Scientific Diving Methods and Applications
Marine science education and research are the most
exciting fields sought after by many people today. Training and experience in
scientific diving methods and understanding its applications are considered to
be the most important component of marine scientist’s skill.
Importance of Learning Scientific Diving Methods
Scientific diving methods help the scientist to observe
marine organisms, their habitats and lifestyle and also to operate experimental
underwater equipment. Some habitats like coral reef drop offs and overhanging
submarine cliffs that are 50m deep can be studied effectively if the scientist
has the necessary skills and training in diving, because remote equipment alone
cannot access these habitats.
Marine scientists who have experience in scientific diving
can view and assimilate a lot of information from the structure and/or behavior
of the organism and its habitat more effectively than by observing them from a
remote camera. Scientific diving methods provide him/her with the capability to
measure and interpret the marine environment clearly.
There are many advanced scientific diving equipment
available now that include reliable rebreathers, acoustic communications, dive
computers, portable compressor and emergency air supply devices that ensure the
safety and comfort of the diver. Underwater marine apparatus like LED
illumination sources, underwater cameras and diving pulsed amplitude modulated
flourometer help enhance the process of data acquisition underwater.
Scientific Diving Methods
Scuba diving is the most common scientific diving methods
used by marine scientists. It requires the diver to use a scuba set to breathe
underwater and carry a source of gas to breathe that is generally compressed
air. Scuba diving allows the diver to stay underwater for longer hours than any
other methods like free diving and breath holding. Open circuit regulator is
linked to one high pressure gas cylinder and this is the most commonly used
scuba set these days. The regulator has two stages. One stage is attached to the
cylinder valve and the next stage is connected to the mouth piece.
Water has a refractive index than air. Only the crystalline
lens of the eyes can focus light underwater and this contributes to
hypermetropia. Individuals suffering from severe myopia can get better view
without using a mask than a normal sighted individual. This problem can be
solved by using masks and helmet.
Scientific scuba diving is performed exclusively as a part
of scientific research or educational activity. Scuba diving requires the
scientists to go in pairs.
Tethered Scuba Diving
Tethered scuba diving is a less commonly used scientific
diving method. It involves the operation of one scuba diver that is tended by
others from the surface by using a safety line. In scientific diving
applications, tethered scuba diving often involves attaching a rope to the
traditional mouthpiece style scuba regulator. The diver is required to perform a
range of underwater tasks, including scientific tasks and research studies.
Tethered scuba diving method requires specific equipment
and protocol. The equipment usually includes standard diver dress like wetsuit,
weight belt and fins. Other items like a full face mask along with voice
communications and safety methods are also included. A cutting device like EMT
shears can be included within the easy reach of the diver.
Full face mask that allows for hardwired communication, dry
suit and dry gloves will give protection to the diver against polluted water. If
it is unpolluted water, wetsuit can be used. However, mask with voice
communication like micro phonic should be worn. The diver should be in hard-line
communication with the surface constantly.
Any type of line can be used along with line signal.
Generally a communication rope is used to allow the surface to communicate with
the diver constantly. While tending the diver, care should be taken to make sure
the line is not hung up and tussled with any sharp underwater objects. The
tether should be fitted with a snap shackle that can be released quickly, so
that the diver can make his way out to the surface.
The communication unit used by the tender to tend the
diver’s line needs to maintain verbal communication with the diver constantly.
Hence, the communication unit should allow the tender to talk with the diver
through a headset and belt clip unit. Harness of the diver is essential to
connect him to the tether line. The harness should provide the tender with the
ability to pull the diver from the water, in case of emergencies.
Emergency gas supply is essential for scientific tethered
scuba diving operations. The gas supply is controlled via a manifold block that
has a one way valve. It has an overpressure relief valve that lets pressure
escape in the event of malfunction.
The diver will be diving alone in tethered scuba diving, so
he needs to understand various things like how to check his air supply and how
to report to topside support in the event of emergencies. Depending on the task
to be performed, the dive is controlled from the surface. The diver needs to
adjust to the instructions and does not have primary control over his diving.
Tethered scuba diving operations typically involve three or
more divers. This allows safe and effective diving by rotating the divers.
Before undertaking a dive, the diver needs to practice how to disconnect from
the tether, free an entangled line and clear a flooded situation.
Tethered scuba diving offers plenty of advantages for any
scientific dive program that requires collecting data underwater. In underwater
that have low to zero visibility, there is a need of clear and constant voice
communications to make comprehensive scientific observations.
Tethered scuba diving method allows the personnel on the
surface to pass the tools to the diver without requiring bounce dive. This
method has been slowly embraced by the scientific diving community, especially
in ice diving and overhead diving environment. Tethered scuba diving can be used
for a wide range of tasks, like standby diver deployment and ship husbandry.
However, some people believe that scuba diving without a buddy may not be safe.
Tethered scuba diving can be used for only specific underwater activities.
Modern equipment and practices have made diving easier and safer.
Global Ocean and planet Earth is responding back as we have
altered the Natural process cycles. We are
Unreceptive to planet earth. Gaia principle. Human individual's actions, and
policy makers, decisions and actions due to thirst for funds and or self-image
via exploitation we have altered the equilibrium of nature. Which is a
consequent to devastating phenomena.
Global Temperature Rise
Many research studies show that average global temperature
has increased by more than 1 °F. Human activities have been releasing tons of
heat trapping gases like carbon dioxide, nitrous oxide, methane and ozone that
impact the natural greenhouse effect and thereby alters the climate of the
earth. Climate is influenced by numerous factors that include natural and human
induced factors. Pollution is one of the major man made problems that
cause global warming. The increase in carbon dioxide concentration has been the
major reason for rise in global temperature over the past 50 years. Human
activities like deforestation and burning of fossil fuel use in producing
electricity, household and industrial uses and transportation cause increased
concentration of carbon dioxide, which in turn alter the earth’s cycles
Global temperature rise is evident in many studies.
Sea level rise, changes in precipitation amount and pattern, earlier timing of
spring events and extensive melting of ice sheets and snow are some of the
evidences of global warming.
Sea Level Rise
Scientific research studies show that sea levels worldwide
have been increasing at a rate of 3.5mm per year since 1990s. Satellite
measurements and tide gauge reading show that the global mean sea level has
increased by 4 to 8 inches. The main reason for rise in sea level is the release
of enormous amounts of carbon dioxide and other heat trapping gases into the
atmosphere. These emissions have caused the temperature of earth to rise. Oceans
absorb around 80% of this high temperature.
Three major factors are linked to sea level rise and
global climate change:
- Thermal Expansion
- Melting of Glaciers and Polar Ice Caps
- Melting of Ice sheets in Greenland and West Antarctica
Water expands when heated. As ocean water warms, it
expands. Over the past 50 years, the rise in sea level is caused due to warmer
oceans occupying more space.
Melting of Glaciers and Polar Ice Caps
Glaciers and polar ice caps are large ice formations that
melt a bit every summer, but balance out when it comes to melting in winter.
However, in the recent years, global warming has caused persistently higher
temperature that has led to greater level of melting in summer and reduced
snowfall in winter. This imbalance causes sea levels to rise significantly.
Melting of Ice Sheets in Greenland and West Antarctica
Huge sheets of ice covering Greenland and West Antarctica
have started melting at a faster pace due to global warming. Scientists believe
that the water that melts above these ice sheets and sea water below them
lubricate ice streams that ooze beneath the ice sheets, causing them to move
fast into the sea. Higher sea temperatures lead to huge ice shelves in
Antarctica to melt from underneath, deteriorate and split off.
Outcomes of Sea Level Rise
Increasing level of sea water can cause devastating
effects. This includes destructive erosion and flooding of wetlands apart from
demolishing the habitats for fish, birds and plants. Higher sea levels can make
bigger and more powerful hurricanes to surge anything that can strip away
in its path. Higher ocean temperatures can lead to stronger storms with heavy
rainfall and higher wind speed.
