ECOLOGY
Ecology is a scientific study of relationship of organism with their natural surroundings
OR
Is the study of relationships of living organisms to each other and their surrounding (physical surrounding)
Importance of studying Ecology
It gives us scientific foundation of understanding some fields of studies such as agriculture which concern with crop cultivation and animal husbandry, forestry, fishery and so on
The study of ecology gives us the basis for predicting and remedying environmental degradation (how to conserve environment)
Help us to understand the likely consequences of massive interventions in the environment e.g. construction of huge dams, deforestation to open space for plantation, agriculture e.t.c
Ecology is an important interdisciplinary science linking physical, biological and social science.
Ecology has given rise to a growing public awareness on environmental issues. This has given rise to development of laws on environment protection, formation of new political perspective e.g. environmentalism in Europe, emergence of environmental consultancies, development of environmental data services / base, e.t.c.
Definition of terms
Environment Refers to the surrounding of organisms. OR
Everything that surround an organism and influence it.
Population is a group of organisms of one species occupying a defined area or habitat at the same time.Community – Any group of organisms belonging to a number of different species that co-exist in the habitat or area and interact through trophic and spatial relationship.
Ecosystem – A community of organisms and their physical environment interacting as an ecological unit.
Habitat is a typical environment of a particular organism or population or community.
OR
An area occupied by a particular organism or population or community.
Biosphere – Is the total volume of the earth in which life permanently exists.
Approaches to Ecology
A proper understanding of ecology requires simultaneously consideration of all factors interacting in a particular place.
Ecologists adopt one of the several main approaches when undertaking a new investigation.
Five approaches can be identified.
Ecosystem Approach
This approach focuses on the flow of energy and cycling of matter in the ecosystem i.e. between the living and non-living component of the ecosystem. In this approach an ecologist relationship (such as feeding) between organisms and environment rather than description of the species.
Community Approach.
This focuses in particular on the biotic component of the ecosystem. In this approach e.g. one examines the plants, animals and microbiology of recognizable biotic unit such as wood land, grass land and heat land. The functional aspects of physical environment is not studied in detail, it emphasis on identification and description of species present and factor that control their presence. Community approach is synonymous to synecological approach.
Population Approach (Ant ecological approach)
This approach focuses on identification and description of individual species in relation to its environment.
Habitat Approach
This focus on description of typical environment of a particular organism, population, community or ecosystem.
Evolutionary and historical approach
This focuses on the changes that have occurred in the organisms over time and the development of technology and culture of the human species.
THE ECOSYSTEM
The ecosystem refers to a community of organisms and their physical environment interacting as an ecological unit.
The term describe the whole complex of organisms living together as a sociological unit and its habitat.
Component of the Ecosystem
The ecosystem is made up of living and Non- living components
The living component of the ecosystem is known as biotic component, these include plants, animals, microorganisms e.t.c
The Non- living component is known as Abiotic component. The Non- living component of an ecosystem is divided into:-
- Soil
- Water
- Climate
Soil and water contain a mixture of inorganic and organic nutrients.
Climate includes environmental variables such as light, air, water, temperature.
ENERGY FLOW AND NUTRIENT CYCLING
The essence of ecological studies lies in understanding how connections between the different organisms and their Abiotic environment work.
Energy flow and biochemical cycling are important functional links between the different ecosystems.
The two factors maintain the stability of the ecosystem. Stability of ecosystem means that the ecosystem can adjust to changes within itself.
The ecosystem is also sustainable i.e. it continues on its own without the necessity for human intervention.
Energy is defined as the capacity to do work.
Living organisms are likened to machines in that they require energy to keep them working i.e. to stay alive.
The Ecosystem like machines is kept working by an input of energy and nutrients. The ultimate source of energy in the ecosystem is the sun.
The sun is a star which releases vast amount of solar energy in space. The solar energy is captured by autotrophs in photosynthesis converting it into chemical energy (in form of food sources)
In the Biotic component photosynthetic organism utilize the sun’s energy directly and pass it to the other components of the ecosystem.
The energy is passed from the photosynthetic organism to the other through feeding relationship. The passage of energy through various component of the ecosystem is known as Energy flow. It is referred to as energy flow rather than energy circulation because (the energy released from the sun after passing through the component of ecosystem does not go back to the sun it is dissipated in the atmosphere as heat remain locked in some component of the ecosystem) it is changed into forms which cannot be used again by the system mainly heat energy.
