Quick spreading of the exotic amphipod Laticorophium baconi (Shoemaker, 1934): another small stowaway overlooked?

Studies of non-indigenous species (NIS) often tend to focus on medium and large-sized taxa with potential for remarkable ecological and/or economic impact, whereas the early detection of small invertebrates is often delayed due to taxonomic chal-lenge, lack of consistent, standardised monitoring efforts and limited funding. This study represents the first records of the marine amphipod Laticorophium baconi (Shoemaker, 1934) in Morocco, Tunisia, Corsica (France), Italy, Greece, Egypt, Saudi Arabia and New Caledonia (France). Furthermore, it reports an expansion of its known distribution in Portugal (earliest and northernmost record for the country and first record for Macaronesia), Spain (earliest record for Atlantic and Mediterranean European waters), and Australia (first record for Indian Ocean). Recreational boating and commercial shipping, mainly through hull fouling and sec-ondarily ballast waters, are proposed as vectors for introduction and secondary spread of L. baconi. The following traits, analysed during the present study, could contribute to its invasive potential: (i) quick and extensive spread of the species worldwide, (ii) high densities in marinas, harbours, hull fouling and other artificial habitats, including aquaculture facilities and floating debris, (iii) high ability for short-term colonisation of empty artificial niches, (iv) diet based on detritus suggesting an opportunistic feed-ing behaviour, and (v) population survival during seasonal fluctuations in different regions. Taxonomic expertise and scientific collaboration, based on multidisciplinary networks of experts, are crucial for the early detection, distribution updates, and risk assessment of small and overlooked stowaways in marine environments.

Financial support for this study was provided by the Ministerio de Economía y Competitividad (Project CGL2017-82739-P) co-financed by the ERDF, European Union, and predoctoral grants from the Spanish Government to PS-A (Reference FPU20/04016), SR-V (Reference FPU21/0246) and JS-V (Reference PRE2018- 086266) and the Regional Basque Government to MS-S (Reference PRE_2020_1_0373). TR was supported by a technical research contract funded by the Andalusian Government (Project I+D+I, US-1265621, co-financed by the Fondo Europeo de Desarrollo Regional-FEDER). GM-L was supported by a postdoctoral contract Margarita Salas (MSALAS-2022-22337, USE-23012-N) of Ministerio de Ciencia, Innovacion y Universidades. SCh was financially supported by doctoral fellowships by Agência Regional para o Desenvolvimento da Investigação, Tecnologia e Inovação (ARDITI-M1420-09-5369-FSE- 000002). The research conducted in Tunisia by SCh and JS-V received funding from the Regional Activity Centre for Specially Protected Areas. The research conducted in Egypt by OMN was financially supported by the Committee for International Cooperation and Development, CICOPS fellowship (2022), University of Pavia, Italy. SEM pictures were supported by a VII PPIT CITIUS grant from the University of Seville (Project 2022/00000255). The material examined from Corsica was collected during the CORSICABENTHOS expedition (PI: Line Le Gall), with a focus on the small benthic biota, and are the marine component of the “Our Planet Reviewed” programme. The Corsica programme is run by Muséum National d’Histoire Naturelle in partnership with Université de Corse Pasquale Paoli and Office de l’Environnement de la Corse (OEC), with the support of Office Français de la Biodiversité (OFB) and Collectivité Territoriale de Corse (CTC). The CORSICABENTHOS 2 took place in October 2020 in collaboration with Réserve Naturelle des Bouches de Bonifacio. The organizers are grateful to Medeleine Cancemi, Jean-François Cubells, Jean-Michel Culioli and Jean-Michel Palazzi for their support. The material examined from New Caledonia was collected during the “Our Planet Reviewed” – New Caledonia expeditions (2016–2019), a joint project of MNHN and Conservatoire d’Espaces Naturels (CEN) de Nouvelle- Calédonie, funded mainly by the Gouvernement de la Nouvelle-Calédonie, Province Nord, Agence Française de la Biodiversité (AFB), the Lounsbery Foundation, and Office des Postes et Télécommunications (OPT), and inkind support from Mairie de Koumac, Société Nationale de Sauvetage en Mer (SNSM), Régiment du Service Militaire Adapté (SMA) de Koumac, Avis Nouvelle-Calédonie, and Socalait. The expedition operated under permits no. 609002-31/2018/DEPART/YM and 609011-55/2019/ DEPART/JJC issued respectively 27 August 2018 and 22 October 2019 by Direction du Développement Economique et de l’Environnement (DDEE) of Province Nord. Our Planet Reviewed / La Planète Revisitée is a global initiative founded in 2007 by Muséum National d’Histoire Naturelle (MNHN) and Pro-Natura International (PNI). The authors thanks the crew of R.V. Alis for the recovery of Lumun nets (10.17600/18001447). The authors would like to thank two anonymous reviewers for their constructive comments to improve the manuscript. We acknowledge the staff of all the ports, marinas and aquaculture facilities who granted permission for conducting the sampling and observational field studies

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