Scientists predict that global warming will continue and
will possibly accelerate. Oceans will therefore continue to rise. A recent study
states that the oceans will rise between 2.5 and 6.5 feet by the end of this
century. This will be enough to submerge many cities along the east coast of the
United States. Some other studies estimate that a complete meltdown of ice sheet
in Greenland would increase the sea level by 23 feet that is good enough to
swamp Los Angeles and London.
Ahmed Djoghlaf, the executive secretary of convention on
biological diversity has stated recently that climate change has become one of
the most important causes of biodiversity loss. If average global temperature
rise 1.5 to 2.5° C, 40 to 70% species could become extinct. A large portion
of such species would be the inhabitants of the oceans of the world. This would
include fish, plankton, marine mammals and coral reefs.
Many research studies on oceanic climate have focused on
the potential impacts of rising temperatures on ocean ecosystems as an outcome
of increasing levels anthropogenically produced carbon dioxide, methane,
chlorofluorocarbons and nitrous oxide. However, there are evidences that the
most important danger for ocean ecosystem may be created by acidification of the
oceans which is the outcome of the invasion of carbon dioxide generated by human
What Causes Ocean Acidification?
- Human Fossil Fuel Use and Deforestation
Ocean acidification occurs when the pH level of the ocean is reduced by
the absorption of anthropogenic carbon dioxide pumped by the burning of
fossil fuels like coal, natural gas and oil for energy into the atmosphere.
Cement production and deforestation also release CO2 into surface ocean
waters. It is estimated that atmospheric carbon dioxide is almost 40% more
than that of pre-industrial periods. Global oceans comprise a sink for Co2.
They absorb one third of carbon dioxide generated by human activities. This
increases the hydrogen ion concentration of the ocean waters and reduces the
pH level. Studies show that the concentration of hydrogen ions in ocean
waters is 30% more than that of pre-industrial periods. It is predicted that
the pH level will be increased by 150% by the end of this century.
The release of nitrogen and phosphorous based chemicals like fertilizers
into the rivers and lakes promote excessive growth of algae and water
plants. They die and decompose in the water; the organic matter and decaying
organism reduce the availability of oxygen in water. This causes death of
other organisms like fish. Eutrophication causes undesirable effects and so
it is considered as a form of pollution. Lake and river waters
affected by eutrophication cause the acidity of ocean waters, especially in
the East China Sea and Gulf of Mexico that receive waters from two largest
rivers in the world- Mississippi and Changjiang.
Impact of Ocean Acidification on
More than 70% of Earth’s surface is covered by the oceans.
Oceans are the habitats of a wide range of diverse flora and fauna that play a
significant role in regulating climate conditions and the level of carbon
dioxide. Since the beginning of industrial revolution (that is for the last two
centuries), oceans have absorbed around 120 billion tons of carbon dioxide
generated by human activities. If oceans have not absorbed this much amount of
CO2, its effects on the climate would be significantly higher.
More than 25 million tons of carbon dioxide is absorbed by
seawater every day. Ocean acidification caused by this process is now happening
at a faster rate. Increased level of Co2 in ocean waters causes the following
major ecological changes
- Ocean acidification dissolves the shells of corals,
snails and urchins
- Higher level of carbon dioxide in water is favorable
for the production of sea grass.
- High CO2 levels are favorable to invasive alien
species that cause damage to ecosystems all over the world.
- As the acidity of oceans increases, climatic changes
happen. It makes the earth to become warmer.
Ocean Acidification Studies in Vulcano Island, Sicily
Ocean acidification studies made in Vulcano Island, Sicily
by scientists reveal that around 10 tons of invisible carbon dioxide, which is
the output of volcanoes is released to the ocean, making the coastal water more
and more acidic. Apart from volcanic sources, industrial plants, cars, planes
and power stations also play a vital role in pumping out increasing amount of
carbon dioxide. This leads to many problems. Millions of marine species are in
the danger of becoming extinct, Reefs that protect the coastal areas are
starting to erode and fisheries also face eradication.
