The impact of marine debris on nature

Marine debris has a negative impact on the environment. For this reason, it is considered to be one of the most serious problems affecting the marine environment, together with climate change, ocean acidification and the loss of biodiversity. Do you want to know more about that?

THE NATURE OF MARINE DEBRIS

Marine debris is any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal ecosystem.

Debris can be made of glass, metal, paper or plastic, but plastic items are the most abundant on a global scale. For example, on European beaches, about 75% of all debris are plastics, followed by metal and glass (OSPAR, 2007).

Most of the marine debris is plastic (Picture: U.S. Fish and Wildlife Service Headquarters, Creative Commons)

It is considered that most of the marine debris come from land-based sources, such as urban and storm runoff, beach visitors and inadequate waste disposal and management, among others.

Unfortunately, marine litter has been found all over the globe: from the poles to the equator, from shorelines to the high seas, from the sea surface to the seafloor.

THE NEGATIVE EFFECT OF MARINE LITTER

Marine litter is well-known to have a negative effect to organisms and ecosystems, but also to economy. This is going to be discussed in the following sections.

IMPACT ON NATURE

The environment and the flora and fauna is affected by marine debris in several ways: by entanglement in or ingestion of debris, transport of contaminants over long distances, new habitat for colonisation, dispersal via rafting and effects at an ecosystem level. Notwithstanding, half of the interactions between organisms and debris were related with entanglement or ingestion.

Entanglement and ingestion of debris is the most common interaction between debris and organisms (Picture: Unknown, Creative Commons).

In fact, impacts of marine debris have been reported for 663 species (Secretariat of the Convention on Biological Diversity and the Scientific and Technical Advisory Panel – GEF, 2012).

All sea turtle species, half of marine mammals and 21% of sea bird species are victims of entanglement or ingestion of marine debris. Overall, about 15% of species are on the IUCN Red List, such as the critically endangered Hawaiian monk seal (Monachus schauinslandi) and the endangered loggerhead turtle (Caretta caretta).

The critically endangered Hawaiian monk seal is a victim of marine debris (Picture: Kent Backman, Creative Commons).

Despite the frequency of entanglement or ingestion varies according to the type of debris, in the 80% of the cases it was plastic items that were found, specially rope and netting (24%) and fragments (20%), followed by packaging (17%), other fishing debris (16%) and microplastics (11%) (Secretariat of the Convention on Biological Diversity and the Scientific and Technical Advisory Panel – GEF, 2012).

Not only the entanglement or ingestion can cause direct death, but also can have sublethal outcomes, such as making it difficult to capture and digest food, sense hunger, escape from predators, reproduce, as well as decreasing body condition and complicating locomotion and migration.

An example of sublethal effects occur with sea turtles: turtle hatchlings find it more difficult to reach the sea when litter is present (Ozdilek et al., 2006).

Microplastics (fragments less than 5 mm in diameter) are of particular concern due to their susceptibility to be eaten by a wide range of organisms. They come from either the direct release or through the fragmentation of larger units.  These particles, when ingested, may cause adverse physical and toxicological effects on organisms. Moreover, these small pieces are susceptible of bio-accumulation throughout the food web.

Moreover, microplastics can easily absorb pollutants and other harmful chemicals, such as persistent organic pollutants (POPs), that, when introduced into the body, can be freed and affect the health of the individual. It has to be taken into account that all plastic sizes can absorb pollutants, so those which are buoyant have the possibility to disperse these chemicals to other areas, thousands of kilometres away.

Buoyant debris has the possibility to disperse toxic chemicals to other areas, thousands of kilometres away (Picture: Cesar Harada, Creative Commons).

Aside from the absorbed chemicals, plastics also have potentially toxic chemicals by itself, such as BPA, flame retardants and antimicrobials, which could be released into the environment and then be transferred to the food web and humans, with adverse consequences.

Another important issue is the accumulation of plastic items and microplastics in specific regions, such as the North Pacific Central Gyre or the north western Mediterranean. In both areas, about 1,340 particles of microplastics per square metre have been found (Goldstein et al., 2012; Collingnon et al., 2012).

