Exploring potential establishment of marine rafting species after transoceanic long‐distance dispersal

Abstract

Aim On 11 March 2011, the Great East Japan Earthquake triggered a massive tsunami that resulted in the largest known rafting event in recorded history. By spring 2012, marine debris began washing ashore along the Pacific coast of the United States and Canada with a wide range of Asian coastal species attached. We used this unique dataset, where the source region, date of dislodgment and landing location are known, to assess the potential for species invasions by transoceanic rafting on marine debris. Location Northeast Pacific from 20 to 60°N. Time period Current. Major taxa studied Forty‐eight invertebrate and algal species recorded on Japanese tsunami marine debris (JTMD). Methods We developed maximum entropy (MaxEnt) species distribution models for 48 species recorded on JTMD to predict establishment potential along the Pacific coast from 20 to 60°N. Models were compared within the context of historical marine introductions from Japan to this region to validate the emergence of marine debris as a novel vector for species transfer. Results Overall, 27% (13 species) landed with debris at locations with suitable environmental conditions for establishment and survival, indicating that these species may be able to establish new populations or introduce greater genetic diversity to already established non‐native populations. A further 21 species have an environmental match to areas where tsunami debris likely landed, but was not extensively sampled. Nearly 100 Japanese marine species previously invaded the northeastern Pacific, demonstrating this region’s environmental suitability for rafting Japanese biota. Historical invasions from Japan are highest in California and largely known from bays and harbours. Main conclusions Marine debris is a novel and growing vector for non‐native species introduction. By utilizing a unique dataset of JTMD species, our predictive models show capacity for new transoceanic invasions and can focus monitoring priorities to detect successful long‐distance dispersal across the world’s oceans.

Oceanic Hitchhikers – Assessing Pathogen Risks from Marine Microplastic

“…Vibrios not all of which are pathogenicare generally sparse in the open ocean, preferring more estuarine salinities, yet strikingly high numbers of vibrios have been reported on microplastic from the mid-North Atlantic Ocean [7,8]. This, combined with the long-distance dispersal potential of floating microplastic [30], raises the important question as to whether the increasing amount of plastic waste in global oceans provides greater opportunities for vibrios and other pathogens to be transported and transmitted to potential hosts, leading to increased outbreaks of disease, compared to the opportunities provided by other, natural particles. Microbes, including vibrios, are known to be associated with a variety of natural substrates such as wood, cellulose, glass, planktonic organisms (Figure 1, Key Figure ), and even birds [31][32][33], which act to increase the survival of vibrios and provide a means of transport across oceanic environments [31].…”

Molecular phylogenies map to biogeography better than morphological ones

“…The relative importances of these two processes remain controversial and probably depend upon environment and time scale. Vicariance is often invoked as a result of the formation of land barriers such as mountains or oceans while dispersal is associated with repeated migrations away from a reservoir 69 or centre of endemism 70 , as well as with biotic interchanges 71 . Species distribution patterns are unlikely to be purely vicariant or dispersive 72 and may be shaped by additional factors such as range expansions 73 , migrations 74 and extinctions 75 .…”

Molecular Phylogenies Map to Biogeography Better than Morphological Ones

“…This can ultimately lead to speciation through physical or reproductive isolation 58 . Such patterns are typical where there are, for example, repeated raftings or other migrations of species away from an island or some other reservoir 59 , as well as biotic interchanges resulting from the merging of landmasses 60 .…”