Instruct: Given a question, retrieve relevant passages that answer the question.
Query: What is algae?
Algae (/ˈældʒi, ˈælɡi/; singular alga /ˈælɡə/) is an informal term for a large, diverse group of photosynthetic eukaryotic organisms that are not necessarily closely related, and is thus polyphyletic. Including organisms ranging from unicellular microalgae genera, such as Chlorella and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to 50m in length. Most are aquatic and autotrophic and lack many of the distinct cell and tissue types, such as stomata, xylem, and phloem, which are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the Charophyta, a division of green algae which includes, for example, Spirogyra and the stoneworts.
As early as 1803 Jean Pierre Étienne Vaucher had published on the isogamy (sexual conjugation) in the algae, but it was in the early 20th century that reproduction and development began to be extensively studied. The 1935 and 1945 comprehensive volumes of Felix Eugen Fritsch consolidated what was then known about the morphology and reproduction of the algae. This was followed in the 1950s by the development of area checklists, led by Mary W. Parke with her 1931 "Manx Algae" and followed in 1953 by her "A preliminary check-list of British marine algae" Although Lily Newton's 1931 "Handbook" provided the first identification key for the algae of the British Isles, it wasn't until the 1960s that the development of such keys became routine. The 1980s with the new emphasis on ecology saw increased study of algal communities, and the place of algae in larger plant communities, and provided an additional tool for explaining geographical variation.
Generally, and except for specific continuous-filtering or continuous-cultivating versions, algae scrubbers require the algae to be removed ("harvested") periodically from the scrubber. This removal of algae has the effect of removing undesired nutrients from the water because the algae used the nutrients in order to grow. The algae is generally removed either:For waterfall versions, the screen is removed from the pipe and cleaned in a sink with running water. The pipe is removed also, and the slot is cleaned with a toothbrush, to remove any algae that have grown up into it. After the algae are removed, the screen and pipe are put back in the scrubber. For upflow versions, the cleaning method depends on the type:
The algae of this paraphyletic group "Charophyta" were previously included in Chlorophyta, so green algae and Chlorophyta in this definition were synonyms. As the green algae clades get further resolved, the embryophytes, which are a deep charophyte branch, are included in "algae", "green algae" and "Charophytes", or these terms are replaced by cladistic terminology such as Archaeplastida, Plantae, Viridiplantae or streptophytes, respectively.
Although it was generally accepted that one could distinguish prokaryotes from eukaryotes on the basis of the presence of a nucleus, mitosis versus binary fission as a way of reproducing, size, and other traits, the monophyly of the kingdom Monera (or for that matter, whether classification should be according to phylogeny) was controversial for many decades. Although distinguishing between prokaryotes from eukaryotes as a fundamental distinction is often credited to a 1937 paper by Édouard Chatton (little noted until 1962), he did not emphasize this distinction more than other biologists of his era. Roger Stanier and C. B. van Niel believed that the bacteria (a term which at the time did not include blue-green algae) and the blue-green algae had a single origin, a conviction that culminated in Stanier writing in a letter in 1970, "I think it is now quite evident that the blue-green algae are not distinguishable from bacteria by any fundamental feature of their cellular organization". Other researchers, such as E. G. Pringsheim writing in 1949, suspected separate origins for bacteria and blue-green algae. In 1974, the influential "Bergey's Manual" published a new edition coining the term cyanobacteria to refer to what had been called blue-green algae, marking the acceptance of this group within the Monera.
The National Algae Association (NAA) is a non-profit organization of algae researchers, algae production companies and the investment community who share the goal of commercializing algae oil as an alternative feedstock for the biofuels markets. The NAA gives its members a forum to efficiently evaluate various algae technologies for potential early stage company opportunities.
