What are four methods that can be used to address Hazardous Algae Blooms (HABs)?

Answer 1

Nutrient Management: Reducing runoff from agriculture and improving wastewater treatment to lower nutrient levels in water bodies.

Physical and Chemical Control: Using alum or hydrogen peroxide to reduce algae growth.

Biological Control: Introducing fish that consume algae or using bacteria and fungi that inhibit harmful algae.

Monitoring and Early Detection: Employing remote sensing, satellite imagery, and in-situ monitoring systems to detect and respond to blooms early.

Answer 2

There are many methods that can be used to address Hazardous Algae Blooms (HABs) with varying degrees of effectiveness. Some methods may be used alone or in concert with others. The following paragraphs outline just four methods that may be used:

1. One of the best and least expensive methods of controlling algal blooms is through prevention.  By controlling the runoff that enters lakes, ponds, and streams, more costly and often less environmentally friendly measures can be avoided or reduced. The timing of application, rate of application, and how fertilizer is applied all affect the amount and types of runoff present in an area. For example, applying nitrogen closer to the period of maximum crop growth, usually in the spring, is more cost-effective because applying nitrogen earlier increases the risks that the uptake by the plants will not be as effective in increasing and ensuring growth and the nitrogen will need to be re-applied. Nitrogen applied too early may also be lost to soil and wind erosion which may require re-application, increased costs, and increased amounts of runoff. Also, the more biological diversity in the vegetation that surrounds bodies of water, the fewer the pathways available to channel runoff into ponds, lakes and streams of any kind. Wetlands, forests, riparian barriers and other forms of complex vegetative systems act as sponges -- absorbing, slowing down, and re-directing even the most harmful contaminants (Brookes et al, 2005). 

1. Biological methods for addressing algae blooms have to be done carefully to avoid complicating an already tenuous situation. For example, rod-shaped bacteria called Pseudomonas fluorescens or P. fluorescens has been shown to be effective in degrading pathogens due to their natural antibiotic properties. For example, P. fluorescens will prevent the growth of various types of mold when found in soil and on plant roots while enhancing plant growth and reproduction (Wellcome Trust Sanger Institute, 2011). However, while the presence of P. fluorescens can be advantageous in the presence of plants, it can be the source of debilitating illness when found in human beings who are more susceptible to its presence especially if they have compromised immune systems. 

1. Chemical treatments of algae also involve the risk of unsettling an ecosystem while trying to heal it from the ravages of an algae outbreak. Historically, treatments such as aluminum nitrate, aluminum sulfate, potassium permanganate, and ferric chloride have all been used to address problematic algae blooms.  Conventional wisdom is beginning to change regarding the use of these traditional chemical methods because scientific studies are finding that pre-treatments are necessary, in many cases, to enhance the flocculating (or coagulating) effects of the traditional treatments that were generally used alone. These chlorine-based and iodine-based measures not only kill the algae, but also eliminate the chlorophyll components that are present within the algae itself. If pre-treatment measures are followed by aluminum-based products or potassium permanganate, the majority of the algae – in the 90% range – can be removed (Shehata, Badr, Wahba, 2002). 

           

1. Physical or Mechanical Methods to remove HABs may involve ultrafiltration which involves the use of a membrane to filter out the algae. Clay Flocculation is another physical/mechanical method that can also be used. This environmentally-friendly method involves the spraying of a clay solution onto a body of water. Algae is attracted to clay particles due to its physical characteristics. Because the clay particles are heavier than water, and even more so after algal cells attach to the clay particles, these particles sink entrapping the cells. The algal cells then die after sinking because at deeper water depths, they have little, if any, exposure to sunlight.

Experiments in which extracts of barley straw have been used have been successful in prohibition of algal cell growth in laboratories. Barley straw has now also proven its usefulness – more successfully as a preventative measure – in reducing outbreaks of blue-green algal blooms. It appears to have its own natural algaecide. The numbers of different types and species of algae have also decreased where loose bales of barley straw have been added to aquatic environments. This may be because the straw provides habitat for zooplankton who then feed on phytoplankton which keeps their numbers in check and reduces the possibility of population explosions.  In addition, barley straw is another readily available product that can be purchased on the local, open market. 

Just remember that there is no uniform, one-size-fits-all method or answer to the world’s eutrophication problems. The effects of seasonal variations, water depth, wind speed, pH, types of algae present, and the types of nutrients feeding into the affected water sources are among just a few of the factors that must be considered when designing algae control prevention and treatments. While eutrophication has become alarmingly common and expensive to treat, prevention of harmful algae blooms is far less costly.