WRiMS notes the origin (source location) of the species at a particular location by country, sea area and/or latitude longitude as available. If the species is reported to have had ecological or economic impacts it is considered invasive in that location. Each record is linked to a source publication or specialist database. A glossary of terminology is available. Links have been provided to species profiles of well-known marine invasive species in the Global Invasive Species Database (GISD) of the IUCN Invasive Species Specialist Group (ISSG).

In using WRiMS, users need to consider possible species misidentifications in the sources, and that for some species it is uncertain which is their native and introduced ranges. Whether a species is ‘invasive’ can vary between locations and over time at a particular location.

In 2008-2009 the IUCN Invasive Species Specialist Group (ISSG) worked on a project, within the framework of the Ocean Biogeographic Information System (OBIS), that developed an annotated dataset of marine introduced and invasive species for the World Register of Marine Species (WoRMS) in order to flag species on the register as "alien and invasive species".

Both online databases and publications were consulted with an aim to achieve global coverage. They include:

• Delivering Alien Invasive Species Inventories for Europe (DAISIE)
• Galil, B. (2009). Taking stock: inventory of alien species in the Mediterranean Sea. Biological Invasions 11(2): 359-372.
• Lasram, F.B.R.; Mouillot, D. (2009). Increasing southern invasion enhances congruence between endemic and exotic Mediterranean fish fauna. Biological Invasions 11: 697-711.
• Hayes, K.R. (2005). Marine Species Introductions. Unpublished data from CSIRO.
• Molnar, J.L.; Gamboa, R.L.; Revenga, C.; Spalding, M.D. (2008). Assessing the global threat of invasive species to marine biodiversity. Frontiers in Ecology and the Environment 6(9): 485-492.

In addition to biological status (represented as occurrence, provenance and invasiveness), annotations included higher taxonomy, origin of species, introduced location, as well as (where available) information on the date of first record/introduction and pathway of introduction.

In 2013-2014, ISSG worked with the Flanders Marine Institute (VLIZ) on a data collection project developed within the framework of the Biology Project of the European Marine Observation and Data Network (EMODnet) to complete trait information related to "invasiveness". The dataset submitted in 2009 was updated using additional data and information from online databases such as:

• The Global Invasive Species Database (GISD)
• The European Alien Species Information Network (EASIN)
• The Information system on Aquatic Non-indigenous Species (AquaNIS)
• The National Exotic Marine and Estuarine Species Information System (NEMESIS)
• and (recently) published literature

The terminology and definitions to describe occurrence, provenance and invasiveness have been revised and expanded. Additionally, any available information on abundance, pathways of introduction and spread, evidence of impacts on biodiversity were documented. The geographic coverage of this dataset is global. Focus was placed on documenting authoritative information on marine species introductions in the recognized marine bio-invasion hotspots.