these eggs also consumed less yolk, grew at a slower rate, and were less able to form their internal gills. Once the sharks hatched from their eggs, there was no difference in survivability between the groups, likely because water temperatures cooled as the year went on, the authors say.
This study is just one piece of the puzzle, so more research is needed to confirm these findings. But should the team's predictions hold true, then a SSP5 world could spell disaster for these fish, as well as other creatures like skate fish, close cousins of sharks.
"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," Coulon said.
While a SSP5 scenario may be unlikely, the team's overall results could still be seen as encouraging, as long as humans can prevent the worst climate future. If we can keep the world a bit cooler and the oceans a tad less acidic, then these fish will still be here, swimming the seas.
"Firstly, it serves as a warning about the responses of other species that may be even more sensitive to environmental change. Secondly, our findings demonstrate that the more moderate SSP2 scenario can limit the damage inflicted on species like the small-spotted catshark, giving us a positive incentive to reduce our greenhouse gas emissions," Coulon said.
- The small-spotted catshark, also known as the sandy or lesser spotted dogfish, is likely to face a substantial decrease in the survival rates of their eggs by 2100 under the worst-case climate scenario, according to a new study.
- This study, led by researchers from the Biology of Aquatic Organisms and Ecosystems (BOREA) Lab in France, suggests that technology, in the form of climate-friendly practices, could play a crucial role in the future of these sharks.
- The study, which was published in the journal Marine Environmental Research, found that under the moderate SSP2 scenario, the survival rate of the small-spotted catshark eggs is likely to be higher, at around 81%.
- If humans can prevent the worst climate future by reducing their emissions and keeping the world a bit cooler and the oceans a tad less acidic, then the small-spotted catshark, along with other creatures like skate fish, could still thrive in the future.
