Introduction: (Initial Observation)
Algae are any of various chiefly aquatic, eukaryotic, photosynthetic organisms, ranging in size from single-celled forms to the giant kelp. Algae were once considered to be plants but are now classified separately because they lack true roots, stems, leaves, and embryos. Some species of algae are edible and are used as gelling agents in some foods. Some other types of algae contain harmful toxins and are hazardous.
If water is going to be used as drinking water, presence of algae can make the process of filtration more complex and costly. Algae is needed in aquariums and lakes to create a balanced ecosystem. With all these, it seems important for us to be able to control the growth of algae. This knowledge will help us to promote algae growth where we need it and stop algae growth where it can be harmful.
In this project we will study the conditions favorable for the growth of algae. We will investigate the effect of light, temperature, and nutrients as a part of our study.
As your science project, you may only choose and study one of the factors that may affect the growth of algae.
Information Gathering:
Find out about algae. Read books, magazines or ask professionals who might know in order to learn about the varieties and the biology of algae. Keep track of where you got your information from.
If you are searching the internet, use keywords such as “Algae Biology” in order to find information about algae as an organism. To learn about possible uses of algae you can search for “Algae used” and for methods of algae control you can search for “Algae control”. Since you are studying the factors that affect algae growth, you should also search for keywords such as “Algae growth”, “Algae temperature”, and “algae nutrients”. The following are some sample information that you may find.
Algae, Basic Biology
By. Jim Wolf C.S.U.N. Marine Biologist
Algae are called “autotrophic organisms”, and this means that they produce their own food by a process called photosynthesis. This process allows for the conversion of carbon dioxide (CO2) and water (H2O) in the presence of light and chlorophyll to create oxygen and simple sugars. This crucial process is responsible for supporting much of the life on this planet. Under conditions of optimum photosynthesis, algae put off large amount of oxygen, clean up the water, as well as provide food for other organisms. Suffice to say that it is a good idea to encourage algae to grow in aquariums for they help to create a more natural and stable environment.
Some of the more crucial factors that affect the growth of algae are: light, water flow, temperature, nutrient concentrations, and competition (both from other algae, as well as many organisms that might eat or compete with the algae). Lets now consider each of these factors in more detail. Light by far is the most critical factor. Many coral reefs are characterized by having very high levels of light intensity, so salt water aquariums require large amounts of lighting. The quantity, spectrum, and duration all influence not only what types of algae are present, but their relative abundance. Using traditional fluorescent lights, it is virtually impossible to over light a salt water aquarium. A photo period (the amount of time the light is actually on) of about 12-16 hours a day is good. If there are many lights on an aquarium, it is a good idea to turn them on and off in succession. This will help simulate the natural rise and fall of the sun. Lighting considerations are tank specific and to compute the amount of light required calls for specific numbers (depth, bulb number, organism types et.) For a good review of the pertinent facts see Martin Moe’s Marine Aquarium Reference.
Nutrient concentrations also affect algae populations. Many types of hair algae and slime algae grow in response to excess nutrients (particularly nitrates and phosphates). Coral reefs are especially low in nutrients, this coupled with the vast amounts of herbivores (plant eaters) keeps algae populations low on reefs. Certain macroalgaes require supplements of iron and other trace elements to keep them healthy. Tanks with poor lighting, excess nutrients, and low flow often have excessive amounts of unattractive slime and filamentous algae. Flow affects algae in the following way. Areas of low flow are referred to as stagnant. In these stagnant waters the algae quickly uses up the available CO2 and nutrients and subsequently stop photosynthesizing. Many desirable macro algae require high flow to insure adequate nutrient supply. These algae should appear to be moving in the current. If this is not so, they may be quickly overtaken by other undesirable “low flow” film forming algae . Temperature usually only affects algae communities if it deviates too much (not a problem in temperature controlled tanks).