Environment Canada reports that the amount of nitrogen and phosphorus available for plant uptake has increased dramatically in the past several decades. The causes are a massive increase in the use of fertilizer, burning of fossil fuels, development of large urban populations, and an upsurge in land clearing and deforestation. Nitrogen and phosphorus loading from human activity has accelerated eutrophication of certain rivers, lakes, and wetlands in the U.S.A. resulting in loss of habitat, changes in biodiversity and, in some cases, loss of recreational potential. Lake Winnipeg suffers from the rapid absorption of the elements phosphorus, nitrogen, and carbon. Eutrophication processes fuel the growth of blue-green algae, also known by its more correct scientific name cyanobacteria. These bacteria normally appear green in color and can turn blue when the algae (bacteria) blooms are dying. As an algae bloom dies, the microscopic cells break down. This process releases toxins in the surrounding water. Once released, some toxins can linger for more than three months until sunlight and the natural population of healthy green algae in the lake degrade them. Cyanobacteria typically thrive off of phosphorus when Lake Winnipeg’s summer temperatures are hot and wind speeds are relatively low. Blue-green algae blooms frequently persist for several months in Lake Winnipeg until colder temperatures, currents, and changes in the seasonal weather can filter them out. The cyanobacteria’s decomposition process consumes oxygen at such a high rate that this can actually suffocate Lake Winnipeg’s native walleye fish species and other aquatic life. Although blue-green algae occurs naturally in Lake Winnipeg, there is no conclusive evidence what normal levels may be. Satellite images show that blooms are occurring more frequently and are covering more surface area of the lake. The Lake Winnipeg algae crisis has grown to such a large scale that the blooms can be seen from outer space.
Algae constitute a polyphyletic group[3] since they do not include a common ancestor, and although their plastids seem to have a single origin, from cyanobacteria,[5] they were acquired in different ways. Green algae are examples of algae that have primary chloroplasts derived from endosymbiotic cyanobacteria. Diatoms and brown algae are examples of algae with secondary chloroplasts derived from an endosymbiotic red alga.[6]
In addition, "turf" algae, which was the focus of Dr. Adey's dumping-bucket design, is replaced by "green hair algae". This is because turf algae tends to be dark brown and thick (like artificial turf on sports fields), and it blocks the light and water from reaching the screen. This slows the growth (and filtering) of the algae because the bottom layers of algae that are attached to the screen start to die and detach. Green algae, however (especially light-green hair algae), allows light and water to penetrate all the way down to the screen if the growth is kept less than 20 mm thick, which allows the algae to grow faster and absorb more nutrients without dying and losing attachment to the screen. This is fortunate because green hair algae is the exact type of algae that grows automatically in a properly constructed algae scrubber.
"S. nigricans" practices a form of agriculture with a species of red algae. The fish will claim a patch of "brown carpet algae" which it defends by chasing away other fish and sea urchins. The fish also pulls up other bits of algae that attempt to grow in the patch and swims outside of its territory to spit the invading algae out. "S. nigricans" do not have cellulases in their stomach, therefore they dispose of algae that they cannot digest. They must limit their diet to cyanophores and rhodophytes, which are delicate species. There are nine algae species that S. nigricans will farm for, and the algae they remove is competitively superior late-colonizing algae as opposed to the algae they can eat. They also remove algae that is competitive and faster growing than their preferred delicate algae. When the fish claiming a patch is removed, the patch is eaten up within a few days. When a patch of the brown carpet algae is caged to keep both "S. nigricans" and other fish out of the patch, other species of algae quickly overwhelm the patch. This seems to indicate the brown carpet algae are dependent on "S. nigricans" for its survival. The presence of "S. nigricans" in ecosystems greatly increases the primary productivity of the area by boosting oxygen, nitrogen, and phosphorus concentrations.
The National Algae Association is a United States non-profit algae production trade organization for commercially minded algae researchers, algae producers and equipment companies.
The land plants, or embryophytes, are thought to have emerged from the charophytes. Therefore, cladistically, embryophytes belong to green algae as well. However, because the embryophytes are traditionally classified as neither algae nor green algae, green algae are a paraphyletic group. Since the realization that the embryophytes emerged from within the green algae, some authors are starting to include them. The clade that includes both green algae and embryophytes is monophyletic and is referred to as the clade Viridiplantae and as the kingdom Plantae. The green algae include unicellular and colonial flagellates, most with two flagella per cell, as well as various colonial, coccoid and filamentous forms, and macroscopic, multicellular seaweeds. There are about 8,000 species of green algae. Many species live most of their lives as single cells, while other species form coenobia (colonies), long filaments, or highly differentiated macroscopic seaweeds.
Since 'algae' is a broad term including organisms of widely varying sizes, growth rates and nutrient requirements, there is no officially recognized threshold level as to what is defined as a bloom. For some species, algae can be considered to be blooming at concentrations reaching millions of cells per milliliter, while others form blooms of tens of thousands of cells per liter. The photosynthetic pigments in the algal cells determine the color of the algal bloom, and are thus often a greenish color, but they can also be a wide variety of other colors such as yellow, brown or red, depending on the species of algae and the type of pigments contained therein.
