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Recreational boating as a major vector of spread of nonindigenous species around the Mediterranean

Abstract : Many stressors, such as climate change, overfishing, pollution and biological invasions, are currently devastating the marine domain. The role of recreational boating in facilitating marine bioinvasions urgently necessitated a proper evaluation, especially in the Mediterranean Sea which hosts 2/3 of global charter boat traffic and is also the global hotspot for alien species. This study addresses this shortfall by completing the firstever Mediterranean basin-wide study investigating the influence of recreational boats in the transfer of NIS from biofouling both in marinas and from boat-hulls. First, a thorough investigation of NIS was conducted in 34 marinas across the Mediterranean (spanning from Spain to Turkey), targeting benthic macroinvertebrates. All marinas were found to host NIS, ranging from 2 to 27 per marina. This first output of this research provides a massive update of new NIS records and updated species distributions for the Mediterranean, and presents three new species in the Mediterranean basin, 51 new NIS country records and 20 new subregional records, which can now be fed into models and databases to gain a better comprehension of the composition and scale of NIS colonizing marina habitats. it was realized that almost 80% of sampled fouled vessels were found to host at least 1 NIS, while 11 was the maximum NIS found on one boat-hull. It was also found that recreational vessels visiting new marinas sometimes carry NIS not yet present neither in that marina nor in the country in which they are visiting, thus providing ample evidence of recreational boating supplying new NIS to marinas. The results of this large-scale Mediterranean marina assessment were combined with other existing data on NIS in Italian marinas for a total sample size of 50 marinas, which were then used to feed both univariate and multivariate statistical tests aimed at identifying which abiotic factors mainly contribute to total species richness of NIS in marinas and also which factors contribute to similar NIS assemblages between marinas. The results revealed that a higher species richness of NIS in Mediterranean marinas was influenced by the following factors: water temperatures above 25°C, a higher number of berths, absence of floating pontoons, proximity to the Suez Canal and proximity to commercial harbours. Whereas the similarities between NIS assemblages amongst marinas were more influenced by environmental factors such as temperature, biogeographical region, climate type, primary productivity and again proximity to the Suez Canal. The significance of the Suez Canal as a prominent factor in both analyses coincides with the general trend of higher total NIS found in the Eastern Mediterranean strongly influencing NIS distributions. The results presented within this thesis, adding to those marinas surveyed from around the world, form a robust case that recreational boating provides an extremely important pathway in facilitating primary NIS introduction events and their associated secondary spread to other coastal areas as ‘stepping stone’ habitats.
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Submitted on : Tuesday, February 18, 2020 - 4:14:11 PM
Last modification on : Friday, October 23, 2020 - 4:37:56 PM


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  • HAL Id : tel-02483397, version 1


Aylin Ulman. Recreational boating as a major vector of spread of nonindigenous species around the Mediterranean. Ecosystems. Sorbonne Université, 2018. English. ⟨NNT : 2018SORUS222⟩. ⟨tel-02483397⟩



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