A New Signal of Tropicalization in the Northeast Atlantic: The Spread of the Spotfin Burrfish Chilomycterus reticulatus in Madeira Archipelago and Its Invasion Risk

Marko Radeta,Rúben Freitas,Paola Parretti,Nuno Castro,Sahar Chebaane,Emanuel Almada,João Gama Monteiro,Mafalda Freitas,Nuno Vasco-Rodrigues,João Canning-Clode,Rodrigo Silva,Francesca Gizzi,Susanne Schäfer,Filipe Henriques

doi:10.3390/d13120639

Abstract

Current trends in the global climate facilitate the displacement of numerous marine species from their native distribution ranges to higher latitudes when facing warming conditions. In this work, we analyzed occurrences of a circumtropical reef fish, the spotfin burrfish, Chilomycterus reticulatus (Linnaeus, 1958), in the Madeira Archipelago (NE Atlantic) between 1898 and 2021. In addition to available data sources, we performed an online survey to assess the distribution and presence of this species in the Madeira Archipelago, along with other relevant information, such as size class and year of the first sighting. In total, 28 valid participants responded to the online survey, georeferencing 119 C. reticulatus sightings and confirming its presence in all archipelago islands. The invasiveness of the species was screened using the Aquatic Species Invasiveness Screening Kit. Five assessments rated the fish as being of medium risk of establishing a local population and becoming invasive. Current temperature trends might have facilitated multiple sightings of this thermophilic species in the Madeira Archipelago. The present study indicates an increase in C. reticulatus sightings in the region. This underlines the need for updated comprehensive information on species diversity and distribution to support informed management and decisions. The spread of yet another thermophilic species in Madeiran waters provides further evidence of an ongoing tropicalization, emphasizing the need for monitoring programs and the potential of citizen science in complementing such programs.

Highlights

Numerous human-mediated actions, like climate change and biological invasions, trigger environmental changes which impact on global biodiversity and ecosystems [1,2]
The oldest record of C. reticulatus obtained with this online survey was registered in 1985, while 2000, 2010, and 2018 had the highest number of first sightings (n = 3)
The present study suggests that C. reticulatus is at a medium risk of establishing self-sustained populations and becoming invasive

Summary

Introduction

Numerous human-mediated actions, like climate change and biological invasions, trigger environmental changes which impact on global biodiversity and ecosystems [1,2]. Ongoing climate change encompasses many ocean modifications, such as temperature changes, ocean acidification, sea-level rise, and consequent variations in ocean stratification, upwellings, currents, and weather patterns [2,3] All of these can have determinant roles in many ecological and biological mechanisms and functioning [4,5]. One of climate change’s most direct ecological effects is species distribution shifts [6], often increasing the proportion of warm-water species in temperate or subtropical regions This phenomenon, commonly referred to as tropicalization [7], has been observed globally and across several marine areas and taxa [7,8,9,10,11]. Evidence from across the globe shows that these shifts of tropical species can promote changes in community structures, often resulting in biodiversity loss [6] and even inverting the net trophic state and carbon balance on some occasions [16]

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Results

Conclusion