Introduction: carried by sea. An aquatic ecosystem is


 More than
two thirds of earth’s surface is covered with water. The earth’s five oceans
and its seas, rivers that comes from rainfall, from snow and ice melting.not forgetting the lakes and ground water even swamps. They
are all connected to present the aquatic area which is a home of huge number of
living things.

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The water is very effective and important
molecule for all organism and it is essential part in life. Most of the
organisms cannot survive without the presence of water. Although, they don’t live inside it such as
human and plants and different organisms, they have provided with food from
inside it, also passengers and goods are often carried by sea.

An aquatic ecosystem
is a community of living organisms socializing with each other and their surroundings
under the water. There are two main kinds of
aquatic ecosystems called saltwater ecosystem and freshwater ecosystems.

Wet lands are areas that are permantly or regularly under
fresh or salty water, such as bonds, rivers, bogs, marshes, estuaries and
mangrove swamps.

While the open
ocean starts at the edge of continental shelf where the seabed plunges suddenly
down the continental slope to greater depths. Its divided into three zones: the
benthic zone is at the bottom, above that the demersal zone, and the pelagic
zone is uppermost.

Ocean currents
are driven by a combination of winds and the earth’s rotation, and they are regulating
permanent or continuous movement of ocean’s
water. The motion of the ocean water is
promoted by forces acting on the water counting the breaking waves, salinity
differences, Coriolis effects, the wind and temperatures

While ocean surface
currents are like large rivers many kilometers wide, on average 100m deep and flowing
at 15 km per hour. also it affect only the top 100m so the ocean deep current
involve the whole ocean

 However, the major currents are spilt on
either side of equator into huge rings called gyres.

This essay is
concentrating on comparing between fresh and salt water and the features that
include each ecosystem.


Plus on that
it will include the types of Ocean currents and their effects in order to work
to neutralize the temperature difference between different areas in the oceans
such the winds do on land. As a body of water warms and cools slowly it’s an
excellent, and fairly stable, transmitter of heat and cold which feeds into the
weather system.





Water covers about 71% of our planet. The fresh
water covers only 2.5% of the total amount of water on earth which is a small
fraction compared to the salt water which covers the rest of the amount of
water. The fresh water and the salt water are the two categories that the
aquatic ecosystem is classified to, however, the brackish water occurs when the
fresh water mixed with salt water. There are very huge differences between
fresh water and salt water, and that differences are arise from the types of
organisms that lives in the two types of water, the salinity content, and the
density. But the main and the most important differences is the salinity
content. Both types of water contain salt which is sodium chloride, but the
salt water contains higher amount of salt than the fresh water have, as a
result, the conductivity of the salt water is higher than the fresh water. If a
person drinks the salt water for example ocean water, that could affect its
healthy and also it can be deadly because that can cause dehydration to the
human body.

The current direction is effected by the
shoreline; the global conveyer belt is a result of ocean currents that influxes
for thousands of kilometers which is essential in verify the climate of other
regions of the earth. Ocean currents can be on the surface of the ocean or in
the deep waters like 300 meters in depth. The currents can also move in both
horizontally or vertically depending on the reasons. While the shape of the
ocean topography, basin, and the land masses bordering the Ocean are influences
by the ocean currents. The masses of cold water that moves from high latitude
towards equator is called ocean currents, it absorbs the heat that comes to the
tropics then it will cool the air above. The cold currents are created while
the air circulating the eastern side of the subtropical high is inflated over
cold water mass, therefore drawn toward the equator. The warm currents are
masses of warm water that have high temperature that moves off from the equator.
When the cold saline water becomes dense and sinks the warm current will be formed,
in addition it will permit the light warm water to influx in the opposite way,
commonly faraway the equator. Ocean currents could affect climate


Main text:

The characteristics of freshwater and saltwater

brackish water has a higher salinity content
than the fresh water, but less salinity than salt water. This condition is
commonly occurs in Baltic sea, black sea, and Caspian sea. There are different
types of organisms that live in such as: northern water snake, Caspian seal,
and bull shark which they are some examples of animals and red tiger lotus,
anacharis, and red mangrove and these are examples of plants that lives in this
type of water.

