In short
- Algae problems occur almost everywhere where water is being stored;
- Stagnant water combined with high water temperatures or high concentrations of excess nutrients such as nitrates and phosphates fuels algae blooms.
Blue-green algae, also known as cyanobacteria, are harmful algae that can cause serious human and animal illnesses, affecting human health and aquatic animals. Besides turning waters green and unclear, these harmful algal blooms cause foul odors and bad taste. They suffocate aquatic plants and other aquatic life by depleting the dissolved oxygen in affected water. Therefore, algae blooms are a serious problem that needs immediate attention in order to prevent harmful effects on marine life, other aquatic animals, and water supplies contaminated with algal toxins.
What are algae?
Algae are a diverse group of plant-like organisms that grow in a wide range of environments. They contain chlorophyll, have simple reproductive structures, and their tissue is not differentiated into roots, stems, or leaves. They range from unicellular, or single-celled, to fairly complex multicellular organisms. Some algae types have such a complex growth that they are mistaken for vascular plants.
The size of average individual microscopic unicellular algal cells is approximately 0.0010 mm in diameter.
Algae are found throughout the world in natural waters, including fresh water, salt water, and brackish waters, and can cause problems in all kinds of settings, from water treatment plants to drinking water supplies, ponds, swimming pools, and cooling towers. The extermination of algae is a problem, as the methods to control algae can be expensive, cumbersome, environmentally unfriendly, or all of these.
Algae can appear on vegetation, in the air, in the soil, and in water systems. Their microscopic spores are continuously carried into pools and other water reservoirs by wind, dust storms, rain showers, and water flow. They grow rapidly in stagnant waters, especially when exposed to sunlight and water temperatures above 4 degrees Celsius. They can form objectionable slime and/or odors. Algae can interfere with proper filtration and they greatly increase chlorine demand. Phosphates and nitrates in water, which are examples of excessive nutrients, only fuel their growth, contributing to harmful algae blooms and blue green algae blooms in affected water bodies.
Types of algae
Algal growth occurs in three basic forms:
- Planktonic
- Filamentous
- Macrophytic
Planktonic algae are single-celled, microscopic algae that float freely on the water surface or ocean surface. When these algal species are extremely abundant, or “bloom,” they turn waters green, sometimes causing harmful algal blooms (HABs) that produce toxins harmful to marine organisms and marine animals. Less often, such blooms turn waters yellow, gray, brown, or red, contributing to phenomena like red tide that can harm marine ecosystems and coral reefs. These HAB species can reach dense concentrations, releasing algal toxins into the surrounding water and water droplets, which may affect the nervous system of marine life, leading to health effects such as neurotoxic shellfish poisoning and paralytic shellfish poisoning.
Filamentous algae are sometimes referred to as “thread algae” or “pond scum.” Filamentous algae occur as fine green threads that form floating mats on the water surface, which are often moved around the pond by the wind. Their dense concentrations can deplete oxygen in the surrounding water, negatively affecting aquatic animals, marine mammals, and fish gills. These algae are also commonly found attached to rocks, submerged trees, other aquatic plants, and boat docks. Skin contact with affected water can cause skin irritation in humans and animals.
Macrophytic algae resemble true plants, as they appear to have stems and leaves. A commonly-occurring macrophytic algae is called Chara or musk grass (due to its strong musky odor). Chara feels coarse to the touch due to lime deposits on its surface, earning it another common name—stonewort. These harmful species can impact the food chain and contribute to algal toxins and harmful effects in the marine environment, including gastrointestinal illness and other health effects related to exposure to algal toxins, which can accumulate in contaminated seafood.
Algae problems
Filamentous and planktonic algae can reproduce at phenomenal rates, and sudden die-offs can cause oxygen depletion, leading to dead zones harmful to marine life. In fish ponds and lakes such as those in the Great Lakes region, including Lake Erie and other aquatic plants supply the oxygen needed in the water basin and flourish when algae no longer compete for resources.
Algae-related problems, including the growth of toxic algae and harmful algal blooms (HABs), are usually caused by excessive nutrients in a water body. From the moment a pond is built, for example, it becomes a settling basin for excess nutrients washing in from the land that drains into the pond’s watershed.
The older a pond gets, the more nutrients will accumulate, increasing nutrient levels and making it more susceptible to algal issues and bloom events. Runoff from fertilized fields, lawns and pastures, feedlots, septic tanks, and leach fields accelerate nutrient loading and algal growth, which can kill fish and other aquatic animals due to depleted dissolved oxygen and the production of harmful toxins associated with harmful algae and blue green algae blooms. Several species of algae are known to produce domoic acid and other harmful toxins that can accumulate in seafood contaminated by such blooms.
Algae growth conditions
Excessive algae growth will starve or suppress other forms of aquatic life, and block sunlight necessary for their proper growth. Taste and odor problems in drinking water and sometimes even fish kills are associated with excessive planktonic algae blooms, which are a common algae disadvantage.
Filamentous algae and macrophytic algae make fishing, swimming, and other recreational uses nearly impossible due to the thick layer they form. Total coverage can restrict sunlight penetration and limit the production of oxygen and food supply necessary for fish and other aquatic animals.
Many of the most blooms are caused by high biomass producers, which can reach dense concentrations and severely impact water quality. When such dense blooms interfere with the intended use of the pond, they need to be controlled immediately to prevent further harmful effects on marine life, other aquatic animals, and the surrounding water bodies contaminated with algal toxins.
Algae control
Filamentous algae mats may be removed with a rake, screen wire, or similar devices. However, this method is labor-intensive and provides only temporary control. In some instances, the algae may seem to grow as fast as they are pulled out, contributing to algae disadvantages such as rapid algal growth, harmful algal blooms, and the proliferation of toxic algae and harmful species in water bodies.
Before dosing chemicals, you should consider potential contamination of domestic water supplies and the waiting periods for watering livestock, eating fish from affected water, swimming, and irrigation, as these environmental factors can influence the presence of harmful toxins, algal toxins, and HAB toxins in affected water.
A “biological control” is when one form of life is used to control another or the balance of life is manipulated in such a way to adversely affect an undesirable pest. It’s wise to be cautious when deciding on biological control. It can backfire when the new species that were introduced become more of a problem than the original pest, potentially affecting marine life, other aquatic animals, and the surrounding marine ecosystems.
Barley Straw has been tested in England by the Centre for Aquatic Plant Management for the control of planktonic and filamentous algae. This testing has been going on over the last 15 years. Barley Straw and other straws have been used sporadically in the United States, with very mixed results, and will not totally solve the problem of excessive nutrients fueling algae blooms, harmful algae proliferation, or blue green algae blooms.