The invasive kelp Undaria pinnatifida is has now spread from Los Angeles to San Francisco Bay, despite eradication efforts.

Earlier, the northward spread of this sea weed – which can grow an inch a day and forms dense underwater forests – was believed to have been stopped at Monterey Bay, but this assumption turned out to be wrong when a biologist at the Smithsonian Environmental Research Center happened to notice a six-foot long piece of kelp attached to a boat in a yacht harbor in San Francisco Bay.

“I was walking in San Francisco Marina, and that’s when I saw the kelp attached to a boat,” said Chela Zabin, biologist at the Smithsonian Environmental Research Center in Tiburon, California. “It was six-foot long, and there is nothing here in the bay that gets to that size. I didn’t want to believe what it was, it’s depressing.”

Further investigation showed U. pinnatifida clinging not only to boat hulls in the marina but to docks and pier pilings as well.

U. pinnatifida was discovered in Los Angeles Harbour in 2000 and within a year reports of its presence had arrived from Catalina Island and Monterey Bay. A federal eradication program was put in place, but the funding dried up last year. Since then, volunteer divers have been the only ones combating the kelp.

Five quick facts about Undaria pinnatifida

• Undaria pinnatifida is a fast growing kelp native to the waters of Japan, China and South and North Korea.

• Within its native range it is an appreciate source of food and if you’ve ever tasted miso soup, this is what you were eating. The Japanese name for this species is wakame.

• U. pinnatifida has managed to establish itself in many different regions outside its native range, such as the Atlantic coast of Europe, the Mediterranean Sea, and the Argentinean coast. By attaching itself to vessel hulls it can hitchhike across the globe in search of new suitable habitats. This kelp can also enter ecosystems via imported oysters, and some people deliberately or accidently introduce U. pinnatifida to local ecosystems by cultivating it for cooking purposes.

• When U. pinnatifida spread to ecosystems not used to its presence, it can grow uncontrolled and prevent native kelp species from getting any sunlight. This can disturb the entire ecosystem.

• U. pinnatifida has been nominated to the list “100 worst invasive species in the world”.

Specimens of the invasive Blue catfish (Ictalurus furcatus) have now grown large enough to reach the top of the food chain in James River, Virginia. A catfish weighing 102 lbs (46 kg) was caught from the river not long ago; the largest caught freshwater fish ever to be reported from Virginian waters.

30 years ago, Blue catfish was deliberately introduced to this U.S. river as a game fish. During recent years, the catfish population has grown explosively while many other fish species have decreased. An eight year old Blue catfish normally weigh a mere 4 lbs (1.8 kg), but as soon as it gets large enough to start catching other fish and devouring fully grown crabs, it begins putting on weight at a rapid pace and can gain as much as 10 lbs (4.5 kg) a year.

Blue Catfish – Ictalurus furcatus. Copyright www.jjphoto.dk

According to Bob Greenlee, a biologist with the state Department of Game and Inland Fisheries, scientists doing sampling used to get around 1,500 catfish in an hour in this river in the 1990s. Today, this number has increased to 6,000. “We have an invasive species that is taking over the ecosystem,” says Rob Latour, a marine biologist with the Virginia Institute of Marine Science at the College of William and Mary.

In an effort to curb the population of invasive Atlantic sea lampreys (Petromyzon marinus) in the North American Great Lakes, researchers are now testing a “love trap” in northern Michigan.

The traps will be scented with an odour produced by male lampreys during mating and researchers hope that this smelly love potion will lure female lampreys into the traps.

“We are trying to fool them into a fatal love,” said researcher Nick Johnson who will spend the next three years evaluating the effectiveness of the method.

The traps will be placed in ten streams around the Great Lakes, since lampreys swim into streams when it’s time to mate. After spawning, they die.

The Atlantic sea lamprey is native to the Atlantic Ocean but has been able to migrate into the Great Lakes through man-made shipping canals. The first specimens where seen in the region as early as the 1830s. By the 1950s, lampreys had decimated native populations of lake trout and white fish by rasping through their skin and sucking out their blood and bodily fluids. Several other populations of large and commercially important food fish had also been severely damaged by the new resident.

Since 1955, Fisheries and Oceans Canada and the U.S. Fish and Wildlife Service have worked closely on the Great Lakes Fishery Commission to control the Atlantic sea lampreys, using lampricides (substances toxic to lamprey larvae), migration barriers, and sterilization of male lampreys. Hopefully, the new pheromone scented traps will prove an efficient addition to their arsenal.

The U.S. Bureau of Reclamation is now carrying out tests in hope of finding out if bacteria can aid them in their struggle against invasive mussel species that are threatening to spread across the West’s waterways.

During the summer of 2008, a preliminary test was executed at Davis Dam on the Colorado River at Laughlin in Nevada. In this dam, Quagga mussels (Dreissena rostriformis bugensis) were exposed to dead bacteria of the Pseudomonas fluorescens species, a non-infectious bacterium that is commonly found in water, soil and food.

Quagga Mussels

During the first test the mussels where exposed to bacteria in jars, but the next test will take place in 10-20 gallon aquariums to in order to more accurately mimic real dam conditions. Water will flow through the aquariums, but will not be released back into the river – it will instead be disposed of through an evaporation pond. A third experiment is also planned, where bacteria will be released in a domestic water intake line which is currently encrusted with a 2-3 inches thick layer of mussels (approximately 5-7.5 cm).

