Marine impactful cryptogenic and alien species in the Greek Seas: A georeferenced dataset (1893-2020)

The GreekMarineICAS geodataset was created as part of the project ALAS: Aliens in the Aegean – A Sea Under Siege project ( https://alas.edu.gr/), with the aim to assess the spatial extent and potential impacts of alien species in the Aegean Sea, and to improve our understanding of the mechanisms driving the impacts of invasive alien species on native marine ecosystems.

Methodology of data compilation: Initially, an ICAS catalogue was created, including species classified as of high impact in the European Alien Species Information Network (EASIN), or as invasive or of high impact in recent review papers. A thorough search was conducted to look for information on the presence of these species in the Greek Seas. Georeferenced data, along with information on the reported date / year of sighting, depth range, abundance and habitat type were compiled using all available types of data sources, including published scientific literature, grey literature (e.g., theses, technical reports, and newspaper reports), offline databases (including records from past projects of universities, research institutes, the ELNAIS database, and citizen science initiatives), online scientific or citizen science databases (Algaebase, GBIF, OBIS, iNaturalist - only research-grade data), social networks (e.g., Instagram and Facebook), as well as through field work involving scientific diving and interviews with marine scientists, fishers and divers that were carried out during the ALAS project. In situ underwater sampling during the ALAS project was carried out in 2020 at 156 sites, and all sampling was conducted using non-destructive visual sampling techniques via SCUBA or free diving, down to a maximum of 20 m depth. Moreover, an unstructured interview approach was applied during the respective interviews with marine scientists, fishers and divers, while a photographic guide of the targeted ICAS was produced and provided during the interviews to enhance the species verification process. Information from social networks was specifically retrieved from the websites of diving centers, which were thoroughly checked for images of ICAS, and once relevant images were found the corresponding information was further validated through direct communication. All data were organized within an Excel spreadsheet and all duplicate records were deleted.

IdentificationAbout this resource

Alternate Identifier: 10.25607/t2smha

Alternate Identifier: d19b9fd8-f411-40aa-966a-481fc8cd0453

Alternate Identifier: http://ipt.medobis.eu/resource?r=greekmarineicas_geodataset

Publication Date: 2025-09-26

Title: Marine impactful cryptogenic and alien species in the Greek Seas: A georeferenced dataset (1893-2020)

Abstract

Dataset Language: ENGLISH

Dataset Creator: Department of Marine Sciences, University of the Aegean - Maria Sini (Research Assistant)

GREECE

Dataset Creator: Department of Marine Sciences, University of the Aegean - Michail Ragkousis (PhD Student)

GREECE

Dataset Creator: Department of Marine Sciences, University of the Aegean - Stelios Katsanevakis (Professor)

GREECE

Dataset Creator: Institute of Marine Biological Resources and Inland Waters, Hellenic Centre for Marine Research - Argyro Zenetos (Research Director)

GREECE

Dataset Creator: Nikoletta Koukourouvli (Cartographer)

GREECE

Metadata Provider: Department of Marine Sciences, University of the Aegean - Maria Sini (Research Assistant)

GREECE

Associated Party: CUSTODIAN_STEWARD

Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Centre for Marine Research - Ioannis Rallis (Marine Biologist, PhD candidate)

Heraklion
,

Associated Party: CUSTODIAN_STEWARD

Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Centre for Marine Research - Dimitra Mavraki (Data Manager)

Dataset Contact: Department of Marine Sciences, University of the Aegean - Maria Sini (Research Assistant)

GREECE

Keywords (GBIF Dataset Type Vocabulary: http://rs.gbif.org/vocabulary/gbif/dataset_type_2015-07-10.xml)

Occurrence

Keywords (none)

biological invasions

Keywords (none)

non-indigenous species

Keywords (Marine Regions)

Mediterranean Sea

Keywords (none)

introduced and exotic species

Keywords (GBIF Dataset Subtype Vocabulary: http://rs.gbif.org/vocabulary/gbif/dataset_subtype.xml)

Observation

Geographic Coverage

Geographic Description: The GreekMarineICAS geodataset covers all coastal waters of the Aegean, Levantine, Ionian, and Adriatic Seas that are included within the Greek reporting obligations under the Marine Reporting Units of the Marine Strategy Framework Directive of the European Union Seas (collectively referred to as the Greek Seas).

Bounding Box

West Bounding Coordinate: 19.116

East Bounding Coordinate: 30.146

North Bounding Coordinate: 41.443

South Bounding Coordinate: 34.38

Temporal Coverage

Range of Dates

Begin Date: 1893-01-01

End Date: 2020-12-31

Taxonomic Coverage

General Taxonomic Coverage: 60 marine ICAS (56 alien and 4 cryptogenic) belonging to 14 phyla, namely Chordata-Teleostei (16 species), Mollusca (14), Arthropoda (seven), Rhodophyta (four), Chlorophyta (three), Chordata – Tunicata (three), Annelida (two), Bryozoa (two), Echinodermata (two), Cnidaria-Anthozoa (one), Cnidaria – Scyphozoa (one), Ctenofora (one), Foraminifera (one), Ochrophyta (one), Porifera (one), Tracheophyta (one).

