Aquatic ecosystem
Introduction
An aquatic ecosystem is an ecosystem in a body of water. Communities of
organisms that are dependent on each other and on their environment live in
aquatic ecosystems. The term aquatic habitat covers a whole spectrum from the
world's oceans to the bays and estuaries around their fringes, from major lakes
(including inland salt seas) to small ponds and to the marshes and swamps that
are often found associated with them. The two main types of aquatic ecosystems
are marine ecosystems and freshwater ecosystem
Marine ecosystem:
Marine ecosystems can be defined as the interaction of plants, animals, and the
marine environment. By “marine,” we mean of, or produced by, the sea or ocean.
The term encompasses the salty waters of the Earth, and is also known simply as
a salt water ecosystem. As 97% of the total water is salt water, marine
ecosystems are the largest types of ecosystems on the planet Earth. Marine
ecosystem , includes ocean and seas. Study of marine habitat is known as marine
ecology or marine biology.
The marine ecosystems have certain unique features. The oceanic environment is
very wide covering 75% of the earth’s surface. The oceanic systems are very deep
in which life extends to all depths. The water is in continuous movement both in
vertical and horizontal dimensions. The water is salty with an average salt content
of 35 g/liter. The concentration of dissolved nutrients is low. Habitat:
Marine habitats are the worldwide largest aquatic habitats on the earth. These
habitats includes seas and oceans and covers 70% of earth surface and contains
many biotic habitats. Life extends to all depths of oceans. Marine environment
includes abiotic factors and biotic communities.
Types of marine ecosystem:
Marine ecosystems includes, abyssal plain (deep sea coral, whale fall, brine pool),
Antarctic, Arctic, coral reef, deep sea (abyssal water column), hydrothermal vent,
kelp forest, mangrove, open ocean, rocky shore, salt marsh and mudflat, and
sandy shore. Some of these regions are very productive. Others are in constant
darkness where photosynthesis cannot occur.
1.Mangrove :
Mangrove ecosystems are comprised of salt-tolerant, woody mangrove trees and
shrubs. They are located in shallow, low-oxygen sandy or muddy areas along
shorelines.
2.Open ocean:
It is the largest marine ecosystem. It contains approximately 65 percent of the
volume of the world ocean. The open ocean zone generally refers to the upper
200 meters (656 feet) of water. This distinguishes it from the deep sea ecosystem
below. It is a highly diverse and dynamic ecosystem that contains a wide variety
of life. The diversity of open ocean organisms ranges from megafauna, or large
animals like sharks, whales, dolphin, and sea turtles tomicroscopic plankton and
small schooling fish. Sea birds and large migratory fish also play an important part
in this ecosystem. Open ocean currents carry nutrients to different parts of the
ocean.
3.Rocky Shore:
These ecosystems are coastal areas with solid rock substrate (foundation). Strong
tidal influences create distinct tidal zones. One of the most physically stressful
marine ecosystems. Organisms that live along the rocky shore must be able to
tolerate extreme changes in temperature, salinity, moisture, and wave action.
Organisms of the rocky shore face some other threats. They must also protect
themselves from terrestrial species like Huma Salt.
4.Salt Marshes and Mudflats
These are low, wet, muddy areas that lie at the interface between the land and
sea. They are either periodically or continuously saturated by salt water. ns, birds,
cats, rodents that have access to the rocky shore. They are one of the most
productive ecosystems on Earth. They contain several different structural zones
that form distinct habitats within the salt marsh, levees, salt panes, pools and
mudflats.
5.Sandy Shores:
Sandy shores are low-lying areas of loosely deposited sand, gravel, or shells.
Sandy shoresare exposed between the extreme high and low tide marks. They are
mostly flat. Sand dunes are exposed shoreline systems of one or more sand ridges
created by the wind. Most sand on the beach comes from the weathering and
decay of rocks, corals, seashells, and minerals. The surface layers of the sandy
shore are always in motion from waves and wind. This makes the ecosystem
unstable for many animals Examples of residential sandy shore species include
hermit crabs, sea urchins, sea grasses, algae, barnacles, snails, sea hares, mussels,
and sea stars. Birds and turtles migrate and use sandy beaches as feeding and
nesting sites.
