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Algae: Nutrient or Nuisance

What Is Algae?

Where They Grow

Algae Types

Diatoms

Green Algae
Blue-green Algae

Test for Blue-green Algae

Toxic Algae

Symptoms from Toxic Algae

Examples of Algae Blooms

Other Types of Freshwater Algae

Algae Blooms

Factors That Increase Blooms

Steps to Reduce Algae Bloom Risk

What is Algae?

"Algae are a diverse group of organisms that occur in various shapes and sizes and have different ecological roles. Thousands of species of algae occur world-wide in both fresh and marine waters. Many species of freshwater algae float in the water, but others are attached to submerged rocks or aquatic plants. Most freshwater species are inconspicuous and do not create problems for humans. There are only a dozen or so, so-called "bad actors" that are considered problem-causing algae.

Algae typically serve as an important and welcome part of a lake or pond ecosystem. They form the base of the food chain and are a vital component of lakes. Algae provide a source of food, energy, and shelter for zooplankton (tiny water animals), fish, and other lake organisms. They can play a crucial role in the ability of an ecosystem to absorb nutrients and heavy metals." (source)

Another reference provides the following description of algae:
Algae are photosynthetic, eukaryotic organisms that do not develop multicellular sex organs. Algae can be unicellular, or they may be large, multicellular organisms. Algae can occur in salt or fresh waters, or on the surfaces of moist soil or rocks. The multicellular algae develop specialized tissues, but they lack the true stems, leaves, or roots of the more complex, higher plants.

What this definition does not tell us is that these "eukaryotic organisms" contain cells in which the nucleus is enclosed by a membrane. What it also does not tell us is that these "eukaryotic organisms" represent all life as we know it except for the kingdom which consists of bacteria and blue-green algae.

As we will see later, since "blue-green algae" cell nucleus are not membrane encased, they do not fit the definition of algae and thus are placed in the kingdom with bacteria.

Why and When Algae Proliferate

Many species of algae are always present in any freshwater but often in such small quantities or as individual cells that they are not visible and not of any concern to the environment. They are, however, available and highly beneficial as food source to higher organisms.

Algae grow when they have the right conditions such as adequate nutrients (mostly phosphorus but nitrogen is important too), light levels, pH, temperature, etc. Generally the amount of phosphorus controls the amount of algae found in a freshwater lake or water body. The more nutrient-enriched a lake, typically the more algae in the lake. As Washington lakes and their watersheds are developed,increasing problems are seen with algae. (source)

Different kinds of algae are prominent at different times of the year. The following excerpt provides an excellent review of this:

In spring diatoms often grow profusely in cool water, which contains silica and abundant nutrients accumulated during winter. They use silica to build their cell walls. Diatoms grow quite rapidly and often give the water a brownish hue

As the water warms, diatoms are outcompeted for nutrients and give way to green algae or yellow-brown algae, which grow faster in the warmer water

Usually by early summer, diatoms, greens, and yellow-browns give way to blue-green algae, also known as cyanobacteria. As the latter name suggests, this type of algae is not a plant but a photosynthetic bacteria. It grows best with plentiful nutrients and warm temperatures. he more nutrients and light available in a lake, the larger its concentration of blue-green algae. (source)

Types of Algae

There are three major groups of algae commonly encountered. These are:

The most commonly encountered groups of freshwater algae are green algae, diatoms, and blue-green algae (more correctly known as cyanobacteria). A large and varied group called green algae are the likely ancestors of terrestrial plants. Green algae contain bright, grass-green pigments, and are more abundant than all the other groups. The cells of green algae may occur singly, as spherical colonies, or as filaments. Sometimes filamentous green algae can create problems when it grows in "cotton candy" type clouds in the water. Generally most green algae are highly palatable and a good food source for zooplankton.

Blue-green algae (called cyanobacteria because of its' color and the fact that it is in the bacteria kingdom) contain green, blue, and often red pigments. Blue-greens create problems when their excessive growth produces algae blooms and some of the varieties produce toxins that are dangerous to humans and animals. As a general statement, cyanobacteria are not beneficial organisms in a lake environment. Blue-green algae are discussed in greater detail below.