BIOCHEMICAL CYCLING (Cycling of Matter)
The chemicals found in living organisms are derived originally from the abiotic components of the ecosystem such as soil, water, air to which eventually return by the way of decomposition dead organic matter.
Bacteria and fungi bring about decomposition obtaining the energy from the dead organism in the process.
Biochemical cycling is the constant cycling of chemical matters needed by living organisms within the ecosystem, the process is called biochemical cycle since both living and non- living part of the ecosystem is involved.
- Light Biotic component heat energy
- Energy
- Nutrients
- Abiotic component
- Energy flow
Cycling of nutrient
ENERGY TRANSFER
The concept of food chain, tropic level and food web.
Energy containing organic molecules produced by autotrophic organisms is the source of food (materials and energy) for heterotrophic organisms.
Green plants, algae and some few bacteria (blue – green bacteria) are photosynthetic. Green plants mainly convert sunlight energy into chemical energy (food) which is used by animals some animals feed on plants in turn these animals are fed on by other animals. In this way the energy is transferred through a series of organisms.
FOOD CHAIN
Refers to the series of organisms each feeding on the proceeding organism and providing raw materials and energy for the next organism.
Each food chain starts with producers
Producers – are the autotrophic organisms or the organisms which in turn are eaten by other organisms.
On the basis of food relations the biotic components of the ecosystem can be put into the following categories.
Producers: These are autotrophs which synthesis the food using sunlight energy.
They include green plants, algae, protoctists and phototrophic bacteria.
Major producers of the aquatic ecosystem are algae, often minute unicellular algae that make up the phytoplankton on the surface layer of the oceans and lakes.
On land the producers are large plants, namely angiosperms and conifers which form the forest grass lands.
Consumers
These are heterotrophs that obtain energy from producers directly or indirectly.
They can be put in various categories.
Primary consumers
These are consumers that feed on producers.
They are referred to as herbivores on land; typical herbivores include insects as well as reptiles, birds and mammals.
In aquatic ecosystem (fresh water and marine) the herbivores are typically small crustaceans and molluscs. Most of these organisms such as water fleas, cope pods, crab larvae, barnacles and bivalves are filters feeders.
Secondary consumers.
These are consumers that feed on herbivores
They are carnivores i.e. feed on flesh
Examples of secondary include carnivores such as wolf, snake.
Tertiary consumers
These organisms feed on secondary consumers (the carnivores)
Example are carnivores like lion, tiger, hawk e.t.c
NB:
Secondary and tertiary consumers may be
Predators which hunt capture and kill their prey
Carrion feeder which feed on corpses
Parasites – in which case they are smaller than their host.
DECOMPOSERS AND DETRIVORES
Decomposers – Are microorganisms mainly fungi and bacteria which live as saprophytes and feed on dead organic matters. They secrete digestive enzymes on to dead materials and absorb the product of digestion.
Detrivores – These are organisms that feed on small fragments of decayed or dead materials termed detritus.
Many small animals feed on these, contributing it to the process of breakdown, because of combined activities of the true decomposers. (Fungi and bacteria) and detrivores (animals), they lead to the breakdown or decomposition of material.
Examples of detrivores are the earth worm
Decomposers and detrivores form their own food chain.
TROPHIC LEVEL
Refers to the stages of food chain
Each group of organism in a food chain form the tropic level (trophos – feeding).
The energy flows one way through various trophic levels.
There are usually four or five trophic levels and seldom more than six. Why?
Energy decreases as one move from one trophic level to another. There is less energy to support the organisms.
The first Trophic level is occupied by producers (autotrophs).
The second trophic level is occupied by the herbivores
The third trophic level is occupied by secondary consumers – the carnivores.
The fourth trophic level is occupied by the carnivores (Tertiary consumers)
ECOLOGICAL PYRAMIDS
Feeding relationship and energy transfer through the biotic component of ecosystem may be quantified and show diagrammatically as ecological pyramids. These shows the induced changes within a single system. Ecologists use these pyramids in gathering data for quantitative comparison of all major world ecosystem.
Pyramids of Numbers
In ecosystems the smaller organisms usually outnumber the
large organisms. Pyramid of numbers shows the number of organisms in
each trophic lever and how they change in successive levels of
ecosystem.