Algae are a diverse group of organisms that cause mayhem even when professional systematists and biologists try to define them in relation to other organisms. There are sufficient morphological, physiological and ecological similarities between them to make the term ‘algae’ an acceptable one, yet it seems that the term ‘algae’ means different things to different people. However, this does not mean that we should shy away from naming them aptly, nor does this mean that we should stop trying to understand the taxonomic relationships amongst the algae, and between algae and other organisms.
Through the years, algal classification has been very unstable. Placements at the kingdom and lower levels, are currently still dynamic. It is interesting to trace the changes in their position in the hierarchy of life.
Click on the buttons below to find out more about their classification.
Algal groups
- Bluegreen algae, (AKA Cyanobacteria). Introduction to the Cyanobacteria, Architects of earth’s atmosphere
- Research on the Biology and Control of Toxic Blue-green Algae under Project Leader, Dr Gary Jones (CSIRO, Australia).
- Cyanosite: A Webserver for Cyanobacterial Research
- CYANOFIX: A European Science Foundation Scientific Programme
on Cyanobacterial Nitrogen Fixation
- Rhodophyta, (AKA red algae). An introduction to the Rhodophyta.
- Coralline red algae. Introduction; Guide to Families, Subfamilies & Genera; Extensive Bibliography; Other information.
- The Rhodophyta (red algal division) occur worldwide, from the Sands Hotel in Las Vegas to the burly
beaches of Australia. Lots of pretty pictures of red algae. - A few pictures of red algae on a Gopher server.
- Chlorophyta, (AKA green algae). Introduction to the “Green Algae”
- Green Algae: Chlorophyta.A site with lots of photographs of green algae.
- The seven veils of Halimeda. Despite its title, this site contains a thorough biological and geological appraisal of a calcareous green seaweed which lives in warm seas, particularly on and near coral reefs.
- Euglenophyta: Introduction to the Euglenoids
- Chromista. Introduction to the Chromista, from microbes to giants. . .
- Brown Algae: Phaeophyta. A site with lots of photographs of brown algae.
- Diatom Home Page, Biology Department, Indiana University. This site contains information of general interest to diatomists and other phycologists along with links to other useful Internet resources.
The green algae is the most diverse group of algae, with more than 7,000 species growing in a variety of habitats. Green algae is also primarily aquatic. Ulva is a small genus of marine and brackish water green algae. It is edible and often called “Sea Lettuce.” Its most distinguishing characteristic is its bright green color.
Algae: occurrence and classification
Occurrence
Found in marine, freshwater, and terrestrial habitats.
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- Marine: phytoplankton, seaweeds and symbiotic dinoflagellates in corals and sea anemones. Freshwater: phytoplankton, free-floating and attached filaments, epilithic (on stones).
- Terrestrial: damp soils, blue-greens important in N-fixation in soils and salt-marshes, walls, trees, bare rock in damp situations. The red colouration on south and south-west facing walls of houses in the Galway area (west of Ireland) is an alga called Trentepohlia and not a fungus as sometimes advertised in the local newspapers.
Classification
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- Seaweeds: Green algae (Chlorophycota); Brown algae (Phaeophycota); Red algae (Rhodophyta); some Blue-green algae (Cyanophycota = Cyanobacteria).
- Marine Phytoplankton: Diatoms (Bacillariophyta); Dinoflagellates (Dinophyta); Chrysophyta (<10 µm in diameter). Other small groups.
- Freshwater Phytoplankton: Diatoms (Bacillariophyta); blue-green algae; Chlorophyta; Prymnesiophyta (<10 µm in diameter).
- Terrestrial algae: Vaucheria and Botrydium (Xanthophyta); blue-green algae; Chlorophyta.
Sewage ponds: Blue-green algae and Euglenophyta.
How is algae used?
Although fish and other seafood products make delicious and healthy meals for people around the world, many American children would not object if they never had to eat another tuna casserole again. But they would object if suddenly there were no more cheese, chocolate milk, peanut butter, pudding, frozen desserts or fruit drinks. What could so many different types of food products have in common? These are just a few food products that contain plants which grow in the sea, seaweed.