Other Types of Freshwater Algae

Other types of algae found in lakes include: Euglenoids, dinoflagullates, brown algae, stoneworts/brittleworts, and desmids. This list is not inclusive of all the kinds of algae that are found in freshwater. Most freshwater algae do not cause problems in lakes. Because they provide a food source for zooplankton, they tend to be rapidly consumed and rarely cause the prolonged blooms that can occur with blue-green algae. Go here to see an extensive photo gallery of various algae.

What we call "algae" covers a whole host of sins not necessarily within the bounds of what scientists call algae. Of these three major types mentioned above, only the diatoms and the green algae are considered by the scientists as algae which is defined as microorganisms falling in a diverse group called Protists. Protists are microorganisms in which the nucleus is encased within a membrane. Most of us have always thought of algae as part of the plant kingdom; but the scientists tell us something different. They say that the protists are not in either the plant or animal kingdom, but rather in a kingdom all their own. The Protist kingdom is one of five life kingdoms; the other four are the animal kingdom, plant kingdom, fungi kingdom, and bacteria kingdom (which includes the blue-green algae). (source).

For an extensive, interesting, and fun ride, take a trip through Protist Park.

Beneficial Algae: The Good but Sometimes Not so Good

Diatoms

Diatoms appear as yellow-green or yellow-brown algae that occur singly or more rarely in colonies. The cell wall comprises two separate valves or shells formed of silica. The two shells fit together to form a box with the top part bigger than the bottom like the two halves of a petri dish.

Diatom Appearance

Because of the silica valves, diatoms often occur in beautiful shapes when viewed under the microscope. The enclosures are covered by many tiny holes arranged in patterns such that they often give an attractive grid picture.

Diatom Locomotion

The system of locomotion of these algae is special. The lower hull has some holes in it and a longitudinal fissure, named a raphe. Part of the cell's cytoplasm (the jelly-like part of the cell between the cell membrane and the nuclear envelope) escapes from this crack and produces a sticky secretion which flows along the raphe, allowing the diatom to move as though it were on tracks. .

Diatom Reproduction

Diatoms reproduce through cellular division and also sexually. Each time an existing diatom divides, the silica valves get smaller. Over time, individual cells of a diatom population become smaller and smaller. Luckily for diatoms, their sexually produced offspring are able to secrete entirely new cell walls. World-wide, diatoms provide a major food resource for zooplankton and also produce atmospheric oxygen (reference).

Some marine diatoms can produce a toxin called domoic acid. Domoic acid can accumulate in shellfish and poison humans (reference). Freshwater diatoms do not produce this toxin.

Diatom Prominence

image of diatom
(image source)
Diatoms are often the first algae to bloom in early spring. : See photographs of diatoms

Diatoms are found in fresh and saltwater, in moist soil, and on the moist surface of plants. Fresh-water and marine diatoms appear in greatest abundance early in the year as part of the phenomenon known as the spring bloom, which occurs as a result of the availability of both light and (winter-regenerated) nutrients. They reproduce asexually by cell division. When aquatic diatoms die they drop to the bottom, and the shells, not being subject to decay, collect in the ooze and eventually form the material known as diatomaceous earth. Diatoms can occur in a more compact form as a soft, chalky, lightweight rock, called diatomite. Diatomite is used as an insulating material and similar products. Diatoms provide a major food resource for zooplankton and also produce atmospheric oxygen reference source. The surface mud of a pond, ditch, or lagoon will almost always yield some diatoms.

Green Algae

"Green algae" represents a large and diverse group and are likely the ancestors of terrestrial plants. Green algae contain bright, grass-green pigments, and are more abundant than all the other groups. The cells of green algae may occur singly, as spherical colonies, or as filaments. Sometimes filamentous green algae can create problems when it grows in "cotton candy" type clouds in the water. Generally most green algae are highly palatable and a good food source for zooplankton.

