I have revised different methods and products used to clean areas like households and ponds, as well as their advantages and disadvantages. I have also started to get into the communities of microbes that one might see in their pond, which is the biofilm that is primarily but not completely bacterial. Now I would like to go over another important group of microbes in the pond ecosystem, algae.
The study of algae is referred to as phycology. I stated in the title that it is “The Forgotten Field of Study”. I am sure there are many scientists who are quite passionate about phycology; however, I am referring to this from my point of view. I am studying cancer and, previously, have been working with bacteria and viruses. I have not studied algae since undergrad, so this is just as excellent a review for me as it is for the reader. I am quite happy to be writing about algae because these life forms are highly varied in their size, habitat, form and even method of reproduction. I found reading this topic for my blog very interesting.
The first thing one needs to know is that the word algae is plural. The singular form is alga. For example, the cyanobacteria are also known as a group as the blue-green algae. Conversely, nori is the red alga called porphyra that is eaten in sushi. Algae are a very important group of life forms. As I mentioned in my first post (Germs Are Not All Bad), algae photosynthesize and create just as much oxygen or more than all the plants in the world combined. Most algae, but not all, utilize photosynthesis to create their own nutrients. Forms of life that do this are called autotrophs, which can create organic compounds like carbohydrates, fats and proteins from inorganic compounds and light. Some algae, however, predate on other life forms for nutrients, these life forms are referred to as heterotrophs (Figure 1). Other algae, yet, are even parasites, heterotrophs that live in association with another life form and at the expense of the second life form. As for the habitat of algae most, like the algae found in ponds, live in water and form the foundations of most aquatic food chains. Algae can also live in soil, on trees, in animals as parasites, and in porous rocks like limestone and sandstone. Algae are also capable of living in varied harsh habitats, like in hot springs, polar ice and snow banks.
Figure 1: The cycle between auto- and heterotrophs. Algae, among other life forms like plants, use photosynthesis to use carbon dioxide and water to form complex organic compounds like proteins, carbohydrates and lipids with the assistance from solar energy. These compounds, in turn, are ingested by the heterotrophs for sustenance. Heterotrophs then produce water and carbon dioxide to continue the cycle.
Algae have varied habitats, but their forms are equally varied. Some of the algae are microscopic, unicellular organisms that can live alone as planktonic cells or in colonies. They can also be multicellular organisms that resemble branched and unbranched filaments, or even discs, tubes, clubs or trees. Algae can also be quite large and have highly specialized cells within them with different functions like the seaweeds which can reach 80 metres in length (Figure 2). Algae also utilize various modes of reproduction. They can reproduce asexually, sexually, and many algae actually utilize both methods of reproduction.
Figure 2: The various forms of algae. The first panel is an example of a brown alga, kelp. The second panel is the cyanobacterium called Nostoc pruniforme, which grows in large spherical colonies. The third panel is Stonewort, which is a green alga. The fourth panel is a microscopic volvox colony, another example of a green alga.
Since there exist various forms, sizes and manners in which algae reproduce, one would imagine there also are many different types of algae. The many types of algae will be enumerated and described here.
1. The cyanobacteria or blue-green algae:
These microbes are quite ubiquitous. They are found nearly everywhere in water and on land. These organisms have even been found in hot springs where the water can reach a blistering 71°C and in the crevices of desert rocks. Cyanobacteria exist as single cells, or as colonies in filaments or gelatinous masses (Figure 2). Cyanobacteria are unique among the algae because they are in the kingdom prokaryotae and are therefore prokaryotes, whereas all other algae are in the kingdom protista and are eukaryotes. Eukaryotes have organised structures called organelles within their cells. These include the mitochondria and chloroplasts, which produce energy for the cell, and the nucleus, which contains the genetic material of the cell. Prokaryotes do not have organelles. Bacteria and cyanobacteria are prokaryotes while most other life forms are eukaryotes. However, though cyanobacteria have no organelles, they do have some membranes within their cell called thylakoids, which contain chlorophyll and other components for photosynthesis. Since cyanobacteria have no organelles but are capable of photosynthesis like other algae and plants, there still exists a debate if they should be classified with bacteria or algae (Figure 3).
Figure 3: An example of the tree of life divided into bacteria and eukaryotes, and archae, which are beyond the range of the subject matter of this post and will not be covered. The kingdom prokaryotae are prokaryotes like cyanobacteria and bacteria. They have no organelle structures within their cells. The eucaryota or eukaryotes have organelles within their cells. The other algae are amongst them. There remains a debate as to where the cyanobacteria ought to be situated in the tree of life.
Another interesting aspect of cyanobacteria is that their ancestors are thought to be the earliest life forms on earth. Fossilized cyanobacteria have been found in rocks over 3 billion years old. These organisms are thought to be the first photosynthesizers which added oxygen to the atmosphere for billions of years before plants. One example of a cyanobacterium is spirulina, which is used in food because it is high in protein. Some cyanobacteria are used in rice paddies as fertilizers, while others produce toxins and in large numbers will cause swimmers’ itch.
2. The green algae:
Green algae are named so due to their photosynthetic chloroplasts which contain the green pigment chlorophyll. They can be unicellular organisms such as the phytoplankton that produce a large amount of oxygen in the atmosphere. Green algae also can be multicellular filaments which one will see in their pond as pond scum. Some of the seaweeds are amongst green algae such as Stonewort (Figure 2), which will grow several feet in length. As well as living in aquatic environments, the green algae have also been found on tree trunks and in soil.