Dr. Jason Hall Spencer, a Marine Biologist at Plymouth
University stated that billions of tons of CO2 we generate each year remain in
the atmosphere, causing it to heat up and driving global warming.
Global Warming Could Trigger Huge and Devastating
Tsunamis and Earthquakes
A new study shows that huge and devastating tsunamis
are more likely to occur during warmer times. Scientists believe that global
temperature rise could trigger mega tsunamis. Tsunamis are huge waves racing
across the ocean and grow to threatening proportions when they reach land. They
are so strong and powerful that they can reach the height of a multi storey
building. They are generated by earthquake beneath the sea surface. Though there
are many other causes like landslides crashing into the sea, tsunamis generated
by earthquakes are more dangerous.
Scientists also found out that increased of earthquakes
around the globe in the past few years related to climate change in many forms.
Warming oceans and warming atmosphere are the major drivers of climate change.
This would have an impact on the slow process of plate tectonics, in which one
plate moves over or below another, causing larger earthquakes, like the
devastated ones occurred in Japan, South America, Indonesia and New Zealand.
Scientists have found out that human activities have
altered the climate significantly and probably they have a role in the movement
of tectonic plates worldwide. The research study shows that our surface climate
would have a great impact in shifting large crystal plates that cause the
continents to drift and cause earthquakes.
Global Warming Reduces Ocean Life and Increases
Atmospheric Carbon dioxide
The food chain of ocean depends on the growth of millions
of microscopic plants. Recent satellite studies show that ocean warming is
reducing the growth of these plants and putting fisheries and marine life at
risk. Marine scientists believe that the growth of plants called phytoplankton
has strong links with ocean warming.
Phytoplankton grows fast in a cool ocean and grows slow in
Warm Ocean. The threatening part is that oceans are warming now due to the
emission of carbon dioxide. If the oceans continue to warm, the growth of these
plants will become even slower. This in turn will reduce the availability of
food and other marine organisms, including marine mammals and birds.
Phytoplankton also plays a significant role in producing similar amount of
photosynthesis by all the plants on land. Reduced growth of phytoplankton
disturbs the atmosphere by reducing the absorption of atmospheric carbon
dioxide. Reduced growth of phytoplankton also leads the ocean to take up less
carbon dioxide, which in turn could accelerate global warming, causing the
ferocious cycle of global temperature increase.
Michael Behrenfeld of Oregon State University stated that
the phytoplankton growth rates reduce as the climate warms. Along with this, the
amount of carbon dioxide consumed by these plants also reduces. This allows
carbon dioxide to accumulate faster in the atmosphere and generate more warming.
Disposal of wastes, carelessness and accidents lead many
pollutants to enter the ocean. Oceans absorb some types of pollutants in some
quantities, but the pollutants are in large quantities. The ocean’s capacity to
take up and recycle pollution can become plagued. Human activities
pollute the ocean in many ways. Waste products like plastic litter, sewage and
industrial wastes dump into the ocean and oil enter the ocean accidentally. The
wastes that contain organic matter decay and reduce the level of oxygen in the
Plastic litter can cause severe pollution, as it
does not get decomposed easily, Marine animals like seals, turtles, whales and
sea birds can get tangled in plastic things. Many animals mistake these items
for food and die, if the plastic blocks their digestive system. Oil spills
entering the ocean coat fish, mammals and birds and kills many of them.
Human activities reduce the levels of oxygen in the ocean
and increase the amount of carbon dioxide released into the ocean. Increases in
atmospheric carbon dioxide raise temperatures on earth significantly and affect
marine and the overall ecosystem. Climate change disturbs life in the oceans and
cause many other problems.
Summary report written and review by DR. Stavros
Kaniklides Ocean Scientist
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