Flotsam, an overlooked vector of alien dispersal from ports

Non-native species in the north Gulf of Aqaba (Red Sea) revealed from environmental DNA

“…NIS may have arrived in other areas within the Red Sea and move to the north of the Gulf of Aqaba by unaided ways, like secondary dispersal drifting with currents and maritime tides (Kraus et al, 2019;Wood et al, 2021). Rafting on floating marine litter (Rech et al, 2018;Fernandez et al, 2022) cannot be excluded either as a way of secondary dispersal, because the most littered Hahashmal beach was the most biopolluted (but it is the closest to the commercial port; thus, it is not possible to distinguish between the two factors). The north of the Gulf of Aqaba is heavily anthropogenic and these results cannot be directly applied to other regions of the Red Sea; instead, they could be taken as a call of attention because planktonic species occupying the Gulf of Aqaba can be transported to other areas by currents and tides.…”

“…We considered the following environmental stressors: the maritime traffic, using the proximity to a port and/or a marina as a proxy; the visible presence of marine litter on the beach as a proxy of floating litter, which is a secondary NIS dispersal vector; the occurrence of pollution visualized from sewage discharges (= disturbed physic-chemical and bacterial environment); and beach frequentation observed (tourism pressure). These factors increase the frequency of NIS that are transported by ships (Ardura et al, 2015) and floating marine litter (Rech et al, 2018;Fernandez et al, 2022) and are often associated with degraded or anthropogenic areas (Pysěk and Richardson, 2010). Dummies 1 (stressor present in a beach) and 0 (stressor absent) were employed.…”

Alien species established in the Bay of Biscay suggest significant contribution of both fouling and dry ship compartments

“…Among the different vectors of the introduction of alien species analyzed (Katsanevakis et al, 2013;Galil et al, 2014;Nunes et al, 2014), ships are one of the most important because the NIS can be transported in different compartments such as ballast tanks, hull biofouling, sea chests, and cargo pallets (e.g., Godwin, 2003;Niimi, 2004;Hulme et al, 2008;Hewitt et al, 2009). Commercial ports with intense maritime traffic are important gateways for new species and could be considered as "alien hotspots" (e.g., Pearce, 2013;; secondary dispersal vectors like recreational boats (Kelly et al, 2012) or floating litter (Fernandez et al, 2022) may expand the NIS to the surrounding areas. Hewitt et al (2009) described ballast water and fouling as major pathways for exotic biota to enter ports.…”