3. The red algae:
Red algae are named so due to their red pigment called phycoerythrin, which absorbs blue light well and reflects red light to make the algae appear red. Blue light is the only light that penetrates well into deeper depths of water, so red algae that will be found in deeper depths will be almost black due to the phycoerythrin masking the pigment of chlorophyll. However, at shallower depths, the algae will appear green due to smaller proportions of phycoerythrin. These algae are mostly multicellular and will form filamentous algae and seaweed, which can be found in ponds, salt water and in damp soil though almost all species are marine algae.
Most of the algae one will see at the seashore will be red algae. One example of red algae is coralline algae. The cell walls in coralline algae become hardened with calcium carbonate, which makes up the material for coral reefs. Coincidently, I am sorting cells in my lab with a technique called flow cytometry, which identifies and sorts cells based on their fluorescent labelling. One of the fluorescent dyes I use is phycoerythrin from red algae.
4. The brown algae:
These algae are named so after their golden-brown carotenoid pigments. They are mostly unicellular and are found in lakes, ponds and oceans as phytoplankton. These algae can pose a problem to pond owners and enthusiasts because, in shallow ponds that can dry up in the summer or freeze up completely in winter, these algae can survive by forming protective cysts. One example of a brown alga is kelp, which can grow up to half a meter per day and reach up to 80m in length (Figure 2).
5. The dinoflagellates:
The dinoflagellates do not necessarily have chloroplasts to photosynthesize like most of the types of algae described earlier. In fact, many species are heterotrophs and parasites. They therefore rely on other organisms for nutrients (Figure 1). Some of these algae use harpoon-like structures called trichocysts to capture other organisms for food. Some photosynthetic species live inside invertebrate species like coral and giant clams and provide nutrients for these organisms by way of photosynthesis in a symbiotic manner while the other organism provides protection for the dinoflagellate.
A large portion of the algae are unicellular and are recognized by their strange structures such as horns, spikes and wing-like structures (Figure 4). Most of the dinoflagellates live in salt water but some can be found in fresh water like in a pond.
Figure 4: The varied forms of the microscopic dinoflagellates. The first panel is Ceratium furca, the second panel is Ceratium umitunoobimusi, and the third is an example of Pfiesteria.
An example of dinoflagellates is the red tide in which there will be a huge increase in photosynthetic dinoflagellates in coastal waters. Certain species will produce toxins which are problematic to ocean life and to consumers of seafood during these algal blooms. The red tide is named after the carotenoid pigments certain algae will possess.
One can now see how truly varied and important algae are. Algae, as alluded to throughout this post, have many uses. They are used in food such as nori, spirulina, dulse and are used as thickening agents in ice cream among many other food types. The pigments are used, for example, when I do cell sorting in the lab, as well as for dyes and colouring agents. Algae are used as fertilizers, such as the cyanobacteria mentioned with respect to rice paddies, and as livestock feed. Algae are also used as biofilters to treat waste water in order to make it fit for human use and can be used to make biodiesel fuel. On top of all their uses, environmentally speaking and for the pond enthusiast, since algae are so ubiquitous and reproduce quickly, they serve as environmental indicators in aquatic ecosystems because these organisms will be the first to change in response to an environmental change. For example, when high levels of nitrates and phosphates are found in a pond, river or lake, the algae will respond with an algal bloom, described earlier as a huge surge in the population of photosynthetic algae. If the pond or lake is small enough or if the size of the bloom is large enough, the algae may serve to detriment plants and fish also present by depleting the oxygen and light in the water.
Algae, like the microbes I described in my first post, are everywhere and as long as one has a pond, there will be algae. Even upon completely cleaning the pond and drying it out or freezing it, algae will survive. Also, algae can also spread through the air as spores. Algae, when it is in blooms, can be a really ugly sight in a pond but normal populations of algae are an essential part to the balance of the pond ecosystem. Since many types of algae can be present in a pond and will have different functions, they will need to be assessed in different ways and this can be done by contacting Village Pond and Garden if algae and the regular maintenance of a pond ecosystem is a concern. With regular maintenance of the pond with plants, bacteria, probiotics and the right cleaning regimen, we will have organisms, including algae and pond enthusiasts happy.
In the next instalment →You Get More Flies with Honey and You Get Better Microbes with Probiotics
• Phycology is the study of algae.
• “Algae” is plural and “alga” is singular.
• Algae create just as much oxygen or more than the plants of the world by photosynthesis. Algae utilize photosynthesis to create their own nutrients, but some algae predate on other organisms for nutrients.
• Autotrophs are life forms that can create their own nutrients such as by photosynthesis, where solar energy, water and carbon dioxide are used to create complex organic compounds.
• Heterotrophs are life forms that need to obtain nutrients by ingesting other life forms.
• Algae can live in water, soil, on trees, in animals as parasites, in porous rocks, in hot springs, snow banks and polar ice. Pretty much algae can live anywhere.
• Algae exist in many forms like unicellular planktonic algae, in colonies, in multicellular filaments and as large seaweeds.
• Many types of algae exist; cyanobacteria, green algae, red algae, brown algae and dinoflagellates.
• There are many uses for algae; they are in food, their pigments are used in dyes, they can be used in fertilizers and livestock feed, and can be used as biofilters to treat waste water so it can be fit for human use once again.
• Normal populations of algae are an essential part of the pond ecosystem. Since many types of algae can exist in a pond with different functions, they need to be assessed, then maintained with plants, bacteria, probiotics and the right cleaning regimen for a specific pond.