Lotic Water Bodies,Physicochemical Parameters and Biological composition

Lotic water bodies

Lotic water bodies are the running water bodies. These lotic bodies are mainly compound river and the streams. The largest lotic body in the world is the Nile river. About 6000 rivers and the streams are reported from Nepal. Major types of the river in Nepal are Sapta Koshi, Sapta Gandaki, Karnali, Mahakali etc. Originally the lotic bodies are snow melt, mountain, natural lake, seepage etc. The volume of the water and the level of the water in the lotic bodies depends on the fluctuation level of rainfall and seasons. He features of the lotic water depends on the basin structure. The lotic waterbodies show the deep rate at highland and erosion is also high in that type of region. In the lowland velocity decreases and hence deposition is high in the region.

The different factors which determine the physicochemical and biological composition of the lotic waterbodies are as given below:

1) Velocity:

Velocity is the major limiting factor of the lotic waterbodies. This velocity depends on the rainfall and the basin structure.

2) Temperature:

The temperature variation of the lotic waterbodies depends on the season and the exposed area.

3) DO:

Dissolved oxygen present in the water bodies is often referred as the DO. The concentration of the DO varies both in the lentic and the lotic waterbodies. The concentration of the DO is generally high in the lotic waterbodies than in the lentic water bodies.

4) Nutrient :

The availability of the nutrient is generally less in the lotic waterbodies than in the lentic water bodies.

5) Substrate structure:

The substrate structure of the lotic waterbodies is usually silt and debris structure.

Physicochemical parameters of fresh water

The properties which determine the physical and the chemical state of the freshwater bodies are correspondingly called as the physical and the chemical properties of the fresh water bodies or they are combined called the physicochemical properties. The parameters which determine the properties of the freshwater bodies are as follows:

Physical parameters:

1: Temperature

Water has the unique properties such as latent heat capacity. Water has high heat capacity and the water can hold the large amounts of heat. That’s why water bodies tend to maintain a relatively constant temperature. The unique thermal properties of the water are best demonstrated by the fresh water bodies. The lentic water bodies undergo the thermal stratification phenomenon which has a significant influence on their inhabitant biotic communities causing seasonal overturn of nutrients. Fluctuation of temperature regulates breeding period, aestivation, hibernation, thermally oriented migration etc. Thus, the effect of the temperature is much pronounced in the lentic water bodies than in the lotic waterbodies.

2: Light

The light influence freshwater ecosystem greatly as it is the major factor for the photosynthesis which occurs only up to effective light penetration depth called as the photic zone. Moreover, the effects caused by the temperature are actually caused by the light as the temperature depends on the photoperiod and the intensity of light. Light affects lentic ecosystem much more than the lotic ecosystem.

3: Colour

As we all know pure water is colorless. Colour produced in the water bodies is due to the presence of the humus material from the decaying organic matter, dissolved substance, minerals etc. There are two types of colour, they are:

A: Apparent color: This apparent color is due to the suspended matters, the reflection of light of the sky, vegetation etc.

B: True color: The true color is the color which is contributed by the dissolved solids only that remain after the removal of suspended matters.

Lentic water is the most colored due to the high amount of the suspended matters and the humus from the decaying organic matter. However, color has no significant effect on the fresh water bodies.

4: Odour:

Pure water is odourless. Odour in the water bodies may be produced due to the presence of the chemical agents like hydrogen sulfide, green chlorine, ammonia, alcohol and the biological agents such as algae, fungi, microorganisms. The fishy odour is produced due to the organic amines; rotten egg odour is due to the hydrogen sulfide. The odour is more experienced in lotic bodies due to a high mixing of the different types of effluents and the high land-water interactions.

5: Taste

Pure water is usually tasteless. Taste in the lentic water is due to decomposition of the organic and inorganic components while the taste in the lotic bodies is due to the dissolved minerals, carbonates, bicarbonates from industrial effluents 0.1 ppm can produce inky taste.

6: Turbidity/ Transparency

Turbidity is a measure of the extent to which light is either absorbed or scattered by the suspended materials. Turbidity decreases transparency, thus clearly water. It is caused due to the presence of the colloidal matters, fine suspended particles, and the size ranging from 0.001 micrometer to 1 micrometer. Flood and the pollution caused high turbidity to the lotic bodies settling of the particles causes less turbidity to lentic bodies.

7: Velocity

Velocity is the limiting factor for the lotic bodies as the distribution of the biochemical and the physical properties depend on the velocity. High velocity causes fewer nutrients deposition, thus less number of organisms. Velocity in the lentic water bodies depends on the wind current and the stratification. But it is very less in comparison with the lotic waterbodies.

Chemical parameters:

1: Biogenic salt and salinity or total dissolved solids

Water contains different types of the anions such as chloride ion, phosphate ion, sulfate ion etc. and cations such as sodium ion, potassium ion, magnesium ion etc. which are responsible for the saltiness of the water. The materials remaining after filtration for suspended solids are considered to be dissolved solids. Dissolved substances have peculiar significance for floating aquatic vegetation and phytoplanktons since these organisms do not depend on the substratum for supply for nutrients.

Salinity and dissolved solid content in the lotic bodies are high due to their high dissolving capacity caused by the velocity than lentic bodies.

2: Hardness

It is defined as the concentration of metallic cations in the solution. Mainly the hardness causing cations are the calcium and the magnesium. The hardness cations react with the anion in the water to form a solid precipitation. The hardness of the lotic water is high because of its high abrasive power due to its high velocity.

3: PH

Bacterial activity has a great effect on hydrogen ion concentration. The microbiologically activated processes such as production of carbon dioxide by the respiring bacterial cells, oxidation of hydrogen sulphide or sulphide to the hydrogen sulphate, production of the organic acids, assimilation of the ammonia as a source of the nitrogen tend to increase the hydrogen ion concentration of the water and decrease in PH of the water bodies.

4: Dissolved oxygen (DO)

It is the amount of the oxygen in the mg/lit remains dissolved in the water. DO is the limiting factor for the lentic water bodies. DO is less in the lentic bodies due to the aerobic decomposition of the organic matter by the microbes which is accompanied by the consumption of DO. Lotic bodies have the high DO due to the interaction of the high velocity flowing water to the atmosphere.

References:

Miller, Jr. G.T. Living in the Environment. Wadsworth Publication, 2003.

S.C., Santee. Environmental Science. India, New Center: New Center Book Agency (P) Ltd, 2004.