Global patterns and processes of establishment risk by non‐indigenous marine fish

Le résumé fourni par la source

Abstract Non‐indigenous species (NIS) are often disregarded in conservation planning despite being a major threat to global biodiversity. Thus, spatially explicit risk assessments jointly accounting for the multiple underlying processes determining NIS establishment are urgently needed. Current assessments mainly consider the likelihood of NIS arrival and environmental suitability of recipient areas, overlooking other key biotic variables determining establishment, like niche overlap and potential interactions with native species. Here, we explore the potential of niche overlap between NIS and native species as an additional component for assessing invasion risk, and propose its integration into a general framework to evaluate the likelihood of NIS establishment at a global scale. Using 121 non‐indigenous marine fishes, this framework combines three key components of the invasion process: (i) connectivity to source areas, (ii) environmental suitability of recipient areas, and (iii) niche overlap with native species. These components are merged into a single metric of potential establishment risk, which we then decompose to examine global patterns and evaluate the relative contribution of each component. Our results show considerable variability in global risk patterns, with the Caribbean Sea and Gulf of Mexico standing out as the most sensitive areas to potential fish invasions due to a naturally suitable environment and the availability of niches for other tropical species, mainly from the Indo‐Pacific. We also examine the potential role of cumulative human impacts and marine protected areas (MPA), capable of elevating or mitigating such risks. Finally, the obtained risk scores largely correspond to the ranges where NIS are currently established. Synthesis and applications . Niche overlap may be critical to consider, even in areas that appear environmentally unsuitable or poorly connected for NIS. Preserving the intrinsic biotic resistance posed by native species can improve the effectiveness of targeted conservation measures. By considering niche overlap alongside connectivity and environmental suitability, the proposed approach can provide an enhanced understanding of the mechanisms behind NIS establishment. Knowing which component may benefit NIS can directly inform management and guide preventive actions. Finally, the proposed framework is aimed at being general and applicable across spatial scales, regions, and invasion scenarios given sufficient data.

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