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

By Grant Voirol, SRC intern

On March 11, 2011, the Tohoku coast of Honshu, Japan was struck by a tsunami reaching heights of 125 feet. The tsunami caused widespread destruction along the coast, casting boats, docks, and other objects into the western Pacific Ocean. Many of these items were homes for marine communities or were soon colonized, turning these floating debris into life support rafts traveling across the Pacific. Circulating through the ocean, these rafts eventually began to make landfall on the western coast of North America and Hawaii (Figure 1). In the five years following the arrival of the first transoceanic rafts in 2012, scientists conducted a massive scale collection of biodiversity levels supported by each of piece of debris found along the coasts of Alaska, British Columbia, Washington, Oregon, California, and Hawaii.

[Figure 1.] Major ocean currents in Northern Pacific Ocean showing the path of that marine debris took following the 2011 tsunami.
(Source: Carlton et al. 2017)

In order to sample the widest range possible, a large-scale coordination took place between the scientists conducting the study and local, state, and federal officials, as well as volunteer beach clean up groups to collect and photograph samples. In total, 634 pieces of Japanese debris were assessed for animal diversity. Scientists found 289 different species of animals on the debris, mostly consisting of invertebrates such as mollusks, crustaceans, worms, and other fouling organisms.  Researchers even found fish native to coastal Japan living in the innards of fishing vessels (Figure 2). Fishing vessels and other larger debris such as docks were able to support much more diverse communities of organisms, while smaller debris such as crates or beams might only support few or one species. Additionally, multiple generations of the same species were found, indicating that these transoceanic rafts are suitable for reproduction to take place.

[Figure 2.] Examples of organisms found by researchers. (A) Dock found with high species richness, (B) Fishing vessel fouled with barnacles, (C) Japanese barred knifejaw fish found in a large fishing vessel, (D) wood beam bored by shipworms, (E) buoy with a single limpet, (F) buoy covered by bryozoans.
(Source: Carlton et al. 2017)

What this study shows is that man-made marine debris is a highly effective way to introduce nonnative species to coastal environments. While still present, very few rafts were composed mainly of natural materials such as wood. Mainly these rafts were consisted of metal, plastics, and fiberglass. These materials can survive for much longer periods in the ocean and therefore represent new ways for species to spread their geographic range. Additionally, the way that transoceanic rafts work increases their chances of spreading organisms from far off ecosystems. Firstly, they move slowly which lets the organisms that are along for the ride acclimatize to their new environment. Secondly, rafts can support large networks of reproducing organisms as opposed to planktonic juvenile organisms that need to grow to reproductive size. Finally, these rafts have an incredibly large geographic range, being able to make landfall at any point along the coast. Previous dispersal methods such as transport by ballast water confine nonnative organisms to harbors. What this means is that as we increase our use of non-biodegradable materials in coastal cities that can be swept away be storm, we are increasing the chances of species dispersal with consequences that we cannot fully predict.


Carlton, J.T., Chapman, J.W., Geller, J.B., Miller, J.A., Carlton, D.A., McCuller, M.I., Treneman, N.C., Steves, B.P., Ruiz, G.M. “Tsunami-Driven Rafting: Transoceanic Species Dispersal and Implications for Marine Biogeography.” Science 357.6358 (2017): 1402–1406.

Does marine debris affect tourist perception and tourism revenue?

By Casey Dresbach, SRC Intern

The top worldwide providers of ecosystem services of both leisure and recreation include coastal areas such as beaches and estuaries (Millennium Ecosystem Assessment, 2005). These natural environments are home to hundreds of thousands of marine organisms, all of which require clean domains to flourish, thrive, and grow in. Unfortunately, human pollution has made its way into these areas, as depicted in Figure 1. “Marine debris” can be defined as any solid, persistent, human-created waste that has been deliberately or accidentally introduced into a waterway or ocean from shorelines to the ocean floor (Oregon Coast STEM Hub, 2017). Not only does this breed of debris directly affect marine species ocean-wide, but current research is also showing that it is taking a toll on both tourism and tourists’ destination choices worldwide.

