Checklist of alien species in the Scheldt estuary in Flanders, Belgium

Latest version published by Research Institute for Nature and Forest (INBO) on 17 May 2021 Research Institute for Nature and Forest (INBO)

Download the latest version of this resource data as a Darwin Core Archive (DwC-A) or the resource metadata as EML or RTF:

Data as a DwC-A file download 62 records in English (18 KB) - Update frequency: as needed
Metadata as an EML file download in English (21 KB)
Metadata as an RTF file download in English (18 KB)


The Checklist of alien species in the Scheldt estuary in Flanders, Belgium is a species checklist dataset published by the Research Institute for Nature and Forest (INBO). It contains information on 61 invertebrate alien species occurring in the Belgian Scheldt estuary, detected between 1835 and now. Here it is published as a standardized Darwin Core Archive and includes for each species: the scientific name, higher taxonomy, stable taxon ID (in the taxon core), the year of first introduction and/or last assessment in Flanders (given as a year or year range in the event date in the distribution extension), coarse habitat information (in the species profile extension) and the native range(s), pathway(s) of introduction and degree of establishment in Flanders (in the description extension). Issues with the dataset can be reported at

We have released this dataset to the public domain under a Creative Commons Zero waiver. We would appreciate it if you follow the INBO norms for data use ( when using the data. If you have any questions regarding this dataset, don't hesitate to contact us via the contact information provided in the metadata or via

This dataset was published as open data for the TrIAS project (Tracking Invasive Alien Species, Vanderhoeven et al. 2017), with technical support provided by the Research Institute for Nature and Forest (INBO). It is selected as one of the authoritative sources for the compilation of a unified and reproducible checklist of alien species in Belgium.

Data Records

The data in this checklist resource has been published as a Darwin Core Archive (DwC-A), which is a standardized format for sharing biodiversity data as a set of one or more data tables. The core data table contains 62 records.

3 extension data tables also exist. An extension record supplies extra information about a core record. The number of records in each extension data table is illustrated below.

Taxon (core)

This IPT archives the data and thus serves as the data repository. The data and resource metadata are available for download in the downloads section. The versions table lists other versions of the resource that have been made publicly available and allows tracking changes made to the resource over time.


The table below shows only published versions of the resource that are publicly accessible.

How to cite

Researchers should cite this work as follows:

Soors J, Van de Meutter F, Van Ryckeghem G, Adriaens T, Reyserhove L (2021): Checklist of alien species in the Scheldt estuary in Flanders, Belgium. v1.8. Research Institute for Nature and Forest (INBO). Dataset/Checklist.


Researchers should respect the following rights statement:

The publisher and rights holder of this work is Research Institute for Nature and Forest (INBO). To the extent possible under law, the publisher has waived all rights to these data and has dedicated them to the Public Domain (CC0 1.0). Users may copy, modify, distribute and use the work, including for commercial purposes, without restriction.

GBIF Registration

This resource has been registered with GBIF, and assigned the following GBIF UUID: 22211949-9a6e-445f-86c0-6a0e019bc055.  Research Institute for Nature and Forest (INBO) publishes this resource, and is itself registered in GBIF as a data publisher endorsed by Belgian Biodiversity Platform.


Checklist; Inventorythematic; checklist; inventory; alien species; Scheldt; estuaries; Belgium; Flanders; TrIAS


Jan Soors
  • Metadata Provider
  • Originator
Research Institute for Nature and Forest (INBO)
Frank Van de Meutter
  • Metadata Provider
  • Originator
  • Point Of Contact
Research Institute for Nature and Forest (INBO)
Gunther Van Ryckeghem
  • Originator
Research Institute for Nature and Forest (INBO)
Tim Adriaens
  • Originator
Research Institute for Nature and Forest (INBO)
Lien Reyserhove
  • Metadata Provider
  • Originator
Research Institute for Nature and Forest (INBO)

Geographic Coverage

The dataset includes information on the presence of alien invertebrate species in Flanders, Belgium

Bounding Coordinates South West [50.67, 2.53], North East [51.51, 5.94]

Taxonomic Coverage

This checklist includes over 62 alien invertebrate species present in Flanders, Belgium

Kingdom Animalia
Phylum Annelida, Arthropoda, Cnidaria, Mollusca, Platyhelminthes

Temporal Coverage

Start Date / End Date 1865-01-01 / 2020-01-01

Project Data

Imagine a future where dynamically, from year to year, we can track the progression of alien species (AS), identify emerging species, assess their current and future risk and timely inform policy in a seamless data-driven workflow. One that is built on open science and open data infrastructures. By using international biodiversity standards and facilities, we would ensure interoperability, repeatability and sustainability. This would make the process adaptable to future requirements in an evolving IAS policy landscape both locally and internationally. The project Tracking Invasive Alien Species (TrIAS) aims to do this for Belgium. For a full project description, see Vanderhoeven et al. (2017,