The closest relatives of the brown algae include unicellular and filamentous species, but no unicellular species of brown algae are known. However, most scientists assume that the Phaeophyceae evolved from unicellular ancestors. DNA sequence comparison also suggests that the brown algae evolved from the filamentous Phaeothamniophyceae, Xanthophyceae, or the Chrysophyceae between 150 and 200 million years ago. In many ways, the evolution of the brown algae parallels that of the green algae and red algae, as all three groups possess complex multicellular species with an alternation of generations. Analysis of 5S rRNA sequences reveals much smaller evolutionary distances among genera of the brown algae than among genera of red or green algae, which suggests that the brown algae have diversified much more recently than the other two groups.
"Scutellastra cochlear" is an important part of the lower tidal community in what is sometimes known as the "cochlear zone". Each adult establishes a scar on the underlying rock and occupies this for the rest of its life. This limpet occurs at greater densities than most other species of limpet but that is partly because juveniles often establish themselves on the shell of larger individuals, feeding on the algae and lichen which grow there, until the juveniles are large enough to establish their own scars on the rock. Densities have been found to vary between about 1,700 limpets per square metre and 90 per square metre, with greater densities being present in areas with the greatest wave motion. This limpet has a strong influence on the structure of the community as it excludes most species of algae and limits the biodiversity in its vicinity to the coralline alga "Spongites yendoi" and the strips of filamentous red algae gardens that fringe each limpet. The limpets do not need to move out of their scars to feed as they can reach enough edible material by rotating themselves in their scar. At low tide, when the limpet is exposed to the air, urea accumulates on the underside of the rim of its shell and diffuses out into the surrounding algae. Here it boosts the supply of nitrogen available to the algae and this increases the algal productivity. "Scutellastra cochlear" is territorial and defends its garden against other limpets.
Algae are found in almost all ponds. There are hundreds of species of algae that can grow in garden ponds, but they are usually noticed only when they become abundant. Algae often grow in very high densities in ponds because of the high nutrient levels that are typical of garden ponds. Generally, algae attaches itself to the sides of the pond and remains innocuous. Some species of algae, such as "blanket weed", can grow up to a foot a day under ideal conditions and can rapidly clog a garden pond. On the other hand, free floating algae are microscopic and are what cause pond water to appear green. Blanket weed, although unsightly, is actually a sign that the water is clean and well-balanced. Green water (free floating algae) means there are too many nutrients in the water, usually from rotting vegetation or too many fish for the space. Killing the free floating algae with chemicals will often cause it to die, rot, and then make the problem even worse as more nutrients enter the water. Adding more floating or submerged (unpotted) plants can help with the green water, as they can take the nutrients out of the water. There are also filters that can be installed to remove the nutrients and all types of algae from the water. Many ponds naturally go green early in the spring and then clear up.
Sewage can be treated with algae,[87] reducing the use of large amounts of toxic chemicals that would otherwise be needed. Algae can be used to capture fertilizers in runoff from farms. When subsequently harvested, the enriched algae can be used as fertilizer. Aquaria and ponds can be filtered using algae, which absorb nutrients from the water in a device called an algae scrubber, also known as an algae turf scrubber.[88][89][90][91]
The Martian insects had lain dormant on their almost dead world, but when the probes from Earth spread algae fields across Mars it gave them a massive new food source and led to a population explosion. The Martian insects are what caused the algae to disappear, but in the process they actually gave Mars breathable oxygen levels, because they produce oxygen as a waste product (explaining why they are so flammable). The insects are also what destroyed the habitat module, as they tore in to get to the food supplies inside.
Algae, the first plant on earth, can be useful for both nature and us. It is extremely edible for many ducks, geese and fish. It also absorbs carbon dioxide and makes oxygen and sugar inside itself. Algae can also be made into medicine, biofuel, fertilizer, pollution control and food. Algae can come in three different colors, brown, red and green. Plus, algae has two sizes, macro algae and micro algae. Micro algae are a quarter of a millimeter large and macro algae can appear to be enormous! You can find algae in all sorts of places such as Northern Canada, Eastern Canada, in Central Africa, and Western Europe. It can be found in rivers, ponds, lakes and wetlands. These places have high levels of chlorophyll, which algae need to grow. But if there is too much algae it can be harmful for the environment. When algae grow it multiplies over, and over again. It is similar to duckweed in a way that it doesn't reproduce; it just grows and then multiplies. This fascinating plant falls under the aquatic family and protist family. This plant can grow in both freezing conditions and warm areas but it prefers warmer water. There are also estimated 27,000 species of algae!
