Before we get down to discussing the various effects of algal bloom upon the surrounding biosphere, let's first take a closer look at what exactly this phenomenon is. Remember the green, sometimes bluish-green, layer that either covers a corner or spans across lakes, ponds and marshes obstructing the view of the depths of these still-water bodies? Well, that's algal bloom for you.
When a water system is affected by the rapid growth and accumulation of algae population upon its surface, appearing to smother it, such a vegetative spurt is known as algal bloom. These blooms can strike any type of aquatic system, it can affect freshwater lakes and ponds to marine coastal waters. Virulent infestation of such blooms of algae in lakes and ponds is a common phenomenon and can mostly be seen during the monsoons and heavy spells of rain.
Most blooms in fresh water occur due to an excess of phosphorus and other nutrition content in the water. This may happen as a result of widespread use of phosphorus based fertilizers. That's the reason why it's common to see such blooms in ponds that are in proximity to agricultural lands. These agricultural nutrients can also find a way to farther drainage basins by traveling through the media of various streams and other water runoffs.
Usually, a small number of specific types of algae, usually certain species of phytoplankton, are responsible for these aquatic algal blooms. A typical bloom can house an algal population, as dense as a couple of thousand algae cells per millilitre of water. Let's, now, take a look at various effects of algae blooms and what consequences they have upon their surroundings.
Effects of Algal Bloom
The following points deal with a wide range of effects of aquatic blooms including visual, environmental as well as adverse health effects of toxic botanical blooms.
- The most common sign of an oncoming bloom is the discoloration of the affected aquatic system which is caused by the increase, over normal levels, in the algal cells in the given area of water.
- Harmful and toxic blooms involving infestations by booming populations of dinoflagellates are known to pose mortal danger to other organisms, as these blooms produce many natural toxins that cause harm to organisms that either live in such infested waters or unintentionally ingest the algae.
- Presence of algal blooms in marine waters are known to be one of the chief causes of shellfish poisonings.
- Dinoflagellates often take upon a reddish-brown hue due to which the infested waters assume a reddish tint. This is the reason behind the occurrence of red tides in coastal waters. You may refer to facts about red marine algae to know more about these microscopic plants.
- The effects of blooms formed of blue-green algae are not caused by any phytoplankton. These blooms are actually populous colonies of cynaobacteria or macroalgal or a combination of both.
- Harmful bloom contamination may occur in sea food as well as drinking water, and consumption of such food and water may lead to serious health issues and even death in humans.
- Usually, the health problems faced by humans on ingestion of, or exposure to, toxic algae includes respiratory irritation, sneezing, coughing and irritation of the skin. The phytoplankton species Karenia brevis is usually responsible for these adverse health effects.
- Aquatic creatures such as fish, shellfish, turtles, can experience severe mechanical damage (like epithelial gill tissue disruption) when exposed to high volumes of algae bloom over a long period of time.
- The oxygen level of infested and surrounding waters also tend to go down due to respiration of algal cells and degradational activities of bacteria in the blooms. This poses a mortal threat to other aquatic life that dwell the surrounding waters.
That was a brief outline of the known algal bloom effects along with the most common causes of why they occur. Although many algae have various beneficial properties and we get a lot of useful products from algae, any uninhibited growth of algal population, especially the toxic species, is a cause for concern. The phenomenon is just like cancer - when cell development exceeds the normal, beneficial rate, an excessive accumulation of tissues takes place leading to a malignant growth that could be the harbinger of impending mortality.