Figure 1

Dr. Sylvia Earle engaging with a Laysan albatross nesting among marine debris. (USFWS – Pacific Region, 2012)

Marine debris is complex in its nature and jeopardizes other coastal entities. The debris has a dual effect on both the marine life as well income generated from local tourism. The interaction between marine debris and tourism is complex because items may form in regions other than the places where the litter is stranded and where tourism occurs (Krelling, Williams, & Turra, 2017). Individuals visiting beaches and coastal regions are more likely so seek alternate destinations if their overall experience is not remarkably enjoyable, and a substantial amount of scattered litter may play into that alternative choice of destination.

The coast of Paraná state in southern Brazil is one of the most frequented tourist destinations in this region (Krelling, Williams, & Turra, 2017). Many tourists, such as second-home owners and users (SHOU) and non-recurrent vacationers, frequent this Brazilian coast. A single SHOU is an individual or group of individuals who have an additional property, or vacation home elsewhere. And a non-recurrent tourist is an individual who has no territorial tie to a destination – is interested in vacation without having loyalty of a piece of land. In a recent study by researchers Allan Krelling, Allan Williams and Alexandra Turra, both the perceptions and reactions of these two distinct groups of beach users were compared. More than 70% of the visitors are SHOU. In fact, some of Paraná’s cities are dependent on property taxes from these second homeowners as well as the expenditures spent by the non-recurrent tourists on services such as food, activities, and other conveniences. Collectively, the two user groups and their tourism revenue drive the economy in the coastal area.

Figure 2

(a) Depicts the entire coastal region of Paraná State in southern Brazil. (Top right) Pontal Do Sul, a highly frequented estuarine beach in the coastal region of southern Brazil. (Bottom right) lpanema, a highly frequented open ocean beach in the coastal region of southern Brazil (Krelling, Williams, & Turra, 2017).)

The study compared both the perceptions and reactions of the two user groups. SHOU and non-recurrent tourists were administered a questionnaire to determine socioeconomic characteristics at two Brazilian sub-tropical beaches: Pontal do Sul and Ipanema, exhibited in Figure 2. Pontal do Sul is an estuarine beach and Ipanema is an open-ocean beach, which is more frequented by non-recurrent tourists. The ultimate goal of the questionnaire was to characterize these beach users’ socioeconomic characteristics such as yearly income, level of education, daily per person expenditure, frequency of trips and period of permanence (Krelling, Williams, & Turra, 2017). The survey also examined perceptions and reactions, especially those regarding the potential negative economic impacts of marine debris. Pontal do Sul and Ipanema were selectively chosen because of their varying geographical characteristics, ultimately adding more variability to the study set.

The general findings showed that SHOU might have a different reaction towards the marine debris than the average tourist. This can be linked to their loyalty to the destination, specifically tied to the property they have there. Results did show, however, that if debris were to reach a significant amount (>15 items/m2), more than 85% of beachgoers would look elsewhere when searching for a coastal region to vacation (Krelling, Williams, & Turra, 2017). If this were the case the stranded litter would threaten the Brazilian economy by reducing local tourism income by 39.1%, (Krelling, Williams, & Turra, 2017) which would present losses up to $8.5 million a year.

In order to improve beach users’ experience, moving forward, an issue like marine debris should be prioritized. Marine debris can be a stressor that impacts coastal tourism worldwide. An evaluation of economic impacts caused by litter presence is a unique approach to analyzing how to minimize the threat litter may pose to tourism revenue. Some factors that may influence a visitor’s beach choice may include beach length, scenery, water quality, amenities (restaurants, shops, etc.), and quantity of litter. The additive effect of these factors determines the overall impression the trip will leave on the visitor. Stranded beach litter is considered to be one of the five most important aspects regarding beach quality in Europe, USA, Mexico, and the Caribbean (Krelling, Williams, & Turra, 2017). More research should be done in order for authorities to decide how to best go about balancing investments to remove marine litter and minimize the potential reduction of tourism revenue. Through integrated planning, the sources of litter can be determined and preventive strategies can be put into play. This would help to avoid a reduction in environmental quality and income generated from tourism.