Green algae are a large and varied group of green pigmented algae which store energy as starch and in central spherical proten structures called "pyrenoids". The green algae contain chlorophyll and make their food by photosynthesis. Forms found in freshwater include unicellular, filamentous and colonial varieties which Include Chlorella, Spirogyra, Scenedesmus, Oedogonium, and Volvox.

micrograph of spirogya green algae
Image Source
Spirogya is a filamentous alga. Its cells form long, thin strands that, in vast numbers, contribute to the familiar green, slimy 'blanket weed' in ponds. Seen under the microscope, each filament consists of an extensive chain of identical cells. Each cell contains a helical chloroplast (a specialized sub-unit within the cell which performs photosynthesis), a nucleus, cytoplasm (the gel-like substance holding all the functional structures other than the nucleus, and a vacuole (a membrane containment which holds essential fluids)enclosed in a cellulose cell wall.

Green Algae make up the division Chlorophyta, which includes about 7,500 species of unicellular organisms. Unifying characteristics of this division include similar photosynthetic pigments that make up the chloroplasta (the specialized sub-unit within the cell which consist primarily of chlorophylls and carotenes). Most green algae store their carbohydrates in the form of starch and their cell walls are composed of polysaccharides such as cellulose.

For the most part, green algae are beneficial to the lake environment. However, in relatively static water and if the conditions are right, filamentous green algae can grow excessively to the point of being a problem.

Filamentous green algae form billowing clouds of slimy or stringy algae in the water. These algae generally grow in nutrient-enriched lakes during the summer and early fall. Mats often form around the tops of aquatic plants. Filamentous green algae can interfere with boater access, recreation, and aesthetics, but are generally harmless. However, many lake groups are concerned with managing the growth of these nuisance algae. Unlike blue-green algae, filamentous algae can be physically removed from the water. However, techniques such as raking may not be effective when large areas of algae are involved. Mats can grow back quickly (source)

One of the most well-known types of green algae is volvox. Volvox forms a spherical colony, and each cell of the colony possesses two flagella and a small eyespot. Spirogyra, Zygnema and Mougeotia are some other common green algae that are often found on the surface of freshwater ponds and ditches. They proliferate rapidly, and form a dense mat like structure on the surface of ponds,

Locomotion by Green Algae

Green algae cells can have two or more organelles (specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own membrane) known as flagella, which are used in a whiplike fashion for locomotion. Flagella are long, thread-like appendages which provide some live single cells with the ability to move

Green Algae Reproduction

Green algae can reproduce both asexually and sexually, and the mode of reproduction is quite diverse. In case of asexual reproduction in algae, the parent cell can divide into two similar parts, from which two identical organisms develop, or the parent cell can divide into one or more fragments, which eventually grow as separate organisms. However, some algae have been found to develop motile or non-motile spores for asexual reproduction.

Sexual reproduction may also takes place through the union of gametes (sexual reproductive cells), which can be identical or different in shape or size. Some algae like spirogyra reproduce by the conjugation method, while certain higher forms of algae follow a reproduction cycle called 'alternation of generations' (source)


Blue-green Algae (Cyanobacteria)

As discussed above:

Blue-green algae (called cyanobacteria because of its color and the fact that it is in the bacteria kingdom) contain green, blue, and often red pigments. Blue-greens create problems when their excessive growth produces algae blooms and some of the varieties produce toxins that are dangerous to humans and animals. As a general statement, cyanobacteria are not beneficial organisms in a lake environment.

Blue-green algae live with other types of algae and microscopic animals in floating "plankton".

Blue-green algae (cyanobacteria) are algae-like bacteria capable of photosynthesis which manufacture their own food. Because they are bacteria, they are quite small and usually unicellular, though they often grow in colonies large enough to see. They are the oldest known fossils and their great abundance along with their ability to produce oxygen are credited with the very existence of oxygen today in our atmosphere. (source) The cyanobacteria have many beneficial attributes and have wide and valuable commercial applications but this discussion will focus on their existence in freshwater.

