A look at submarine mountains
MARCH 8, 2014 will forever linger in my mind. On that date, I was leaving Kuala Lumpur International Airport from the domestic departures terminal for a flight to Kuching at the same time as the fated passengers were checking in at the main terminal for their intended f light to Beijing on MH370.
We may never know where that aircraft actually went but the floating debris seem to point in the direction of the Indian Ocean.
Subsequently, international oceanic exploration teams from many nations have spent many thousands of man hours scouring that ocean’s bed.
However, as a result of these undersea investigations, we do have clearer images and charts of huge sections of the sea floor of the Indian Ocean. Of course, this will never compensate for the tragic loss of life on that aircraft flight. Our ocean depths
My column on May 15 entitled ‘Plumbing the ocean depths’, highlighted our exploration of the deepest abysses in the ocean floor but made no mention of seamounts.
The positions and heights of these undersea mountains are as critical to submariners as land-mountains are to aircraft pilots. We will never know how many nuclear powered submarines have collided or experienced a near miss with uncharted seamounts. Only one instance has ever been recorded. Untangling the mysteries of seabeds
Several years ago, I was invited by a Sabahan friend to accompany him on his boat trip to the islands of Tunku Abdul Raman Marine Park off the shores of Kota Kinabalu.
He told me of the Second World War shipwrecks that were somewhere on the seabed but could not give me precise locations for the waters had never been charted.
Some months later, upon my return to the United Kingdom, I was invited as a guest to tour the UK’s Hydrographic Survey Department in Taunton, Somerset, where maritime navigation charts are produced for nations worldwide.
There in the print room an instructor proudly announced that a new maritime chart was coming off the rollers of the electronic press before my eyes. Low and behold, it was none other than the charted waters of western Sabah with precise information on seabed obstacles to sailors.
Mariners have tried to unravel the mysteries of the shape of the seafloor since time immemorial, using basic plumb lines and, since the early 1920s, echo sounders with their bounce back beams.
Each method has given us a bit more knowledge. More recently, satellite altimetry combined with sonar soundings have produced computer models of the seabed in certain areas.
Today, we have a multi-beam sonar system, which will allow a ship to map a section of the seafloor several hundreds of metres wide and then to translate this data, via computer software, to an instantaneous chart and computer model of the seabed.
In June, an agreement was signed by 150 oceanographic institutes worldwide to complete a comprehensive seabed map by 2030 of our planet’s ocean floors.
A United Nations-backed organisation, the General Bathymetric Chart of the Oceans, will oversee this with the assistance of Google.
To give you some idea of the task ahead, the UK waters to date have so far been mapped up to 300km offshore for only one third of its total territorial waters. With unmanned submarines, the future scale of seafloor mapping will be able to scan volcanic vents, canyons, inaccessible zones under icecaps, shifting seabed sand dunes and potential underwater landslide locations which could generate tsunamis and yet more discoveries. Seamounts
Technically, a seamount is a volcanic feature of more than 1,000 metres high rising from the seafloor. There are some that break the ocean’s surface to create islands such as the Galapagos and Hawaii.
Most seamounts are conical in shape and of volcanic origin arising from locations near midoceanic ridges.
There, through the divergence of oceanic and continental plates, upwelling of magma from the Earth’s interior fills the gaps caused by the moving plates for the volcanoes to be carried in a conveyor-like system away from the point where the magma first hit the seabed surface.
Today these seamounts appear as isolated features standing boldly from the seafloor.
Some are derived from weaknesses in the Earth’s lithosphere where upwelling magma from the mantle below breaks the seabed surface in what are called mantle plumes.
Tristan da Cuhna is a typical example offset to the MidAtlantic Ridge and again is now an inactive volcano where the moving oceanic plate has pushed the volcano away from the point where it was first formed.
In fact, we know very little about the number of seamounts in the oceans and geologists have placed a best guesstimate at between 10,000 and 100,000 with nearly 50 per cent of these in the Pacific Ocean, with most of the remaining ones in the Indian and Atlantic Oceans.
The largest concentration of seamounts in the Pacific Ocean is thought to be the Indonesian and Philippine islands. Marine life at different depths
As Mount Kinabalu with its majestic stature harbours ecological niches at different altitudes in both its flora and fauna, so does a seamount. In 2000, marine scientists attempted to catalogue, in a census, all known species of marine life worldwide.
Cold water corals were discovered on New Zealand seamounts at depths of over 1,000 metres.
Already many thousands of entirely new species of marine life have been discovered with as many as 600 found on only five seamounts. Most seamounts, because of their volcanic geology, offer quite hostile environments to marine life and seem only to attract corals, sea fans and sponges.
These forms of life are often referred to as ‘snatch feeders’ filtering nourishment as drifts past them.
As winds ascend and descend mountains, so do ocean currents around seamounts. Cold ocean currents rise up to the surface upon hitting a seamount, thus upwelling vital nutrients for the growth of phytoplankton.
This is the food of many fish species and consequently fish shoals abound near the summits of seamounts.
Further up the food chain, tuna, sharks and whales appear for the fish feast. It appears that many of the latter use certain seamounts as stopping places in their annual migration patterns of movement. Future of seamounts
As more and more is discovered about the riches of sea life and underwater geology so seamounts could be ‘politically engineered’ as national possessions.
We have witnessed, in recent years, verbal international battles and, indeed, one war, in 1982, waged over the sovereignty of islands, often prompted by economic or strategic gain. The countries concerned often know much about the underwater riches in terms of oil, gas and mineral potential in disputed waters.
I fear that with increased knowledge of the riches that seamounts have to offer, fish wars will soon develop as nations start to claim them as within their alleged territorial waters.
In some parts of our world, where parts of the continental shelf fishing have been banned because of fish stock depletions, already deep sea trawlers have looked further afield even in the direction of seamounts.
One researcher has likened the effect of a deep sea trawl net dragged across the cold water coral fisheries of a seamount to a military tank ploughing its way through a back garden vegetable plot.
The marine life of seamount locations must be preserved for these are unique ecosystems.