Works Cited

Krelling, A. P., Williams, A. T., & Turra, A. (2017, August 15). Differences in perception and reaction of tourist groups to beach marine debris that can influence a loss of tourism revenue in coastal areas. (H. Smith, Ed.) Marine Policy.

Millennium Ecosystem Assessment. (2005). Ecosystems and Human Well-being: Synthesis. Washington, DC: Island Press.

Oregon Coast STEM Hub. (2017). Marine Debris – Composition and Abundance. (L. C. Schools, O. C. Newport, N. M. Program, & S. G. (Oregon), Producers) Retrieved from Conserve Wildlife New Jersey:

USFWS – Pacific Region. (2012, January 11). Dr. Sylvia Earle talks to an albatross nesting among marine debris. (A. Collins, Producer) Retrieved from Wikimedia Commons: https://commons.wikimedia.org/wiki/ File:Dr._Sylvia_Earle_talks_to_an_albatross_nesting_among_marine_debris.jpg

Marine Pollution: A Look into the Great Pacific Garbage Patch

By Hannah Armstrong, RJD Intern

Plastics, among other pollutants, are one of the most commonly found in oceans and on beaches globally.  This is mainly for two reasons: first, plastic is very durable and often low in cost, so it is universally used for consumer and industrial products, and second, plastics do not biodegrade completely, remaining in the world’s oceans and on beaches for extended periods if not cleaned up.  All of this accumulating debris can be detrimental for marine life.  Seals, turtles and seabirds often get entangled and drown in abandoned fishing nets and other miscellaneous debris, and toxins both from the breakdown of plastics and those that the plastics themselves absorb, can collect in marine organisms and be damaging to their health and to the aquatic food web as a whole.

In the North Pacific Ocean, there is a gyre that has caused such a drastic collection of debris that it has earned the name The Great Pacific Garbage Patch.  A gyre, as defined by the National Oceanic and Atmospheric Administration (NOAA), is a major spiral of ocean-circling currents; global winds result in ocean currents circling clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere, with an area of high pressure in the center.  In the North Pacific Subtropical Gyre, these ocean circulation patterns are what caused, and is still causing, the substantial amount of debris accumulation, ultimately forming the Great Pacific Garbage Patch.  The Great Pacific Garbage Patch is comprised of the Eastern Garbage Patch, which is located near Japan, and the Western Garbage Patch, which is located in the waters between California and Hawaii.

Screen Shot 2014-11-18 at 8.22.09 PM

A representation of the ocean currents and zones in the North Pacific Region. The two green shaded circles depict the Western and Eastern Garbage Patches, where a substantial amount of marine debris has accumulated (Howell et al. 2012).

Charles Moore, the oceanographer who was among the first to draw media attention to the Great Pacific Garbage Patch, noted that in the last two decades alone, the deposition rate of plastic accelerated past the rate of production.  Moreover, his research on plastics in the ocean showed that between 1960 and 2000, the world production of plastic resins increased 25-fold, while recovery of the material remained below 5%; and between 1970 and 2003, plastics became the fastest growing segment of the US municipal waste stream, increasing nine-fold.  According to Moore, marine litter is now 60–80% plastic, reaching 90–95% in some areas (Moore 2008).  This build-up is already beginning to render its consequences on the marine environment and its inhabitants.

The most obvious concern with a debris build-up caused by the previously described convergence zones is the negative effects it poses on the marine life.  Specifically, this pollution affects at least 267 species worldwide, including sea turtles (86%), seabirds (44%), and marine mammal species (43%) (Laist 1997).  In 2009, Young et. al directed their attention toward an area southeast of the Kroshio Extension near Japan.  They observed a population of Laysan Albatross (Phoebastria immutabilis), taking note that the foraging area of adult albatross originating from Kure Atoll overlapped with the range of the Western Garbage Patch.  This, they realized, is what lead to the transfer of marine plastics from adult albatross to their young.  In fact, the albatross chicks from Kure Atoll, in comparison to the Oahu albatross sample used, were fed nearly ten times the amount of plastic despite having a relatively similar amount of available natural food.  While Young et al. were unable to determine the level of mortality as a result of this plastic ingestion, they did observe mechanical blockage of the digestive tract, reduced food consumption, satiation of hunger, and potential exposure to toxic compounds (Young et al. 2008).