Cyanobacteria are called "blue-green algae" because of their color and because they make their own food (like algae) but in fact cyanobacteria have no other relationship to algae and instead are part of a separate life kingdom they share with bacteria.

Cyanobacteria may be single-celled or colonial. Depending upon the species and environmental conditions, colonies may form filaments, sheets or even hollow balls. Some filamentous colonies show the ability to differentiate into three different cell types. Despite their name, different species can be red, brown, or yellow; blooms (dense masses on the surface of a body of water) of a red species are said to have given the Red Sea its name. There are two main sorts of pigmentation. Most cyanobacteria contain chlorophyll a, together with various proteins called phycobilins, which give the cells a typical blue-green to grayish-brown colour. A few genera, however, lack phycobilins and have chlorophyll b as well as a, giving them a bright green colour. (source)

Nitrogen Fixation

Cyanobacteria have the capability to fix atmospheric nitrogen and some freshwater blue-green algae species do not need much of the nutrient nitrogen present in the water because they use nitrogen gas from the air to grow. These "nitrogen-fixing" algae actually increase nitrogen levels in the water. Lower levels of the nutrient phosphorus in the water usually limit growth of the blue-green algae. Therefore, reducing phosphorus levels in water bodies is the most effective means of preventing blooms of blue-green algae. (source)

Blue-green algae is most common in late summer. Small amounts of blue-green algae look like tiny yellowish or greenish blobs floating in the water. In calm conditions, blue-green algae can form a thin greenish film on the surface of the water.

Blooms of blue-green algae may vary greatly in appearance, depending on their intensity and age, as well as local conditions. More intense blooms can colour the water greenish, making it look like green paint; or they may form a greenish-yellow sludge resembling pea soup on the surface or along the shoreline. Only when it dries out does blue-green algae actually turn bluish or even purplish in colour, when colourful phycocyanins are released as its cells decompose. Blue-green algae may also give off a characteristic musty or mouldy smell. (source)

Test For Blue-green Algae

Try a couple simple tests that will indicate whether or not the algae is blue-green algae:

  • Put some algae in a jar, and let it stand undisturbed for about an hour. If greenish particles rise to the surface, the algae is blue-green algae.
  • Test using a stick whether the algae is a solid mass that can be lifted out of the water. If strands of algae remain on the stick, the algae is harmless filamentous algae; but if the algae disperses into particles when you touch it with the stick, it is probably blue-green algae.
If you determine that it is blue-green algae, it is not possible to know whether or not it is toxic except by laboratory tests. However, one source has reported that about half of the blue-algae blooms tested proved to be toxic. Therefore, until you know otherwise, treat all blue-green algae blooms as though they were toxic.

To determine that the bloom is indeed blue-green algae and that it is toxic, submit a sample to an approved laboratory. Scoop it up into a small, clean sealable glass or plastic container and store it in a cool place until you can, as soon as possible, get it to the laboratory.

Toxic Blue-green Algae

The following discussion is an excerpt from the cited Indiana DNR web-site. The discussion is equally applicable to Missouri lakes:

A number of blue-green algae species release toxins that can cause death in mammals, birds, and fish and illness in humans.

Like others in this group, Cylindrospermopsis (cyanobacteria) produces oxygen by photosynthesis and can fix nitrogen from the air and so can live without relying on nitrogen sources in the water. This particular species grows abundantly (blooms) in subtropical freshwater lakes and rivers with high levels of phosphorus and other nutrients. In recent years, this species has begun replacing other bloom-forming algae as the dominant alga following the nutrient enrichment of lakes, reservoirs, and rivers around the world and appears to be moving into more temperate climates. It has been found in Zimbabwe, Hungary, Thailand, Mexico, Australia, Brazil, and more recently in the southeastern United States. Surrounding states where Cylindrospermopsis has been found--but not in bloom condition--include Michigan, Illinois, and Ohio.

