Record-Breaking Marine Sponge Bleaching in New Zealand’s Fiordland

Record-Breaking Marine Sponge Bleaching in New Zealand’s Fiordland

Scientists have reported a historic mass bleaching of over 50 million marine sponges in Fiordland, New Zealand, marking the largest event of its kind ever documented.

A study revealed that the 2022 bleaching incident slashed the sponge population by nearly half. James Bell, lead author and marine biologist at Te Herenga Waka, Victoria University of Wellington, attributed the event to a severe marine heatwave lasting 259 days, which elevated water temperatures by 4.4 degrees Celsius above the norm.

Spanning 1,000 kilometers along the west coast of New Zealand’s South Island, the heatwave caused the typically chocolate-brown Cymbastella lamellata sponges to bleach to a stark white.

“This was not only the largest global sponge bleaching event but also the largest recorded sponge mortality event,” Bell stated. He noted that over 90 percent of the sponges were bleached, though some showed signs of recovery, indicating a potential adaptation to heat stress.

Bell explained that changes in the microbial communities hosted by the sponges suggest a rapid evolutionary response to the warming waters, offering a glimmer of hope for their future adaptability.

“Despite this optimism, more research is essential to understand the long-term impacts of increasing marine heatwaves on this crucial species,” Bell concluded.