Screen Shot 2014-11-19 at 2.05.42 PM

A photograph of a dead Laysan albatross chick with a diversity of plastics in its stomach. Ingestion of marine debris is a detrimental issue or marine organisms and seabirds (Young et al. 2008).

In addition to threats of ingesting pollutants, marine species face threats of entanglement and a phenomenon known as “ghost fishing.” This occurs when fishing gear is lost or abandoned, but continues to fish and wipeout resources (Moore 2008).  As a means of remediating entanglement, often a result of nets and six-pack soda rings among other pollutants, some manufacturers aim to chemically alter the plastic in the event that it ends up in the ocean.  Chemical changes can allow the polymer to absorb UV-B radiation from sunlight, breaking it down into a smaller, less-harmful product.  The resulting polymer, however, is hardly more biodegradable (Moore 2008).

With the ever-increasing abundance of plastics in the marine environment, concerns too, are growing.  With other environmental problems, most notably climate change, it will be critical to begin (and continue) to study and understand how rising atmospheric and sea temperatures will affect ocean circulation, wind and debris movement patterns.  If drastic changes occur within the North Pacific region, and specifically the area encompassed by the Great Pacific Garbage Patch, then the resulting marine pollution accumulation and retention and could be drastic as well.



Derraik, Jose G.B. The pollution of the marine environment by plastic debris: a review.  Marine Pollution Bulletin 44 [842-852].  2002.

Howell, Evan A et al. On North Pacific circulation and associated marine debris concentration.  Marine Pollution Bulletin 65-1 [16-22].  2012.

Moore, Charles James.  Synthetic polymers in the marine environment: A rapidly increasing, long-term threat.  Environmental Research 108-2 [131-139].  2008.

Young, Lindsay C et al. Bring Home the Trash: Do Colony-Based Differences in Foraging Distribution lead to Increased Plastic Ingestion in Laysan Albatrosses?  Plos One. 2009.


Ghostnets: marine debris is “ghostfishing”

by Emily Rose Nelson, RJD Intern

Annually 640,000 tons of fishing gear is lost, abandoned, or discarded at sea. This deserted fishing gear is known as “ghostnets” and has the potential to “ghostfish” by itself for decades. Ghostnets are a growing issue due to their ability to trap and kill large quantities of commercially valuable fish and threatened species, leading to a loss in food and biodiversity. This waste is of even more concern than other types of marine debris because it is developed specifically to catch marine organisms, often leading to their death.

It is clear there is a lot of trash in the oceans, however little is known about where debris occurs and what organisms it is interacting with. In order to address the problems resulting from ghostnets it is necessary to answer these questions. A team of researchers in Australia set out to understand some of the impacts abandoned fishing gear could have on biodiversity. By combining physical and ecological approaches they were able to predict entanglement risk (expected interactions between nets and turtles) of marine turtles in the Gulf of Carpentaria (GOC) region of Australia.

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Fatal Attraction: Debris and Sea Turtles

by Nick Perni, RJD Intern


For decades there has been a steady increase in the production of plastic materials. Due to negligent disposal techniques and the resiliency of the material, plastic accounts for 80% of all Marine debris in some areas. The large abundance of plastic in the world’s oceans and coastal areas has detrimental effects on marine organisms. Sea turtles in particular have been heavily affected; all six species have been recorded to ingest debris nearly 90% of which is made up of plastic. The two main ways that plastic debris affects turtles is by entanglement and ingestion. Entanglement can kill organisms by preventing it from escaping predators or drowning the animal. Ingestion can also be lethal; many animals that ingest plastics can suffer from a punctured or impacted digestive system and are also susceptible to chemicals leeching from the plastic.

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