Have you ever looked in an aquarium and seen a bright green plant that made the aquarium look very pretty? Don’t let this plants pretty color fool you; it is an invasive species in the wrong habitat. An invasive species is essentially an invasion altogether. In terms of ecology an invasive species is when either a plant or animal is introduced to a different area from their natural habitat and cause environmental or economical harm. Giving this definition I will discuss Caulerpa Taxifolia. Caulerpa Taxifolia is a macro algae invader that is a multicellular plant native to warm saltwater. It is one of the most invasive green alga in the seas. It is considered invasive because it has the ability to spread over large areas in the ocean while forming dense mats, causing ecological and economic issues such destroying sea weed, sea grasses, fishes, commercial fishing, boating.
Caulerpa is a salt-water plant with structures that look jut like roots, stems and leaves. The roots of Caulerpa are called rhizoids, which grow into the ocean floor to absorb water and nutrients. Caulerpa have leaf like structures that stick up called fronds, which are a bright green color and are photosynthetic. The stems of Caulerpa are called stolon, which grow above the ocean floor; the stolon when fragmented grows a new Caulerpa plant. Its normal habitat is in tropical waters around the world such as the Indian Ocean. Caulerpa taxifolia is not invasive in its native habitat and reproduces sexually. Grazing marine predators that co-evolved with the alga controls its rapid growth in its native habitat. It was typically used in aquariums for decorations and was cloned in Germany for display then sent to France & Monaco where Zoo employees accidentally introduced it to the Mediterranean Sea when they were cleaning their aquarium tanks in the 1980s. (Caine,Bowman & Hacker 2011). Professor Alexander Meinesz confirmed Caulerpa invaded the Mediterranean after his student discovered the seaweed around 1988. Caulerpa was observed by Professor Meinesz to thrive in cold water and rapidly spread across waters within a few years which set the stage for it become a major and costly invading species. From 1989 to about 1997 Professor Meinesz observed it spread about 11,000 acres. (Caine,Bowman & Hacker 2011). From the 1980s to the 2000s Caulerpa spread rapidly from France, Italy, Germany, Croatia, Spain, Tunisia and California. In California is when Caulerpa began to be eradicated but for Europe and The Mediterranean Sea it was too late and left un-eradicated. As it began to spread so quickly it was nicknamed the “Killer Algae”. Sounds very scary right or is sensationalism on the part of the media? I will explain how it is really a killer later on.
Caulerpa affects ecology and economy in many ways. It produces a large leaf like canopy that blocks water flowing in oceans vegetation, which leads to reduced energy, and a decrease of oxygen in the bottom of the ocean. It is known to produce a chemical that is toxic to organism that it perceives to think of a predator, which is mainly fish. It is a threat to coastal marine life such as kelp forests, fish; eel grass beds, marine mammals, sea birds, and poisidonia. It forms a dense mat, which then can live on surfaces such as rock, sand or mud. Caulerpa has the capability to grow 1inch per day and only needs fragmented segments to starts a new plant. It rapid reproduction shows its capability to spread and become invasive to the ocean ecosystem reducing the biodiversity of native plants and animals. It decreases local fishing communities; it harms tourism, boating, diving, and costs about 7 million dollars to eradicate. (Diaz, S. 2012)
Caulerpa is a current topic because of it ability to rapidly spread and become invasive. There is the concern that humans can accidentally introduce it to oceans when fragmented pieces attach to fishnets, or boat anchors and by aquarium dumping. Caulerpa reproduces asexually in non-native sites so it only needs a fragmented piece to create a fully developed clone of itself. There are numerous sanctions put in to place to stop it spreading such as the passing of the Assembly 1334 Bill in 2001. (Diaz, S. 2012).The bill says that Caulepra can’t be owned or sold. It has been put on the Federal Noxious Weed List and also tarps are installed over areas that have Caulerpa and injecting chlorine gas under the tarps to kill the Caulerpa. (Diaz, S. 2012) Over 7 Species of Caulerpa such as C. Scalpelliformis, C.Brachypus & C. Filiformis are continuously being found despite the measures to eradicate it. It was recently discovered in Wandoor, and South Andamans in January of 2013.( P. Karthick*, R. Mohanraju, K. Murthy, Ramesh Ch, and Narayana S. 2013)They have followed steps put in place to control/eradicate it from any type of further invasion.
Caulerpa is puzzling and interesting at the same time due to the fact that it can survive in waters that are freezing or many different habitats. As a matter of fact early on Caulerpa continued its rapid spread despite the fact that many thought the freezing waters would automatically kill Caulerpa. It has the ability to tolerate a large amount of salinity, temperature or sunlight, which makes it uniquely an invasive species. It is interesting in a way that it does not need the whole species to begin its invasiveness. Caulerpa only needs fragmented pieces in order to disperse to different areas for invasion. This fragmentation can happen by simple fishing boats in the oceans or fishing nets. Caulerpa has shown it can be toxic to herbivores such as seas urchins and fish. It releases a toxin called Caulerpyn mainly against grazers such as Mediterranean bream, Saupe, Sarpa Salpa. The fishes that are affected by the toxins of the Caulerpa in turn decrease the economic stability for the fishermen who depend on the fish to make a living, since the fish that absorb the toxin is no longer edible for humans. Another main interesting fact about Caulerpa is that it has overtaken the ocean floor and caused a decline of sea grasses like Posidonia Oceanica. This is a seagrass meadow that allows various species to use it as a habitat for vegetation. In the presence of Caulerpa, P. Oceanica leaves/blades are reduced leading to minimal grazing by fish that use its vegetation as a habitat. This then leads to a decline in the species that use this habitat.
The main hype about Caulerpa was brought about from the media calling it a “Killer Algae”. By giving it that name it makes it seem as if the Caulerpa is toxic to humans. Caulerpa is not toxic to humans and there have not been any reported deaths to Caulerpa. In my opinion the only reason it should be called a “Killer Algae” is because initially it survived in cold water, rapidly spread and caused massive costly problem in the Mediterranean Sea. Caulerpa creates dense mats, which then destroyed the habitat for fish. Caulerpa can thrive in just any community but they compete for space, light and nutrients by sending toxins into water to kill predators as a defense mechanism. This ultimately destroys the natural habitat they invade. Giving these characteristics and the unknown devastation it would cause in the Mediterranean is why it was nicknamed the “Killer Algae”. At that time it seemed as if there wasn’t a way to control or eradicate Caulerpa. Later on there were methods put in to place to control the “Killer Algae”. I believe by following the guideline set in place the sensationalism will die down. I don’t think we can deny Caulerpa but we can control it with steps such as Tarps and chlorine poisoning. If not controlled it will continue to cause un-eradicable economic and ecological harm as it initially did in the Mediterranean Sea.
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P. Karthick*, R. Mohanraju, K. Murthy, Ramesh Ch, and Narayana S.(Jan 2012-Jan-2013)
A SURVEY AND NEW DISTRIBUTIONAL FINDINGS OF CAULERPA SPECIES IN WANDOOR, SOUTH ANDAMAN, INDIA http://www.scienceandnature.org
