How do algal blooms form

High turbidity occurs when a lot of water is running through the system high discharge after a rain event. Low turbidity occurs when there is only a small amount of suspended matter present in the water column.

Low turbidity can be due to slow moving or stagnant water that allows suspended articles to settle out of the water column. When turbidity is low, more light can penetrate through the water column.

This creates optimal conditions for algal growth. In return, growing algae create a turbid environment. School of Science.

Department of Earth Sciences. Skip to main content. Nutrients Nutrients promote and support the growth of algae and Cyanobacteria. Temperature Early blue—green algal blooms usually develop during the spring when water temperature is higher and there is increased light. Light Blue—green algae populations are diminished when they are exposed to long periods of high light intensity photo-inhibition but have optimal growth when intermittently exposed to high light intensities.

Stable Conditions Most of blue—green algae prefer stable water conditions with low flows, long retention times, light winds and minimal turbulence; other prefer mixing conditions and turbid environments. Turbidity Turbidity is caused by the presence of suspended particles and organic matter flocs in the water column.

Sep 9, - - 0 comments. Although there is no officially recognized threshold level, algae can be considered to be blooming at concentrations of hundreds to thousands of cells per milliliter, depending on the causative species.

Some algal blooms are the result of an excess of nutrients particularly phosphorus and nitrogen into waters and higher concentrations of these nutrients in water cause increased growth of algae and green plants.

With more food available, the bacteria increase in number and use up the dissolved oxygen in the water. At the high cell concentrations reached during some blooms, these toxins may have severe biological impacts on wildlife. Algal blooms composed of phytoplankters known to naturally produce biotoxins are often called Harmful Algal Blooms, or HABs.

Reference Terms. Algal blooms may occur in freshwater as well as marine environments. Algal bloom concentrations may reach millions of cells per milliliter. Colors observed are green, yellowish-brown, or red. Bright green blooms may also occur.

These are a result of blue-green algae, which are actually bacteria cyanobacteria. As more algae and plants grow, others die. This dead organic matter becomes food for bacteria that decompose it. When the dissolved oxygen content decreases, many fish and aquatic insects cannot survive. This results in a dead area. Algae vary from small, single-celled forms to complex multi-cellular forms. An algal bloom is a rapid increase in the density of algae in an aquatic system.

Algal blooms sometimes are natural phenomena, but their frequency, duration and intensity are increased by nutrient pollution. Algae can multiply quickly in waterways with an overabundance of nitrogen and phosphorus, particularly when the water is warm and the weather is calm. This proliferation causes blooms of algae that turn the water noticeably green, although other colors can occur.

Some species of algae grow in clumps covered in a gelatinous coating and have the capability to float, allowing cells to stick together into large surface scums in calm weather.

Other algae form thick mats that float on or just below the surface along the shoreline. In the St. Johns River, blooms most often are composed of cyanobacteria, also known as blue-green algae. Cyanobacteria are bacteria that, like plants, use solar energy and carbon dioxide to grow photosynthesis.

Cyanobacteria occur naturally in both freshwater and marine salt water bodies. Blooms also can be caused by dinoflagellates single cell microorganisms [phytoflagellates] that include luminescent forms in marine or estuarine water bodies red tides are an example of a dinoflagellate bloom. The potential for blooms comes from nutrient pollution, an overabundance of the essential plant nutrients nitrogen and phosphorus. These elements enter waterways from point sources such as industrial and wastewater treatment plant discharges , nonpoint sources such as septic tanks and stormwater runoff from urban areas, farms and residential areas , and from nutrient-enriched rainfall.

When the concentrations of nitrogen and phosphorus increase in a water body, the right combination of temperature, sunlight and low flow can trigger an algal bloom. Stormwater facilities are designed to capture polluted runoff.

The ponds help remove nutrients and sediments before these pollutants can reach fragile waterways. The public plays an important role in reducing nutrient pollution. Each of us can use fertilizers wisely, such as only when lawns show nutrient deficiencies, according to manufacturer directions and avoid using fertilizers just prior to a rain. In addition, we can each use chemicals responsibly, properly maintain stormwater systems and connect to a central sewer system where possible.

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