- The release of marine debris into the oceans and seas is a global issue of growing concern. These materials are harmful to marine environments and can also transport non-native species to novel habitats. Non-native species floating on marine litter is one of the lesser known impacts associated with marine debris. In fact, nearly 300 living coastal marine species traveled thousands of kilometers on debris items from the 2011 Great East Japan Earthquake and tsunami and reached the Hawaiian Archipelago and North American coast. It is unclear if marine debris provides a novel transport vector that transports additional species or simply an assemblage similar to one transported on other known vectors, such as hull fouling, ballast water, and aquaculture. Therefore, I characterized the distributional, environmental, and life history traits of the species identified on Japanese tsunami debris with (n=36) and without (n=61) prior transport on known anthropogenic vectors to determine if there are distinct traits associated with species that are transported on anthropogenic vectors. A more detailed comparison of species traits was then completed among the four, most commonly reported prior vectors ballast water, hull fouling, aquaculture, and natural rafting and secondary spread (defined as the transport of organisms through drifting currents, where the species are directly in the water column, or traveling on floating natural rafts), to characterize traits that may make species more amenable to transport on specific vectors. I used Non-Metric Multidimensional Scaling ordinations, Multi-Response Permutation Procedures, and Indicator Species Analyses. Species with prior anthropogenic transport were more commonly on hardpan and artificial substrates, in temperate reef and fouling ecosystems, at cold water temperatures, suspension feeders, had prior invasion history, and exhibited a greater salinity tolerance than species without prior anthropogenic transport. Ballast water species were more commonly in areas with warm temperate, subtropical, and tropical water than the species without prior ballast water transport. Species with prior aquaculture transport were in flotsam, kelp forests, occur in cold and cool temperate waters more often than the species without prior aquaculture transport. Natural rafting and secondary spread species occurred more often in pelagic, cold, and saltier waters than the species with no prior natural rafting and secondary spread. Overall, I found the species with prior anthropogenic transport have the ability to colonize on artificial substrates and live in fouling ecosystems, which has obvious implications for the transport potential of these species. They also have a high tolerance to environmental stressors such as a range of salinity, which can facilitate successful species transport. In this work I identified traits that may increase the tendency for coastal invertebrates to travel on human-mediated transport vectors, and can thus increase our scientific understanding of species dispersal.
Non-native species transport is only one of many recognized risks associated with marine debris. Research on ocean debris is ongoing, yet many of the impacts are unknown. There is a need for more research to understand the impacts of marine debris and to encourage the prevention and reduction of marine pollution. Therefore, a survey was distributed to Oregon stakeholders with an ultimate goal to prioritize and rank marine debris research topics relevant to Oregon. The survey was sent out to interested citizens, citizen scientists, researchers, and managers. With limited available funding and the need to bridge knowledge gaps, the prioritization and ranking of marine litter research topics can help to improve research efficacy and applicability. After surveying 116 participants, three marine debris research priorities emerged as highest priority for Oregon stakeholders surveyed: 1) marine debris impact on Oregon’s ecosystems, 2) microplastics impact on Oregon’s ecosystems, and 3) investigate best approaches for working with industry to reduce plastic waste, especially packaging. These results highlight general concern for ecological impacts and can help to prioritize future marine debris research efforts in Oregon. In addition, research on marine debris as a vector for non-native species was a lower priority topic, suggesting this concern may not fully be addressed unless it becomes a larger, increasingly documented issue.