Many kinds of seaweed are eaten by people because they are full of vitamins and iodine. Asian cultures use seaweed like green beans and carrots are used in the United States. But because American people have not developed a taste for seaweed, manufacturers use derivatives from seaweed instead. These alginates, carrageenan, and beta carotene, act as stabilizers, thickeners, and colorants in the foods Americans eat today.
Seaweeds are really not a weed but large marine algae that grow in the coastal waters of many countries. They include thousands of species from microscopic plants called phytoplankton to huge floating/anchored plants commonly seen washed up on shore. The three main groups of seaweed are brown, red, and green algae and each one provides important ingredients for manufacturing foods. For example, carrageenan is a generic term for compounds extracted from species of red algae used in stabilizing and gelling foods, cosmetics, pharmaceuticals and industrial products. Alginates are extracted from brown algae and are used to make water-based products thicker, creamier, and more stable over extreme temperatures and time, making the product last longer. From green algae a natural pigment, beta carotene, is removed and used as a yellow-orange food coloring in food products and is currently believed to help prevent certain forms of cancer.
Question/ Purpose:
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to identify the environmental factors and nutrients that affect the growth of algae. We will test the effects of temperature and light on algae growth and try to determine whether or not nitrate or phosphate levels affect the growth of algae such as might be found in your local streams and/or lakes. Nitrates are commonly found in farm and lawn fertilizers. Phosphates are common in fertilizers, animal wastes, and detergents. Both substances could reach streams and lakes via runoff from storm waters and if they contribute to algae growth, such runoff needs to be controlled.
Identify Variables:
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
Independent or manipulated variables that we will test in our investigation are:
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- Light (Presence, absence)
- Temperature (cold, warm)
- Nutrient phosphate (presence, absence)
- Nutrient Nitrate (presence, absence)
Note that in each experiment you can only test one variable and you must keep all other variables constant.
Dependent variable that we will monitor and record is the rate of algae growth.
Controlled variables are the type and source of algae and water.
Hypothesis:
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. The hypothesis for this project should state your belief as to whether or not light, temperature, Nitrates, and Phosphates will contribute to algae growth.
This is a sample hypothesis:
I think light, warm temperature, and both phosphate and nitrate nutrients can promote the growth of algae.
My hypothesis is based on my gathered information that algae (like plants) produce their own food by the action of photosynthesis. So the same nutrients and conditions that are good for plants, are also good for algae too. The only difference is that algae live in water.
Experiment Design:
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Do I need to measure the amount of algae?
In the following experiments you may visually compare the experimental algae growths against your control and determine if the growth rate is increased or decreased. You do not need to measure the exact amount of algae.
If for some reason you need to measure the amount of algae, following are different methods that you may do this:
1. Using microscope to count the number of algae cells in one drop of your sample. This method is good for certain types of algae that give a green color to water; however, they are not visible by naked eye.
2. Using Secchi Disk: Algae reduce the clarity of water. Secchi Disk is a measure of the clarity of the water, and a quick, simple, and accurate method for estimating lake water quality. A black and white disk (called a secchi disk) is lowered into the water until it just disappears from sight–this depth measurement is recorded. The deeper the measurement, the clearer the water. in rivers and lakes. Secchi Diskis available at MiniScience.com.
3. The most efficient method is measuring the algae weight. In this method you filter the sample onto a pre-weighed filter then reweigh–the difference is the wet weight. To measure dry weight, filter onto a pre-weighed filter and dry the sample overnight in a low temperature oven (about 60 degrees C) then reweigh to get dry weight by difference.
Experiment 1:
What Effect Does Nitrate and Phosphate Levels Have on the Growth of Algae?
Materials Needed:
1. Three glass or clear plastic containers. If you can obtain them, test tubes would be ideal, 15ml or so in size. You can also use small plastic or glass soft drink bottles.