.In a trophic lever based pyramid of numbers the organisms
of a given area are first counted and then grouped in their trophic
levers.
.There is a progressive decrease in the number of animals at each successive level
.Plants in the first trophic level often outnumber animals
at the second trophic level but it will depend on the relative size of
organism
Types of Pyramid of numbers.
Pyramid of Biomass
This take consideration of the total mass of the organisms (biomass) estimated at each trophic level. Ideally the dry mass is compared.
The estimation of dry mass is done by weighing representative individuals (sampling).
The rectangle is drawn in proportation of the mass at a particular trophic level. The biomass at the time of sampling is considered.
This is known as the standing mass or standing crop mass.
Drawback of Pyramid of Biomass
It is more laborious and expensive in terms of time and equipment.
It does not allow for changes in biomass at different time of the year e.g. deciduous tree have a large biomass in summer than in winter, when they have shed their leaves.
The rate at which the biomass accumulates is not taken into account. A mature tree has a large biomass which increases slowly over many years.
Inverted pyramids of biomass are obtained only for aquatic ecosystem. This frequently happens in food chains which start with phytoplankton. These organisms are very small and have a much more rapid town over than their 200 plankton predators.
The pyramid of biomass can be bulged at the middle.
They do not show the rate production (productivity that is the amounts of materials and energy passing from one trophic level to the next).
In a given period of time, period such as one year for example a fertile, intensively grazed pasture may have a small standing crop of grass but higher productivity.
Pyramid of Energy
These are type of ecological pyramid drawn based on the amount of energy at each trophic level.
This shows how much energy passes from one trophic level to the next the length of the producers bar is proportional to the amount of solar energy annually in photosynthesis.
The length of other basis shows the rate at which energy passes along the food chain.
The pyramids of energy take into account the rate of production in contrast to pyramids of numbers and biomass which depict the standing states of organisms at a particular moment in time. The energy at each trophic level is estimated by establishing of the energy value for that trophic level.
NB: The transfer of energy from producers to primary consumers is less efficient than between the other trophic level.
The average efficiency of transfer from plants to herbivores is about 10% and from animals to animals is 20%.
Like other type of ecological pyramids, the energy decreases as you move from lower to higher trophic levels.
The following are the possible causes of this:
Some energy is used for metabolic activities at each trophic level, mainly respiration.
A lot of energy is lost in form of heat hence is not available in the ecosystem energy lost in respiration cannot be transferred to other living organisms.
Some energy is locked in animal or plant parts which cannot be eaten e.g. Bones, horns, nails, and feathers of animals and cellulose materials of plants which are indigestible.
Organisms do not assimilate some of the materials taken in as food.
The consumer population is unable to harvest enough of the food population.
The diagram below represents a pyramid of energy for an aquatic ecosystem.
Carnivores to top carnivores 88
Herbivores to carnivores 1603
Producers to herbivores 14,098
pyramid of energy for silver springs, Florida (energy flow in KJ m-2 yr-1)
NB:
Each bar of a pyramid of energy represents the amount of
energy per unit area or volume that flow through that trophic level in
given time period.
Usefulness of Pyramid of Energy.
It takes into account the rate of production, in contrast to pyramids of numbers and biomass which depict the standing states of organisms at a particular moment in time.
It allow different ecosystem to be compared including the relative importance of population within one ecosystem.
They tell how much energy is required to support each trophic level because only a proportion of energy in a level is transferred to the next.
Energy pyramid are never invested nor do they have a central bulge
Energy pyramids are more informative than the pyramid of number and biomass.
Input of solar energy can be added as an extra rectangle at the base of pyramid of energy.
Disadvantages of Ecological Pyramid of energy.
They are the most difficult to obtain data
They are not an accurate method of representing energy content of the ecosystem.
General criticisms of Ecological pyramids
The pyramids of numbers, biomass and energy depend on assigning living organisms to trophic level. While the correct level is obvious for plants and obligate herbivores. Many carnivores and omnivores eat a varied diet and thus their trophic level varies according to the food selected.
It is hard to fit dead material (detritus) and other waste together with their consumers into conventional pyramids. These materials are important as a food source.
