InvasiveSpecies

Invasive Species

An invasive species is a non-native species introduced to an area that has an adverse economic, ecologic, or environmental effect on the native ecosystem.

Pterois miles

Invasive species spread and excel in the ecosystems that they invade because of a lack of competition or a lack of predation from native organisms. In the context of coral reefs, invasive species frequently refers to the lionfish, which is native to the Pacific and is currently invading the Caribbean Sea and Atlantic due to its voracious appetite and lack of natural predators.

Impact

There are a plethora of community-wide impacts that occur when non-native species are introduced to a certain area. For example, the introduction of one invasive specie can often facilitate the invasion of a second invasive specie by altering the overall structure of the ecosystem . Although many types of organisms or plants will not directly affect the trophic structure of the ecosystem, they will cause some sort of ecological shift in the previously homeostatic ecosystem. For example, one study noted that the invasion of a type of algae did not cause a direct shift in the trophic structure of the ecosystem, but rather inhibited the growth of a native kelp forest which was subsequently overrun by the non-native specie .

Common examples

Lionfish

Lionfish are any fish of the genus Pterois. They are venomous predatory fish native to the Indo-Pacific region. Two species, Pterois miles and Pterois volitans have established themselves as a significant invasive species in the Caribbean, Gulf of Mexico, and Atlantic Ocean. Lionfish are popular aquarium fish due to their bright warning coloration.

Sightings and Dispersal

Lionfish were most likely introduced into the Caribbean, Gulf of Mexico, and Atlantic Ocean by aquarists. The prevailing theory is that six lionfish were released accidentally into Biscayne Bay due to the destruction of a beachside aquarium by Hurricane Andrew. The current population of lionfish in these areas are likely the descendants of these six fish, along with other lionfish which were released by aquarists, either accidentally or intentionally.

Another theory for the appearance of Lionfish in the Caribbean, Gulf of Mexico, and Atlantic Ocean is that at some point in their lifecycle, lionfish were taken into the ballast tanks of ships traversing the Panama Canal from the Pacific side and released in the Atlantic. This theory is generally not given much credence by respected experts.

Appearance and Distribution

Lionfish are commonly found from Florida to Cape Hatteras along the East Coast of the United States. Juveniles have been found further north, though they do not generally survive the cold winter temperatures. They are widespread in the Bahamas, Bermuda, and the Greater Antilles, and the Western Caribbean coasts of Mexico, Belize and Honduras. Sightings have been reported as far south as Colombia, Aruba, and Panama, and as far north as Rhode Island.

Impact on Coral Reef Ecosystems

There are a variety of mechanisms in which the lionfish invasion can alter a coral reef ecosystem. One proposed mechanism is through the predation of native herbivores. Because the lionfish have such a voracious appetite, they have the potential to wipe out all of the grazers in a coral reef ecosystem. Once all of the grazers have been predated, the ecosystem is extremely vulnerable to an overwhelming increase in coral reef algae.

A coral reef overrun by algae

Overrunning algae can potentially harm the coral reef by preventing sunlight and nutrients from reaching the coral, thus breaking down the symbiotic relationship between the coral and zooxanthellae. This could lead to extensive coral bleaching.

Effects on Fisheries

The Lionfish invasion has the potential to greatly affect coral reef fisheries. Because the lionfish are large and have no natural predators, they can eat most of the larger fish that already inhabit coral reef systems. Coincidentally, these large fish are also being predated upon by fishermen, who typically desire the catch high volumes of large fish. Coral reefs are already experiencing an abundance of pressure on their trophic organization due to fishing pressure. As such, the lionfish invasion can only serve to compound that pressure on the coral reef ecosystem.

Furthermore, the lionfish invasion subsequently harms the fishery because the fishermen cannot catch the same mass of fish as they previously were. The fishermen may even resort to fishing down the food web, which could prove detrimental to the entire ecosystem and fishery.

Control and Management

Because experts consider any attempts to reverse the invasion to be futile, efforts are now being concentrated on controlling the lionfish population. Several methods of control have been suggested, including encouraging revitalization of local predator species, limiting lionfish trade among aquarists, encouraging lionfish fishing and consumption amongst humans, and killing easily spotted specimens.

One way to control the lionfish population in the Caribbean would be to maintain a healthy population of species that prey upon the lionfish, including large groupers, sharks, and other species that feed on lionfish eggs and juveniles. Divers in Palau have noted that locations with large concentrations of large and medium sized groupers often have fewer lionfish. Protecting Caribbean grouper and shark populations would lead to an increased number of predators, limiting the lionfish population. Another method of limiting lionfish population explosion is reducing the fishery pressure on species that occupy the same ecological niche as the lionfish.

Another proposed method of controlling the population explosion is encouraging fishing of lionfish. While divers and spearfishermen are already encouraged to kill all lionfish that are easily spotted and captured, steps could be made to educate people on the culinary uses of lionfish. If lionfish was made a staple of Caribbean and Atlantic diets, fishing pressury would surely limit the population explosion.

Algae

There are a variety of invasive algae that inhabit Caribbean coral reefs. They include Graciliara salicornia, Hypnea musciformis, Avrainvillea amadelpha, and Kappaphychus spp. .

Amphipods

Some amphipod inhabitants of coral reefs are also invasive .

Sponges

There are also some non-native varieties of sea sponges that inhabit coral reef systems .

Management Plans

One example of an invasive species management plan is the Aquatic Invasive Species Project in the Hawaiian Islands. Its goals include:

• Coordination and collaboration between agencies
• Prevention
• Monitoring and early detection
• Response, eradication, and control
• Education and outreach
• Research
• Policy

Another management system is the Seychelles Invasive Species Project. It is an ongoing project with the primary objectives of:

• Enhancing the capability of staff and institutions involved in monitoring
• Improving awareness of local communities to the threats posed by these introduced organisms and their economical impacts

Comments

I would consider mentioning the lionfish derbies they have down in the bahamas/florida

Maybe change "to an overwhelming increase in coral reef algae." to "to algal blooms".

I think your pictures need to be cited

Maybe add a pic or two of an amphipod or invasive sponge. We don't know what an amphipod is.

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