As technologies are developed and spread across the world, the effects of these technologies on the environment are becoming more apparent. Nations all over the world are changing agricultural practices, and how people raise and handle their crops is becoming more mechanized for peoples with the money to effect the change. Most of all, agrichemicals, such as ammonium nitrate, are becoming more widely used as a means to obtain higher yields. Unfortunately, with the advancement in any technology, comes a price. When any nutrient-rich chemicals leach into waterways, it is bound to impact the environment. One such impact is on algae populations. Chemicals such as ammonium nitrate and phosphates used by humans are over feeding algae populations in oceans in lakes, causing damage to aquatic ecosystems and creating serious problems for fishermen, who rely on the ocean as a means to live.
What is Algae and Why is it a Problem?
Algae are a type of photosynthetic life form that inhabits aquatic environments. Although many people would characterize algae as a type of plant due to its use of the sun for energy, most species of algae are actually protists. Different species can live in either fresh or salt water environments. Algae tend to favor the surface of a body of water, as less sunlight penetrates the water at greater depths. Algae are an integral part of aquatic ecosystems, providing food for fish and other forms of sea life. Many species of algae are helpful or benign in an area, but some species produce toxins or are more prone to take over an ecosystem. When an environment contains the right amount of resources, harmful algae can often bloom, choking out much of the life that had once occupied that region.
A common term for one type of bloom is “red tide.” Red tide occurs when poisonous one or more poisonous varieties of dinoflagellates bloom in an area. Dinoflagellates make up a large portion of algal species. It is important to note that not all dinoflagellates are toxic. Red tide is so named because it tends to turn the water red or reddish brown. Red tide mostly occurs in coastal regions, and fertilizers play a large role in providing the nutrients needed by the dinoflagellates to bloom.
Another type of algae that tends to bloom and which many have heard of is blue-green algae. Blue-green algae is in fact not a type of algae at all, but rather a family of photosynthetic bacteria known as cyanobacteria. Different species of cyanobacteria can be found in either fresh or salt water. Like other forms of algae, cyanobacteria will often bloom in the right conditions, and most cyanobacteria tend to live on the surface of a body of water, where they can receive the most sunlight. Many species of cyanobacteria produce toxins that can affect the nervous, hepatic, and dermatologic systems. Some toxins can cause tumors or other health risks as well. Because many species can and do survive in fresh water, drinking water all over the world can be at further risk for contamination. Most species that produce toxins tend to produce multiple toxins, creating more complex problems.
Toxins produce by algae can devastate a local area. Many species of algae produce harmful toxins, and some species even produce multiple types of toxins. While it may seem like an obvious solution is to use pesticide on the algae, pesticides can have affect other organisms in an environment negatively as well. In addition, the toxins are not destroyed by pesticides. The situation can become worse if pesticides are used because the toxin is released into the water as the algae decompose, rather than remaining encapsulated in the algae as it would have been had the algae not died. In many cases, organisms that eat the algae aren’t affected by its toxin because the toxin is not in a high enough concentration to cause damage. However, the toxins tend become more concentrated the species that prey on the organisms that originally consumed the algae. As one moves up the food chain, the toxins accumulate, and problems arise as a result of the toxins. The highest level predators tend to be the ones with the most debilitating damage, and can even die from it. Even if they don’t die, the different toxins can have different effects, including brain damage and harm to pregnant organisms’ fetus, creating problems for future generations.