Blue-green algae can successfully compete against other groups such as green algae and diatoms because they can store phosphorus for later use and are not preferred as food by zooplankton (microscopic animals), larval fish and other animals that graze on many kinds of algae. When blue-green algae dominate the aquatic community, they can become a nuisance by forming surface scums, producing obnoxious taste and odor compounds, and sometimes releasing toxic or irritating substances into the water.

Cylindrospermopsis is very small, even in comparison to other microscopic algae, and is made of a filament that is either linear or coiled and composed of rectangular cells with basal heterocysts (nitrogen fixing cells). Unlike many other blue-greens, it does not form scum at the water surface but does produce a brown tint to the water that cannot be easily distinguished from suspended sediment or other types of algae that appear brown, such as diatoms.

Cylindrospermopsis, when found in large quantities, can produce several substances that show toxicity in laboratory studies, including: (1) cylindrospermopsin, which is mainly toxic to the liver, but can affect the kidneys, heart and other organs, and may be carcinogenic and genotoxic; (2) saxitoxin, which is a neurotoxin that can cause paralytic fish poisoning leading to paralysis and respiratory distress in fish eaters; and (3) anatoxin-a, which is a neuromuscular agent that can result in paralysis, respiratory distress and convulsions. These and other toxins can also be produced by several other species of blue-green algae. Humans and animals are primarily exposed to toxic effects by drinking or swimming in untreated water.

In waters where Cylindrospermopsis has been identified, state agencies suggest that people, pets and livestock avoid swallowing water from these reservoirs or immediately downstream until results of laboratory analyses are available. Because the alga grows most rapidly in warm, sunny weather and during periods of little rainfall, the probability of finding the alga or its toxins would be very low during the winter months. Cylindrospermopsis tends to bloom here in late summer (August to early September).

The discovery of this organism blooming (growing abundantly) in a Midwestern lake was a surprise to most scientists since Cylindrospermopsis, originally found in Australia, Brazil, and more recently in Florida and North Carolina, was thought to be a subtropical organism. The species has been found more recently in several Midwestern states. Along with many other exotic and nuisance organisms, Cylindrospermopsis could potentially be spread by human or natural influences. Zebra mussels, Eurasian watermilfoil, fish diseases and other damaging species can be carried to new areas by anglers, boaters, shipment of pond plants and during other activities that transport water across distances. The decisions you make about discarding fish, water or aquatic plants are critical in slowing or preventing spread of nuisance species that can destroy fisheries and aquatic resources. How you discard unused bait fish, where you dump bilge water or water from your live well, where you dispose of live fish or fish parts, and what you do with plants from your pond or plants attached to your trailer or boat can affect the spread of unwanted species. Many of these problem species are too small to see in the water in your bait bucket or live well. Once these exotic nuisances are deposited in waters, it can be very difficult or impossible to remove them and reverse the negative impacts. Help prevent problems by never moving water or animals from one lake or river to another one.

Effect on Humans and Animals

No human deaths from blue-green algae, including Cylindrospermopsis, have been reported in the United States. People exposed to blue-green algal blooms by swimming in affected lakes or rivers have experienced skin irritations, allergic reactions, gastrointestinal symptoms, and respiratory problems. Nausea, vomiting, and liver damage have been implicated after consumption of the blue-green toxin cylindrospermopsin in finished drinking water in Australia. Liver failure occurred in people in Brazil following an incident during which growth of a different blue-green algae (Microcystis) produced toxins in water used for intravenous kidney dialysis. Most of the knowledge about the toxicity of these compounds, including dose-response interactions, comes from animal experiments. Because human toxicity from direct algal exposure has rarely been documented, there are no dose-response data or even experimental data in humans.

Some people are more sensitive to chemicals causing allergic reactions or toxicity. In general, children, older people and individuals with sensitive immune systems may be more susceptible to these effects. Pets and livestock are more likely to drink large quantities of raw lake or river water, potentially resulting in negative health effects.