BIOCHEMICAL CYCLES – The cycling of Matters
The chemicals found in living organisms are derived originally from the abiotic components of the ecosystem such as soil, water and air to which they eventually return by way of the decomposition of waste products or dead bodies of organisms. Bacteria and fungi bring about decomposition; obtain energy from the waste products and dead organisms in the process.
Biochemical cycling is the constant cycling of chemical materials needed by living organisms within the ecosystem.
The process is called biochemical cycle since both living and non-living parts of the ecosystem is involved.
Distinction between chemical cycling and energy flow.
Chemicals in the ecosystem are constantly recycled and used again, on the other land; energy transferred within the ecosystem is changed into forms which cannot be used again by the system, mainly heat energy. Because some of the energy is lost we cannot talk of recycling rather than the flow of energy through the ecosystems.
To maintain the ecosystem, frequent and regular inputs of solar energy is needed.
Cycles can be recognized for all chemical elements that occur in living systems. The biogeochemical cycles for carbon (C), Nitrogen (N), Sulphur (S) and Phosphorus (P) are very important. These elements from the major macronutrients in Biochemical cycles for Nitrogen and carbon.
NITROGEN CYCLES
Nitrogen is an abundant element in the atmosphere. Nitrogen makes up about 78% of the atmosphere by volume, yet very few organisms can use this gaseous nitrogen directly instead they depend upon soil minerals, especially nitrates as their source of nitrogen plants cannot incorporate nitrogen into organic compounds and therefore depend on various types of bacteria to make nitrogen available to them.
Nitrogen deficiency commonly limits plant growth. This is the main reasons that nitrogen is commonly applied in the form of artificial fertilizers.
The nitrogen cycle can be summarized as follow.
Nitrogen Fixation
This refers to the conversion of the free nitrogen (N2) in the atmosphere into nitrates, ammonia or other ammonium compounds. This is accomplished in several way
i.Biological fixation – This occurs when nitrogen (N2) is reduced and added to organic compound by action of Nitrogen – fixing bacteria such as Azobacter and clostridium, the cyano bacteria in aquatic system and some free living bacteria in the soil are able to reduce nitrogen gas to ammonia (NH3).
Other nitrogen – Fixing bacteria e.g.: Rhizobium infects and lives in modules on the roots of leguminous plants. They make reduced nitrogen and organic compounds available to the host plants.
ii.Electrochemical and photochemical fixation
In this process nitrogen gas is converted to nitrate (NO3) in the atmosphere by lightening and other cosmic radiations on oxygen and Nitrogen lightening and other cosmic radiation provide high energy needed for nitrogen to react with oxygen.
iii.Industrial fixation – Fixed by chemical fertilizer industries to the nitrogen cycle when they convert nitrogen gas to nitrate for use as fertilizers.
Nitrification
Nitrification is the production of nitrates. Nitrogen is converted to Nitrate (NO3–) in several ways.
By lightening and other cosmic radiation
By the action of nitrifying bacteria ammonia (NH3) in the soil is converted to Nitrates by certain soil bacteria in a two – step process flost, nitrite producing bacteria convert ammonia to nitrite (NO2–) this is achieved by free living bacteria such as Nitrosomonas.
2NH3 + 3O2+ 2NO2– + 2H+ + 2H2O
Ammonia oxygen nitrite hydrogen ion water
The second step involve the oxidation of the Nitrite by other free living bacteria e.g. Nitrobacteria and nitro coccus
2NO2–+ O2 2NO3–
Humans make a most significant contribution to the nitrogen cycle when they convert nitrogen gas to nitrate for use in fertilizer.
Nitrogen used by plants and animals.
Plants take the nitrates from the soil and form proteins. When animals eat plants the proteins are converted into animal proteins. The breakdown of protein is excreted in the form of urea or uric acid or ammonium compounds. In the soil or water, decomposition of the waste takes place and nitrogen is converted back to free nitrogen involving number of steps.
Decomposition by Microorganisms
Like Actinomycetes and fungi and by ammonofying bacteria. These convert wastes and decayed and dead boodles to ammonia or ammonium compounds.
Denitrifying bacteria
Denitrification is the conversion of nitrate to nitrogen gas. These are denitrifying bacteria in both aquatic and terrestrial ecosystem. Examples are the Pseudomonas and Thiobacillus, Detoxification counter balance nitrogen fixation but not completely. More nitrogen fixation occurs especially due to fertilizer production.