The fresh water has a very low salinity content
and it is usually less than 1% compared to the salinity of the salt water that
is approximately 3.5%, which means
that 35 grams of salt must dissolved in one liter. Also, there are many regions
in fresh water such as: ponds and lakes, steam and rivers, and wetland. The
wetland is the land that is saturated and appear wet for part of the year.
There are different types of the wetland such as marshes, swamps, and bogs.

The lakes are classified
according to the type of nutrient state into two types: The lakes that are poor
of nutrients called Oligotrophic. The other type is the lakes that are rich of
nutrients called Eutrophic. Different life zones are appeared in the lakes and
ponds. The first type of zone was littoral zone it is the region which is
nearest to the shore, different type of protozoans, invertebrates, fishes, and
reptiles are lived there. Secondly, the limnetic zone which is makes the sunlit
body of the lake, some small fishes such as minnows, and killifish. These small
fishes survive by eating the plankton, and they can be as a food for the big
fishes like bass. The third zone is the profundal zone which is the region that
is at the lower level of light penetration, other organism can adept in this
area like the zoo plankton, invertebrates, and fishes such as: catfish and

Finally, the benthic
zone which is consists of the matters that settles in the bottom of the water
like the dead organisms that accumulate in the bottom of the lake, sand,
inorganic sediment.

Mostly the fresh water
is precipitation from atmosphere is different form such as: mist, rain, and
snow. Then, this dissolved material which was formed from the atmosphere (fresh
water) also fallen as mist, rain, and snow. There are a lot of organisms that
capable to live in fresh water, for example plants, such as: cattail, water
lilies, and blue flag iris. Also some animals could live in this type of water
such as: hippopotamus, golden fish, otters.

However, the salt
water composed of a high salinity content compared to fresh water and it is the
type of water that is the most abundant in our earth. Also, it is conserned the
most bio diversity environment. Many organisms are lived in this type of water
like: seaweeds, coral reef, shortfin, Mako shark, octopus, and killer whale.
Some type of fishes lives in salt water. They have less salt in their body
tissue than the surrounding water because the environment that lives in is vary
salty that is why the water drown from their body tissue.

Moreover, because of
the dissolved salt which is sodium chloride, the saltwater is denser than fresh
water. So, this give an explanation of the specific volume of salt water that
is appear more heaver than the same volume of fresh water.

Seawater have
several ions like chloride (Cl?), sodium (Na+),
sulfate (SO24?), magnesium (Mg2+), calcium (Ca2+), and potassium (K+).  The viscosity
of salt water is higher than that of fresh water this is due to its higher
salinity. The density of salt water also is higher than the fresh water. The
freezing point of the salt water is lower than that of pure water also, the
boiling point of the salt water is higher than the fresh water.

In some cases, the human bodies can float in
seawater, however, this can not occur in fresh water this is due to salts that
exists in salt water that make it denser. Oceans water is an example of salt
water that is consists of different types of zones that organisms can live in
each zone can accumulate different types of organisms. The oceans water
comprised of four zones. The first zone is epipelagic zone (0-120 m), this type
of zone does not contain a high concentration of phytoplankton and has a
deficiency of inorganic nutrients. The second type of ocean’s zone
is mesopelagic zone (120-1200 m) that varies type of organisms like some
species of shrimps, squids, and fishes that can adapted to the absence of
light. The third zone is the bathypelagic zone (1200-3000 m) it is deep and dark
area that some organisms live there such as: sperm whale, anglerfish, and
viperfish. The fourth zone is the abyssal zone (3000- bottom). Organisms like
glass sponges, sea cucumber, and tripod fish live there.

Our county was a good source for the fresh
water that was attract the people to settle in our area and help in farming especially
in the north of Bahrain. Ain Umm Al-Sujur, Ain Abu Zaydan, and Ain Adhari were the most
important sources of fresh water. Nowadays, Bahrain depend mostly on the non-conventional sources of water. This is due to the high
population of the people in a certain area that lid to the depletion of fresh
water. The salt water was widely abundant in Bahrain because it is an island
that the sea water surrounded it in all the side.


ocean currents can effect on climate and weather?!

