marine plastic debris – Shark Research & Conservation Program (SRC)

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Ocean Plastics

March 18, 2019/in Conservation, Ocean News /by aanstett

By: Nick Martinez, SRC Intern

The world’s oceans face a variety of challenges ranging from rising sea levels and sea surface temperatures, to overfishing and excessive amounts of anthropogenic debris being tossed into the oceans. Many studies have focused on the large scale effects of each of these dire issues, yet few have ventured into the realm of marine plastics and how these objects actually aid in the dispersal and recruitment of various species throughout the oceans of the world. Since the earliest known recording of anthropogenic waste in the world’s oceans back in the 1970’s (Goldstein et al. 2014), scientists have begun paying particular attention to the way many sessile species have proven to be a key foundation species in the recruitment and dispersal of various organisms throughout the world. Due to the anatomy of these sessile species, scientists have found a variety of microecosystems thriving on the surface of these plastics. Barnacles and other sessile species turn the smooth, unprotected surfaces of the plastics into a more structured surface where rafting organisms can hide and seek shelter from the otherwise harsh pelagic conditions. Because these ocean plastics have been virtually transformed by sessile organisms, these plastics and other anthropogenic debris augment a natural floating substrate in the open ocean, allowing “islands” of substrate-associated organisms to persist in an otherwise unsuitable habitat (2014). In other words, these sessile species have been able to successfully recruit and colonize these ‘floating islands,’ granting them the unique opportunity to create an environment where other organisms can survive and travel vast distances across the Pacific and Atlantic oceans (Fig 1). While this is certainly a unique way of nature overcoming one of our many detrimental anthropogenic effects, there is in fact a small trojan horse that this feat of nature carries throughout the world’s oceans. With the ability to travel vast distances across the ocean, scientists have begun uncovering the major issue of invasive species dispersal and global disease spread between the ‘floating islands’ and foreign ecosystems. To understand exactly how this is possible, a closer look into the plastics and their superiority over biotic debris must be taken into account.

Figure 1. In boxes a, b and c we can see a collection of barnacles that have colonized the various plastic substrates. In box d, we see a small trigger fish that has made the floating debris its home. In boxes e and f we see a close up view of the lethal folliculinid ciliates that cause skeletal eroding band disease in corals (Gill and Pfaller 2016).

For hundreds of millions of years, organisms have had limited travel on floating marine algae, plant trunks, pods, or other biotic floating parts (Barnes et al. 2004). In fact, scientists were previously aware of marine organism dispersal to other parts of the world via debris transportation. However, the key difference between the biotic and anthropogenic debris is that anthropogenic debris lasts significantly longer than biotic debris. The ability for plastics to resist degradation, made it highly persistent to haline environments and environments exposed to harsh UV light for long periods of time. For this reason, ocean plastics have drastically increased the dispersal for many marine organisms throughout the world (Carlton 1987). The plastics alone, however, would be nothing without the various sessile taxa that have transformed the smooth substrate of the plastics into a more rugged surface suitable for protection from the harsh pelagic conditions. With protection from the harsh conditions, organisms are more likely to successfully recruit to that environment and survive long periods of time. Thus, with a significantly longer lifespan and the ability for organisms to successfully recruit onto the transformed surfaces of the debris, ocean plastics have been able to transport organisms from as far south as the southernmost tip of South America to the northernmost reaches of Greenland (Fig. 2). While this is certainly a unique feat of nature, it poses a lot of issues regarding species invasion and the forced eradication of native species over time.

Figure 2. This figure shows a collection of plastic debris sampled from the southern to the northern hemispheres of the Atlantic oceans. The dark circles represent floating debris while the open circles represent debris sampled on the shores of small islands. Each sample produced an abundance of various organisms all thriving off of the ecosystem created by barnacles (Gill and Pfaller 2016).

Figure. 3. In this figure we see a collection of histogram charts displaying the abundance various taxa found on or around floating debris (Goldstein et al. 2014).

