Marine microbiolgy and movement of water.pdf

Water Movement Upwelling and Downwelling Surface water circulation and ground water circulation

1. MARINE MICROBIOLOGY,
MOVEMENT OF WATER IN MARINE
ENVIRONMENT, AND ITS IMPACT
ON MARINE LIFE

MIC-510

2. WATER
Physical and Chemical Properties
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3. Ocean cover most of Earth’s surface
•The oceans influence global climate, team with biodiversity, facilitate
transportation and commerce, and provide resources for us
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•Oceans
influence
the
atmospher
e,
lithosphere,
and
biosphere

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 About 71% of the surface of earth is covered by sea water
Avg depth 3.8km, volume 1370 X 10
6
km
3
Largest depository of organisms on the planet
Term “Oceanography” coined from OKEANOS (oceanus).
Oceanus was applied to the sea beyond the pallor's of Hercules; the North
Atlantic Ocean.
“Graphia”(Greek) refers to the recording & describing. So, the word
Oceanography does not appropriately describe the science of the seas.
Oceanographers investigate, interpret and model all aspects of the ocean
processes; using the most modern and sophisticated techniques of
scientific and mathematical equations
Water is the substance that surrounds all marine organisms. It also
contains bulk of marine plants as well as animals. This is the place where
variety of chemical reactions taken place.

5. The oceans contain more than
water
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96.5% water
3.5% dissolved
compounds includes:
Ions of dissolved salts
Nutrients
(e.g. nitrogen and phosphorus)
Dissolved gas (Oxygen is
added by plants, bacteria, and
atmospheric diffusion)
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SEA WATER

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1000 gm sample of water contains 35 gm of dissolved compounds,
generally called as salts.
Salinity defined as the total amount of dissolved substances. Previously
‰ parts per thousand; term used for salinity. Now, PSU; practical salinity
units replaces the old unit.
salinity of sea water 35 psu(35‰)
Salinity varies with in a range of 34-37 psu from the open sea to coastal
areas
Difference in salinity occurs due to evaporation and precipitation
High evaporation rate results higher values of salinity like subtropical
areas, similarly lesser evaporation resulted less salinity like temperate
oceans
While equatorial salinities are low coz of precipitation in the inter tropical
convergence
Salinity can be established by measuring a single property; which is
mostly Chlorinity



Dissolved compounds and Salinity

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SIX inorganic ions are: chlorine, sodium, sulphates, magnesium,
calcium and potassium called as Major ions. They are about
99.28% of total ions.
Minor ions constitute the 0.71% by weight included
(Bicarbonates, bromide, boric acid, strontium)
inorganic salts. Including phosphates and nitrates; required by plants
to synthesize organic matter from photosynthesis. But nitrates and
phosphates do not exist in constant ratio with other ions/ elements
Similarly silicon dioxide; required by diatoms and radiolarians to
construct their skeletons
Trace amount of elements like iron, manganese, cobalt and
copper.
They are very important for the production of plants like if the nitrates
and phosphates present abundantly but absence of trace elements like
iron could act as the limiting factor for their growth

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Salt content of sea water plays a definite role on its properties
The salt contents also have the effect on freezing point like 35 psu
of sea water sample has the freezing point -1.9 °C.
Upon freezing the salts are excluded and density decreases as a
result ice floats on surface.

9. Solubility of Gases
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Solubility of gases in sea water is the
function of temperature; lower the
temperature; greater the solubility.

Therefore, colder water can hold more
oxygen than the warmer water

10. Solubility of Oxygen

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Oxygen is not distributed uniformly with depth in the ocean.
Maximum amount of oxygen content in 10-20 m depth, where
photosynthetic activity by plants and diffusion from
atmosphere often leads to super saturation
With the increase in depth the oxygen content declines,
reaching a minimum value like between the depth of 500 and
1000 m (oxygen minimum zone), values may reaches to zero.
Below to that depth the value of oxygen may increases but
may not reaches to surface values
The oxygen increase below the oxygen minimum zone results
from the influx of the cold, oxygen rich water that originally
sank at high latitude
Carbon dioxide is abundant in seawater. The major reservoir
of carbon dioxide in the ocean is bicarbonate ion.
Seawater is slightly alkaline with pH 7.5-8.4.