CARBON CYCLE
Carbon is an element found in all organisms. It is a basic
building block of all living things it is essential part of
carbohydrates, fats and proteins. Carbon is present in the atmosphere as
carbon dioxide the carbon enters the ecosystem through the producers.
In carbon cycle organisms in both terrestrial and aquatic ecosystem, exchange CO2 from the air and through photosynthesis they incorporate carbon into food that is used by themselves and heterotophs.
When any organism respires a portion of carbon is returned into the atmosphere as CO2.
In aquatic ecosystem, the exchange of CO2
with atmosphere is indirect. Carbon dioxide from the air combines with
water to give carbonic acid, which break down to bicarbonate ions.
(HCO3–). Bicarbonate ions are the source of CO2 for algae, which produce food for themselves and for heterotrophic.
Similarly when aquatic animals respire, the CO2 they give off becomes bicarbonate. The amount of bicarbonate in water equilibrates with the amount of CO2 in air.
Carbon cycle can be summarized as follows.
The producers (green plants and algae) use CO2 to make food.
Herbivores eat plants and carbon gets into the body of carnivores.
Both plants and animals respire. The process returns CO2 to the atmosphere.
When plants and animals die, the decomposers break down dead bodies and carbon is released to the soil where it is absorbed by plant roots.
Some organic matter does not decompose easily instead, it build up in the earth’s crust oil and coal were formed from the building of the plants and animal’s matters millions of years ago.
The burning of fossil fuels has added much of carbon in the atmosphere in form of CO2.
Reservoirs of Carbon
Oceans and seas are large reservoir of carbon in form of HCO3–. This can be used to build up shells of marine organisms. Some reaction change bicarbonate into CO2 that return to the atmosphere.
Living and dead organisms contain organic carbon and serve as one reservoir for carbon cycle.
Living things particularly trees remains of plants and animals are estimated to hold billions of tons of organic carbon.
Some plants and animals remains before complete decomposition, were subjected to physical process that transformed these into coal, oil and natural gas. We call the material fossil fuels.
Calcium carbonate that accumulate in limestone and calcium carbonate in carbonate shells.
The influence of Human on carbon cycle
The activities of human beings have increased large amount of CO2 in the atmosphere. These activities includes:
Burning of fossil fuels e.g.; coal and oils used for running machines and automobiles. These results into release of much CO2 and other gases in the atmosphere.
Burning of fuel wood i.e. firewood and charcoal
Deforestation i.e. destruction of forests through burning on cutting trees.
Deforestation reduces the total world volume of photosynthetic materials and thus reduces consumption of atmospheric carbon dioxide in photosynthesis.
Removal of the tree canopy exposes the forest floor to sunlight and warmer temperatures. In forest or woodlands with significant filter and soil humus contents this expose will favor accelerated rates of decomposition and carbon dioxide release.
ECOLOGICAL NICHE
Ecological niche is the ecological team which is used to refer to the physical space as well as its functional role of a particular group of organisms.
Ecological niche have been defined in different ways.
The niche of organism is defined as its profession or total role in a community, e.g. an organism can be producer, consumer, predator, scavenger or a decomposer.
Defined as a place occupied by a species in an ecosystem and the way it use the resources of the ecosystem.
The niche of an organism means its place in a biotic environment and its relation to food, enemies, habits and biological factors.
A Population of each species within a community has a separate need. No two species within a community can have the exact same need. If two species do occupy the same need, it leads to competition until one is displaced.
Similar habitat in the world have similar ecological niches but may have different animals e.g. Open grasslands all over the world produce a need for fast running herbivores like horses, kangaroo, and antelopes.
ECOLOGICAL SUCCESSION
Formation of a community
A group of organisms of different populations co. existing in the same habitat
Community ecology focuses on the development and stability of the communities.
A community is built up over a period of time
Does the community remain the same indefinitely?
A community is a dynamic unit
A stable community is established through number of stages which are orderly.
During the time of development there will be an orderly and progressive replacement of one community by another till a relatively stable community is established. This is called ecological succession.
Ecological succession is the process in which a community is evolved from simple beginning to more complex which is more or less stable. A complete succession is called a sere.
A sere is made up of a number of several stages.
A complete stable community is called a climax community.
Types of Ecological succession
Primary succession
Secondary succession
Primary succession – Is a type of succession when the community is established where no community has previously existed.
