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Ten years ago I was working in Pennsylvania at a U.S. Fish and Wildlife Service laboratory working on lake trout and Atlantic salmon restoration projects.  While I was there I was aware that we had a laboratory in Florida that worked on exotic species but was really sure what that meant. I had my own work to do so I went on about my business.  And then while on a visit to Florida to learn about the sturgeon restoration going on here, I learned a little more about exotics. About 6 months after the visit to Gainesville I applied for and accepted a job at the Gainesville laboratory and now exotics are all I do. I first started by documenting occurrences of exotics, that was, and still is the kind of information the government wants to compile. The lab had started to compile a list of exotic fishes in the US before I got there. When I arrived I began to keep track of where the zebra mussel was spreading.  Now we are trying to compile documentation of any aquatic organism that is outside of its historic natural range. Originally our laboratory was established to test whether exotics could serve good uses such as biocontrol of aquatic weeds and algae with tilapia. In some cases research has unfortunately been responsible for a few introductions.
First, the US Congress recognized the problem and had their own staff compile a report. This is very good report but it stated that information on harmful nonindigenous species was scattered, obscure, and highly variable in quality and scientific rigor.  The effects of many species have never been studied. With poor documentation as the report stated, the magnitude of the problem has probably been underestimated.  So we are doing are part to help improve the knowledge base of at least the aquatic end of the exotic spectrum. Some species like the African honey bee, the fire ant, and more recently the West Nile virus are a human health risk.  While others like the Melaleuca tree and the zebra mussel threaten widespread disruption of ecosystems by displacing native plants and animals.
The first introductions probably occurred over 500 years ago with the earliest European settlers. These most likely were ship hull fouling an boring organisms. Things like barnacles and shipworms.
Mollusks, crustaceans fish, plants, sponges, etc.
But because of the possibility of introductions 500 years ago, it is difficult to determine what is native to the region’s marine waters and what is not.  We refer to these species as cryptogenic.
There is actually some anecdotal information from ancient times about how they stocked carp and goldfish. From this graph it appears that fish introductions actually peaked worldwide in the 1960s. Either they ran out of new species to stock or they were happy with what they have. Recent introductions mostly for a human food source now seem to be a lot of clams, mussels, and crustaceans such as shrimp and crayfish.
A majority of species have been introduced into only a few countries. Eighty-six percent of the species introduced have been recorded from 10 countries or less.  This graph is read for example the first column means that 29 countries have only had 1 species introduced, 6 countries have had only 2 species introduced and so on.  I am concerned with the farthest bar to the right that says 1 country has had 70 foreign species of fishes introduced in it and that happens to be the US.  Canada falls out at 17 foreign species, Mexico with 33, and Hawaii with 45 species of foreign fish.
Number of Nonindigenous Aquatic Species Introduced into the US. This includes interbasin transfer within the US.
There are almost as many ways for introductions to occur as there are introductions. But here is a list of the most well-known and documented. I found one example of shipping water very interesting.  Several years ago 3000 Pacific oysters were shipped from California to Woods Hole.  The shipment had 2 certificates stating the oysters were parasite and disease free.  That was all well and good but only 10% of the shipment was checked which I believe is standard. After arriving at Woods Hole, the oysters were washed and the water saved. There was a total of 29 species of algae, diatoms, protozoans, and invertebrates detected in the water the oysters were shipped in.
This truly is a global problem. The Russians are have problems in the Caspian Sea with exotic jellyfish where one bay was nearly solid with them.  And in China, largemouth bass are becoming a problem as a result of stocking.
Number of Nonindigenous Aquatic Species in the US by Pathway of Introduction
Here is a short list of pathways which could lead to the introduction of exotic organisms.  I don’t want to forget to mention the rate of introductions steadily increase as commerce and free-trade increase as well.  New pathways for the possible introduction are also occurring.
Percentages of All Aquatic Species in the US Introduced from Other Continents
Many scientists believe there are characteristics which help a species survive in a new environment.  Here is one list.
No large comprehensive study has been undertaken yet like those done in San Francisco Bay and Chesapeake Bay.
What we know about Florida. Fish are mostly freshwater species.