12. MOVEMENT OF
WATER

13. Seawater Movement

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Large masses of moving water are called currents. In the
oceans there are major surface currents, subsurface currents,
and tidal currents.
Local areas have more complicated current patterns but the
global currents are rather easily explained.

14. Factors effecting movement of
water
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Temp and salinity in combination control the density of ocean
surface water
Simply as the salinity increases, the density increases while
increase in the temp caused, the decrease in density
Change in pressure also results in the increase in density

15. Seafloor topography can be rugged and
complex
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The seafloor consists of:
Volcanoes
Steep canyons
Mountain range
The planet’s longest range is under water
Mounds of debris
Trenches
Some flat areas
And fault lines!
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16. Seafloor topography can be rugged and
complex (cont’d)
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Bathymetry = the measurement of ocean depths
Topography = the physical geography or the shape and arrangement of
landforms
Continental shelves = gently sloping areas that underlie the shallow
waters bordering continents
Continental slope = connects the continental shelf to the ocean floor
Abyssal plain = flat bottom of the deep ocean
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17. A stylized bathymetric profile of the ocean
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18. •Winds are the primary force causing seawater movement at
the surface of the ocean. These surface winds are responsible
for the major ocean currents and waves. The causes of the
winds are almost completely due to the energy from the sun
in the form of heat. As the sun heats the air it becomes less
dense and rises. Since the greatest amount of heat is
centered at the equator there is a large mass of rising air
there.

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As this heated air rises it cools and spreads out near the top of
our atmosphere. Eventually it becomes cool enough to fall at
about 30 degrees both north and south of the equator. The falling
air hits the surface of Earth and spreads out - some air moving
back toward the equator and some air moving toward 60 degrees.
The air at the poles is very cold and dense relative to the
surrounding air masses so it is sinking and spreading out across
the surface of Earth on its way toward 60 degrees.
The air at 60 degrees is warm enough (in comparison to the polar
cold air) to rise, cool, and spread out in a similar fashion to the
equatorial air. This pattern, due to the temperature of the air,
creates a 3-cell wind pattern on Earth - the circulating cells near
the equator are called Hadley cells, the temperate cells are called
Ferrel cells and the cells surrounding the poles are called Polar
cells. The southern hemisphere is a mirror image - also with the
three cells.

20. Earth's atmospheric wind cells due to the differential heating and cooling of the
atmosphere by the sun

21. The Coriolis effect is caused by the rotation of Earth

Earth's surface winds are influenced by the rotation of Earth and the Coriolis effect.
As Earth rotates the surface of Earth moves under the three circulating cells
(Hadley, Ferrel, and Polar) causing a drag on the surface wind. This drag makes
moving masses veer right in northern hemisphere and left in southern hemisphere
in relation to the surface of Earth.

22. •Imagine a giant at the North Pole who prepares to jump to an
island in the middle of the Pacific Ocean (say Hawaii). Now,
imagine yourself, standing in Hawaii, viewing this giant as it
leaps into the air and fly toward you. You see the giant coming
right toward you at first but the Earth is rotating and you move
with the Earth toward the east. As you watch the giant it
appears to you that the giant veers to its right and falls into
the ocean (missing Hawaii) - all due to the rotation of Earth.
This effect is the Coriolis effect (in simple form) and affects
all moving masses going over long distances.

23. Earth's surface winds are the result of the wind cells and Coriolis effect.

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The Trades, Westerlies and Polar Easterlies are Earth's major winds.
 These winds result from the circulating cells and the Coriolis effect. The
Trades (0-30 degrees North and South) are an easterly wind and blow
from east to west. (Winds are named for the direction from which they
come rather than the direction that they go ... the opposite naming
system to the way we name currents.
The Westerlies (30-60 degrees North and South) are a westerly wind,
blowing from west to east. The Polar Easterlies (60-90 degrees North
and South) are an easterly wind, blowing from east to west. Major
weather patterns are moved around Earth by these large scale wind
systems.

