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Alexandrium

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Alexandrium
Red tide shore 2.jpg
Scientific Classification
Species
  • A. andersoni
  • A. diversaporum
  • A. lusitanicum
  • A. taylori[1]
Alexandrium tamarense.jpg
Microscopic view of Alexandrium

Alexandrium is a genus of algae which causes Red Tide, harmful algal blooms (HABs) that grow out of control and dilute the color of the water and infect the sea life[2]. Red tide occurs naturally, when the concentration of microscopic algae grows very high.[3] While the tides can be very beautiful, it causes severe problems for the economy because it kills much of the marine life. These beautiful algal blooms also pose a threat to the health of both marine animals and humans.

Anatomy

Alexandrium under a microscope

Algae is a simple plant that lives in water. A bloom of algae is simply a colony of algae[2]. Alexandrium often produces poison.[4] Each is a single-celled organism capable of swimming a short distance with the help of two flagella. [5] They are unarmored cells and are photosynthetic. They are typically around 20 to 45 micrometers long and 10 to 15 micrometers deep.[6]

Life Cycle

Alexandrium forming a cyst

Algae can reproduce both sexually and asexually. Sexual reproduction consists of the union of a male and female gamete. Red algae reproduces asexually by producing monospores, which are walled, spherical cells lacking flagella, that are carried by currents After germination, it forms a new organism.[7]

Alexandrium’s life cycle is able to be broken into four major phases. The first phase is not completely understood by scientists at this point in time, but there are a few theories about it. The most common theory is that the algae go dormant at certain periods of the year. While the algae are in this state, they sink to the ocean floor. Later, when the water is warmer, the algae releases itself. In the second phase, the algae focus on growing in population. As a result, this is when the boom progressively grows larger and larger. At this point, the algae concentration of the bloom can, if conditions are favorable, double within a few weeks. In the average bloom, the concentration is somewhere around one-thousand cells per liter. As the bloom increases, oxygen depletion zones begin to form. These zones occur because the bloom use so much oxygen as it grows, as well as the process of disposing of fish that the boom kills.

The third phase is, essentially, conservation. While the bloom starts to head towards the shore by the currents and the wind. The bloom grows even larger once there thanks to increased nutrient levels. The extra nutrients allow the bloom to remain for several days, if not weeks, and sometimes, the bloom can remain for months. The final stage in the algae life cycle is dispersing. The ocean current and wind eventually draw the bloom back out and they separate.[6]

Ecology

Map of specimen collection locations for Alexandrium

Various species of Alexandrium have been reported in the temperate oceans around the world. Species that are potentially toxic have been seen along the Northeast coasts of North America and Canadian Maritime provinces[8]. The most well-known harmful algal bloom in the United States is along the Gulf Coast in Florida every summer. There is national concern that these blooms harm not only people’s health, but that of economies as well. They can be harmful to the ecosystems, like when large amounts of the algae die, the decomposition depletes oxygen levels so much that animals must leave the area. If they do not, they will die[2]. Florida has lost millions of dollars in revenue because of the blooms' effects on the ecosystem[9]. Not all blooms are harmful, though. Most are actually quite beneficial, since the algae act as food for oceanic creatures and serve as a major energy source[2].

However, large amounts of deaths in fish and some diseases in mammals have been linked to these blooms[10]. Humans can become sick from the toxins produced by these blooms, but the illnesses are rare. When they do occur, they are nearly unbearable and even fatal. Fish, on the other hand, as well as birds, shellfish and mammals, often die because of these blooms[2]. Shellfish are often prone to contamination because they filter feed. Toxic plankton is filtered from the water, and the shellfish then becomes contaminated. The toxin produced is called sxitoxin, and is one of the strongest scientists have discovered[4]. Despite the problems connected with this toxin, some good has come from it. In an attempt to develop an anti-toxin, researchers have possibly discovered a treatment for Cystic Fibrosis[10].

Red Tide

Red Tide in the ocean

When the quantity of certain algae rapidly grows, they come together [11] and form what is called a harmful algal bloom (HABs). Even though most people call these blooms red tides, most scientists use the term HABs[2]. The algae becomes so large in population that it discolors the water[10], red, as the name implies [2]. However, despite this common name, and that these HABs generally turn the water a rusty red color, the discoloration can range from pink to orange and brown to yellow. [11] Algae related to these HABs are usually spread by tides and winds, currents, storms and watercraft[10]. Some scientists think that the root cause of the blooms is high temperatures and little to no wind or rainfall[3], but it is generally thought to include also low sanity, high nutrient content and calm seas as well[10]. Red tide occurs all over the world, and reports imply that they are occurring more and more frequently, and that they are increasing steadily[11]. Scientists have not yet found a way to control them[3].

The algae makes powerful toxins [10] that affects the central nervous system of fish, causing paralysis and taking away their ability to breathe[3]. Scientists have no explanation for why the blooms produce these toxins[10].The toxins produced also make shellfish harmful if eaten[2]. Some fish and krill are unaffected by the poison, but if they are eaten, all the poison they have accumulated is released into the organism that consumed them. Mass fish deaths and certain diseases in mammals have been linked to eating shellfish in the course of a red tide bloom[10]. While humans are at the beach, wave action can allow some of the blooms poison into the air, which can cause certain respiratory issues, particularly in those with respiratory sicknesses[11]. However, if large amounts of toxins are consumed, humans can suffer from several diseases. One such disease is Paralytic Shellfish Poisoning (PSP), which cause disrupted nerve functions and paralysis, and in extreme cases, asphyxiation. Others are Diarrhetic Shellfish Poisoning (DSP), which leads to diarrhea, nausea, vomiting, abdominal pains and cramps, although it is not lethal, and Amnesic Shellfish Poisoning (ASP), with symptoms including dizziness, disorientation and memory loss[10]. If you think that you or someone else has been exposed to the bloom’s toxins, it is strongly advised to seek proper medical attention or visit the nearest hospital emergency room or medical clinic. If neither of these options are available, it is strongly recommended that you contact the nearest poison control center[4].

Video

Red Tide is an international occurrence.

Gallery

References

  1. Authorlastname, Firstname. Alexandrium Wikispecies. Web. Accessed May 13, 2014.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 National Ocean Service. A-red-tide-is-a-common-term-used-for-a-harmful-algal-bloom Ocean-service.noaa. Web. Last updated January 23rd, 2014.
  3. 3.0 3.1 3.2 3.3 Unknown Author. Frequently-Asked-Questions Texas-Parks-and-Wildlife. Web. Accessed May 13, 2014.
  4. 4.0 4.1 4.2 Unknown Author. Red-Tide-fact-sheet Health-and-Human-Services. Web. Accessed May 13, 2014.
  5. Hampton, Mike. What is Red Tide? The Keep. Web. Written January 5, 2014.
  6. 6.0 6.1 Black, Andy. The Florida Red Tide Jr-Science. Web. Written June 9, 2006.
  7. Anderson, Robert. algae Encyclopedea-Britannica. Web. Last updated January 27, 2014.
  8. Produced by: NCCOS Volunteer Phytoplankton Monitoring Network Alexandrium-spp. Coastal-Science. Web. Accessed May 13, 2014.
  9. Unknown Author. Red-Tide-and-Red-algae-effects Start1. Web. Accessed May 13, 2014
  10. 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 Bruckner, Monica. Red Tide - A Harmful Algal Bloom Microbial-Life. Web. Last updated March 3rd, 2014.
  11. 11.0 11.1 11.2 11.3 Lallanina, Marc. What-causes-Red-Tide Live-Science. Web. Published March 11th, 2013.