Is Cylindrospermopsis the only blue-green alga that can have health effects?

The toxic effects associated with Cylindrospermopsis are common to several other species of blue-green algae. There are more than 50 major types of freshwater blue-green algae, and about one-third of them can produce some form of toxins. Blue-green algae are a harmless, natural part of the water system in small numbers. But when they dominate the plant community, the algae can interfere with the ecological health and human use of the water by producing offensive taste and odor compounds and sometimes forming a thick scum on the surface. Decaying algae consume oxygen in the water, causing fish kills if oxygen levels drop too low. A scum of algae floating on the surface can shade out beneficial plants that provide habitat for fish and wildlife. (source)

What are the symptoms of toxic effects of blue-green algae?

Symptoms of swallowing water with toxic amounts of substances produced by blue-green algae can include stomach or head aches, diarrhea, cough, respiratory distress, and eye or ear irritations. Similar symptoms can also be caused by swimming in and swallowing water that contains E. coli or other bacteria, viruses, and disease-causing microbes. Some other blue-green algae and tiny parasites that cause swimmer's itch can also produce a rash after contact with the water. Humans, pets or livestock could be similarly affected by toxins from blue-green algae. In rare cases, animals have been known to die from drinking water contaminated with toxins produced by blue-green algae.

Are fish caught from these waters safe to eat?

The toxins produced by freshwater blue-green algae do not appear to bioaccumulate in fish and other edible aquatic life in lakes and rivers to the degree that they can in some seafood. Toxic results from consumption of freshwater animals have not been documented. Anglers should always take a common sense approach to eating fish caught from lakes or rivers. If the fish looks or smells unhealthy or was dead when you found it, then don't eat it. If an angler is concerned, avoid lakes with heavy algal blooms.

Should I report illness in humans or pets after swimming in water?

There are no reported problems with human health effects of blue-green algae toxins in United States at this time. In the event someone suspects they may have become sick from exposure to toxins produced by blue-green algae, contact your family physician so that pertinent information can be relayed to the state department of health. If pets fall ill with the symptoms indicated above after swimming in or drinking from lakes or rivers, explain these circumstances to your veterinarian.

How can I tell if the water contains Cylindrospermopsis?

Where the state is aware of potential risks associated with blooms of this alga, local health departments and citizens will be notified through an advisory. The mouse bioassay is an established laboratory method to determine presence of some toxic substances in algae, and there are numerous other analytical methods for determining the kind and amount of chemicals found in algae-tainted water. Field testing kits for toxins are not yet available. Unlike several other blue-green algae, Cylindrospermopsis does not form a surface scum. Dense algal cells typically are located in a band several feet from the surface in a reservoir, lake or other slow moving or still water. These cells are extremely small and do not create a color in the water that would easily distinguish it from other algae. There is no taste or odor associated with Cylindrospermopsis or its toxins. Compounds, such as geosmin and MIB, that cause taste and odor problems in some Indiana drinking water supplies, are not thought to pose a health risk to humans and are not necessarily associated with blue-greens that may produce toxins. Allergic reactions to lake water, such as skin rashes, eye or ear irritation or a cough, are also not necessarily an indication of the presence of toxins. Therefore, it would be highly unlikely that the public could provide observations of local algae blooms that could be readily identified with this species. (source)

To see an extensive gallery of fantastic photos of blue-green algae, go here


This Too Could Happen Here

Our Lake of the Ozarks' businesses are all too aware of the adverse effect the beach closings due to high E-coli counts have had on the lake economy. We do not need another threat to the public such as that suffered in Oklahoma by the businesses surrounding Grand Lake.

Read this excerpt from the Joplin Globe:

On Friday, just as businesses on Grand Lake were preparing for the Fourth of July weekend crowds, came the warnings from the Grand River Dam Authority board. The public was (and still is) being advised to stay out of the water because of a large bloom of blue-green algae. The Oklahoma Department of Environmental Quality said the danger is the algae's ability to produce and release toxins into the water. If the toxins are swallowed, reactions might include upper respiratory problems, eye irritation, vomiting and diarrhea.

