Aquatic invasion patterns across the North Atlantic.

Ross N Cuthbert,Syrmalenia G Kotronaki,Elizabeta Briski,Gregory M Ruiz,James T Carlton,Paul Fofonoff

doi:10.1111/gcb.16016

Abstract

Biological invasions are a major driver of biodiversity loss and socioeconomic burden globally. As invasion rates accelerate worldwide, understanding past invasion dynamics is essential to inform predictions of future invaders and impacts. Owing to a high diversity of pathways and current biosecurity gaps, aquatic systems near urban centres are especially susceptible to alien species establishments. Here, we compiled and compared alien species lists for three different aquatic recipient regions spanning the North Atlantic: Chesapeake Bay, Great Lakes-St. Lawrence River and North and Baltic Seas. Each system is a major trade centre, with a history of invasions, and characterized by a strong natural salinity gradient. Our goal was to compare the alien species across systems, to test for similarities in the taxonomic composition and geographic origin as well as species overlap among the three regions. We selected specific macroinvertebrate, algal and fish taxa for analysis, to control for uneven taxonomic and biogeographic resolution across regions. Cumulatively, we identified 326 individual alien species established in these aquatic systems, with the North and Baltic Seas most invaded overall (163), followed by Great Lakes-St. Lawrence River (84) and Chesapeake Bay (79). Most invasions were from Ponto-Caspian, Eurasian, Northwest Pacific, Northwest Atlantic and North American origins, and mostly comprised Arthropoda, Chordata, Mollusca and Annelida. However, origins and taxonomies differed significantly among destinations, with Ponto-Caspian species particularly successful invaders to the North and Baltic Seas then Great Lakes-St. Lawrence River, but less so to Chesapeake Bay. Nevertheless, approximately eight-tenths of invaders established in only one region, indicating disparate invasion patterns and a high potential for future aliens to accrue from increasingly diverse source pools and pathways. These results support biosecurity strategies that consider a broad range of geographic origins and taxonomic groups to limit the translocation, arrival and spread of alien species worldwide.

Highlights

Human-mediated movements of species have significantly altered biogeography, biodiversity and community structure worldwide, as well as caused substantial socioeconomic burdens and losses of ecosystem services (Blackburn et al, 2019; Capinha et al, 2015; Cuthbert, Pattison, et al, 2021; Turbelin et al, 2017)
We examined similarities in invasion patterns among systems by determining individual species that invaded more than one region, with respect to their geographic origin and taxonomic grouping
We found that invasions to Chesapeake Bay were dominated by taxa of North American, Northwest Pacific and Eurasian origins, Great Lakes-St

Summary

Introduction

Human-mediated movements of species have significantly altered biogeography, biodiversity and community structure worldwide, as well as caused substantial socioeconomic burdens and losses of ecosystem services (Blackburn et al, 2019; Capinha et al, 2015; Cuthbert, Pattison, et al, 2021; Turbelin et al, 2017). Alien species accumulations have accelerated among many taxonomic groups and locations in recent centuries (Seebens et al, 2017) These anthropogenic introductions have stemmed from increased globalization of trade and transport networks (Bonnamour et al, 2021; Hulme, 2009), greater accessibility of alien species source pools (Seebens et al, 2018), habitat modifications (Pauchard & Alaback, 2004) and climate changes (Hellman et al, 2008). As these processes intensify, rates of invasion are expected to continue in future, with alien species establishment projected to increase by 36% in coming decades worldwide (Seebens et al, 2021). To aid predictive efforts for future invasions and their impacts, it is essential to understand the past geographic and taxonomic patterning of invasion dynamics

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