Not all wavelengths of light can support photosynthesis. The photosynthetic action spectrum depends on the type of accessory pigments present. For example, in green plants, the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with absorption peaks in violet-blue and red light. In red algae, the action spectrum is blue-green light, which allows these algae to use the blue end of the spectrum to grow in the deeper waters that filter out the longer wavelengths (red light) used by above ground green plants. The non-absorbed part of the light spectrum is what gives photosynthetic organisms their color (e.g., green plants, red algae, purple bacteria) and is the least effective for photosynthesis in the respective organisms.
In the last 30 years Lake Winnipeg has experienced a steady surge of blue-green algae growth and although algae grows naturally in the lake, excessive blue-green algae blooms are caused by high ratio levels of nitrogen and phosphorus draining into the lake via rivers and surface runoff. Up to five and a half million people rely on the health of Lake Winnipeg. The lake is an economical powerhouse that supports a $100 million a year tourism industry and a $25 million a year fishing industry. Healthy algae populations play an important role in keeping lake Winnipeg's ecological systems balanced. Green algae provides food for zooplankton, which are then eaten by larger fish in the lake. However the toxins that blue-green algae release can destroy fresh water ecosystems and can be dangerous for humans and other species. Very high levels of the algae toxin microcystin closed Victoria Beach off from the public in the summer of 2003. Grand Beach and other surrounding settlements along the lake are often closed for a short time during summer months due to E. coli and algae-toxin related threats. Immense algae blooms have appeared in the northern part of Lake Winnipeg in the last decade with hundreds of square kilometers of the lake covered with a thick toxic layer of blue-green algae. Local residents in surrounding communities say the blue-green algae is well known for creating deadly water conditions in prairie dugouts and have been known to even kill livestock. Commercial and aboriginal fishermen on the lake often find their nets temporarily disabled during the summer months because of the thick algae conditions. The Lake Winnipeg algae blooms are considered the worst algae problem of any large freshwater lake in the world.
The National Algae Association (NAA) is a non-profit organization of algae researchers, algae production companies and the investment community who share the goal of commercializing algae oil as an alternative feedstock for the biofuels markets. The NAA gives its members a forum to efficiently evaluate various algae technologies for potential early stage company opportunities.
Blue Marble Production is a Seattle-based company that is dedicated to removing algae from algae-infested water. This in turn cleans up the environment and allows this company to produce biofuel. Rather than just focusing on the mass production of algae, this company focuses on what to do with the byproducts. This company recycles almost 100% of its water via reverse osmosis, saving about 26 000 gallons of water every month. This water is then pumped back into their system. The gas produced as a byproduct of algae will also be recycled by being placed into a photobioreactor system that holds multiple strains of algae. Whatever gas remains is then made into pyrolysis oil by thermochemical processes. Not only does this company seek to produce biofuel, but it also wishes to use algae for a variety of other purposes such as fertilizer, food flavoring, anti-inflammatory, and anti-cancer drugs.
An algae scrubber filters water by moving water rapidly over a rough, highly illuminated surface, which causes algae to start growing in large amounts. As the algae grow, they consume nutrients such as nitrate, phosphate, nitrite, ammonia, ammonium and even metals such as copper from the water. These nutrients are normally a problem in aquariums and ponds because they cause nuisance algae to grow, and also because they cause sickness and/or other problems in aquarium fish, invertebrates and corals. An algae scrubber allows algae to grow, but the algae grow inside the filter instead of in the aquarium or pond. This removes excess nutrients (scrubs the water), diminishing nuisance algae in the aquarium or pond . Nuisance algae in the aquarium or pond are not to be confused with the desired algae in the algae scrubber filter itself. The algae that grow in the algae scrubber can then be removed, or fed back to the livestock.
Algae fuel is a biofuel which is derived from algae. During photosynthesis, algae and other photosynthetic organisms capture carbon dioxide and sunlight and convert it into oxygen and biomass. This is usually done by placing the algae between two panes of glass. The algae creates three forms of energy fuel: heat (from its growth cycle), biofuel (the natural "oil" derived from the algae), and biomass (from the algae itself, as it is harvested upon maturity).