Taxonomic Classification

Taxonomic Rank Name: Class

Taxonomic Rank Value: Teleostei

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Mollusca

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Arthropoda

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Rhodophyta

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Chlorophyta

Taxonomic Classification

Taxonomic Rank Name: Subphylum

Taxonomic Rank Value: Tunicata

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Annelida

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Bryozoa

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Echinodermata

Taxonomic Classification

Taxonomic Rank Name: Subphylum

Taxonomic Rank Value: Anthozoa

Taxonomic Classification

Taxonomic Rank Name: Class

Taxonomic Rank Value: Scyphozoa

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Ctenophora

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Foraminifera

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Ochrophyta

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Porifera

Taxonomic Classification

Taxonomic Rank Name: Phylum

Taxonomic Rank Value: Tracheophyta

resourceLicensesLicense Information

Intellectual Rights

This work is licensed under a

Creative Commons Attribution Non Commercial (CC-BY-NC) 4.0 License

Resource License

License Name: Creative Commons Attribution Non Commercial 4.0 International

URL: https://spdx.org/licenses/CC-BY-NC-4.0.html

Identifier: CC-BY-NC-4.0

Distribution

Online

URL: http://ipt.medobis.eu/archive.do?r=greekmarineicas_geodataset

Additional Metadata

Metadata

GBIF Metadata Block

Date Stamp: 2026-04-14T08:23:49Z

Citation: Sini M, Ragkousis M, Katsanevakis S, Zenetos A, Koukourouvli N (2025). Marine impactful cryptogenic and alien species in the Greek Seas: A georeferenced dataset (1893-2020). Version 2.4. Hellenic Center for Marine Research. Occurrence dataset https://doi.org/10.25607/t2smha accessed via GBIF.org on 2026-04-14.

Bibliography

Ragkousis M., Sini M., Koukourouvli N., Zenetos A., Katsanevakis S. (2023). Invading the Greek Seas: spatiotemporal patterns of marine impactful alien and cryptogenic species. Diversity 15, 353. doi: 10.3390/d15030353

Tsirintanis K., Sini M., Ragkousis M., Zenetos A., Katsanevakis S. (2023). Cumulative negative impacts of invasive alien species on marine ecosystems of the Aegean Sea. Biology 12(7), 933. doi: 10.3390/biology12070933

• Project

Title: ALAS: Aliens in the Aegean – A Sea Under Siege project

Abstract: The GreekMarineICAS geodataset was created as part of the project ALAS: Aliens in the Aegean – A Sea Under Siege project ( https://alas.edu.gr/), with the aim to assess the spatial extent and potential impacts of alien species in the Aegean Sea, and to improve our understanding of the mechanisms driving the impacts of invasive alien species on native marine ecosystems.

Funding

Study Area Description

Descriptor: Greek Seas

• Method

Method Step

Description: All data were organized within an Excel spreadsheet and all duplicate records were deleted.

Sampling

Study Extent: Greek Seas

Sampling Description: Methodology of data compilation: Initially, an ICAS catalogue was created, including species classified as of high impact in the European Alien Species Information Network (EASIN), or as invasive or of high impact in recent review papers. A thorough search was conducted to look for information on the presence of these species in the Greek Seas. Georeferenced data, along with information on the reported date / year of sighting, depth range, abundance and habitat type were compiled using all available types of data sources, including published scientific literature, grey literature (e.g., theses, technical reports, and newspaper reports), offline databases (including records from past projects of universities, research institutes, the ELNAIS database, and citizen science initiatives), online scientific or citizen science databases (Algaebase, GBIF, OBIS, iNaturalist - only research-grade data), social networks (e.g., Instagram and Facebook), as well as through field work involving scientific diving and interviews with marine scientists, fishers and divers that were carried out during the ALAS project. In situ underwater sampling during the ALAS project was carried out in 2020 at 156 sites, and all sampling was conducted using non-destructive visual sampling techniques via SCUBA or free diving, down to a maximum of 20 m depth. Moreover, an unstructured interview approach was applied during the respective interviews with marine scientists, fishers and divers, while a photographic guide of the targeted ICAS was produced and provided during the interviews to enhance the species verification process. Information from social networks was specifically retrieved from the websites of diving centers, which were thoroughly checked for images of ICAS, and once relevant images were found the corresponding information was further validated through direct communication.

qualityControl

Description: For taxonomy, the WoRMS has been used and for localities the Marine Region Gazetteer

Marine impactful cryptogenic and alien species in the Greek Seas: A georeferenced dataset (1893-2020)

Default

IdentificationAbout this resource

Geographic Coverage

Bounding Box

Temporal Coverage

Range of Dates

Taxonomic Coverage

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

Taxonomic Classification

resourceLicensesLicense Information

Resource License

Distribution

Online

Additional Metadata

Metadata

GBIF Metadata Block

Project

• Project

Study Area Description

Methods

• Method

Method Step

Sampling

qualityControl