Humans aren’t completely removed from the harm done by toxic algae. Algal toxins can cause Amnesic Shellfish Poisoning (ASP). ASP is a condition in humans in which an algal toxin—namely, domoic acid—induces symptoms like vomiting, nausea, diarrhea, abdominal cramps, headache, dizziness, confusion, disorientation, loss of short-term memory, motor weakness, seizures, cardiac arrhythmias, coma, and can even cause death in high enough concentrations. ASP is so named because short-term memory loss tends to be one of the more common symptoms and the disease most often arises as a result of eating shellfish that had consumed toxic algae. Another disease caused by the eating of shellfish that had eaten toxic algae is paralytic shellfish poisoning (PSP). PSP is caused by saxitoxin, and symptoms can start as little as 30 minutes after consuming contaminated shellfish. At first, the symptoms are tingling of the lips, tongue, face, neck, fingertips and toes; followed by headache, dizziness and nausea. If the poisoning is severe enough, muscular and respiratory paralysis can take hold. Death occurs as a result of the respiratory system becoming sufficiently paralyzed, so that the victim can no longer breathe. As a result of the illnesses that are by algal toxins, the Department of Health Services requires shellfish growers in areas with a history of blooms to screen their harvests and test phytoplanton for levels of toxins. If the concentrations become too high, monitoring increases and admonitions against eating—and even quarantines on—the sea life in the area are set in place, cutting deeply into the pockets of fishermen who rely on the shellfish for their livelihoods. However, toxins are not the only problem caused by harmful algal blooms.
Deoxigenation of an area can also be a result of blooms. This issue seems somewhat counterintuitive; algae, much like any other photosynthetic organism, don’t use oxygen, but rather produce it as they harness the sun’s energy. However, the algae are only the indirect cause of hypoxic environments. When algae—or any other organism, for that matter—die, they become food for bacteria. As the bacteria decompose the algae, they also use oxygen in the water to help with their life processes. In ordinary circumstances, populations of bacteria are limited by the amount of dead organisms in their immediate environment, and the levels of oxygen in the water are more or less in balance. However, during an algal bloom, much more algae are present. When that algae dies, more food is available for local bacteria, and the bacteria population in that area rapidly increases. While the oxygen levels were balanced prior to the bloom, they can’t support the swiftly growing bacteria, and the amount of oxygen decreases. As a result, the concentration of oxygen eventually diminishes to a point at which fish and other organisms living in the water that rely on oxygen die off in the area. Fishermen can no longer effectively fish in that area even if the algae are not toxic, as the populations of fish are severely cut. If the hypoxic conditions are bad enough, they can often combine with toxicity to form a dead zone.
A dead zone is exactly what its ominous title suggests: an area in which almost nothing can survive. Dead zones are created when an algal bloom of epic enough proportions causes such severe toxic and hypoxic conditions and uses enough of the nutrients in the water in a habitat that the area can no longer support life and the ecosystem collapses. What’s more, dead zones are a growing problem. Dead zones affect an area 245,000 square kilometers. One of the best known dead zones is in the Gulf of Mexico, where the dead zone cycles every year. The cycle starts when algae begin to multiply. Eventually, they become a bloom. The algae die, harbingering the death of any other species that lived there. The dead zone grows, then begins to recede. Just as the area begins to recover, the process is started over again.
The Causes of Harmful Algal Blooms
Algal blooms are sometimes natural occurrences. Nutrients are naturally collected from the banks of rivers and washed downstream until they reach the mouth of the river. Then, the nutrients wash out into the ocean and support many coastal species. The algae—which may or may not be toxic—near the coast may bloom if the water conditions are ideal. That being said, extra nutrients—such as those found in fertilizers, detergents, and untreated sewage—are often introduced to rivers, causing larger, more frequent, and, overall, more damaging algal blooms. Fortunately, bans on phosphates in detergents are slowly spreading, and sewage treatment is a fairly common practice, but fertilizers are still a major problem.
Much like plants, algae tend to grow more with the addition of fertilizer, especially fertilizers containing ammonium nitrate and phosphates. Fertilizers tend to seep into the groundwater, which can seep into rivers and streams. The fertilizers eventually end up in lakes and oceans, significantly increasing the amount of nutrients available to species. When the fertilizers reach the algae, they rapidly grow and can eventually result in an algal bloom, potentially upsetting the ecosystems in which the algae had played an integral role in shaping and developing. While fertilizers may not have created much of a problem at their inception, fertilizer production and subsequent use has grown with to feed growing populations. In 1843, the commercial fertilizer industry was born with the development of a process to make superphosphate. In 1849, mixed fertilizers were starting to be sold commercially, and fertilizers became more readily available to the average American farmer. By the 1890s, the average fertilizer consumption per year was 1,845,900 tons. As fertilizers were refined and improved and more was learned about which nutrients were most important to which crops, the amount of fertilizer consumed by American farmers continued to increase, feeding the problem of harmful algal blooms. Over time, much of the world has adopted the use of fertilizers for their crops, making harmful algal bloom an even more insurmountable task.
