Consequences of Algal Blooms
If there is a decrease in the number of grazers in the environment in which the algae are occurring, the algae would thrive as there would be not be enough of these available on the algae to keep the algae population under control. Temperature plays a key factor as most algae especially blue-green algae thrive in warmer temperatures. The optimal temperature for algae growth is usually 25 ? C and most algae are not able to survive in cold conditions. An increase in nutrients is also a factor in the increase in algal blooms.
When nutrients containing phosphorus and nitrogen enters water ways from agricultural land and through soil erosion this causes an increase in algal blooms since nutrients encourage growth of algae. This process is known as eutrophication and is an increasing problem globally. Algal blooms out compete organisms and decolorize water. Some algae are able to produce toxins known as neurotoxins and are referred to as Harmful Algal Blooms (HAB’s). The cyanobacteria which are blue-green produce harmful toxins which have harmful effects on humans, birds, shellfish, fishes and other marine organisms.
A few forms in which HAB’s can occur are red tides and golden tides. Red tides belong to a group of dinoflagelates and are produced by microscopic alga called Karenia brevis, and golden tides belong to the group chrysophyta. There are many consequences of the occurrence of HAB’s such as death of aquatic life, health and economic effects. The accumulation of algal blooms affects aquatic life in many ways. Too much algae clogs the gills of fish thereby irritating the gills of the fish and eventually suffocating them since it is difficult for the gills to take in oxygen.
When there is a rapid increase in algae, they use up all the available nutrients needed for their survival such as Phosphorus and nitrogen. This causes mass mortality of the algae which causes bacteria which assist in the decaying process of the algae to increase. These bacteria use up most of the oxygen supply in the water causing aquatic organisms which depend on oxygen for survival to die or migrate. Some algae release dinoflagellate toxins which are very deadly and have been known to kill mussels, fish and abalone which ingest and digest these deadly toxins.
Marine animals are not only affected animals such as cattle, fish, birds, sheep, pigs and a variety of other animals have died through the inhalation and consumption of these species. Humans are also affected by the toxins released by algal blooms. When humans inhale the toxins released by the algae this has many harmful effects. Also, when fish and shellfish consume algae the toxins accumulates inside their body. When larger organisms feed on them the toxins are passed up the food chain and eventually to humans who eat seafood.
Some of the diseases which occur in humans due to toxins found on algae include Ciguatera fish poisoning (CFP), Neurotoxic shellfish poisoning, (NSP), Brevetoxin/repiratory irritation (BRI) and amnesic shellfish poisoning (ASP). CFP is a gastrointestinal illness caused by a marine toxin called ciguatoxin or maititoxin. Ciguatoxin has a tendency to accumulate inside large fish such as barracudas, snappers, and other marine fish. CFP is then transferred to the humans through consumption. Symptoms due to the contraction of CFP include nausea, diarrhea, vomiting, increased heartbeats and tingling of hands and feet.
NSP is caused through the consumption of infected shellfish. This leads to severe symptoms such as respiratory problems, diarrhea and vomiting. BRI is caused through the inhalation of harmful toxins released by the HAB’s. The symptoms include shortness of breath, coughing, sneezing and eye irritation. ASP is caused by the accumulation of domic acid in shell fish which are produced by the organisms Pseudo-nitzschia. The effects of the consumption of the affected food by humans include confusion, memory loss, disorientation, stress and in some cases result in coma and death.
There are many economic consequences due to the accumulation of algal blooms. Many industries, fisheries and shell fish beds have been either closed, or decreased in their number of productions. Fish sales decline because consumers are afraid of purchasing fish for fear of toxins. This causes fish vendors to lose a lot of sales and money and many fall into bankruptcy. Closure of many tourism and recreational facilities has also resulted in mass economic losses skyrocketing into the millions, especially for countries which depend on tourism as their primary source of income.
Health impacts have also caused severe financial losses as a lot of money now has to be allocated for the treatment and cure of the diseases caused by algal blooms. Many water systems and supplies have also been contaminated by algal blooms, this result in increased cost of water purification methods in order to make water potable. Also, Governments must now allocate finances for the prevention and treatment of algal blooms. The aquaculture industry have also been impacted economically due to blooms namely Heterosigma threatening to destroy endangered salmon thereby impacting on the salmon industry.
There are many ways in which algal blooms can be monitored and kept under control. The Harmful Algal Bloom and Hypoxia Research and Control Act which was established in 1998 which recognizes the impact of algal blooms to aquatic life, human health and coastal systems. Through this act there are many implementations put in place to help monitor and prevent these HAB’s. There are now programs in place which monitor the outbreaks of algal blooms and in which there is constant testing of shellfish and fish.
Monitoring of water for the occurrence of dead fishes, beaching of marine life and observation of colour appearing in water are done to detect the outbreak of neurotoxins so that warnings can be issued when found. Also, research is being done for the detection of toxic phytoplankton in water ways. In this way methods can be done to prevent outbreaks before they even occur. Satellite monitoring is also one of the methods implemented for the detection of offshore blooms. This method allows for warning and alerting areas of potential outbreaks before it occurs so that methods can be put in place for their prevention.
Algal blooms have many consequences. They threaten the breakdown of ecosystems, kill marine life, and have many harmful effects on humans. They also have huge economic effects and cost millions of dollars in losses and millions have to be spent for their prevention and control. Although algae are a vital part of the aquatic system in that it provides food and shelter to many organisms. Too much of a good thing can be a bad thing. Therefore algal blooms need to be prevented and kept under control so that there would be an aquatic ecosystem in the future for everyone to admire and enjoy.