Feature Story                                                             March 2012

Find Your NEMESIS of the Deep in the National Estuarine and Marine Exotic Species Information System  

The solitary tunicate Styela clava (club sea squirt), a comon invader on the East and West Coast of the US. Image courtesy of Anya Dunham, Department of Fisheries and Oceans, Canada.
If you’ve been following the Daily Invader, you’ve probably been waiting for the National Estuarine and Marine Exotic Species Information System (NEMESIS) to come online. NEMESIS is the national and enhanced version of the Chesapeake Bay Database, upon which Daily Invader has been based. NEMESIS was developed by the Marine Invasions Research Laboratory at the Smithsonian Environmental Research Center as a way to synthesize information on introduced marine and estuarine invertebrates and algae. We use these data to analyze patterns of marine invasions and answer global questions about the transport and spread of introduced species in the continental United States.Information on freshwater introductions can be found in the Nonindigenous Aquatic Species (NAS) database, a complementary database run by the United States Geological Survey (USGS). Working closely with the USGS, we have designed NEMESIS as a sister database to NAS allowing joint syntheses across marine and freshwater habitats in the United States.

The information provided in NEMESIS is a detailed accounting of how and when introduced species are moved and where they established populations. Marine and estuarine species have been moved around the world for hundreds of years. Most marine species are transported through trade. Trade includes introductions resulting from transport of organisms associated with ships (hull fouling and ballast water), the goods themselves, such as those associated with the seafood or pet trade, and the intentional introduction of species used to create new fisheries. The mechanisms of transport have changed overtime - today people rarely intentionally introduce species - but introduced species still occur with the products shipped around the world or on the ships themselves. As trade and globalization increase so does the risk of new invasions.

The coloneal tunicate Didemnum vexillum (rock vomit) is a recent indrocucion in Alaska. Image courtesy of Melissa Frey, Royal BC Museum, Canada.
In addition to data on how and when species invasions occur, NEMESIS also documents what is known about the impact of those species on the invaded region. For example, the tunicate Didemnum vexillum (commonly known as D vex or rock vomit) is a well-known global invader present along the West and East Coasts of the United States that was recently discovered in Sitka Alaska, further north than its previous range limit in British Columbia. This species is of major concern in much of its introduced range because it grows rapidly and can completely cover aquaculture nets, shellfish beds, and sensitive marine environments. This notorious fouling organism has been the subject of many studies, including several studies detailing its economic impacts on fisheries and aquaculture in New Zealand, which cost thousands of dollars in eradication efforts, and numerous ecological impacts in the United States including competition and habitat change.

The creation of NEMESIS required years of research and literature review and remains an ongoing project. Records are updated as new species are reported and new research is available. Because of the volume of records in NEMESIS, we are rolling out the database one taxonomic group at a time starting with the tunicates following intense internal review. Tunicates (class Ascidiacea), also known as ascidians or sea-squirts, are filter feeders that grow on hard surfaces such as docks and rocks or in some cases sandy marine sediments. The November 2011 Feature Story “All in the Family: the Tunicates” provides an overview of the group and describes their importance in the marine environment.

NEMESIS is a complex, yet easy to use, database that provides information at multiple scales of detail. Researchers, managers, and students can familiarize themselves with a particular species through brief overviews and species maps that provide the species’ native and introduced regions at a glance, as well as records detailing the history of spread and bay specific collection locations as available. Users can also generate species lists for select bays and find references to primary research papers on a given species or region. Summary reports for each taxonomic group are also available and cover the means of introduction, the timeline of invasions, and the number of species by bay. For example, a summary of tunicates shows that most tunicates introduced to North America were introduced through hull fouling. There are tunicate introductions on the East, West, and Gulf coasts, but the southwestern coast from San Francisco Bay southward has the greatest number of introduced tunicates.  

The data found in NEMESIS has been published as part of several large studies. The two most recent studies (below) were published in 2011. For more information on NEMESIS visit our website.

Ruiz, GM, PW Fofonoff, B Steves, A Dahlstrom. 2011. Marine Crustracean Invasions in North America: A Synthesis of Historical Records and Documented Impacts. In Galil, B., PF Clark, JT Carlton (eds.). In the Wrong Place - Alien Marine Crustaceans: Distribution, Biology and Impacts. Invading Nature - Springer Series in Invasion Ecology, Vol. 6, ISBN: 978-94-007-0590-6

Ruiz, GM, PW Fofonoff, B Steves, SF Foss and SN Shiba. 2011. Marine Invasion History and Vector Analysis of California: a Hotspot for Western North America. Diversity Distrib. 17:362–373.