Brian P. Steves

Tsunami-driven rafting: Transoceanic species dispersal and implications for marine biogeography

Long-distance life rafting When coastal ecosystems are affected by storms or tsunamis, organisms can be rafted across oceans on floating debris. However, such events are rarely observed, still less quantified. Carlton et al. chart the rafting journeys of coastal marine organisms across the Pacific Ocean after the 2011 East Japan earthquake and tsunami (see the Perspective by Chown). Of the nearly 300 mainly invertebrate species that reached the shores of the U.S. Pacific Northwest, most arrived attached to the remains of manmade structures. Science, this issue p. 1402; see also p. 1356 Two hundred seventy-nine coastal marine species have been recorded crossing the Pacific by rafting after the 2011 East Japan tsunami. The 2011 East Japan earthquake generated a massive tsunami that launched an extraordinary transoceanic biological rafting event with no known historical precedent. We document 289 living Japanese coastal marine species from 16 phyla transported over 6 years on objects that traveled thousands of kilometers across the Pacific Ocean to the shores of North America and Hawai‘i. Most of this dispersal occurred on nonbiodegradable objects, resulting in the longest documented transoceanic survival and dispersal of coastal species by rafting. Expanding shoreline infrastructure has increased global sources of plastic materials available for biotic colonization and also interacts with climate change–induced storms of increasing severity to eject debris into the oceans. In turn, increased ocean rafting may intensify species invasions.

Invasion history and vector dynamics in coastal marine ecosystems: A North American perspective

The known extent of biological invasions exhibits strong variation with respect to space, time, taxonomic group, and vector. Using a synthesis of nonindigenous species (NIS) occurrences in North America, we characterized the invasion history for coastal marine ecosystems by invertebrates and algae through 2010, to evaluate variation and existing patterns at a continental scale. This study updates a previous analysis of invasions for the same taxonomic groups in North America, providing a first assessment of changes in the last 11 year period (2000–2010). Overall, we documented 450 marine and estuarine NIS that are considered to have established populations in tidal waters of North America, representing a 51% increase in NIS richness compared to the earlier analysis. Of the 152 species added, 71 species (47%) have first documented records since the year 1999, and 81 species (53%) were additions attributed to earlier time periods due to recent reports and further analysis. Across all time periods, taxonomic groups with the largest contribution were Crustaceans (112 species) and Molluscs (80 species), together providing 43% of the total species richness for North America. Species richness was unevenly distributed among coasts, with most documented on the Pacific Coast (310 species) and fewer on the Atlantic Coast (189 species) and Gulf Coast (88 species). Commercial ships have contributed between (a) 44–78% of the initial (primary) invasions of all nonindigenous species to North America and (b) 52–82% of NIS in the last 30-year time interval, being driven by transfers associated with ballast water and hull biofouling. Importantly, invasion dynamics are a shifting landscape, where the past may not predict the future, especially with emerging trade patterns and global to local environmental changes. Thus, effective management to reduce future invasions requires a dynamic and multi-vector approach, instead of single vector strategies based on past history alone.

Marine Crustacean Invasions in North America: A Synthesis of Historical Records and Documented Impacts

We examine the history and relative importance of marine crustacean invasions for North America. Nearly 400 non-native species of invertebrates and algae have established populations in marine and estuarine waters of North America. Of these documented invasions, 28% are crustaceans, contributing the largest number of species of any taxonomic group. Crustaceans also dominate non-native species richness on each coast of North America, but there are strong differences in the total number of non-native species and in their taxonomic distribution among coasts. Crustaceans contribute prominently to the current knowledge base about marine invasions, due both to the large number (proportion) of documented introductions and also the extent of research on the group; they are thus a potentially important model for understanding marine biological invasions in general. Using an analysis of available literature, we evaluate what is known about the impacts of 108 non-native crustaceans in North America. Ecological and economic impacts are reported for many (28%) of these species, but they are rarely well documented, resulting in low certainty about the magnitude, spatial scale, and temporal scale of effects.

Japanese Tsunami Marine Debris Objects and Their Associated Taxa

A single CSV file containing descriptions of Japanese tsunami debris objects (object type, date intercepted, location found, size) and the unique taxa found on each. Please see the README.txt for detailed descriptions of each column.