About the Data

The Marine Invasions Research Laboratory at the Smithsonian Environmental Research Center (SERC) developed NEMESIS as a resource for researchers, resource managers, and others to provide comprehensive information on introduced marine and estuarine species of invertebrates and algae with established populations in the continental United States and beyond.

Introductions occur when species are moved beyond their historical geographic range by human activities. Marine and estuarine species have been moved around the world since the time of the Vikings. Globalization increased the number of species introductions from a slow drip during early colonization to a firehose during industrialization, when the movement of species for trade and aquaculture peaked. Increased awareness and regulations are tightening the valve on the proverbial firehose, but new marine species are still arriving as unintentional introductions associated with trade, for example shipping related pathways such as ballast water and hull fouling. The impacts of many introduced species have gone unnoticed and unreported, while others have fundamentally changed the structure and function of ecosystems and impacted many dimensions of human society.

NEMESIS, CalNEMO, Chesapeake Bay, Panama – what’s the difference between these databases?

NEMESIS is the newest and most complete database available. It includes species records for about 500 marine and estuarine species of invertebrates and algae introduced to the United States. CalNEMO contains the exact same records as NEMESIS, but only California introductions and occurrences are displayed. The Chesapeake Bay database was created about ten years before NEMESIS and has a broader taxonomic scope and slightly different information. In addition to marine and estuarine species introductions, the Chesapeake Bay database also includes some terrestrial species and vascular plants. PanNEMO contains records of introduced species of invertebrates and algae introduced to Panama. Some of these species are also introduced to the United States and can be found in NEMISIS.

What information will I find?

Species records include:

  • Photographic images and descriptions;
  • Information on the biology, ecology, and effects (impacts);
  • Global distribution maps of native and introduced range;
  • Mechanisms (vectors) of introduction;
  • History of introduction and spread;
  • References to available literature for the species and invasion information.

In addition to detailed information on individual species, we also provide summary reports and graphics organized by geographic location or taxonomic groups of species. For example, a user can examine (a) the current number and identity of introduced species with established populations for a specific bay or biogeographic region, (b) the mechanism of introduction (or vector) and time of first record associated with a species in a particular taxonomic group or geographic location.

How were the data collected?

The data compiled in NEMESIS come from published literature. Dr. Paul Fofonoff does the lion’s share of the literature review and is the primary decision-maker as to what information is included. Additional information is gathered from the surveys conducted at SERC, described here (link to surveys project page), and from trusted unpublished reports. After Dr. Fofonoff compiles the species record, it is edited by Dr. Christina Simkanin. CalNEMO records are also reviewed by Sharon Shiba from the California Department of Fish and Wildlife and the Panama records are reviewed by Dr. Mark Torchin from the Smithsonian Tropical Research Center. Finally the records are reviewed by one or more taxonomic experts, and then made publically available online. These public records are updated as new information becomes available.

Do the databases differ in scope?

Yes, NEMESIS, CalNEMO, and PanNEMO focus on introduced marine and estuarine species of invertebrates and algae that have established populations, but the Chesapeake Bay database, because it is much older, has a broader taxonomic scope including species from nearly all taxonomic groups. The Chesapeake Bay Database includes species that are established, failed, extinct, and cryptogenic (meaning the native/introduced status is unclear) and information on residency (i.e. the time a species spends in the Bay system), something that is less explicit in the other databases.

Can I use these data in my publication?

These data can be used in your publication so long as you cite the database. Please contact Dr. Paul Fofonoff (fofonoffp@si.edu) if you need more detailed information on our data collection and review process.

Fofonoff PW, Ruiz GM, Steves B, Simkanin C, & Carlton JT. 2018. National Exotic Marine and Estuarine Species Information System. https://invasions.si.edu/nemesis. Access Date:

I found a mistake in a species record.

If you find a mistake in one of the records please contact Dr. Fofonoff at fofonoffp@si.edu.