6.Coral reef:
A ridge of rock in the sea formed by the growth and deposit of coral. Coral reefs
are large underwater structures composed of the skeletons of colonial marine
invertebrates called coral.
Reefs as Ecosystems
Cities Of the Reefs are the big cities of the sea. They exist because the growth of
corals matches or exceeds the death of corals. It is a race between the
construction cranes (newcoral skeleton) and the wrecking balls (the organisms
that kill coral and chew their skeletons into sand).
Difference between Oceans and seas:
Ocean
Oceans around the world are interconnected. Although it is much dense around
the margins of continents and islands.
Sea:
While Sea is in continues circulations because of air , temperature differences of
equator and poles set up strong winds which together with rotations of the earth,
create definite currents. Sea is dominated with waves and tides. Sea water is
saline and salinity is up to 30-35 ppt. Higher salinity is mainly due to the chloride
ions present in water. Seas and oceans constitute the marine ecosystems.
In terms of geography, seas are smaller than oceans and are usually located
where the land and ocean meet. Seas are found on the margins of the ocean and
are partially enclosed by land. Example, the Bering Sea is part of the Pacific
Ocean.
DEPTH ZONES IN OCEANS:
It consists of three zones as Continental shelf, continental slope and deep ocean
basins.
The continental shelf: extends from the coast to a depth of 130 m. The width
averages to about 75 kilometers. This shelf zone collects much of the sediments
(deposits of sand and mud) that are carried by the rivers from land.
The continental slope: begins at the outer edge of the shelf. The slope is much
steeper than the shelf and plunges to great depths of 3.6 kilometers. The width
ranges from 20 to 100 kilometers. Submarine canyons extends into these slopes.
The canyon heads may form some deep sea fans .
Deep ocean basin: The area between continental slope and deep ocean floor is
known as continental rise. The deep ocean basin is called as the abyssal plain.
Abyssal hills, sea mounts and deep sea trenches are the physiographic features of
the basin.
Oceans Area (Sq.km) :
•
• The Pacific Ocean 181 3,940
•
• The Atlantic Ocean 94 3,580
• Sea:
While Sea is in continues circulations because of air , temperature differences of
equator and poles set up strong winds which together with rotations of the earth,
create definite currents. Sea is dominated with waves and tides. Sea water is
saline and salinity is up to 30-35 ppt. Higher salinity is mainly due to the chloride
ions present in water. Seas and oceans constitute the marine ecosystems.
In terms of geography, seas are smaller than oceans and are usually located
where the land and ocean meet. Seas are found on the margins of the ocean and
are partially enclosed by land. Example, the Bering Sea is part of the Pacific
Ocean.
DEPTH ZONES IN OCEANS:
It consists of three zones as Continental shelf, continental slope and deep ocean
basins.
The continental shelf: extends from the coast to a depth of 130 m. The width
averages to about 75 kilometers. This shelf zone collects much of the sediments
(deposits of sand and mud) that are carried by the rivers from land.
The continental slope: begins at the outer edge of the shelf. The slope is much
steeper than the shelf and plunges to great depths of 3.6 kilometers. The width
ranges from 20 to 100 kilometers. Submarine canyons extends into these slopes.
The canyon heads may form some deep sea fans .
Deep ocean basin: The area between continental slope and deep ocean floor is
known as continental rise. The deep ocean basin is called as the abyssal plain.
Abyssal hills, sea mounts and deep sea trenches are the physiographic features of
the basin.
Oceans Area (Sq.km) :
•
• The Pacific Ocean 181 3,940
•
• The Atlantic Ocean 94 3,580
•
•
• The Indian Ocean 74 3,840.

