Deep Sea Scientific Discoveries

There’s an adage that we know more about the surface of the moon than we do about the depths of the ocean. This may well be true, but marine biologists, oceanographers and other scientists are working hard to rectify this gap in our knowledge. In November 2009, a group of researchers working on the Census of Marine Life released some of their findings for this year. The 10-year project won’t in fact be completed until some time in 2010, but their extensive research so far has revealed more than 17,500 species – many of which previously undiscovered – that live in the deep sea ⁽¹⁾.

Alvin and the Scientists

Beneath the first few hundred metres of the sea’s surface waters, the environment is cold, dark and under intense pressure and so was generally thought of as being a pretty inhospitable place for organisms to live. This assumption led scientists to believe that very few organisms could survive this extreme habitat. In 1977 however, a team of researchers from several institutions across the US, headed up by Dr. John Corliss, descended to more than 2000m underwater in a submersible craft called Alvin and made a startling discovery ⁽²⁾.

Black smokers

Corliss and his team uncovered the presence of hydrothermal vents in the seabed; volcanic fissures in the ocean floor where hot water, rich in chemicals, bursts through to mix with the cold, deep water. It had already been guessed that such volcanic activity might exist under the sea, but until Alvin’s voyage to the Galapagos Rift, nobody had ever seen it ⁽²⁾. Furthermore, these hydrothermal vents, or “black smokers” – so called because of the plumes of dark “smoke” rising up from the vents (water rich in iron oxides) – appeared to support life.

Chemolithoautotrophy

Plants make their own food by harnessing the energy in sunlight to convert inorganic carbon (CO₂) into sugars during the process of photosynthesis. Anyone who has ever Scuba dived down to 20 or 30 metres will know that even at these relatively shallow depths, the wavelengths of visible light are lost (the so-called “red shift” phenomenon) so that everything seems to appear more and more blue. Descend a few more metres and you would find that the ocean becomes pitch black. Therefore, in the deep ocean, photosynthesis is not an option and plants and algae cannot survive. In hydrothermal vents however, certain primary producing bacteria exist that are described as chemolithoautotrophic; they are able to produce their own food by using the energy from chemical reactions derived from the chemicals emitted by the vent ⁽³⁾.

Deep sea ecosystems

Whereas organisms on land consume plants as the basis of their energy requirements, strange tube worms, grazing crabs and eerie jellyfish-like creatures living in hydrothermal vent areas have evolved to feed on these chemolithoautotrophic bacteria, and higher organisms such as a variety of species of fish, feed on them in turn. More recent research has uncovered more communities of weird and wonderful animals living in other types of deep-sea habitats including cold-seeps found around the edges of continental plates, where chemical-rich waters ooze from the sea bed; underwater mountains, or seamounts that support a vast diversity of isolated organisms; even creatures that feed on pockets of crude oil or the slow-decomposing carcasses of whales that drift to the bottom of the ocean ⁽⁴⁾.

Some highlights from the 2009 Census findings

It would be beyond the scope of this article to describe each of the species identified between the 344 researchers from 34 countries working on 5 different Census of Marine Life projects, but here are a few highlights.

Worms having a whale of a time

A research team working on the Census of Diversity of Abyssal Marine Life (CeDAMar) project in the Antarctic Ocean identified a new species of Osedax worm 500m underwater. These worms (the white anemone-like creatures shown in the picture) have adapted to life without light by utilising whale bone for their energy requirements and are not only restricted to the Antarctic; 17 species in total have been recorded in waters as far apart as Sweden, California and Japan ⁽¹⁾.

Dumbo octopods (Photo: David Shale)

The Mid Atlantic Ridge Ecosystem Project (MAR-ECO) have discovered 9 new species of an octopod organism nicknamed “Dumbo” (Grimpoteuthis sp.) because of the ear-like fins which “flap” like the ears of Dumbo the Disney elephant. These octopus-like creatures were found abundantly in waters 1000-3000 metres deep. A “jumbo Dumbo” was even spotted that was estimated to be up to 2 metres long ⁽¹⁾.

A bed of cucumbers (Photo: Larry Madin, Woods Hole Oceanographic Institution)

Because of the seemingly lack of diverse features of abyssal expanses of deep sea bottom mud, the ocean floor has historically been thought of as something of a black hole unable to support life. Modern research suggests that in fact, mud on the seabed is teeming with small creatures, and in some areas studied, approximately 99% of species found were new to science. A surprising find was the rich biodiversity of sea cucumbers including this transparent specimen living at a depth of 2750m in this apparently bland landscape ⁽¹⁾.

Mysteries of the deep

A researcher heavily involved with the Census projects, Dr. David Billet of the UK’s National Oceanography Centre said, “The distribution of species in the deep sea is full of mysteries” ⁽¹⁾. As a keen Scuba diver, discoveries like these at the bottom of the sea, which use state of the art technology and highly innovative research methods, sends excited shivers down my spine. I, like many others, are fascinated by “what lies beneath” and wait impatiently for the mysteries to be unravelled – with not a little jealousy that it’s not me in that submersible craft!

Knowledge is power

However, unlocking the mysteries of the deep brings with it great responsibilities. Increasingly, we cannot plead ignorance to our planet’s plight as we learn more and more about its secrets. Billet’s colleague, Robert S. Carney, puts it very well when he says, “The abyss has long been viewed as a desert. Worse, it was viewed as a wasteland where few to no environmental impacts could be of any concern. “Mine it, drill it, dispose into it, or fish it – what could possibly be impacted?” And, if there is an impact, the abyss is vast and best yet, hidden from sight. [But the] Census of Marine Life deep realm scientists see and are concerned” ⁽¹⁾.

1. Press release of the Census of Marine Life, From the edge of darkness into the black abyss: marine scientists census 17,500+ species and counting, November 2009
2. Corliss, JB, Dymond, J, Gordon, LI, Edmond, JM, von Herzen, RP, Ballard, RD, Green, K, Williams, D, Bainbridge, A, Crane, K and van Andel, TJ, Submarine thermal springs on the Galapagos Rift, Science 203: 4385, 1979
3. Zhou, H, Li, J, Peng, X, Meng, J, Wang, F and Ai, Y, Microbial diversity of a sulphide black smoker in Main Endeavour hydrothermal vent field, Juan de Fuca ridge, Journal of Microbiology 47: 3, pp. 235-247, 2009
4. Shrope, M and Pickrell, J, Instant expert: Mysteries of the deep sea, New Scientist, 2006

Published - Fri 4th Dec 2009 13:06:53