Oceans cover 71 percent of our planet’s surface, proving a home to 300,000 known species and about one million unknown species of plants and animals. These vast bodies of water also help absorb carbon dioxide from our atmosphere and regulate the earth’s temperature. The ocean plays a vital role in the survival of our planet, but the damaging effects of a warming planet is causing changes that put the health of our oceans — and countless species — at risk.
The heating of the atmosphere has directly impacted the ocean, which has absorbed an estimated 90 percent of the planet’s greenhouse gas-related heating, according to a report by the International Union for Conservation of Nature.
Also, the carbon dioxide absorbed by the ocean is causing acidification at a rate 30 times faster than what would happen without human interference, altering the pH balance and affecting calcium carbonate levels. Ocean acidification harms coral, plankton, shellfish and other species that use calcium carbonate to help form their shells and skeletons. Plankton and shellfish play an important role in the ocean’s food chain, so when one species suffers, all suffer.
Climate change is the greatest global threat to coral reef ecosystems and coral bleaching is one of most visually dramatic effects, a stress response caused by high water temperatures that can lead to coral death.
Bleaching occurs when the colorful algae that live inside the corals are expelled. That can happen because the water is too warm or too cold, or because of extreme low tides. But bleaching is disastrous for coral reefs, because the algae provide about 90 percent of the coral’s energy. Without it, the coral goes white as it starves. Previous studies have shown that global warming is causing corals to bleach and sometimes die. This latest study gives hard numbers on how often these bleaching events are now happening compared to the past.
“The amount of acceleration that we saw was really surprising,” says study co-author Mark Eakin, a coral reef expert and the coordinator of NOAA’s Coral Reef Watch. It “is mind-boggling and very frightening when you consider what that means for the future of coral reefs.”
As ocean temperatures rise, oceanic diseases proliferate, and species like sea stars struggle to survive. It was the starfish arms walking off on their own that alerted biologist Steven Fradkin that something was terribly wrong at Starfish Point at Olympic National Park.
The observations he made and shared June 7, 2013, would turn out to be the first reported sighting of a mysterious starfish wasting disease that in 2013 and 2014 would devastate more than 20 species of starfish from Alaska to Mexico.
In its geographic scope, the number of species of starfish affected, and duration of the outbreak — still not over — the sea star wasting syndrome Fradkin first documented is now understood to be the largest observed die-off of a wild animal in the ocean. Scientists working ever since to understand the outbreak have published the first evidence of a link between warmer ocean temperatures and the devastation of the wasting disease.
“We were able to show warmer temperatures were related with the higher risk of disease,” said Drew Harvell, professor of ecology and evolutionary biology at Cornell University and a co-author of the study, along with Fradkin and others.
Unlike most species, jellyfish are well-suited to climate change. They thrive in oceans where oxygen levels are depleted, and increases in temperatures can actually boost their ability to reproduce. Jellyfish aren't just an inconvenience for swimmers. They are evidence of a perfect storm of human impacts destabilizing marine ecosystems.
Climate change, unsustainable fishing practices and agricultural chemicals are all suspects in the explosion in jellyfish numbers. But jellyfish blooms come with consequences. As the species proliferate, they can have a negative impact on wild fish populations and cause an irreversible unbalance in marine ecosystems.
To leave you with some good news, a recent research conducted in new Zealand places sea sponges as "winners" in the battle of global warming and ocean acidification. The research found, that though the sponges may be sensitive to the rising seawater temperatures, the sensitivity is reduced due to the ocean acidification. This is a result of the sponges receiving nutrition from symbiotic organisms which gather energy from the sun.
“Our research confirms the importance of studying the combined effects of ocean warming and acidification, and demonstrates the importance of examining the response of a species across different life-history stages when determining an organism’s overall response to environmental change”, says PhD student Holly Bennett, who develop the study with Associate Professor James Bell and Professor Simon Davy from Victoria’s School of Biological Sciences, alongside Dr Nicole Webster from the Australian Institute of Marine Science (AIMS).
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