Water as abiotic factor -Dr. Vidhin Kamble

The abiotic factors in an ecosystem include all the nonliving elements of the ecosystem. Air, soil or substrate, water, light, salinity and temperature, etc  all impact the living elements of an ecosystem.

The Earth is a watery place. But just how much water exists on, in, and above our planet? About 71 percent of the Earth's surface is water-covered, Among these, oceans are the largest reservoirs, holding about 97% of the earth’s water. Of the remaining 3% freshwater, about 78% is stored in ice in Antarctica and Greenland. About 21% of freshwater on the earth is groundwater, stored in sediments and rocks below the surface of the earth. Rivers, streams, and lakes together contain less than 1% of the freshwater on the earth and less than 0.1% of all the water on the earth.

Water is called universal solvent,  essential for life on Earth. It is essential to the chemical reactions within living organisms, is one of the key components for photosynthesis and is the placeholder in cells. Water also serves as a living environment for aquatic creatures. As such, changes in quantity and quality of water impact living systems.

Depending upon the environment of the place of occurrence, water can quickly change its phase. Water is available in three phases:

1.     Solid

2.     Liquid

3.     Gas or vapors

The water on earth found in

a)     The ocean

b)    lakes

c)     vegetation

d)    snowpack

e)     glaciers

f)      Air

g)     Clouds

 

The availability if water is important abiotic factor which affect the life of organisms in an ecosystem. The organisms are adopted accordingly to sustain their life.

Water is equally important for plants. It performs the following important functions in plants:

1. Water is essential for the germination of seeds and growth of plants.

2. During the process of photosynthesis, plants synthesize carbohydrates from carbon dioxide and water. Therefore, water is one of the essential components for the plant.

3. Water acts as a solvent for fertilizers and other minerals, which are taken up by the plant roots in the from of solution. Thus, water serves as the medium in which plants absorb soluble nutrients from the soil.

4. Water serves as medium for transport of chemicals to and from cells.

5. Water pressure in plant cells provides the firmness to the plants.

6. Aquatic life is possible in water only.

 

The water cycle, also known as the hydrologic cycle or the hydrological cycle, describes the continuous movement of water on, above and below the surface of the Earth.

The five parte of the water cycle are as follows :-

The major components of the hydrologic cycle are precipitation (rainfall, snowfall, hale,

sleet, fog, dew, drizzle, etc.), interception, depression storage, evaporation, transpiration,

infiltration, percolation, moisture storage in the unsaturated zone, and runoff (surface runoff,

interflow, and baseflow).

1)    Evaporation

2)    Condensation

3)    Precipitation rainfall, snowfall, hale, sleet, fog, dew, drizzle, etc.)

4)    Infiltration

5)    Run off

Evaporation:

Evaporation is the process by which water changes from a liquid to a gas or vapor state. The rate of evaporation depends on how dry the air is and the temperature difference between air and water.  Evaporation from snow and ice, the direct conversion from solid to vapour, is known as sublimation.

Transpiration is the process by which water evaporates from plants. Evaporation and transpiration are often combined into a single term called evapotranspiration.

 

Condensation:

Condensation is the process by which water vapor in the air is changed into liquid water. As air rises it  cools. Cold air holds less water than warm air. Thus, as the air cools, clouds form. Some clouds form during the day as the air temperature and evaporation increase. Other clouds are associated with weather systems, such as a warm or cold front, in which warm air is forced over colder air.

 

Precipitation :

Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow It happens when clouds can no longer hold water. The  water then falls to the earth because of gravity.

Precipitation that falls to the Earth is distributed in four main ways:

1)    Some is returned to the atmosphere by evaporation,

2)    Some may be intercepted by vegetation and then evaporated from the surface of leaves,

3)    Some percolates into the soil by infiltration, and the remainder flows directly as surface runoff into the sea.

4)    Some of the infiltrated precipitation may later percolate into streams as groundwater runoff. Direct measurement of runoff is made by stream gauges and plotted against time on hydrographs.

Infiltration:

Infiltration is the process by  which water soaks into the ground. Infiltration is faster on dry soils and in sandy soils compared to wet and clay soils. This is because the pore spaces in the sand are much larger than in  the clay and can therefore transport more water.

 

Runoff :

Surface runoff is precipitation or melted snow that runs off over the landscape. Runoff occurs when the rate of precipitation or snowmelt is greater than the rate of infiltration.

 

Impact of water environment  on plants animal life:

 

1. Increases in water temperature can cause changes in aquatic plants.

For example, as the temperature increases, the rate of photosynthesis increases. As photosynthesis increases, the number of aquatic plants increases. This can lead to a number of plants or an algal bloom. The faster plants grow, the faster they die. When they die they are decomposed be aerobic bacteria, which consume oxygen in this process. This event may also decrease the amount of dissolved oxygen in the water, which organisms need to survive.

2. Increases in water temperature can also cause changes in aquatic animals.

For instance, as water temperature increases so does the organism’s metabolism. When this occurs, they need more dissolved oxygen and more food supply. If the amount of dissolved oxygen needed is unavailable, they may die.

Cold water holds more oxygen than warm water. The more oxygen in the water, the more living things it can support. They may also die at a faster rate because of their increased metabolism and because they can not tolerate extreme heat. 

Some animals may be able to acclimate to a certain range of water temperature. Other animals may be able to migrate to regions where the water temperature is best for them. This may affect the food chain and may cause the depletion of a food source for other aquatic species.

3. The temperature of the water may also influence the sensitivity of aquatic animals' ability to resist toxic wastes, parasites, and diseases. Bacteria and other disease-causing organisms grow faster in warm water.

4. Increases in water temperature can affect the hatching and development of aquatic animals. Fish larvae and eggs usually have a more narrow temperature requirement than adult fish. Also, 

The optimal temperature of Brine Shrimp embryos to leave their shell is at 25 degrees Celsius or 77 degrees Fahrenheit.

 5. An excess of nutrients, such as nitrogen and phosphorus in the water, leads to an increased growth of toxic algae and aquatic plants, that cause poisoning and death in fish and other animals who feed on them.