SYDNEY, June 14 (Xinhua) -- A new study collaborated by Australian and New Zealand researchers has shed light on the impacts of climate change on the marine environment, warning that higher ocean temperatures can threaten the survival of sea sponges.
According to the research published Wednesday in the ISME Communications journal, when ocean temperature rise from 28.5 degrees Celsius to 31.5 degrees Celsius, the three-degree increase can induce necrosis, microbial dysbiosis, and nutrient cycling imbalance in a sponge species commonly found on the Great Barrier Reef -- Stylissa flabelliformis.
Scientists from the University of New South Wales (UNSW Sydney), the Australian Institute of Marine Science, and the Victoria University of Wellington concluded that the healthy symbiosis will be deeply impacted by ocean warming by 2100, as seawater temperatures are forecast to hit 31.5 degrees Celsius.
"We've already seen marine heatwaves wipe out sponges in the Mediterranean and impact sponges in New Zealand," said Emmanuelle Botte, lead author of the study and research officer at UNSW Sydney.
"We are seeing that some sponge species are not as resistant as we first thought to climate change. This research reveals that the breakdown of the symbiosis between the host and its microbes could create a chemical imbalance in the sponge and cause its decay," Botte noted.
Marine sponges play essential roles in the ocean, such as habitat formation, benthic-pelagic nutrient coupling, and secondary metabolite production. They are also a source of remarkable microbial diversity.
"They live in symbiosis with microbes, which fulfil vital roles for the sponge: they recycle nutrients, produce energy and defend the sponge against predators and diseases. Some microbes even detoxify the sponge's body. They are a bit like the liver and kidneys of the sponge," said Botte.
However, the newly-released study indicated that the rising temperatures led to a complete loss of archaea.
"We found that this microbe was the only one that could detoxify the ammonia produced by the sponge. And without this microbe, toxic ammonia would have accumulated in the tissue," said Botte.
The expert voiced her concern that climate change does not only impact the big animals.
"There is a risk of eroding the biodiversity of unassuming animals and the microbes they host, which are key for healthy oceans and more generally life on our planet," she added. ■