•
Southern Ocean 21,960,000
•
• Arctic ocean (smallest) 5,427,000
Abiotic factors:
Marine abiotic factors includes temperature, sunlight , salinity, pH, water ,
dissolved oxygen ,pressure, nutrients wastes and soil. Temperature, salinity and
depths of oceans and seas are barriers for the free movement of , to which a
marine organisms go through . Some marine ecosystems go through extreme
changes in temperature, light availability, oxygen levels, and other factors on a
daily basis. Others are fairly stable and only change slightly at different seasons.
Temperature:
It is most important abiotic factor of a marine ecosystem because marine life
dependent upon it. Constant and stable temperature helps organisms in living
and developing habitat.
Sunlight:
Sunlight plays an essential role in the marine environment. It powers the process
of photosynthesis that, directly or indirectly, provides energy to nearly all forms
of life on earth.
Pressure:
The pressure at sea level is 760 mm Hg, or 1 atmosphere (14.7 pounds per square
inch). Because water is so much denser than air, for every 10 meters (33 feet)
below sea level in
the ocean, the pressure increases by 1 atmosphere. For instance, the pressure at
an average ocean depth of 3,700 meters is 370 atmospheres.
Metabolic Requirements:
The availability of nutrients strongly influences the distribution of organisms in
the marine environment. The term nutrient refers not just to food but also to all
of the organic and inorganic materials that an organism needs to metabolize,
grow, and reproduce.
Metabolic Wastes:
All organisms produce waste products when they metabolize. Animals excrete
nitrogen-rich waste products. Most of the time, waste products of metabolism
are either removed from the environment or broken down and recycled by a
variety of organisms, especially bacteria. Certain small tide pools and coastal
marsh areas are especially susceptible to the problems of accumulating metabolic
wastes because the exchange of waste-laden water with new, uncontaminated
water is limited. Biotic factors:
The oceans are home to around 230,000 species of organisms. Some of the
mammals that live in the ocean are whales, seals, sea lions, dolphins, sharks,
porpoises and walruses. The 20,000 species of fish include tuna, cod, salmon, blue
marlin, mackerel, halibut, sardines, flounder and grouper. Other creatures in the
ocean include jellyfish, octopus, sea turtles, squid, lobsters, shrimp, krill, marine
worms, eels, plankton, starfish, seahorses, sea cucumbers and sand dollars. Kelp,
seaweed, algae and coral are some of the plants that live in the ocean.
Other factors which are normally not encountered . But the marine organisms are
affected by the factors like
a) Depth of oceanic water
b) change in salinity
c) change in temperature
d) change in turbidity
e) and other environmental factors.
Freshwater Ecosystem:
Fresh water sources are rivers, streams, lakes, reservoirs, ponds and glaciers etc.
These water bodies known as fresh water bodies as their salinity is less then 0.5
ppt. Study of fresh water habitat are also called as Fresh water Ecology.
Freshwater Ecology:
It is divided into two groups:
1- Lentic habitats or standing water habitat:
Lentic habitats are the still and standing water habitats. Example of lentic habitats
are ponds, lakes, marshes, swamps, bogs, reservoirs etc. A lentic ecosystem
entails a body of standing water, ranging from ditches, seeps, ponds, seasonal
pools, basin 8marshes and lakes. Deeper waters, such as lakes, may have layers of
ecosystems, influenced by light. In these habitats water is to be reserved naturally
or artificially.
2-Lotic habitats or running water habitats:
Lotic aquatic systems are those systems which contain flowing waters. The mass
of water in these systems is in a state of perpetual motion. Streams and rivers are
familiar examples of such systems. The basic function of these lotic bodies of
water is to carry the surplus rain water back to the sea. Examples include: creeks,
streams, runs, rivers, springs, brooks and channels.
Abiotic factors:
Non living organisms of freshwater Ecology.
Temperature:
Temperature plays an important role in freshwater biomes. Depending on the
season, temperature may be uniform or disparate between different layers of
ponds and lakes.
