As invasive species have moved up the list of top environmental concerns, the responsibility for monitoring and regulating their introduction and spread has rested mostly at the state level. We report on an ongoing investigation, sponsored by the Northeast Aquatic Nuisance Species (NEANS) Panel, into the non-native aquatic and wetland plant species listed by government groups and NGOs as priorities for management in each New England state. The most and least frequently listed species for New England are presented based on the number of states in which they are listed (No judgments have been made as to the validity of the lists used in the analysis).

The majority of the most commonly listed species are already well established in the region, but there are also many species, present on only one or two lists, that pose a potential threat to the region. The criteria used for each list, along with the categories of "invasiveness," both of which are reported here, influenced which species were listed.

With increasingly limited funding, and limited legal options to deal with severe invasions, we conclude that states would benefit from the creation of a list of invasive species of concern for the entire New England region, allowing them to focus more attention on early detection of the introduction of potential invaders.

Lists from 25 state, national, local and regional sources were used for this analysis. Only lists that specifically designated non-native species as "invasive," of concern, or having management priorities were included in the survey; lists simply designating species as non-native were excluded. A species was entered into the database if it appeared in any list from one of the six New England states (Connecticut [CT], Massachusetts [MA], Maine [ME], New Hampshire [NH], Rhode Island [RI], Vermont [VT]). Lists that covered regions encompassing more than one state were designated as New England [NE]. Species present on federal lists were only included if already present in New England, already present on a species list from New England, or if designated as a species of concern by the Eastern Region (Region 9) of the USDA.

For each species entered into the database, the following information was recorded:

1. Species Name - The scientific and common names and family of each species were collected, with synonymy noted when present.
2. Vectors - Any known vectors of introduction for a species were noted. In some cases vectors were reported in sources other than the species lists.
3. Origin - The part of the world to which each species is native was recorded, when known. Species for which origin was unclear (cryptogenic) and species that are considered native in any part of the Northeast U.S. were noted.
4. Date of introduction - The date of introduction was recorded, though it should be noted that many species have multiple introductions.
5. Additional Information - When possible, a relevant web source was noted, with the intention of allowing the user of the database to view an image and get more background information about each species.

In addition, each species was scored by the following:

1. List by region -Each species was ranked according to the number of regions it appeared in, with a potential limit of 8 regions (lists from the six New England states, New England regional lists, and Federal lists).
2. List Status - A separate matrix was created to show the categories used to signify the levels of priority of species created for each list. These categories differ from list to list, with 18 categories noted for the 25 source lists.

The list currently contains 70 freshwater and marine aquatic and wetland species. The majority of species on the list occur in wetland habitats (57%), with 37% of the species occurring in freshwater habitats, and 6% in marine habitats (algae).

There is a wide range of vectors, both intentional and accidental, for listed species. Vectors are known for 70% of the data set, with approximately 40% of the listed species introduced for cultivation. Other vectors include the shipping industry, sport fishing and aquarium hobbies, and natural dispersal via water currents or animals. Almost half of the species with known vectors had more than one known avenue for their introduction and spread.

The majority of species with known origins are native to Asia or Eurasia (58%), though there is representation from all other parts of the world. Approximately 9% of the species listed are categorized as native to the U.S.

Priority Nuisance Species Lists by Location, with criteria and categories of invasiveness

Frequency Distribution: graph showing how likely a plant is to be listed on any species list.

Top Twelve Non-Native Plants of Concern that occur in aquatic/wetland habitats, ranked by the number of regions in which each species is listed.

Bottom Sixteen Non-Native Plants of Concern that occur in aquatic/wetland habitats.

State-by-state comparison of priority nuisance species lists.

The compilation of the most commonly listed invasive species for the New England region is valuable in that it provides information on the current focus of invasive species management. However, the fact that lists for the region are stacked with species that are already firmly established in several states indicates that the lists produced by governmental and non-governmental groups are focused on control of established species, rather than prevention of new introductions. A regional invasive species list would provide additional value for New England by listing lesser-known, potentially invasive species, including those that have been introduced to a neighboring state, but have not yet crossed the border. Such a list would allow concerned parties to prepare for potential invasions in advance, to more effectively manage potential transport vectors, and to focus monitoring efforts.

• More Early Detection and Rapid Response
• Rapid response plans are a less economically and ecologically expensive alternative to fighting an established invasive
• Identification of priority transport vectors will lead to focused prevention and management strategies
• Better State to State Communication
• Dialogue between states is especially important for those that share borders (Invasives ignore political boundaries!)
• Identification of topics for which more research is needed (Can Eichhornia crassipes survive in Maine, given that it can overwinter in Massachusetts?)
• Opportunity to streamline categories of "invasiveness" (This study found 18 categories on 25 lists!)
• Fewer Successful Invasions!
• Direction of the limited resources available for control to the most important invaders
• More effective outreach campaigns are possible with the resources of the entire New England region

• Where is the species list?
  Because the list was compiled from a number of sources in each state, many of which are still in "Draft" status, the master list is currently undergoing a peer review and is not available to the public at this time. However, many of these sources are freely available on the web (Links can be found here).


• Isn't [insert species name here] native?
  Determining what is "native" can be complicated. For example, there are many plant species considered native to the Southeastern U.S. that have been introduced to New England as ornamentals, and some have established wild populations. We used the determination of the organization that produced the list for our analysis, and it is possible that a species considered native in one state might be considered invasive in another.


• Why do you list upland plant species?
  Any species listed by a source as significantly impacting wetlands was included in the survey. Some species may be categorized as upland, but can also be found in marshland or riparian ecosystems.

The research and design for this poster was done by Jennifer Forman Orth, as part of her work for the NEANS Panel, with significant assistance from Jason Baker.

The authors wish to thank the members of the NEANS Panel for their assistance during the data gathering portion of the project, and for their feedback following the preliminary results.