Pomacea canaliculata channeled applesnail – SA            Daphnia lumholtzi – AF, AA
Cipangopaludina chinensis Chinese mysterysnail -AS      Marisa cornuarietis, giant rams-horn snail – SA (FRESHWATER)                                                             Melanoides tuberculatus, red-rim melania – AF, AS
Hemichromis letourneauxi – African jewelfish AF - south Florida
Oreochromis aureus - blue tilapia AF
Tilapia mariae – spotted tilapia AF
Monopterus albus - swamp eel  AS
Xiphophorus helleri – green swordtail  CA
Ctenopharyngodon idella – grass carp AS
Pterygoplichthys disjunctivus - vermiculated sailfin catfish  SA
The Asian clam is very common in Florida, you many not know it’s an exotic.  We are not sure how it got but it first was discovered in the Pacific Northwest in the 1920s and is spreading throughout the country. It was originally thought that it would not survive the warm southern temperatures based on the temperatures of its native waters, but it’s doing quite well everywhere.  If there’s one thing that helps a species to survive in a new environment is its ability to adapt -- genetic plasticity.  The African clawed frog is a common pet store item and it is established in south Florida along with the Cuban tree frog that came in accidentally in shipping crates.
There are not many marine fishes which have been introduced. Here is one: Scatophagus argus. Scat, Seahorse Key (Gulf of Mexico),1992, Asia,  Aquarium release.  Little impact if any.
Cromileptes altivelis. Another is the Panther grouper, Found a couple time in Coffee Pot Bayou, from the South Pacific, probable aquarium release.
Penaeus monodon, Asian tiger shrimp, Captured in Florida from aquaculture escapes in South Carolina, not established.
Platychirograpsus spectabilis - sabre crab. This crab came from the western Gulf of Mexico in the 1930s on imported cedar logs, found in the Tampa region.
Scylla serrata. The serrate swimming crab is from the Pacific, intentionally introduced in the 1990s to create a new fishery but did not establish.
Charybdis hellerii. An Indo-Pacific crab on east coast of Florida.  Ballast water introduction?
Petrolisthes armatus. Green porcelain crab. This crab is native to the tropical Atlantic, Bahamas, and Caribbean, may have come with shipments of seed clams and is established.
There are 3 barnacles considered not native to Florida, B. amphitrite, B. reticulatus and B. trigonus.
We have two mammals in Florida.  The nutria has been documented but the capybara I have mostly heard through personal communication of local residents.  Myocastor coypus denude a lot of of marsh habitat.
Perna viridis group. Discovered in 1999 by TECO, a probable ballast water introduction, well established, edible where it is legal to harvest.
I collected this specimen last Monday.  I noticed a large amount of reproduction this year.  I did not see this the year before.  I think this species is just getting started, perhaps. ~ 2”
Let’s not forget about plants, a plant like Hydrilla has had huge impacts her in Florida as you I’m you’re aware of.  Millions of dollars are spent every year in Florida to control it and . . .
Water hyacinths.  The situation with plants both aquatic and terrestrial far outweighs the problems with most of the animals. Exotic insects may be the exception there.  The western US has has some real bad terrestrial plants such as leafy spurge, yellow star thistle, and salt cedar. The National Park Service is extremely concerned there.
These are relatively new invaders of which both occur in Florida.  Minima is native to central America and molesta to South America. Minima can be found in most region of Florida except the far west panhandle. Molesta is the more invasive of the two and was discovered in SW Florida near Naples.
Molesta has chocked off several large rivers in Asia.  We knew this was a bad one and now it’s here in the US.– Giant Salvinia from the water garden trade
This is list of several plants closely associated with the aquarium trade.  It  is pretty well documented that hydrilla and parrot’s feather came from aquaculture, more specifically the aquarium trade.
These are several Great Lakes invaders and might do well in Florida if they get here.  Most of us are familiar with which the zebra mussels spread. Cercopagis is a small crustacean also spreading quickly to all the Great Lakes and the Finger Lakes of New York State. It’s native to the Caspian region of Eurasia. The snail, a native of New Zealand, is also in the Snake River system in Idaho and is doing well, hundreds of thousands per square meter. They have spread into Yellowstone Park probably unknowingly by fisherman. The state of Montana has closed small isolated areas to fishing where the snail is found to keep it from spreading.