In a study conducted on the effects of Lepas barnacles (a proven foundation species for ocean plastics) by Gil et al. 2016, shows that these organisms were able to recruit a higher abundance of mobile taxa not previously observed on any floating debris. In fact, Gil goes on to state that the structural habitat provided by the Lepas barnacles could facilitate settlement of immigrating organisms e.g., adults or larvae originating from faraway coastlines or other rafts (Fig. 3). For this reason, Gil states that the barnacles’ ability to recruit a diverse array of species can prove detrimental to coastal ecosystems around the world. With the ability to successfully recruit and disperse organisms over long periods of time, there’s no way of stopping the invasion of foreign species to coastlines around the world. In addition to the dispersal of invasive species to foreign coastlines, scientists have also found an abundance of a folliculinid ciliate native to the South Pacific and Indian oceans that has managed to make its way to the Caribbean and the Hawaiian islands via plastic debris (Goldstein et al. 2014). This disease is a lethal pathogen that triggers skeletal eroding band disease in corals and while it was predominantly a disease with a fixed environmental range, ocean plastics have allowed the pathogen to cross borders and affect foreign reef systems. With the discovery of ocean plastics as being a viable source for transportation and dispersal, scientists have come to realize the detrimental effects of plastic debris beyond just polluting the ocean’s waters. Though scientists have all called for further studies regarding this topic, there is no doubt that the active limiting of plastic debris being thrown into the ocean needs to be taken more seriously.

Work Cited:

Barnes, D. & Milner, P. Drifting plastic and its consequences for sessile organism dispersal in the Atlantic Ocean. Mar. Biol. 146, 815–825 (2005).

Carlton JT. Patterns of transoceanic marine biological invasions in the Pacific Ocean. Bull Mar Sci 41:452–465 (1987).

Gil, M.A., & Pfaller, J.B. Oceanic barnacles act as foundation species on plastic debris: implications for marine dispersal. Scientific reports (2016).

Goldstein, M., Carson, H. & Eriksen, M. Relationship of diversity and habitat area in North Pacific plastic-associated rafting communities. Mar. Biol. 1–13, doi: 10.1007/s00227-014-2432-8 (2014).

Plastic debris contamination in the Acoupa weakfish (Cynoscion acoupa) in a tropical estuary

May 15, 2017/0 Comments/in Conservation, Ocean News /by a.anstett

By Elana Rusnak, SRC intern

The Acoupa weakfish (Cynoscion acoupa) is an economically important fish that lives along the tropical east coast of the American continents. They tend to live in estuary systems—calm, brackish water habitats—as juveniles and sub-adults, and then move to saltier areas as they age. Tropical estuaries are one of the most productive ecosystems on Earth, and they provide shelter, food, and developmental grounds for many species of fishes and invertebrates. Unfortunately, since estuaries are more sheltered environments, plastic debris tends to accumulate and be ingested by the many species that make the estuary their home. A study by Ferreira et al. in 2016 explored the feeding habits of all life stages of the Acoupa weakfish in the Goiana Estuary in Brazil, and described the plastic debris contamination of the area and how it affects these economically important fish.

In this study, the fish were subdivided into three study groups: juvenile, sub-adult, and adult. They were observed and captured in the upper, middle, and lower parts of the Goiana Estuary, with the lower part being the saltiest. About 470 juveniles, 25 sub-adults, and 33 adults were used in this study. The stomach contents of each fish were removed and examined to determine the ratio of plastic debris to their natural diet (fish, crustaceans, worms, seaweed, plant fragments). The researchers found that in almost every fish, the majority of the stomach contents consisted of plastic debris, followed by crustaceans and fish (64.4% of juveniles, 50% of sub-adults, and 100% of adults were contaminated with plastic). Multicolored plastics were also found in the digestive tract, and a few specimens had nothing in the stomach other than plastic debris.

Plastic debris inside a penaeid shrimp, a primary food source for adult Acoupa weakfish (Ferreira et al., 2016)

Zoomed in image of red plastic debris inside the digestive tract of an Acoupa weakfish specimen (Ferreira et al., 2016)

So what does this all mean?

First, the Goiana Estuary waters are polluted with plastic debris at densities comparable to half the density of the fish larvae that reside in it (Lima et al., 2015). This indicates that this estuary system is very polluted. Moreover, the Acoupa weakfish isn’t the only organism ingesting all this plastic. The direct ingestion of plastic debris might primarily occur during the early stages of the Acoupa weakfish, whereas sub-adults and adults ingest debris through the trophic food chain (their prey ingests the plastic, then it is left behind in the adult fish’s stomach). This occurs through a process called biotransferrence. The presence of plastic in the digestive system is also problematic, as it can lead to digestive injuries and induce starvation. Since the Acoupa weakfish is a top predator in their estuarine habitat, they are more susceptible to food web disturbances.

This fish is not only a primary food source for the locals in the area, but it is also commercially fished. If they are filled with plastic, they are not getting the nutrition they need to become large, healthy fish. Without this growth, both the locals and the commercial industry will suffer. This study really showed the large-scale change that needs to begin now with regards to reducing plastic waste and keeping our environment clean and healthy.