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The major ocean currents result from the winds, presence of
continental land masses, and Coriolis effect. The largest
surface area subjected to surface winds is around the
equator where the water is moved from east to west by the
Trades.
As this water hits a continental mass, on the western side of
the ocean, it piles up and flows right (north) in the northern
hemisphere and left (south) in the southern hemisphere due
to the Coriolis effect. The warm tropical water is thus
moved across the oceans from east to west and divided by
the continents where it flows toward the poles and begins
cooling.
Polar water is pulled toward the equator on the eastern
sides of the oceans to replace the moving tropical water.
This creates the major surface ocean currents which are
clockwise gyres in the northern hemisphere and
counterclockwise in the southern hemisphere.

26. Earth's surface ocean currents are caused by the winds, continental land mass
obstruction and the Coriolis effect.

27. •Western Boundary Currents (on western sides of
oceans) go north in northern hemisphere and south
in southern hemisphere. They are rather narrow,
deep, fast, and warm. A good example of a Western
Boundary Current is the Gulf Stream in the Atlantic
Ocean off the East Coast of the USA. 
Eastern Boundary Currents (on eastern sides of
oceans) go south in northern hemisphere and north
in the southern hemisphere. These are rather wide,
shallow, slow and cold. A good example of an
Eastern Boundary Current is the California Current
in Pacific Ocean off the West Coast of the USA.

28. Western (example = Gulf Stream) and eastern (example = California
Current)

29. •The center of the gyre may be calm like in the Sargasso Sea (*)
in the North Atlantic Ocean (where the water circulates round
and round)or it may have lateral currents from winds like in
the North Pacific. These centers are generally saltier than
other areas with more evaporation and less mixing. 
Only one current, the West Wind Drift, goes around Earth
completely uninterrupted by continents. This current
surrounds Antarctica.

30. Ocean water flows vertically and
horizontally, influencing climate
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Upwelling = the vertical flow of cold, deep water towards the surface
High primary productivity and lucrative fisheries
Where winds blow away from, or parallel to, coastlines
Downwelling = oxygen-rich water sinks where surface currents come
together
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31. •Upwelling is a unique subsurface current that is actually a
vertical current, bringing nutrient rich water to the surface.
This happens in areas where winds blow on the surface with a
relatively strong force. Upwelling areas have high biological
productivity as the nutrients enhance the food chain. Most
upwelling areas are off the west coasts of continents or in the
middle of the equatorial parts of oceans. Often these are
seasonal areas and include examples like the equatorial area
off Peru and the West Coast of the USA.

32. Upwelling
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33. Major upwelling areas of the world.

34. •In the Atlantic ocean the Antarctic bottom water is denser
than the North Atlantic bottom water and may creep up to 35
degrees north on the bottom. In the Pacific Ocean the North
Pacific bottom water is denser and creeps down to nearly 15
degrees south latitude on the bottom. Each water mass has
its own signature salinity, temperature and density.

35. Defination/ concepts :
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Waves are a more localized movement of seawater than
currents. They are created by a disturbance to the surface of
the ocean which could come from wind, an earthquake, or
undersea landslide. Waves travel out in a circle (called wave
trains) from the center of the disturbance. Each wave has a
crest and a trough. The crest is as high above what was the
flat, calm surface of the water as the trough is below that
level. Waves are classified as to their wave period (how long it
takes a single wave to pass a particular point).
TIDES

36. CIRCULATION OF WATER

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Seawater movements are very complicated . Surface currents, subsurface
currents, vertical currents (like upwelling), downwelling (where water is
sinking, like near the poles), and tides all contribute to the mixing of the
oceans of Earth. Each particular place on Earth has its own unique specific
currents, many of these seasonal. 
Ocean water is in constant motion, moved and mixed by currents, wave and
tides
Below the surface layer the ocean environment is quite uniform hence
providing marine life a similar conditions of motion, temperature and salinity
in any ocean at any time
Oceanic motion brings food and oxygen, replenishes nutrients, removes the
waste, disperses floating organisms
Vertical and horizontal motions of water observed in ocean/sea
Vertical water motions in the sea are much slower than horizontal motions AT
SURFACE due to surface currents 1.5m/s
Displacements of organisms in vertical direction are depended in the change
in conditions(light, salinity, temperature and nutrient supply)