The Niangua Arm of Lake Ozark is now on the EPA 303d list for excessive phosphorus content. Excessive phosphorus will encourage blue-green algae growth. LOWA, through a grant from EPA via Missouri DNR is currently actively pursuing efforts to alleviate this potentially very serious problem.

Similar official warnings were issued in August of 2011 for lakes in the Kansas City area and many lakes in Kansas as in the following excerpt from KMBC online:

KANSAS CITY, Kan. -- The United States Army Corps of Engineers and Kansas Department of Health and Environment are warning visitors of Milford and Hillsdale Lakes about harmful blue-green algae in the water…

More about the outbreak of Blue-green Algae on Grand Lake
If the prospect of an outbreak of blue-green algae has not already gotten the attention of Lake of the Ozarks businesses, read this excerpt from The Ozark Angler:

Posted 02 July 2011 - 01:29 PM
Just FYI to anyone fishing or boating on Grand Lake. The lake has a severe Blue Green Algae bloom going on. The GRDA has issued a statement that you should not swim or make contact with the water. Other experts have stated that they don't recommend eating the fish out of the affected parts of the lake. It doesn't appear to be overtaking the Main Lake but Duck Creek, Party Cove, Bernice State Park, and a few other areas are very toxic right now...Very bad for business at the marinas. Only saw about 10 boats on the lake in a couple of hours.

Another Real Example of What Could Happen Here

Lake George: Lake George is a major tourist area in New York not unlike our own Lake of the Ozarks.
Lake George In 2008, more than 60 algae bloom locations were documented on Lake George from July to November. (reference) "People who have spent decades on the lake told us they never saw anything like this," is a quote from the New York Times Union.

Algae Blooms

Several species of true algae as well as the cyanobacterias can cause various nuisance effects in fresh water, such as excessive accumulations of foams, scums, and discoloration of the water. When the numbers of algae in a lake or a river increase explosively, this is called an algal "bloom".

Algal blooms are natural occurrences and mild blooms in stagnant water conditions such as at the very end of coves can be expected during the year. Such blooms tend to be more prominent during periods of hot weather. Warm days, stagnant conditions, and adequate nutrient supply are a sure recipe for algae blooms. While there are natural sources for the nutrients, human activity can and often does aggravate the situation.

We are responsible for increasing the nutrient loading when the runoff from our yards carry our fertilizer into the lake, or when our septic systems or waste disposal systems are not working properly, from the fertilizer added to golf courses, from agricultural fertilizers and in general by not taking steps to minimize sediment run-off into the lake.

These algae blooms can be ugly and smelly and clog up our swimming, boating, and fishing areas. But that is only the tip of the problem. They can be toxic to the point of causing us severe illness and in some cases even death to our pets. But we've discussed the toxic algae in other sections of this web page. And that is still not the worse. If severe enough, the algae bloom will deplete the oxygen from the lake and this will cause death to the higher aquatic animals. Our fish will die. Repeated blooms over extended areas will cause our property values to decline.

Although algae blooms may be caused by what we usually consider beneficial algae, they are more often caused by the dreaded blue-green algae. This is due to several reasons such as the fact that the blue-green algae are actually bacteria and are tiny micro-organisms that are almost always widely dispersed in the water and therefore available to grow if the conditions are right. Also, the zooplankton that feed on the algae and tend to keep it under control do not like the blue-greens as a food source. And finally, unlike the true algae types, the cyanobacteria have nitrogen-fixation capability. This means that they do not need the nutrient nitrogen to be in the water because they can take the nitrogen from the air and convert it into a useable source. Therefore, phosphorus becomes the only nutrient source they need to grow exponentially. And what's even worse, the blue-green algae have the ability to store phosphorus for later use if an excess is present.

Let us do all we can to prevent algae blooms that have the capability of turning the Lake of the Ozarks into a dead lake.