Solutions
If fishermen—and aquatic environments at large—are to survive, something must be done to combat the unnaturally high frequency of blooms and their devastating effects. However, determining a solution to the problem of harmful algal blooms can be exceedingly difficult due to the environmentally sensitive nature of the problem. If all—or at least too much—of the algae in an area is killed off, then the food web of that area will be upset and many of the organisms that relied on algae either directly or indirectly will starve. In addition, many pesticides that could be used to kill the harmful algae in an area may also kill generally beneficial algae and other aquatic life, yielding no improvement over the dead zones that exist currently, and creating serious problems in areas where harmful algal blooms have not yet reached such a dire state. Even if a particular pesticide only killed one type of algae, as mentioned before, the toxins produced by and contained within some species of harmful algae would be released into the water as the dead algae decomposed, and the area of the algal bloom would remain reletively inhospitable to life.
If pesticides can’t be used beneficially, then what could be done to prevent the problem? Already some measures have been taken to prevent the key nutrients that lead to harmful algal blooms from flooding into the oceans. Many states and municipalities ban the use of phosphates in detergents. While bans on phosphates in soap helps, it does not completely eliminate the problem. In addition, many people oppose the bans because the detergents that are available to them which don’t contain phosphates don’t clean as well as the detergents with phosphates. Many people are so dissatisfied, that they find ways of circumventing the bans, such as going to neighboring states which still allow phosphates in their soaps. If bans on phosphates are to be successful, better detergents need to be developed that are of a similar—or even better—quality for cleaning.
In some situations, various chemicals are used to treat toxins that are released by algae. Chlorination, ozonation, and activated carbon have all been used to treat water sources to eliminate toxins produced by algae. Unfortunately, both the addition of chlorine and ozone to water, while moderately effective in destroying toxins, prove also to be moderately effective in destroying fish and other aquatic life if the levels of either chemical is too high. Activated carbon, on the other hand, is also used in filters for aquariums, and is much less likely to harm fish. Unfortunately, none of these methods are completely effective, and many toxins, such as microcystins produced by some species of cyanobacteria, are left unaffected. In addition, none of these methods are effective in preventing hypoxic conditions.
Because of the toxin release and oxygen depletion that results from algal death, it is far better to remove the algae from a harmful bloom before they die than to kill them. In order to remove algae, microfilters would be needed to sift through an area. At present, some technology exists to do this, but it is exceedingly expensive. Further research needs to be done in the area of microfilters to find a way to implement them more cheaply. The price would likely go down as more was discovered and better methods were put into place to make microfilters. Another unfortunate pitfall is that, due to the necessary fineness of the filter for catching algae and cyanobacteria, the filtration process in an area would take copious amounts of time and larger species may be harmed. To help cut down on time, several filters could be used in an area at once. As for the potential problem for larger species, the filters would need to be built so that organisms that could propel themselves could back out of the filter if needed.
Ideally, the concentrations of nutrients like nitrates and phosphates that flow into the ocean from farms and other human-based causes need to decrease to prevent the growth of algal blooms in the first place. It is, however, unrealistic to expect farmers to quit using fertilizers on their crops, as it would significantly decrease their profits and the amount of food available to the public. Instead, biofilters containing bacteria that utilize the nitrates in the water could be used. These filters could be installed as components to already existing dams. For rivers which are undammed or receive runoff from farms downstream of any dams, filters could be placed in different sections of the river. The housing for the filters would not span across the entire river, so fish would still be able to swim up and down stream. Because water would still be able to move downstream without going through the biofilters—either through fish ladders or in the area around the housing for the biofilters that weren’t in dams—so there would still be a high enough concentration of nutrients that the oceanic regions at the mouths of rivers would still be able to sustain life.
References
Evolutionary history of Algae
A History of American Agriculture
