Published: 23 Jun 2022 13:36 GMT
After ocean temperatures rose dramatically, marine sponges in New Zealand’s waters are experiencing the greatest bleaching ever recorded to date. The situation puts millions of these aquatic creatures at risk, warn scientists, quoted in the local press.
In May, oceanographers first detected that hundreds of thousands of sponges had lost their natural color off the country’s southern coast. However, over the past month, researchers have estimated that New Zealand’s waters actually had millions – or even tens of millions – of bleached porifera.
“To my knowledge, this is the largest temperate sponge bleaching event reported anywhere in the world,” said James Bell, a marine biologist at Victoria University of Wellington.
The researcher noted that preliminary experiments just conducted confirmed the scientists’ hypothesis that the likely cause of this bleaching was unusually high ocean temperatures.
Robert Smith, an oceanographer at the University of Otago (New Zealand) said that two marine heat waves in New Zealand caused record high water temperatures, which in some areas reached five degrees above normal.
At the same time, Bell stressed that the heat is not killing the sponges, but it is affecting the microscopic organisms that live in them and are responsible for photosynthesis and the production of a chemical substance that repels fish.
In the absence of these defenses, the porifera become edible to predators, which could wipe out many of these marine creatures. The scientist also warned that not all species are capable of recovering from severe color loss, so some may never recover.