2. Distilled water (In science experiments you must use distilled water. Regular water may already contain chemicals that affect your experiment results. If you don’t have access to distilled water, use any drinkable water. To make sure that your water sample does not contain chlorine, boil it for about 10 minutes and let it cool again. Chlorine is a strong oxidizer that can harm plants and small aquatic animals.)
3. Graduated cylinder or other means of measuring liquid volume. In a pinch a scaled measuring cup from the kitchen can be used so long as you are also using soft drink bottles as the containers for this experiment.
4. Liquid fertilizer. This can be obtained from local garden shops or hardware stores. Check the label to make sure it has a high nitrate/phosphate content. Compare among available brands of liquid fertilizer to obtain the highest concentration.
5. 10% nitrate/phosphate fertilizer solution. Prepare by mixing 1 part liquid fertilizer with 9 parts distilled water.
6. 20% nitrate/phosphate fertilizer solution. Prepare by mixing 2 parts liquid fertilizer with 8 parts distilled water.
7. An algae culture if available. Most high school and college biology labs should have such a culture. Chlorella algae culture (Ward’s) would be ideal. Otherwise you can take a sample of algae from a local stream or lake. Place the algae in a small open-mouth container, add distilled water and gently stir the algae so as to break up major clumps. This can then be used as a starter culture.
8. A light source, preferably direct sunlight.
Procedure:
1. Label the first container “distilled water” and fill it ¾ full with distilled water. This is the control container against which the experimental containers will be evaluated.
2. Label the second container “10% nitrate/phosphate solution” and the third container “20% nitrate/phosphate solution”. Fill both containers ¾ full with the appropriate solution.
3.Gently mix in the algae culture. If test tubes are used, 10-20 drops of the algae culture should be placed into each tube. If soda bottles or other containers are used, a larger quantity of culture, 2-3 teaspoons should be added. Shake each container gently to mix the contents.
4. Place the containers on a window sill or other well lit area where they can remain unmoved for the duration of the experiment. Alternatively, a grow-light may be used in the experiment must be kept inside away from windows.
5. Consider taking photographs of the containers at the beginning of the experiment, and every three days thereafter. Good photos would be an asset on the display board.
6. Check the test tubes every day for the duration of the experiment. Record any observations on a data table. Look for cloudiness, color, and any other change in the liquids. If small test tubes have been used, five or six days should be sufficient to complete the experiment. If larger containers were used it might be well to let the experiment proceed for up to ten days.
Algae growth will be noted by any increase in the density of the algae as well as an increase in the shade of green color in the containers.
When observations are complete, reach and record your conclusions.
Experiment 2:
What effect does the temperature have on the growth of algae?
Materials Needed:
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- Three small containers
- Aged water (tap water kept outside for a day in an open container)
- Graduated cylinder or other means of measuring liquid volume.
- Three larger cups or any other larger plastic container
- An algae culture if available. Otherwise you can take a sample of algae from a local stream or lake. Place the algae in a small open-mouth container, add distilled water and gently stir the algae so as to break up major clumps. This can then be used as a starter culture.
- A light source, preferably direct sunlight.
- Ice and warm water.
Procedure:
1. Label the first small container “room temperature” and fill it ¾ full with aged water. This is the control container against which the experimental containers will be evaluated.
2. Label the second container “Cold” and the third container “Warm”. Fill both containers ¾ full with the aged water.
3.Gently mix in the algae culture. If test tubes are used, 10-20 drops of the algae culture should be placed into each tube. If soda bottles or other containers are used, a larger quantity of culture, 2-3 teaspoons should be added. Shake each container gently to mix the contents.
4. Now you need to keep one container in cold temperature, one in room temperature and the other in warm temperature. They all should get the same amount of light. For example you can use your larger containers as bath for smaller containers. One large container can have ice water, the other room temperature water and the last one warm water. Place the the containers on the bath.
5. Consider taking photographs of the containers at the beginning of the experiment, and every three days thereafter. Good photos would be an asset on the display board.
