New deep sea sponge discovered

02 October 2017 | Research
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Dr Tan (left) and Mr Lim discovered a new species of marine sponges with their international collaborators

A new marine sponge thriving in the deep abyss of the remote East Pacific Ocean has been uncovered by NUS Tropical Marine Science Institute researchers Dr Tan Koh Siang and Mr Lim Swee Cheng in a joint effort with their international collaborators.

The small white sponges Plenaster craigi were found on the sea floor of the metal-rich Clarion-Clipperton Zone (CCZ) of the East Pacific Ocean, a region spanning 5 million square kilometres that is targeted for deep-sea mining. The scientists believe that the sponges can one day be used to examine the impact of mining in the region. The findings were published in Systematics and Biodiversity on 25 September.    

Plenaster cragi appears to be a common sponge that is likely to have a wide distribution across the CCZ. Its ecological response can act as a measure of the extent of disturbance caused by mining activities in the region.

Dr Tan and Mr Lim made the discovery when they joined a 46-day international expedition to the CCZ in 2015 to establish a biological baseline at two different exploration areas. During the trip, the teams on board collected numerous samples from depths exceeding 4000m and worked in 12-hour shifts to process the samples.

Among the diverse array of organisms collected, the tiny irregularly shaped snow-white sea sponges that were attached to the metal-rich rocks caught the researchers’ attention. “The unique morphology of the star-shaped spicules convinced me that these were a completely new group of sponges never seen before,” said Mr Lim, who has been working on the biodiversity of sponges since 2002.

Sea sponges are best known from shallower waters, with just five per cent of sponges having been discovered from depths exceeding 500m. Little is known of sponges living in the abyssal depths of the Pacific Ocean, a vast and remote region that is little explored and poorly understood.

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Plenaster craigi, which is abundant at a depth of 4000m in the CCZ, can be used to measure the impact of future mining in the region

Their collaborators at The Natural History Museum in London carried out a detailed DNA analysis and confirmed that the marine sponge is indeed a new species.

The tiny Plenaster craigi, measuring less than 10mm across, may play a big role in conserving biodiversity in the region. As the sponges were found in high abundance and are relatively easy to identify and count, this species can potentially be used as an environmental indicator to gauge and mitigate the effects of future mining operations on marine life.

Plenaster craigi appears to be a common sponge that is likely to have a wide distribution across the CCZ. Its ecological response can act as a measure of the extent of disturbance caused by mining activities in the region,” explained Dr Tan.

The new sponge’s full scientific name is Plenaster craigi Lim & Wiklund — after the abundant star shapes inside their bodies and the leader of the survey expeditions, Professor Craig Smith from the University of Hawaii — and was named by Mr Lim and his UK collaborator Dr Helena Wiklund. The work leading to the discovery of the new sponge species was supported by the Keppel-NUS Corporate Laboratory, Ocean Mineral Singapore and UK Seabed Resources.