Ocean Currents Affect Climate by horizontal
current moving southward or northward that is brings warm or cold water for
extremely long distance. The supplant cold water will cool the air whereas the
warm water will increase the air temperature.

For example, water from the tropical atlantics
moves from the north over the gulf stream immerse the western Europe shores
therefor creating a mild climate. The mild climate increases the temperature of
the region greater than the regions across the Atlantic but on the same

 Formation of
deep water current occurs during winter the surface is cooled and makes the
surrounding water denser. When the water surface become thicker, convective
overturning process takes place that the dense water mixing downwards extending
to the bottom. The dense mixed water expansion out in the bottom of the ocean.
When this mixing is done in higher latitude, a circulation pattern is formed
where warm water moves pole-wards from the tropics therefore, surrendering heat
to the atmosphere produces in the transportation of heat pole-wards. The cycle
repeats over and over impact the transfer of heat from the equator to the

Movement of ocean current is affected by salinity,
wind, topography and earth’s
rotation influences the current flow by bringing cold water from the depths to
the surface by pushing away the surface water. That’s why the ocean is colder on the east coast than the west coast. The colder water come
down and moves towards Indian, pacific and Atlantic basin. the changes in
current in influences the coastal climate by carrying lots of heat.

Ocean current have a considerable effect on the
weather. The greatest as well confirmed flows set in the movement by the wind
and the rotation of earth that takes the enormous rotation currents form to the
south and north of the equator in the Sothern and northern hemispheres, and the
current in the east flowing is in the southern of the most
significant weather making characteristic of these large current is the
conveyance of cold and heat.

Moreover, the ocean impacts landward
temperature by conservative them, like a large body of water warms and cools
far less quickly than earthly environments. 
The coastal areas frequently see lower temperature in summer and in
winter is warmer. Additional affect can form from the great ocean currents of
the world.

From equatorial areas the currents can
transport balmy air far north. For example, The Gulf Stream that produce in the
Gulf of Mexico, allow coral reef formalization off Florida and Bermuda–farther
north than the normal tropical zone of reef development–and warms northwestern
Europe beyond, say, the portion of North America at the same latitude. In fact,
evidence propose that when gulf stream flow is reduced it can have helped
trigger that called little ice age of northwestern Europe from 13th
to 19th centuries. In this period the temperature was continuously
reduced as a result the winter become longer and growing season decrease and
the mountain glaciers and other major effects increase. The conflicting air
temperature encourage by wide traveling currents of the ocean effect cloud
cover and precipitation. There are many great rotating currents in the world’s oceans, that have
westward-flowing waters at the equator that changed poleward in conveyer-belt
fashion to come around. Where they skirt continents, these gyres as they
called, that can significantly affect the local weather. moreover, southwesterly winds flowing onshore in southwestern
Africa are cooled by the Benguela Current, the northward arm of the South
Atlantic Gyre. And this is forms persistent fog over the Namib Desert, supply
critical moisture to the environment and also demonstrate a navigational
hazard, as the wrecks of Namibia’s Skeleton Coast attest.

In addition, boundaries of the warm Gulf Stream
flowing northeastward and the cold southward Labrador Current in the North
Atlantic is a result of fog. Gulf Stream cools after it was warm as it drifts
on the Labrador, condensing. like in the Namib, this orderly fog together with
icebergs shed from Greenland, chronic to that stretch of ocean that make for
sometimes sinister seafaring conditions.

Warm temperature carries by ocean currents can
assist atmospheric instability and the potential for storms and precipitation.
This is the situation case for air masses on the western boundary currents of
the North Pacific and North Atlantic gyres, the Kuroshio and Gulf Stream.



Finally, the water plays an
array of vital roles in ecosystems across the planet. Although many other
substances are necessary for life and for ecosystems to exist, without water
nothing else would function to produce life as we know it.

And because
ocean currents lead to inflow of nutritious water (water with planktons and
other kinds at the bottom of the food chain) to places where there is less,
bringing fish with it in a seasonal manner of great importance for marine life
and the worlds fishermen



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