Factors that can produce excessive algae blooms

  • Runoff into waterways with nutrients (nitrogen and phosphorus) from land clearing and soil erosion
  • inadequate sewage and septic systems
  • agriculture fertilizers
  • industrial effluent
  • lawn fertilizers
  • waste from livestock, pets or wildlife.
  • Lack of flow in reservoirs or in pooled parts of rivers -- rain can flush algae from the system and disrupt its growth.
  • Warm, sunny weather provides both heat and light to stimulate algae growth. Warmer winters and an early spring thaw can increase plant abundance.
  • Clear water can also increase the depth to which light reaches and cause a larger band of algae to grow.
  • Drought years can cause an increase in abundance of algae and other aquatic plants by reducing sediment runoff and increasing penetration of light, as well as causing water bodies to be shallower and with lower flow than usual.

The benefits of better land management may take many years to improve water quality because resuspension of nutrients from lake sediments can continue to support growth of algae. Therefore, contingency methods that provide short-term control and drinking water treatment may be necessary. Where surface waters are used for recreation or watering of livestock and pets, application of chemicals that kill algae, such as copper sulfate, may temporarily control algal growth. Several standard methods of treating drinking water are thought to successfully remove toxins or reduce their concentration to a safe level.

Steps to Reduce Algae Bloom Risk

In the reference above from Lake George, a Natural-Resource Specialist was quoted as saying:

While the specific cause of an algae bloom is difficult to determine, some steps that can be taken to reduce the risk include the following:

1) Eliminate using fertilizers and pesticides (see EPA Pesticide Labeling on commonly used products). Test your soil if you suspect that it is deficient of nutrients and add a top dressing of organic compost to your gardens and lawn in lieu of a fertilizer. Excess fertilizer that leaves your property unnecessarily feeds algae and aquatic plants in Lake George. Pesticides may eliminate (kill) zooplankton and aquatic invertebrates that feed on the algae. Without zooplankton and invertebrates present in the natural food chain, algae blooms proliferate and the fish that would normally feed on zooplankton and invertebrates have no food, and may disappear.

2) Your onsite wastewater treatment system (OWTS), or generally referred to as a septic system, should be pumped out and inspected every couple of years. The inspection should conclude that the tank and absorption field are functioning as intended. Replace your failing system before contamination to either groundwater or the lake has occurred. If your system is old, anticipate that a replacement may be necessary, which is a homeowner's responsibility.

3) Plant a shoreline buffer to treat and infiltrate stormwater that may be leaving your property and entering the lake. During a storm, watch where the water flows on your property (off your roof, driveway, sidewalk, deck or a sloping bank) and plant a rain garden to temporarily pond and then infiltrate stormwater in the appropriate areas in order to keep the rain water on your property. Precipitation should infiltrate the ground where it falls, allowing nutrients and pollutants to infiltrate the ground, recharging the groundwater after it has been cleansed and treated by the soils and vegetation on site. Planting a shoreline buffer will also deter geese and water fowl from entering your property, as these visitors prefer open spaces where their predators can be watched.

These recommendations from Lake George apply equally to us here at the Lake of the Ozarks.

List of Other Web Sources

Algae Bloom Monitoring

Green Algae Facts

Cyanobacteria in Vermont

Harmful Algae Blooms (HAB):

Cyanobacteria; Blue-green Algae Facts, info from Vermont Dept of Health

Green Algae Facts

Types Of Algae, Ecological Relationships, Factors Limiting The Productivity Of Algae - Species, Brown, Green, and Pigments:

Bloom Occurences and Impact

Is Your Beach Safe for Swimming?

Non-point Source Pollution and Lake Ecology (from LMVP program

a USGS reprt on Harmful Agae Blooms

Bacteria Museum

University of California Museum of paleontology”

Wikipedia-Cyanobacteria

Algae Description and Trypes

Algae Description and Types

Blue-green Algae in Florida Waters

Cylindrospermopsis (Blue-green algae in Indiana waters)
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