37. CHANGES WITH DEPTH

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Temp in the oceans also has a marked variation with depth.
Below the 100m surface layer the temperature decreases rapidly, wit
depth to 1000m; that zone of rapid change in temp called as
THERMOCLINE.
Below the thermocline, the temp is relatively uniform over depth,
showing a small decrease to the ocean bottom
Similar situation happens with the middle latitude surface water
SALINITY.
Salinity increases rapidly to about 1000m, this zone of relatively
large change in salinity with depth is called as HALOCLINE
Beneath the halocline the uniform conditions extend to the bottom
The oceans have a well mixed surface layer up to 100 m and then
the density increases rapidly with the depth of about 1000m. below
1000m its almost uniform.
The region between 100 m to 1000 m is termed as Pycnocline

38. Ocean water is vertically structured
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Temperature declines with depth
Heavier (colder saltier) water sinks
Temperatures are more stable than land temperatures
Water’s high heat capacity
It takes much more heat to warm water than air
Oceans regulate the earth’s climate
They absorb and release heat
Ocean’s surface circulation
Thermocline = below surface water, temperature decreases rapidly with
depth
Halocline = salinity changes with increasing depth
Pycnocline = below the surface zone
Density increases rapidly with depth
Deep Zone = below the pycnocline
Dense, sluggish water
Unaffected by winds, storms, sunlight, and temperature


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When the density of water increases with depth, the water
column from surface to depth is stable. If there is more
dense water on top of less dense water, the water column
termed as unstable.
Vertical over turn of water ?
When the density at the surface increases, this results in the
vertical moment of water (top to bottom exchange of water)
called Vertical circulation
This circulation is dictated by the changes occurred at
surface water in temperature and salinity, so this vertical
circulation is also termed as Thermohaline circulation

40. •Major subsurface currents in the oceans are
most often due to differences in the
density of water masses. A slow subsurface
circulation of water develops with the
sinking of cold water at the poles and its
creeping across the ocean bottom with the
meeting of north polar water and south polar
water. There is a layering (due to density)
near the equator. This is called thermohaline
circulation (due to density differences in
seawater caused by temperature and salinity)
and some scientists predict it takes around
400 years for the water to complete this
cycle.

41. The upper waters of the oceans flow
horizontally in currents (cont’d)
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Thermohaline circulation = global oceanic circulation system of upwelling
and downwelling currents
Ocean water flows horizontally – wind systems and air pressure
Gyre = an oceanic current that flows in a circular motion
Coriolis force = artifact of Earth’s rotation
There is concern that climate change might disrupt both the thermohaline
circulation and gyres/ currents (such as the Gulf Stream that keeps the UK
temperate)
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42. The upper waters of the oceans flow horizontally in currents
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43. Upwelling and Downwelling Zones
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When the dense water (from surface) sinks and reaches a
level at which it is denser than the water above. But less
dense than the water below, then it spreads horizontally as
more water descends behind it
The dense water that has descended displaces water
upward and hence completing the cycle
As the water is in fixed quantities in oceans, so it requires
movement of water between these locations (continuity of
flow)
Areas of thermohaline circulation; where water sinks are
called downwelling zones and
Areas of thermohaline circulation ; where water rising are
called as upwelling zones

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Down welling transports oxygen rich surface water to depth where it
needed for the deep living animals. Similarly up welling returns water
with dissolved, decay - produced nutrients from the depth to surface
(where they act as fertilizers)
When the circulation of water caused by wind driven surface currents
When the surface water are driven together by the wind or against the
coast then a SURFACE CONVERGENCE is formed
Water at the surface convergence sinks/down well
When the wind blows the surface water away from each other or away
from a coast then it is termed as SURFACE DIVERGENCE and water
from below is upwelled
During the slow movement of water from surface to depth and back,
the water continually mixes with adjacent layers of water and
gradually exchanging chemical and physical properties

Water may take up to 1000 years in greater ocean depths before it
again reaches the surface

45. La Niña and El Niño demonstrate the
atmosphere-ocean connection
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El Niño
Equatorial winds weaken
Warm water flows eastward and suppresses upwellings
Alter weather worldwide
Canada abnormally warm and dry
La Niña
Opposite to El Niño
Weather: Canada abnormally cool and wet
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