E.g. On sandunes, volcanic island larva flows (bare rocks). The area is devoid of any organisms.
2.Secondary succession – Occurs where a community has been disrupted and the surface is completed or largely devoid of vegetation. It may be due to earth quake, fire or even clearing of forest by man.
METHODS OF STUDYING ECOLOGY
Sampling Technique
Sampling technique is a method of establishing a sample.
Sample – is a number of items all things taken from large group and used to provide information about the whole group.
Types of sampling
(i) Random sampling
Is a type of sampling in which every item of the universe has an equal chance of inclusion in the sample
(ii) Systematic sampling
It involves selection of every in the item in a list (an element of randomness is introduced into this kind of sampling by using random numbers to pick up the unit to which to start.
(iii) Stratified sampling
Is a type of sampling in which the population is divided into several sub population on that are individuals more homogenous group than the total population.
The size of a sample (sample size)
This refers to the number of item to be selected from the set of objects (population or universe) to constitute a sample excessively.
ADVANTAGES OF SAMPLING
It makes the study easier since few organisms are involved.
Since only few organisms are under study this save time and reduce the financial cost if large group of organisms were to be studied.
Sampling methods
- By transects
- By quadrants
- Point frame
- Pit fall
- Box trapping.
- Ways of establishing a sample
- Transects – line transect
- Belt transect.
- Quadrants – quadrat
- Pin frame (point quadrant)
- permanent quadrat.
Line transect
Is a method where a tape or string is run along a ground in a straight line between two points or poles .
Belt transect
A belt transect is simply a strip of chosen width through the habitat made by setting up two line transects say 0.5m to 1m a part.
What is a Quadrant?
A quadrant frame is a metal of wooden frame preferably collapsible to facilitate carrying, which forms a square of known area such as 0.25m2 or 1m2
The way a quadrant is used
i) Random throw
ii) Used with line transects
The use of these methods depends on (number of factors) nature of investigation.
Other types of quadrants
Pin frame (point quadrant).
This is a frame bearing a number of holes through which a pin “such as knitting needle can be passed”
Permanent quadrant
This is used in long term ecological investigation involving the study of community change (succession or seasonal changes).
- Other methods
- Computer program
- Direct observation
- Photographs
- Pit fall trap
- Box trapping
Capture – recaptured methods
This methods involves capturing the organisms, marking it in some way without causing it any damage and replacing it so that it can resume a normal role in a population e.g. Fish are netted.
The capture – recapture method of sampling is used to try to estimate the entire population, a sample of animals is caught and tagged their number noted and then released into their habitat. Later another sample is captured and the proportion of tagged animal in this sample should be representative of the proportion of tagged animal in the whole population and then the total population size can be estimated using this formula.
Total = original no tagged x total recaptured
No. of tagged on recapture
Some examples of how to use this formula
Example 1
50 animals are caught and tagged and released. Later 220 animals are caught and it is noted that 35 of their animals are tagged. What will be the total population estimate?
= 50 × 220 ÷ 35
= 314.28
Example 2.
A biologist caught 100 deers in a forest, tags them and
releases them back in the forest. A year later he caught 90 of which 12
had tags, estimate the total population of the dear.
The use of quadrats direct observation and photography are known as direct counting methods, where as capture recapture technique is indirect counting method.
Different methods that are used to establish the samples provide the means of calculating three aspects of species distribution.
Species density
This is the number of individual of a given species in a given area such as 10 per meter2 (10m-2)
Species Frequency
This is measure of the probability (chance) of finding a given species with any one throw of a quadrat in a given area.
Example:
If the species occur once in any 10 quadrats it has a frequency of 10%.
Species cover
This is a measure of the proportion of ground occupied by the species and gives an estimate of the area covered by the species as a percentage of the total area.
Capture method by removal
In this method the number of animals captured is recorded and the animal kept. This procedure is repeated a further three times and the gradually reducing number recorded. A graph is plotted of number of animals captured per sample against the previous cumulative number of animal captured. By extrapolating the line of the graph to the point at which no further animal would be captured (i.e. number in sample = 0)
Example
|
Sample |
No. in sample |
Cumulative sample size |
|
1. |
120 |
|
|
2 |
93 |
120 |
|
3 |
60 |
213 |
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