These two species both from Asia are really taking off in the Mississippi and Ohio river drainages.  One bighead taken from the upper Ohio River was 47 pounds, possibly a world record.  Animals seems to grow larger in a new environment without factors such as predation and diseases acting on them. The carp are mainly feed on phytoplankton and algae.  Therefore, they may be competing with the native paddlefish and other organisms depending on algae such as mussels.
Drymonema dalmatinum  in the northern Gulf of Mexico in 2000.  Native to Atlantic and Pacific but not the Gulf. It is suspected that a weather event or change in the Gulf currents brought this jelly to the northern Gulf.  Has a potent sting to many.
Phyllorhiza punctata Australian spotted Jellyfish. Was found in the northern Gulf of Mexico in 2000.  It is suspected that a weather event or change in the Gulf currents brought this jelly to the northern Gulf from the Caribbean.  Gets to 20 inches across. 
Indigenous to Indo-Pacific.
Introduced to Mediterranean, Hawaii
Introduced to the western tropical Atlantic late 1960s / early 1970s
Until recently, primary Atlantic concentration in southern Caribbean
Rapana venosa. Introduced from Europe into the Chesapeake Bay several years ago.  It feeds on shellfish such as oysters which all know is an important industry there.
Eriocheir sinensis. From Asia, a probable ballast water introduction into San Francisco Bay. They travel mimes and miles upstream to spawn in fresh water. This species really took off in central California but its number have dropped now. The state was pulled dump truck loads of them from water pumping stations so critical to California’s irrigation systems.
Carcinus maenas. This is an old introduction from Europe into the northeastern US, but recently into the northwestern coast of US. There is fear that it will compete with the native crabs that are a valuable commercial commodity.  A more recent introduction to the northeast is the Japanese shorecrab, Hemigrapsus sanguineus.
Biofouling is one main problem of how exotics can impact us. Here are some zebra mussel attached to the submerged portion of an outboard motor.  The larvae can be pumped into the engine’s cooling system and cause problems if they are allowed to settle and grow there.
Outboard propeller. Here you can see a little better how they might tend to cause problems.
These are green mussels with barnacles covering one of the bridge pilings over Old Tampa Bay from last year. With the way they attach, they could cause structural damage to the integrity of the concrete over time.
A bridge piling in Tampa Bay.  The green that you see are this year’s  reproduction of green mussels. Each bridge piling on all three bridges was cover on all fours sides. Some a little heavier than others.
Green mussels are also attaching to navigation aids.  In parts of Asia where they are not native, the weight of the mussels can actually sink the buoys.  In the great lakes, zebra mussels were sinking buoys there also.
At Mote Marine in Sarasota, a few green mussels were found in a water intake at their dock.
Economic Impacts all come done to dollars and cents.
Mechanical cleanup is costly
Biocontrol is expensive
Pesticides are expensive
Herbicides are expensive
Costs usually passed onto consumers and taxpayers
Biological Impacts
Degradation of host environment
Displacement of natives
Extinction of natives – out west this a problem with several of the rare desert fishes. Aquarium species are being reared in the warm thermal springs.
Hybridization with natives
To be honest, it’s very difficult to control organisms once they get established. For the future, prevention is the best method of control and why it is so important.  Getting laws changed and new ones passed is extremely difficult because each segment of this trade has a lobby that fights any regulation on their industry. I believe that discovering new pathways and eliminating them may have possibilities of slowing down the flow of new organisms. Boiga irregularis - Native to Indonesia, New Guinea, Australia - 13,000/sq. mi. in forest on Guam
It’s easy to buy anything on line these days and there is no way to get it all inspected. There’s simply not enough manpower.
Elevate the issue in DOI agencies to get funds
Attain an adequate level of survey / inventory activity to monitor invasive species
Develop better methods to assess status and impacts
Increase efforts in areas with many invasive species and in high biodiversity
Identify new “hotspots” and gaps in information
What can you do as educators to help?
Educate people about impact
Elevate local invasive species issues to governments and public.
What can the public do?
Clean and dry boating and fishing equipment
Do not empty bait bucket
Do not empty livewell
Do not purchase known invasive animals and plants. Many are still for sale.
What can you and the public do?
Learn to identify exotics
Learn which waters are infested
Learn the laws concerning prohibited species which is not easy.
This is very import than we teach people not to release their pets. Some other options may be to give to someone else, the pet store may take it back and resell it. To euthanise an aquatic pet use can freeze them.
For you scholarly types here is some recommended reading.