Killer Algae - The Beautiful Nightmare

Hola! Bonjour! Hi :D. This week we take a look at one of the most devastating marine IAS, the killer algae (scientific name: Caulerpa taxifolia).  

Image Copyright The University Of Hawaii

Don't be fooled by Caulerpa taxifolia's beautiful appearance. It's only beautiful on the outside!

Origin

Location of the origin of the "killer algae." Image Copyright Google Maps

With such a name as "killer algae", one would suspect that this resulted from a lab experiment gone wrong. Ironically enough it did ! In the 1970's aquarium fanatics and scientist from all over the world were trying to develop an ornamental plant beautiful enough to decorate aquariums. However, scientists at the Saltwater Aquarium at the Wilhelma Zoo in Stuttgart Germany were successful in doing so ! After several tests were done on this strain of algae, the scientists concluded that this plant would revolutionize the salt water aquarium industry due to its bright green color and high tolerance level. Little did they know they had concocted a vile mutation of the Caulerpa taxifolia ! They shipped it several institutes including an oceanic museum in Monaco where it was first sited in the natural environment.  

Current Distribution

• Mediterranean Sea
• Southern California 
• Australia 

Characteristics That Make This Organism So Successful

Tolerance Level : Highly tolerant in nutrient deprived areas along with highly polluted environments. Can even survive out of water for 10 days ! Can survive in a relatively wide range of salinity and varying temperatures (from tropical to temperate). 

Reproduction: Fragmentation. Can multiply rapidly from the tiniest fragment of the organism and smother whole coral ecosystem or sea grass beds within a matter of years!

Caulerpa taxifolia smothering a Coral Ecosystem. Image Copyright Alexandre Meinesz. 

How did this strain of algae get into the natural environment?

The main cause of introduction into the natural environment was the dumping of this beautiful nightmare from aquariums. Even the tiniest piece of this algae has the reproductive ability to multiply from a small patch of a square meter to several acres in just a few years. Additionally one of the usual vectors which aid in the spread of exotic species is ballast water from ships involved in transport. This was the case in the Oceanic Museum in Monaco. From the Mediterranean sea it has multiplied and traveled great lengths to reach as far as South California and even Australia ! 

Impact

Due to its reproductive ability, the killer algae rapidly multiplies and displaces local sea grass beds. By displacing the sea grass beds, which were commonly eaten by the local biodiversity, it dramatically disrupts the whole dynamic of the  local marine ecosystem. An additional characteristic of this organism is that it contains toxins that are harmful to certain species of fish ! Who thought this thing could get any worse? With the presence of toxins, there is also the possibility of bio-magnification where the concentration of this toxin increases up the food chain.  This impact has severely affected the ecosystems of not only the Mediterranean, but also South California and Australia. This is not centralized to that of a biological viewpoint but can also be assessed based on its economic impacts. The disruption of the marine ecosystem directly affects the fisheries sector of the economy. Also the cost of mitigation usually costs millions of dollars. 

Methods of Mitigation
Currently, the distribution of this green menace is so widespread that mitigation is a big undertaking. However, one of the main methods of mitigation used by the governments of the previously mentioned areas is public education. This tactic doesn't directly remove the current algae from the water, but with proper knowledge of how to deal with aquarium waste water will significantly reduce future spread of the current problem. The National Sea Grant has outlined several ways the public can aid in the spread of the problem: 

• Never dump unwanted aquarium water into the ocean. Freeze it for 24 hrs and dump in a landfill.
• Reporting sightings of this algae to the relevant authorities.
• Educate yourself about the Caulerpa taxifolia.

Apart from social mitigation of the problem, countries such as the U.S. have developed physical methods to remove the algae from the water. In this scenario, they cover a colony of the algae with big tarps to block out sunlight. Next they add chlorine to kill the organism under the tarp along with whatever biodiversity that got trapped under there. took them This method was seen as effective in eradicating the pest for the United States, however, it costed over $7 million US dollars during the period of 2000-2005. 

The following video outlines the method of removal used by the US: