Assessing and Comparing Various Treatment Methods for Toxic Heterosigma Akashiwo Algal Blooms
Alexander Sun, Andy Liang
Eric Hamber Secondary
Floor Location : M 082 D

Around the world, algal blooms run rampant destroying wildlife and exhausting ecosystems of their valuable nutrients. The most notorious of the algal blooms is the “Red Tide”. Red Tide is actually an umbrella term, which includes numerous species of algae such as Karenia brevis which is native to the Atlantic Ocean and Heterosigma akashiwo which is native to the Pacific Ocean. This project was mainly focused on the Pacific algae Heterosigma akashiwo due to the fact that it impacts our local area, and we want the results of our project to have an effect on our province.

Our project evaluates and compares different treatment methods to eradicate and control these algal blooms. Treatment methods tested were barley straw extract, algaecide and a Heterosigma akashiwo Virus. Dried barley straw is to prevent algae blooms by releasing humic acid into the water as it decomposes. As the acid slowly releases into the water, it further reacts with oxygen and sunlight, eventually producing hydrogen peroxide. A concentrated extract was used for this project to expedite the reaction. The algaecide used is called Rhinox Cleaner, with the active ingredient being Sodium Carbonate Peroxyhydrate. The virus used had a very specific host range, only targeting the algae and causing lysis within 48 hours.

Even though the experiments are ongoing, our preliminary results show that the use of algaecide consistently eliminated the most algae, compared to the viral treatment. However, it also drastically changed the pH level of the water, rendering it unusable in biodiverse ecosystems. In the past, barley straw was not used as a treatment option for blooms. Instead, large barrels of barley straw were used to prevent the algae from blooming. We found from our experiment that if we introduced the barley straw after the bloom, it will still inhibit the growth of new algae. The virus, even though less effective than the algaecide, was still able to reduce algae populations algae populations significantly. Due to the very specific host range of the virus, the environmental impact of the virus should be minimal.

We are currently experimenting to find the ideal concentrations of each treatment. Pending final results, a combination treatment methodology may be the most optimal: induce algae death with a viral infection, and prevent subsequent regrowth with barley straw extract.