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About the Specis
About the Specis
Common Name:Killer Algae (hybrid form)
Scientific Name: Caulerpa taxifolia
Origin: Tropical oceans and seas of the world, Indian Ocean
Identification: A bright green algae with feathery branches that vary in length from 5-65 cm. in tropical waters, while the hybrid form grows much larger with plants up to 10 feet
Phylum or Division: Chlorophyta
Class: Ulrophycea
Order: Caulerpales
Family: Caulerpaceae
Scientific Name: Caulerpa taxifolia
Origin: Tropical oceans and seas of the world, Indian Ocean
Identification: A bright green algae with feathery branches that vary in length from 5-65 cm. in tropical waters, while the hybrid form grows much larger with plants up to 10 feet
Classification:
Classification:
Phylum or Division: Chlorophyta
Class: Ulrophycea
Order: Caulerpales
Family: Caulerpaceae
First Introduction
First Introduction
Caulerpa Seaweed is thought to be introduced in the Mediterranean, Australia, and southern California by aquarists who sought the attractive saltwater plants due to their ability to remove nutrients (such as phosphates and nitrates) and to be a source of food for fish. In addition, they were captivity bred for a number of years by the Saltwater Aquarium at the Wilhelmina Zoo in Stuttgart, Germany. Once obtained, the hobbyists soon realized that the seaweed grew at an exponential rate, too fast for their liking. To combat the excess, they would sell it via online platforms such as eBay or release it in nearby waters. The first detection of the invasive species was in 2001 in southeastern Florida, where blooms were overgrowing, thus displacing the natural ecosystem.
Reasons of Establishment
Reasons of Establishment
It is an extremely hearty plant that can withstand severe nutrient deprivation; in fact, it can survive out of water for up to 10 days. It can thrive in even heavily polluted waters, establish most habitats, and adjust to any area, even those that are nutrient-poor such as sandy bottoms, rocky outcroppings, and mud. C. taxifolia can exist at a variety of depths and can cover up to 100% of the sea bottom from the surface to a depth of 35 meters, some observed at depths up to 100 meters. Although patches are limited at such depths, it appears to grow to the underwater boundaries of plants. It can persevere in a variety of temperatures, from tropical to temperate waters. It contains a toxin that is not harmful to humans but may be lethal to certain species of fish and invertebrates and may interfere with the eggs of some marine organisms.
New Ecological Role
New Ecological Role
Usually, where C. taxifolia exists, it becomes the dominant form of plant life because of its capacity to reproduce speedily. They out-compete other aquatic life, diminishing biodiversity, and form a carpet in the area. C. taxifolia is known to have crowded out the seagrasses that had provided food and security for a variety of fish and invertebrates, a nursery for a new life, and protection for the coastline. On the ocean floor, there are modified nutrients of sediments as the impenetrable algae increases across, in addition to increased oxygen consumption with the decay process. Also, there is concern about a potential transfer of toxins within the food chain from those few organisms that may consume it. For example, several mollusks have been shown to have a two to threefold increase in concentrations of metabolites and therefore become lethal to predators. One study showed that sea urchins sequentially starved rather than consume it.
Effects
Effects
Clogged nine waterways in New South Wales and two in South Australia
Clogged nine waterways in New South Wales and two in South Australia
Infested two lagoons in Southern California
Agua Hedionda Lagoon, Carlsbad andHuntington Harbour, Huntington BeachInfested two lagoons in Southern California
Monocultures extend hundreds of kilometers along the Mediterranean coastline
Monocultures extend hundreds of kilometers along the Mediterranean coastline
Ecological impacts associated with the introduction of C. taxifolia have been well documented over the years, with all of the impacts being negative on the ecosystem. In all instances of invasion, they were able to grow faster, deeper, and larger than they normally would in the native warmer tropical waters.
E-Commerce
E-Commerce
Walters, Brown, Stam, and Olsen suggest that e-commerce is the primary current mode of dispersal of the seaweed. Between April 2003 and April 2005, they conducted a study to determine the diversity and availability of Caulerpa species via e-commerce and local retail outlets. The study involved 22 volunteers and over 200 internet search hours, with each person finding as much as they could in a 48-hour time frame using preferred search keywords. Seaweed bought was from 90 internet sites (30 commercial retailers and 60 eBay auctions) from central Florida.
Figure 2. States/Countries with Caulerpa available for purchase from eBay auctions. Numbers associated with pie-charts indicate the number of auctions.
Figure 1. States with Caulerpa available for purchase from commercial internet retailers. Numbers associated with pie-charts indicate the number of retailers.
Federal laws restrict the exportation of Caulerpa species. However, of the 60 eBay auctions won, only three vendors included information showing that they were aware of the restrictions on interstate transport. There were a few sellers who warned not to dump in bodies of water. The average cost for a handful of any species locally was $4.00, and 43% of retailers sent some for free. The average cost for any single species from internet retailers was $43.08 and $18.09 from eBay (including shipping and handling).
Figure 3. Percent availability of Caulerpa species from eBay auctions and online, Central Florida, and Southern California.
Efforts of Abolition
Efforts of Abolition
Laws/Education
Laws/Education
In 2001, California imposed stricter laws, which made it illegal to sell or possess C. taxifolia or eight other species that resembled it.
The Aquatic Nuisance Species (ANS) Task Force started a National Management Plan in the fall of 2005 which concentrated solely on maintaining investigation and outreach. The USDA-APHIS is currently considering whether to heighten supervision of this genus.
Biological Controls
Biological Controls
Elysia subornata and Aplysia depilans, tiny aquatic slugs, natural predators of C. taxifolia have been recommended to combat the population of the alga. The Elysia subornata is believed to feed solely on C. taxifolia, absorbing out the liquid inside the stem: causing alga to become obsolete. The slug absorbs the alga's poison and protects it from being eaten. However, this slug cannot survive in colder waters.
In Carlsbad, California the outbreak was successfully stopped through a two-year process in which a heavy tarp was used to cover the plants entirely, and then chlorine was inserted as sodium hypochlorite, directing the poison on the target species. The tarp remains in the same area, which will be checked repeatedly over the next five years.
Mechanical Controls
Mechanical Controls
Although this approach provides short-term success, the plant spreads with fragmentation, small parts that inevitably break off. So when efforts are made to extract the plant, it only assists it to spread further. There have been attempts to remove them with pumps to uproot the plant. However, it resulted in the regeneration in, or around the same location with a quickened growth percentage.
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