Precipitation
Precipitation is responsible for replenishment of water in freshwater bodies.
Water cycle plays an important role in this respect. Depending on their size, rivers
and lakes affect the climate.
Water characteristics:
Water characteristics such as depth and whether the water body is static (nonmoving) or dynamic (moving) distinguish freshwater biomes. Rivers and streams
are moving freshwater. Younger rivers cut a straighter and direct path through
the ground and rock.
Biotic Factors in Freshwater Biomes:
Algae, fish and aquatic invertebrates are well known biotic factors of a freshwater
ecosystem. Other important biotic factors include aquatic plants, birds and land
animals.
Invertebrate:
Earthworms (and other segmented worms), Dragonflies, Water mites, Leeches,
Water fleas, Crayfish, Freshwater mussels, Fairy shrimp, Crabs, Mayflies, Water
striders.
Fishes:
Salmon, Bluegill, Catfish, Trout, Lake herring, Sturgeon, Minnow are major biotic
factors of freshwater ecosystem.
Rivers:
A river is a large, natural flowing freshwater, flowing towards an ocean, sea, lake
or another river. In some cases a river flows into the ground and becomes dry at
the end of its course without reaching another body of water. Rivers are
characterized by a one-way flow from the uplands, where they were fed by
rainfall and springs, to their junctions with the sea at estuaries.
World largest rivers:
•
• The Nile River, located in northeastern Africa, is the longest river in the
world at about 4,132 miles.
•
• The Amazon River is the 2nd most large and deepest river in the world.
Pakistan's largest river
Indus river important river in southern Asia and it is shared between Pakistan,
India, and china.
Rivers of pakistan:
Dasht River , Kech River, Basol River, Hingol River , Nal River, Porali River, Hub
River ,Malir River, Lyari River (no more river only drain now),Indus River,Panjnad
River, Chenab River, Ravi River, Jhelum River, Neelam river etc
Streams:
A stream is a body of water with surface water flowing within the bed and banks
of a channel. The stream encompasses surface and groundwater fluxes that
respond to geological, geomorphological, hydrological and biotic controls.
Simplest stream ecosystem are the coldest and driest .
•
• Cold streams
In polar and alpine regions, glaciers accumulate snow in winter and to some
extent melt in summer, releasing water to a complex and fluctuating set of
channels. In winter there may be no flow and every thing will be frozen solid. But
the pressure of ice can cause some melting at the bottom of glaciers but in time
of warming climates melting may be substantial even in winter as the glaciers
recedes.
Lake:
A lake is an area filled with water, localized in a basin, surrounded by land, apart
from any river or other outlet that serves to feed or drain the lake. Lakes lie on
land and are not part of the ocean, and therefore are distinct from lagoons, and
are also larger and deeper than pond.Lakes can be contrasted with rivers or
streams, which are usually flowing. Most lakes are fed and drained by rivers and
streams.
•
• Lake Saiful Muluk: Saiful Muluk is a mountainous lake located at the
northern end of the Kaghan Valley, in the Mansehra, Khyber Pakhtunkhwa,
Pakistan. International level famous lake due to its beauty.
pond
A pond is
an area filled with water, either natural or artificial, that is smaller than a lake. It
may arise naturally in floodplains as part of a river system, or be a somewhat
isolateddepression (such as a kettle, vernal pool, or prairie pothole). It may
contain shallow water with marsh and aquatic plants and animals.
WETLANDS:
Wetland is a distinct ecosystem that is flooded by water, either permanently or
seasonally, where oxygen-free processes prevail. Wetland ecosystems can be
classified along a hydrological continuum from those that have very little
hydrological throughput to those that closely coupled to rivers, estuaries, or lakes.
Some wetlands can have high hydrological (minerotrophic), whereas others are
fed mainly by precipitation.
Reference
•
• Marine ecosystem. (2017, May 29). Retrieved June 03, 2017, from
https://en.wikipedia.org/wiki/Marine_ecosys tem