Marine litter can serve as a means of transport for many species, with the potential risk to facilitate transport of exotic and invasive species.

Marine litter can serve as a means of transport for exotic species to other areas (Picture: Thank You Ocean).

As mentioned above, marine debris can be a potential new habitat for some species, altering the equilibrium in some areas such the open ocean or sandy seabeds. They would be, first, colonised by microorganisms and, then, by macrobiota, like molluscs, crustaceans, fishes, cnidaria and echinoderms. In case the debris floats, the organisms can be transported to other regions. So, debris may be responsible for the introduction of exotic species.

Finally, in some ecosystems the negative effect of debris has been described, such as on coral reefs, soft sediment habitats and in the sandy intertidal zone.  To give an example, in coral reefs from Majuro Atoll coral cover and species diverisity decreased with increasing debris abundance.

Ghost fishing, accidental fishing from lost or abandoned nets, apart from the economical impact, also negatively affects the populations of wild animals such as turtles, cetaceans, sea birds and fishes.

The effects of ghost fishing (Picture: Doug Helton/NOAA)

The effects of ghost fishing (Picture: Marion Haarsma).

IMPACT ON ECONOMY

Marine debris can have a negative effect on economy because of economic losses to commercial fishing and shipping, in addition to recreation and tourism.

The economic loss for the fishing industry can be important. For example, Scottish losses are between US $ 15 – 17 million per year (KIMO, 2008) due to the loss of fishing time and repairs for removing debris from fishing gear, propellers and water intake pipes.

Ghost fishing means a removal of commercial species from the fishery. In Oman, the cost of ghost fishing was US $145 per trap after 3 months and US $168 after 6 months (Al-Masroori et al., 2004).

Removing debris from harbours and beaches also reduces the revenue. In the UK, removing litter from harbours amounts to US $3 million per year (Mourat et al., 2010).

Tourism is also affected by marine debris, since reduces the attractiveness of the coastline and beaches. Thus, activities such as sport fishing, whale watching and diving are reliant on healthy ecosystems.

Tourism may be negatively effected by marine debris (Picture: Zak Noyle).

Marine debris has a huge impact on the environment and economy. Now, watch that video, think about it and take action.

What are you willing to do for reducing all these negative effects? Leave your comments!

REFERENCES

• Al-Masroori, H., Al-Oufi, H., McIlwain, J. & McLean, E. (2004). Catches of lost fish traps (ghost fishing) from fishing grounds near Muscat, Sultanate of Oman. Fisheries Research, 69, 407-414.
• Collignon, A., Hecq, J., Galgani, F., Voisin, P., Collard, F. & Goffart, A. (2012). Neustonic microplastic and zooplankton in the North Western Mediterranean Sea. Marine Pollution Bulletin 64, 861-864.
• Goldstein, M., Rosenberg, M. & Cheng, L. (2012). Increased oceanic microplastic debris enhances oviposition in an endemic pelagic insect. Biology Letters n press doi: 10.1098/rsbl.2012.0298.
• KIMO. 2008 Fishing for Litter Scotland Final Report 2005 – 2008 (ed. K. I. Miljøorganisasjon), pp. 20: KIMO.
• Mouat, T., Lopez-Lozano, R. & Bateson, H. (2010). Economic impacts of Marine litter, pp. 117: KIMO (Kommunenes Internasjonale Miljøorganisasjon).
• OSPAR (2007). OSPAR Pilot Project on Monitoring Marine Beach Litter: Monitoring of marine litter on beaches in the OSPAR region. London: OSPAR Commission.
• Ozdilek, H; Yalcin-Ozdilek, S; Ozaner, F & Sonmez, B. (2006). Impact of accumulated beach litter on Chelonia mydas L. 1758 (green turtle) hatchlings of the Samandag coast, Haty, Turkey. Fresenius Environmental Bulletin. 15. 95-103.
• 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. 76, 61 p.
• Thevenon, F., Carroll C., Sousa J. (editors), 2014. Plastic Debris in the Ocean: The Characterization of Marine Plastics and their Environmental Impacts, Situation Analysis Report. Gland, Switzerland: IUCN. 52 pp.
• Cover picture: ©Jordi Chias/uwaterphoto.com.

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