Melanie Gosling
Environment Writer
SCIENTISTS who dived deep into the “twilight zone” around Hawaiian islands have found a host of new marine species in an ecosystem rarely seen.
Their finds include a new species of starfish and a new sea horse. The discoveries were made on a 28-day expedition on board a research ship from the US National Oceanic and Atmospheric Administration (NOAA) on the deep coral reefs in the Papahanau-mokuakea Marine National Monument – one of the islands in northwestern Hawaii.
The scientists needed to get to depths of between 60m and 90m – far deeper than conventional scuba diving equipment allows, according to a Eurekalert release. To reach these mesophotic coral ecosystems, the researchers used an advanced diving technology known as a closed-circuit rebreather system.
This equipment absorbs the carbon dioxide that the diver breathes out, which allows the unused oxygen from each breath to be reused. Oxygen is added to replenish what the diver has used.
Randall Kosaki, NOAA’s deputy superintendent at Papahanaumokuakea, said in the statement that during the dives researchers surveyed fish around the northern atolls and found that all of them were endemic – occurring only in the Hawaiian Islands and nowhere else in the world.
“This is the highest level of endemism recorded from any marine ecosystem on Earth,” Kosaki said.
They came across many marine creatures that they could not identify, and which they believed were species completely new to science. Apart from the seahorse and starfish, their finds included sea cucumbers, sea urchins, algae and fish. These specimens will be sent to specialists at a number of museums around the world to establish the identity of the creatures.
The scientists were the first to dive on several open-ocean “seamounts” – undersea mountains that rose from the seabed in about 500m of water, with their summits about 30 to 90m from the surface of the sea. The coral reefs also showed the impact of global warming as about 30 to 40 percent of the corals at depths of between 10 and 30m were bleached. Coral bleaching is caused by higher than normal sea temperatures. Researchers said this showed that even remote, highly protected areas were not immune to global climate change.
The divers were also being studied to see the effects of extreme dive exposure on the body. The Papahanaumo-kuakea Marine National Monument is a World Heritage Site, which includes 10 islands and several atolls. Encompassing 360 000km², it is one of the largest marine protected areas in the world.
It is also a place of deep cosmological and traditional significance for native Hawaiian culture.