6. Check the test tubes or small containers every day for the duration of the experiment. Record any observations on a data table. Look for cloudiness, color, and any other change in the liquids. If small test tubes have been used, five or six days should be sufficient to complete the experiment. If larger containers were used it might be well to let the experiment proceed for up to ten days.
Algae growth will be noted by any increase in the density of the algae as well as an increase in the shade of green color in the containers. You may record your observations in a table like this:
| Temperature | Algae Growth |
| Cold | |
| Room Temperature | |
| Warm |
Visually grade the algae growth with numbers from 0 to 100. Use 0 for no growth. Use 100 if the entire container is the same color and contains the same density algae as your initial algae culture.
Finally use the above results table to draw a bar graph. Your graph will have three vertical bars labeled cold, normal and warm. The height of each bar is the growth grade you assigned.
When observations are complete, reach and record your conclusions.
Experiment 3:
What effect does the light have on the growth of algae?
Materials Needed:
-
- Three small containers.
- Aged water (tap water kept outside for a day in an open container)
- Graduated cylinder or other means of measuring liquid volume.
- An algae culture if available. Otherwise you can take a sample of algae from a local stream or lake. Place the algae in a small open-mouth container, add distilled water and gently stir the algae so as to break up major clumps. This can then be used as a starter culture.
- A light source, preferably direct sunlight.
- Ice and warm water.
Procedure:
1. Label the first small container “room light” and fill it ¾ full with aged water. This is the control container against which the experimental containers will be evaluated.
2. Label the second container “Light” and the third container “Dark”. Fill both containers ¾ full with the aged water.
3.Gently mix in the algae culture. If test tubes are used, 10-20 drops of the algae culture should be placed into each tube. If soda bottles or other containers are used, a larger quantity of culture, 2-3 teaspoons should be added. Shake each container gently to mix the contents.
4. Now you need to keep the three containers in different light conditions, however the temperature must remain the same. The container labeled Light can be placed next to a fluorescent light bulb. Cover the fluorescent bulb and the container with a box or aluminum paper such that only that container will get the light. The container labeled Dark must be covered with aluminum foil or black paper so it will get no light. The other container will remain in the room and gets the room light whenever it is available.
5. Consider taking photographs of the containers at the beginning of the experiment, and every three days thereafter. Good photos would be an asset on the display board.
6. Check the test tubes or small containers every day for the duration of the experiment. Record any observations on a data table. Look for cloudiness, color, and any other change in the liquids. If small test tubes have been used, five or six days should be sufficient to complete the experiment. If larger containers were used it might be well to let the experiment proceed for up to ten days.
Algae growth will be noted by any increase in the density of the algae as well as an increase in the shade of green color in the containers.
When observations are complete, reach and record your conclusions.
Experiment 4:
What effect does cupper sulfate have on the growth of algae?
Procedure:
Get two identical clear containers and fill them up with water containing algae, specially single cell phytoplankton that make the water green.
Add some copper sulfate solution to one of the containers and observe the results within 24 hours. If your samples are in a test tube, 5 to 10 drops of saturated copper sulfate solution suffice. If you are doing your experiment in a larger container increase the amount of cupper sulfate in relation to the size of your container. About 1% is a good ratio for this experiment.
Materials and Equipment:
List of material can be extracted from the experiment section. Prepare the final list after you complete all your experiments because you may need to substitute some materials with others. Secchi Disk is available at MiniScience.com.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
Calculations:
No calculations is required for this project.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Conclusion:
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
The conclusions should discuss whether or not the observations supported the hypothesis. You should compare the amounts of algae growth that occurred in the distilled water to that which occurred in the 10% and 20% solutions and from this, draw conclusions about excessive nitrates and phosphates in the environment.
you will also compare the algae growth in the tubes that were exposed to the light and those remained in the dark. Similar comparison must be made for algae growth in different temperatures.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
Possible Errors:
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
