Kategorie: News
A future too warm for baby sharks
Research has found that warming of the world's oceans due to climate change causes baby sharks to be born smaller, more exhausted and more malnourished. They are born in an environment that is already harder for them to survive in than it used to be.
Fish are directly affected by ocean warming. But there are also species that are benefiting from the effects of global warming; jellyfish or algae are only visible signs of the change. More dramatic still is the change due to global warming that is taking place underwater. Mostly it is animals, like the shark, that suffer and are pushed to the edge of existence.
Carolyn Wheeler, is leading a study looking at the effects of increased temperatures on the growth, development and physiological performance of epaulette sharks (an egg-laying species found only on the Great Barrier Reef). She is a doctoral student at the ARC Center of Excellence for Coral Reef Studies at James Cook University and the University of Massachusetts.
Co-author, Professor Jodie Rummer, also of Coral CoE at JCU, explains that the temperature of the world's oceans will rise in the next century, to as high as 31 ° C.
"The hotter the conditions, the faster everything happens, which could be a problem for sharks. Embryos grow faster and use their yolk sac faster, which is their only source of food as they develop in the egg case. This cause them to hatch earlier than usual." says Carolyn Wheeler.
Not only are the hatchlings smaller, but they have to find a food source to feed on directly after hatching, due to lack of energy. All this, just because the temperature, makes the development faster.
The ocean temperature is of very great importance for the future of all sharks, both egg-laying and living species.
"The epaulette shark is known for its resilience to change, even ocean acidification. If this species can't cope with warming waters, how will other, less tolerant species do?" said Dr. Rummer
Because sharks, but also other similar species like the ray, grow very slowly, they also don't reproduce as often compared to other fish. This further threatens shark populations.
The study suggests that sharks of the future will not only be disadvantaged by rising temperatures, but will also be born in an environment that is already warmer than they can tolerate.
"The study offers a worrisome future because sharks are already threatened," Ms. Wheeler said.
"Sharks are important predators that keep ocean ecosystems healthy. Without predators, entire ecosystems can collapse, which is why we need to continue to study and protect these creatures.“
"Our future ecosystems depend on us taking urgent action to limit climate change," Dr. Rummer said.
The research was a collaboration between the Anderson Cabot Center for Ocean Life and the New England Aquarium in Boston. In fact, the New England Aquarium has a successful breeding program for epaulet sharks.