“We are always looking for new, more effective techniques for managing mussels, and this one looks very safe and very promising,” says Reclamation scientist Fred Nibling. “We’ll have a series of tests where we’re going to be testing off-line, off the river, so we can have the data to where we can apply for the permits to test elsewhere.

If the initial testing proves to be successful, the Bureau of Reclamation hopes to have a larger scale test approved by the Environmental Protection Agency.

The U.S. Bureau of Reclamation got the idea to use Pseudomonas fluorescens from Daniel Molloy, a researcher at the New York State Museum who discovered that both zebra and quagga mussels died if they ingest the bacterium. He confirmed the effect in 1998 and the method was patented by the museum. Eventually, the Californian firm Marrone Organic Innovations was awarded a National Science Foundation grant to commercialize the technology.

According to Molloy’s research, a mussel needs to ingest a high density of a strain of the bacteria in order for the bacteria to be lethal. If the density is high enough, a toxin inside the bacterium cell will efficiently devastate the digestive tract of the animal.

One advantage with Pseudomonas fluorescens compared to conventional anti-mussel treatments like chlorine is that mussels recognize chlorine as dangerous and close their feeding valves to keep the chemical out. They do however happily devour Pseudomonas fluorescens. Another important aspect is that research has found that Pseudomonas fluorescens does not kill fish or shellfish.

If large scale testing also proves successful, the Bureau of Reclamation say they wish to meet with municipal public works and water authority officials before the bacterium is put into general use. “We want to make sure they’re very comfortable and they have a chance to ask questions,” says Nibbling.

Zebra mussels

In May this year, hundreds of Asian swamp eels were discovered in and around Silver Lake in historic Gibbsboro, New Jersey. This was the first finding in New Jersey, Asian swamp eelbut not the first finding in the United States. Unlike Florida, Georgia, and Hawaii – the three other U.S. states where this species have been discovered – New Jersey is however subjected to harsh winters and a breeding population of Asian swamp eels in New Jersey confirms the suspicion that this Asian invader has no problem adjusting to the
chilly climate of northern North America.

The Asian swamp eels were found by a local college student checking on frogs and turtles in the Silver Lake. As he spotted snake-like heads peeking from the water, he decided to photograph them and post the pictures online. This lead to the “snakes” being identified as Asian swamp eels, Monopterus albus, and prompted a call to the local authorities.

In its native environment in Asia and Australia, the swamp eel Monopterus albus inhabits gentle hill streams, estuaries and lowland wetlands, and it is a common species in rice paddies. It has developed a long row of traits that makes it an apt survivor in many different kinds of environments. Unfortunately, these traits also make it the “perfect” invasive species and biologists fear that the Asian swamp eel may wreck havoc with existing North American ecosystems, especially if the predatory species of these systems prefer to target familiar prey rather than catching the newcomers.

– The Asian swamp eel can survive long periods of drought by burrowing in moist earth, and can therefore take advantage of seasonally appearing, short-lived bodies of water.

– If its home becomes unsuitable, e.g. because of drought, this eel simply crawls ashore and make its way to a more suitable home by slithering over land, just like a snake. This makes it hard to eradicate from bodies of water using poison or similar; there is always the risk of at least two specimens getting away over land and forming a new breeding colony in nearby waters.

– The Asian swamp eel can tolerate a wide range of oxygen levels in the water since it is capable of absorbing oxygen from the air above the surface through its skin. This skill doesn’t only come in handy in oxygen depleted waters; it is also what makes it possible for the fish to travel impressive distances over land.

– This eel prefers freshwater habitats, but can tolerate brackish and saline conditions, which increases its chances of always finding a suitable home.

– It eats all sorts of prey, not only fish, crustaceans, amphibians, and other aquatic animals, but detritus (decaying organic matter) as well. Highly specialized feeders have a much harder time adjusting to new habitats and are therefore less likely to become problematic invasive species.

– This eel is a protandrous hermaphrodite, which means that it can change its sex. All specimens are born male, but can turn into females if necessary. This means that if an aquarist releases two male specimens into a lake, one of them can turn into a female to make reproduction possible.

In Georgia, the first specimens of Asian swamp eel was discovered in 1994, and three years later eels were found in Florida as well. The Hawaiian history of combating swamp eels is much longer as the first specimens are believed to have been released in Hawaiian waters about 100 years ago. In Georgia and New Jersey, biologists blame aquarists of having caused the situation by releasing their pets into the wild. In Florida and Hawaii however, Asian food markets and fish-farmers are considered more likely sources. Asian swamp eels are typically sold fresh in food markets and can be kept alive for long periods of time as long as their skin is kept moist.

New Jersey authorities are now focusing on containing the creatures while trying to figure out a way of annihilating them. “We’re not panicking yet,” says Lisa Barno, chief of the New Jersey Bureau of Freshwater Fisheries. “It’s more that it’s just an invasive species we’d rather not have. We’re still documenting the true extent of the problem, but right now it seems to be fairly contained.” One of the immediate goals is to prevent an expansion downstream to the Cooper River and a watershed leading to the Delaware River. Since May, only one Asian swamp eel has been discovered outside the Silver Lake.