Cold and entirely without light, the deepest regions of the ocean were long believed to be barren and uninhabitable. In the body of scientific knowledge, discovery of life within the deep blue planet is relatively young. Although it covers 66 per cent of the global seafloor area, the deep ocean has remained a 鈥榖lack box鈥� in terms of global patterns of biodiversity 鈥� until now.
In an effort to better understand the kind of life found at these depths, an international team of scientists, including two Dal researchers, has mapped and predicted seafloor biodiversity for the first time. .
鈥淚鈥檓 sure that I鈥檓 not alone in thinking that the deep sea is a fascinating environment, and utterly unique,鈥� says a co-author of the study and adjunct professor in the Department of Biology. 鈥淚t鈥檚 cold, lightless and under extremely high pressure 鈥� yet there鈥檚 a magnificent and beautiful diversity of life there.鈥�
The study used records from many of the world鈥檚 museums and existing scientific literature to map the location of different species of brittle stars. These spindly-legged relatives of starfish are a dominant part of seafloor life. Their presence at all depths makes brittle stars an ideal species group to reveal changing patterns of diversity with depth. The researchers found that deep-sea brittle stars show patterns of diversity that are unlike anywhere else on Earth.
Surprising discoveries
The highest biodiversity, globally speaking, is found in the tropical regions of the planet 鈥� both on land and in shallow depths of the ocean.
鈥淎s you move deeper [in the ocean], everything changes,鈥� says , a Biology professor and co-author of the study. 鈥淲e鈥檝e found a new mechanism by which diversity is generated.鈥�
In the surface depths of the ocean, sunlight is the prime form of energy driving evolution to develop rich biodiversity, and it鈥檚 more consistently found at high intensity in the tropics. But in the deep ocean, life and diversity must rely on a different kind of fuel. One of the paper鈥檚 key findings demonstrates that higher amounts of biodiversity in the deep ocean are actually found at the planet鈥檚 higher latitudes near continents, starkly contrasting the relationship between geography and biodiversity that biologists have been familiar with for decades.
Dr. Worm explains the break in pattern can be attributed to the large-scale algal blooms that occur off the coasts in tandem with seasons experienced at higher latitudes. A buildup of nutrients in the winter and increased sunlight in the spring causes the rapid growth of plankton at the surface. As the bloom grows and drifts, clumps of plankton start to sink down to the ocean floor. Coined 鈥渕arine snow,鈥� these sinking particles fuel 鈥� through chemical energy rather than solar 鈥� biodiversity in the deep.
International collaboration for conservation
Museum Victoria and University of Melbourne PhD candidate Skipton Woolley led the study. Drawn to AV俱乐部 for its long-standing expertise in marine biodiversity research, Woolley worked on campus for several months to collaborate with Dr. Worm and Dr. Tittensor. The team鈥檚 research is an important first step for conservation efforts in the deep ocean. Slow to grow and recover, the sea floor faces increasing threats from mineral exploration, deep sea fishing trawlers and climate change.
鈥淲ith the mining of minerals on the seafloor slowly becoming a reality, it鈥檚 vital that we understand the conservation needs of animals that live at these great depths,鈥� says Woolley.
鈥淭here鈥檚 a lot of discussion at the United Nations on biodiversity on the High Seas 鈥� the Areas Beyond National Jurisdiction,鈥� adds Dr. Tittensor, who鈥檚 also senior marine biologist at the United Nations Environment Programme World Conservation Monitoring Centre. 鈥淭his is the type of work that will feed into these discussions.鈥�
The team hopes that as data from around the world is collected, global maps of seafloor diversity will continue to become more detailed and cover a wider range of marine life, increasing knowledge about the distribution of marine biodiversity.
With files from .