The Competition Between The Two Green Algae

: Essay, Research Paper


This experiment tested the hypothesis that the pure algae populations of Ankistrodesmus and Chorella will demo growing in the figure of beings, and the assorted population will set up a dominant species. Each population should besides make its transporting capacity. All of the populations had the same resources available.

The sampling of 0.5ml of each population was used to number the figure of beings. A Neubauer slide and microscope will be needed to make this. From this count, find the figure of beings in 1ml. After making this process for three hebdomads the beings in the pure samples should hold grown in size and reached a carrying capacity. The assorted population of the two algae species should demo that one species is dominant over the other. The consequences of the experiment support this hypothesis.

Both the pure samples of Ankistrodesmus and Chorella increased dramatically in size and so reached their carrying capacity. The assorted population showed that Chorella is the dominant species over the Ankistrodesmus.


This experiment was conducted by utilizing the green algae: Ankistrodesmus and Chorella. Most species of green algae live in shallow fresh water environments. The can populate on moist stones, trees, and dirt ; some can populate shallow ocean Waterss. Green algae normally occur as individual cells or as multi-cellular, filamentous fibrils, hollow balls, or level sheets ( Postlethwait and Hopson ) .

This experiment was used to analyze the growing of the algae and the effects of competition when grown in a limited resource. Competition is a competition between challengers for the same resource and home ground. The experiment was concerned with numbering the figure of algae in 1ml. There was a pure sample of both Ankistrodesmus and Chorella. There was besides a population that contained a mixture of the two algae.

Two types of competition were observed. Inter-specific competition occurs within a population of different species. Intra-specific competition occurs within a population of the same species ( Starr and Taggert ) . If a resource is abundant so there is no competition. Gauses Law provinces that one species will ever hold an advantage over the other when viing for the same resource ( Marshall and Walton ) . The species that has the advantage over the other will set up itself as the dominant species.

During the experiment a transporting capacity will be observed for all populations of algae pure and assorted. After a period of rapid growing the population will get down to level off. This grading off marks the transporting capacity of the environment. Transporting capacity can be affected by several factors. Birth rate and in-migration can increase the size of population. Death rate, natural catastrophes, and out-migration can diminish the size of a population. The sum of available resources can besides impact the carrying capacity ( Marshall and Walton ) .

The biological inquiry was the consequence of growing of algae and the competitions in the populations. The justification of this experiment is to analyze how competition affects the different populations.

Methods and Materials

The independent variable tested was the clip used for the observation, which covered three hebdomads. The dependent variable was the figure of algae counted. There are three side-arm flasks incorporating the populations of algae. There is one population of Ankistrodesmus and one population of Chorella each in a separate side-arm flask. The 3rd side-arm flask contains a mixture of equal parts of the two types of algae antecedently mentioned. The control group was the pure samples, while the experimental group was the assorted population ( Marshall and Walton ) .

After the Neubauer slide and screen faux pas were sterilized with 90 five per centum ethyl alcohol, the stuffs are to be placed on a clean paper towel. Using a unfertile 1ml syringe, take 0.5ml of the population from the side-arm flask. Samples were taken from the other two flasks when this population has been counted. Make certain to twirl the side-arm flasks before taking the population to see that the population is equally distributed ( Marshall and Walton ) .

After taking the sample, place the tip of the acerate leaf into the channel of the Neubauer slide and shoot a little part under the screen faux pas so it fills the grid. The sample will travel by capillary action to make full the channel. Then put the slide on the microscope phase and number the figure of beings in the grid. The count was taken from each of the two grids called Levy Counting Chambers ( Marshall and Walton ) .

Add together the figure of beings in the two grids, this equals the figure of beings per 1 mm3. To cipher the figure of beings in 1 ml. , multiply the figure of beings in 1mm3 by 1,000.

This is because 1000 mm3 = 1 milliliter. ( Marshall and Walton ) .

The same processs were followed and the same stuffs were used for each of the other hebdomads. Data was collected and recorded on the tabular arraies.


The estimated figure of species changed from hebdomad to hebdomad. The populations of the algae increased in size from Week 1 to Week 2. The pure population of Ankistrodesmus increased from 32,000 to 656,000 from Week 1 to Week 2. From Week 2 to Week 3 the Ankistrodesmus population decreased from 656,000 to 562,000. This showed an addition followed by a lessening or leveling off period.

The pure Chorella population showed about the same consequences as the pure Ankistrodesmus population did. The Chorella population increased quickly from 702,000 in Week 1 to 1,071,000 in Week 2. The population decreased from 1,071,000 to 968,000 in Week 3. This population besides reached its carrying capacity.

The mixture of the Ankistrodesmus and Chorella populations did non demo the same consequences as the pure samples did. The Ankistrodesmus population somewhat increased from 122,000 in Week 1 to 146,000 in Week 2. Alternatively of the population leveling off or diminishing somewhat as the pure populations did, this population increased from 146,000 to 178,000 in Week 3. The Chorella population more than doubled from 241,000 in Week 1 to 517,000 in Week 2, and so increased once more to 746,000 in Week 3. Even though the population kept increasing it seemed to be grading of. The Ankistrodesmus population was the dominant species in the mixture.

Table 1 shows how the populations of the different samples changed from hebdomad to hebdomad.

Graph 1 shows how the populations of the pure samples of Ankistrodesmus and Chorella changed from Week 1 to Week 3.

Graph 2 shows how the Ankistrodesmus population established its laterality over the Chorella population.

Table 1: Summary of all Population Growth over 3 Weeks

Sample # per milliliter. During Week 1 # per milliliter. During Week 2 # per milliliter. During Week 3







This experiment evaluated competition among algae species. The undermentioned hypothesis was formed and tested. The pure algae populations Ankistrodesmus and Chorella will demo growing of the population. The assorted population of the two species will vie and one species will go a dominant species.

In the pure samples of algae the competition was intra-specific. Each algae competed with one another for the infinite and visible radiation available ( Starr and Taggart ) . In population H, the pure sample of Ankistrodesmus and in population G, the pure sample Chorella, there was a dramatic addition followed by a lessening or leveling off period. This confirmed that the population had reached their carrying capacity. The Ankistrodesmus population had less beings than the Chorella population did at the terminal of the experiment. This could let another hypothesis: The Chorella population will increase faster than the Ankistrodesmus population. A different experiment would be needed to prove this hypothesis.

In the assorted population F, the Chorella population behaved about the same as it did in the pure sample. It increased rapidly and so started to level off. However, the Ankistrodesmus population did non get down to level off, it kept increasing. The Chorella population established itself as the dominant species in the mixture.

The pure populations of Ankistrodesmus and Chorella showed population growing. The assorted population showed which species would go the dominant species. A transporting capacity was besides found in the population growing.

Some mistakes of the experiment could be that there was non an equally distributed sample because the side-arm flask was non swirled. Estimating the population to a big figure could besides increase the mistake of the experiment.

In decision, competition is a portion of mundane life. A species will vie with members of the same species every bit good as members of different species. Many factors can find which peculiar type of beings will hold an advantage when viing. The figure of the beings that do last and reproduce will make a carrying capacity when the environment runs out of resources.


Marshall, Joseph A. , and Walton, Cheryl L. , 1999, Micro-sampling 1-4, Competition 1-3, Explorations in Biology.

Postlethwait, John H. and Hopson, Janet L. , The Nature of Life, 3rd Edition, p. 481.

Starr, Cecie and Taggart, Ralph, 1998, 8th Edition, Population Ecology, Biology: The Unity and Diversity of Life, p. 793-803.

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