Works cited

Ferreira, G.V.B., Barletta, M., Lima, A.R.A., Dantas, D.V., Justino, A.D.S., Costa, M.F. 2016. Plastic debris contamination in the ife cycle of Acoupa weakfish (Cynoscion acoupa) in a tropical estuary. ICES Journal of Marine Science 73: 2695-2707.

Lima, A. R. A., Barletta, M., and Costa, M. F. 2015. Seasonal distribu- tion and interactions between plankton and microplastics in a tropical estuary. Estuarine, Coastal and Shelf Science, 161: 93–107.

Percentage of Seabird Species Ingesting Plastic Expected to Reach 99 Percent by 2050

March 7, 2016/0 Comments/in Conservation, Ocean News /by aanstett

By Laura Vander Meiden, SRC Intern

A recent study has found that if current rates of plastic introduction into the ocean continue, by 2050 approximately 99 percent of all seabird species will have ingested plastic. The study, published in September of 2015, uses a computer model based upon an analysis of data provided by past plastic-ingestion studies to come to these conclusions.

Unaltered remains of an albatross chick at Midway Atoll. Photo by Chris Jordan of the US Fish and Wildlife Service.

Plastic debris harms seabirds and other marine organisms through both entanglement and consumption. Entangled birds can lose motor abilities reducing their ability to feed and fly. Consumption of plastic can lead to pieces accumulating in the digestive system, taking up gut space typically available for food. This negatively impacts an individual’s body condition and severely reduces its ability to care for itself. In some cases, the plastic completely blocks the digestive system, leading to death. Additionally, plastics in the ocean absorb harmful chemicals that can leach out and cause damage to a seabird’s internal organs. Since approximately half of all sea bird species are in decline, these deleterious effects of plastic debris on seabirds are very concerning.

An analysis of data published in studies from 1962 to 2012 shows that 59 percent of the seabird species studied had been found to ingest plastic. Likewise, researchers found that 29 percent of the individual birds sampled in each study contained plastic in their digestive systems. Trends in this data show an average increase of 1.7 percent a year in the proportion of individuals studied that had ingested plastic. To put this in perspective, if that trend continued and those studies were to be redone today, plastic would be found in over 90% of the individual birds sampled.

Using this data, researchers created a computer model to determine areas of risk for seabird species worldwide. The model included 186 species of sea birds. Surprisingly the location of highest estimated impact was not in the Pacific Ocean, home of the infamous Great Pacific Garbage Patch, but at the boundary of the Southern Ocean between New Zealand and Australia. Though concentrations of plastic debris here are lower than other sites, this area is home to a large number of seabird species that are prone to plastic ingestion. This increases the area’s risk above those of locations with higher plastic concentrations.

It is important to remember that seabirds are not the only marine organisms affected by plastic debris. An assessment conducted by the United Nations Convention on Biological Diversity found that in 2012, 663 species were affected by marine waste, with 80 percent of the impact coming from plastic marine waste. This is up 40 percent from a previous assessment completed in 1997. Half of all marine mammal species, every species of sea turtle, and one fifth of seabird species were reported to be affected. Fifteen percent of these species are on the International Union for Conservation of Nature (IUCN) Red List, meaning they are at risk of extinction. Species of highest concern include the Hawaiian monk seal, loggerhead sea turtle, and white-chinned petrel.

The seabird study states that ingestion rates rise with increased exposure to plastic. Therefore, if the introduction of plastic into the marine ecosystem was reduced, the study’s projection that by 2050, 99 percent of seabird species will be ingesting plastic could possibly be avoided. Unfortunately, the problem will only continue to get worse unless waste management practices improve and plastic production is reduced. Commercial plastic production first began in the 1950s, over 60 years ago. If current rates of production continue, during the next 11 years we will produce the same amount of plastic as has been created since plastic production first started. Because plastic doesn’t easily biodegrade, this will effectively double the amount of plastic found on Earth.

The United Nations proposed several actions to begin to alleviate this problem. The proposed actions include reduction in the use of plastic as a packaging material, increased producer responsibility, and improved consumer awareness. These solutions are in contrast to past proposals that have only focused on waste management. However in order for a serious impact to occur, change will likely have to take place at international, national and local levels.

Works Cited

Wilcox, C., Van Sebille, E., & Hardesty, B. D. (2015). Threat of plastic pollution to seabirds is global, pervasive, and increasing. Proceedings of the National Academy of Sciences, 112(38), 11899-11904.

Secretariat of the Convention on Biological Diversity and the Scientific and Technical Advisory Panel—GEF (2012). Impacts of Marine Debris on Biodiversity: Current Status and Potential Solutions, Montreal, Technical Series No. 67.