Harmonizing risk scores for alien freshwater and brackish molluscs

TY - JOUR

T1 - Harmonizing risk scores for alien freshwater and brackish molluscs

AU - Thunnissen, Naomi W.

AU - Leuven, Rob S.E.W.

AU - Collas, Frank P.L.

AU - van der Velde, Gerard

AU - Jongejans, Eelke

N1 - Data archiving: no NIOO data

PY - 2026/4/27

Y1 - 2026/4/27

N2 - In Northwestern Europe, effective management of alien freshwater and brackish water molluscs requires timely and comparable information on their invasion status and potential impacts. By harmonizing various types of risk scores from existing risk assessments, this study provides an up-to-date overview of the invasion status and impacts of invasive and potentially invasive molluscs in the Netherlands, with relevance for Northwestern Europe as a whole. We compiled a comprehensive list of 70 species, including 27 already established in surface waters, 41 present in the aquarium and water gardening trade, and two additional species included based on their invasive history in surrounding countries. Based on climate matching, 30 species are likely able to survive in the wild in Northwestern Europe. For 29 of these 30 species with a climate match, a total of 130 published risk assessments from 19 sources were available and harmonized to enable comparison among species. These assessments primarily address impacts on biodiversity and ecosystems, but also consider human health and the safety of infrastructure. Harmonization showed that 16 species pose a high risk, 9 a medium risk, and 4 a low risk. While harmonization provides an efficient way to synthesize existing risk information, differences among assessment protocols and the types of risks considered can lead to inconsistencies. Overall, this study supports more consistent and timely risk evaluations and provides a robust basis for prioritizing alien mollusc species for management.

AB - In Northwestern Europe, effective management of alien freshwater and brackish water molluscs requires timely and comparable information on their invasion status and potential impacts. By harmonizing various types of risk scores from existing risk assessments, this study provides an up-to-date overview of the invasion status and impacts of invasive and potentially invasive molluscs in the Netherlands, with relevance for Northwestern Europe as a whole. We compiled a comprehensive list of 70 species, including 27 already established in surface waters, 41 present in the aquarium and water gardening trade, and two additional species included based on their invasive history in surrounding countries. Based on climate matching, 30 species are likely able to survive in the wild in Northwestern Europe. For 29 of these 30 species with a climate match, a total of 130 published risk assessments from 19 sources were available and harmonized to enable comparison among species. These assessments primarily address impacts on biodiversity and ecosystems, but also consider human health and the safety of infrastructure. Harmonization showed that 16 species pose a high risk, 9 a medium risk, and 4 a low risk. While harmonization provides an efficient way to synthesize existing risk information, differences among assessment protocols and the types of risks considered can lead to inconsistencies. Overall, this study supports more consistent and timely risk evaluations and provides a robust basis for prioritizing alien mollusc species for management.

KW - alien species

KW - aquatic snails

KW - bivalves

KW - harmonization of risk scores

KW - horizon scanning

KW - introduction pathways

KW - risk scanning

U2 - 10.3391/mbi.2026.17.2.02

DO - 10.3391/mbi.2026.17.2.02

M3 - Article

AN - SCOPUS:105044198569

SN - 1989-8649

VL - 17

SP - 215

EP - 238

JO - Management of Biological Invasions

JF - Management of Biological Invasions

IS - 2

ER -