Title Tracking Invasive Alien Species (TrIAS)
Identifier TrIAS
Funding TrIAS is funded by the Belgian Science Policy Office (BELSPO) call for Belgian Research Action through Interdisciplinary Networks (BRAIN).
Study Area Description Belgium
Design Description The project builds on two components: 1) The establishment of a data mobilization framework for alien species data from diverse data sources and 2) the development of data-driven procedures for risk evaluation based on risk modelling, risk mapping and risk assessment. TrIAS uses facilities from the Global Biodiversity Information Facility (GBIF,, standards from the Biodiversity Information Standards organization (TDWG, and expertise from the Open science lab for biodiversity ( to create and facilitate a systematic workflow. Alien species data are gathered from a large set of regional, national and international initiatives, including citizen science data, with a wide taxonomic scope from marine, terrestrial and freshwater environments. Observation data are funnelled in repeatable ways to GBIF. In parallel, a Belgian checklist of alien species is established, benefiting from various taxonomic and project-based checklists foreseen for GBIF publication.

The personnel involved in the project:

Sampling Methods

Prior to 2008, sampling was conducted every third year at fixed intertidal and subtidal stations in an increasing quantity of sites: from 51 sampling sites in 1999 up to 75 in 2005. At each sampling site, 3 core samples (diameter: 3.5 cm; depth: 10 cm) were collected. In case of subtidal samples, these were obtained from a Reineck boxcorer (diameter: 15 cm; depth: 10 cm). Sampler size was chosen to reduce highly laborious sorting effort of samples with high densities of oligochaetes (occasionally more than 1 106 individuals m-²). Sediment samples were stored in 4% formaldehyde. In the laboratory, samples were sieved in two steps over mesh sizes of 250 μm and 1000 μm. Benthic invertebrates were sorted, identified to species level, and counted. Since 2008, samples have been collected each year, following a stratified random sampling design; 212 stations are stratified by salinity zone, subtidal depth, and intertidal elevation. Two core samples (diameter: 4.5 cm; depth: 15cm) were collected at each station, fixed in 4% formaldehyde, and taken to the laboratory. These were sieved over mesh sizes of 500 μm and 1000 μm and subsequently treated as described for the samples collected prior to 2008. Since 2013 hyperbenthic monitoring occurs at 6 fixed stations; five locations along the Scheldt and one along its major tributary the Rupel. Other locations are sporadically sampled. For regular monitoring a bongonet (diameter, mesh 1mm) is pulled back and forth by 2 persons at low tide over 100m (total distance 200m). As part of projects, occasional samplings occur with the bongo net or less frequent using a benthic sledge (width 1m, heigh 50cm). Samples are always taken along the shoreline at low tide, with the exception of a series of bongo net samples taken from a boat near the surface in the navigation channel. All samples were fully sorted and all species identified to the lowest level possible. Very large samples (1000s of specimens) were subsampled (usually 1/8).

Study Extent Within the Belgian part of the Schelde estuary, benthos has been monitored by INBO since 1996. Most of the alien species were found since then.
Quality Control All records are individually validated by species experts (resource creators of this dataset).

Method step description:

  1. The source data for this standardized checklist is a Google Spreadsheet and re-uploaded regularly at
  2. This raw data file was uploaded to a GitHub repository (
  3. We developed a RMarkdown script to document and perform the transformation of the data to Darwin Core, which includes the following steps:
  4. Perform some basic data cleaning of the raw data.
  5. Generate stable and unique identifiers for each taxon (taxonID).
  6. Create a taxon core file (
  7. Create a distribution extension file (, including standardization of the distribution date range and event dates.
  8. Create a species profile extension file (, with coarse habitat information.
  9. Create a description extension file (, with standardized pathway of introduction (using the pathway vocabulary from the Convention on Biological Diversity (2014)), native range, and degree of establishment (based on Blackburn et al. (2011)).
  10. The resulting Darwin Core data files are uploaded to the INBO IPT and documented with metadata.
  11. The dataset is published and registered with GBIF.

Bibliographic Citations

  1. Blackburn TM, Pysek P, Bacher S, Carlton JT, Duncan RP, Jarosik V, Wilson JRU & Richardson DM (2011) A proposed unified framework for biological invasions. Trends in Ecology and Evolution 26: 333-339.
  2. Convention on Biological Diversity (2014) Pathways of introduction of invasive species, their prioritization and management. UNEP/CBD/SBSTTA/18/9/Add.1. Secretariat of the Convention on Biological Diversity, Montreal.
  3. Vanderhoeven S, Adriaens T, Desmet P, Strubbe D, Backeljau T, Barbier Y, Brosens D, Cigar J, Coupremanne M, De Troch R, Eggermont H, Heughebaert A, Hostens K, Huybrechts P, Jacquemart A, Lens L, Monty A, Paquet J, Prévot C, Robertson T, Termonia P, Van De Kerchove R, Van Hoey G, Van Schaeybroeck B, Vercayie D, Verleye T, Welby S, Groom Q (2017) Tracking Invasive Alien Species (TrIAS): Building a data-driven framework to inform Collection data

Additional Metadata

Alternative Identifiers 22211949-9a6e-445f-86c0-6a0e019bc055