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The Indo-west Pacific (IWP) coral-reef damselfish Neopomacentrus cyanomos is well established across the southwest Gulf of Mexico (SwGoMx). Comparisons of mtDNA sequences of the SwGoMx population with those from conspecifics from 16 sites scattered across its native range show that the SwGoMx population is derived from two of four native lineages: one from the north-west Pacific Ocean, the other from the northern Indian Ocean. Three hypotheses address how this species was introduced to the SwGoMX: (1) aquarium release; (2) borne by cargo-ship; and (3) carried by offshore petroleum platform (petro-platform). The first is unlikely because this species rarely features in the aquarium trade, and “N. cyanomos” traded to the USA from the sole IWP source we are aware of are a misidentified congener, N. taeniurus. The second hypothesis is unlikely because shipping has not been associated with the introduction of alien damselfishes, there is little international shipping between the IWP and the SwGoMx, and voyages between those areas would be lengthy and along environmentally unfavorable routes. Various lines of evidence support the third hypothesis: (i) bio-fouled petro-platforms represent artificial reefs that can sustain large and diverse populations of tropical reef-fishes, including N. cyanomos in the SwGoMx; (ii) relocation of such platforms has been implicated in trans-ocean introductions leading to establishment of non-native populations of such fishes; and (iii) genetic characteristics of the SwGoMx population indicate that it was established by a large and diverse group of founders drawn from the regions where many SwGoMx petro-platforms originated.
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Global shipping routes
Figure S1 - Global Shipping Routes (from Halpern et al. 2008. A Global Map of Human Impact on Marine Ecosystems.Science319: 948, DOI: 10.1126/science.1149345, Figure S2, with permission from AAAS). Red routes are the most heavily travelled.
Figure S2 - Numbers of petro-platforms and drill-ships used in the southwest Gulf of Mexico that were constructed at different locations in the Atlantic and Indo-west Pacific. Source of locations; www.infield.com/rigs , accessed July 20 2017.