Marine Plastics

Question 1

Mass production of plastic started only around 1950 Production increased from 2 Mt in 1950 to 380 Mt in 2015
Cumulatively, around 8,300 Mt of virgin plastics have been produced; around 30% of this is in use today

Answer 1

But most plastic products have a relatively short useful lifespan - the largest market sector for plastic resins is packaging, i.e. materials designed for immediate disposal

Question 2

In most sectors, typical plastic products are in use for 1-10y

Answer 2

Some recycled
Some incinerated
Most discarded to landfill or the ocean

Question 3

Most of the plastic ever produced - approximately 6,300Mt - has become waste
None of the commonly used plastics are biodegradable (bioplastics account for ~1% global plastic production)

Answer 3

As a result, most plastic waste - almost 80% - has been accumulated in landfills or the natural environment
Sunlight causes fragmentation into ‘microplastics’, particles mm or 𝜇m in size
Plastic waste is so ubiquitous it has been suggested as a geological indicator of the Anthropocene

Question 4

Cumulative plastic waste generation

Answer 4

Will rise dramatically, with most waste being either incinerated or discarded

Question 5

Where does it come from?

Answer 5

Fishing and aquaculture, shipping, ocean science, wastewater discharge, improperly managed waste

Question 6

‘Mismanaged waste’ is material that is either littered or inadequately disposed
Inadequately disposed waste includes disposal in dumps or open, uncontrolled landfills

Answer 6

Mismanaged waste can enter the ocean via inland waterways, wastewater outflows, and transport by wind or tides

Question 7

Jambeck et al. estimate the amount of mismanaged plastic waste generated annually by people living within 50 km of a coast worldwide
For each coastal country they consider:
1. The mass of waste generated per capita annually 2. The percentage of waste that is plastic
3. The percentage of mismanaged plastic waste that has the potential to enter the ocean as marine debris

Answer 7

~2,500 Mt of municipal solid waste was generated in 2010 by 6.4 billion people living in 192 coastal countries
~11% (275 Mt) of this waste is plastic
Based on the population living within 50 km of the coast, ~99.5 Mt of plastic waste was generated in coastal regions
~31.9 Mt of this was mismanaged
~4.8 to 12.7 Mt entered the ocean in 2010
This represents 1.7 to 4.6% of the total plastic waste generated in those countries

Question 8

Between 88–95% of the plastics entering the sea from land originate from just 10 river catchments:

Answer 8

Yangtze, Indus, Yellow River, Hai He, Nile, Meghna- Bramaputra-Ganges, Pearl River, Amur, Niger, Mekong
8 of these are in Asia, mostly in middle-income countries

Question 9

Samples from ~2000m in the Rockall Trough, 1976-2015

Microplastics ingested by 45% of individuals of the two species examined

Answer 9

Levels relatively constant over the whole survey period

Microplastics have been ubiquitous in this deep sea system for >40y

Question 10

“Three decades ago these islands, which are some of the most remote on the planet, were near-pristine. Plastic waste has increased a hundred-fold in that time,

Answer 10

it is now so common it reaches the seabed. We found it in plankton, throughout the food chain and up to top predators such as seabirds.”

Question 11

“We enumerated >53,100 anthropogenic debris… resulting in a minimum estimate of 37.7 million pieces of plastic debris weighing 17.6 tons on the sandy beaches of Henderson Island in 2015… these [do not include]..

Answer 11

. items buried >10 cm below the surface and particles <2 mm (<5 mm in the beach-back area) and debris along cliff areas and rocky coastlines”
Lavers and Bond, 2017

Question 12

Plastic debris on beaches creates a physical barrier, which: reduces sea turtle laying attempts

Answer 12

lowers diversity of shoreline invertebrate communities

increases the hazard of entanglement for coastal-nesting seabirds

Question 13

“The 17.6 tons of anthropogenic debris estimated to be present on Henderson Island

Answer 13

account for only 1.98 seconds’ worth of the annual global production of plastic”
Lavers and Bond, 2017

Question 14

“We found many native, faunal colonists of floating plastics — the so-called ‘plastisphere’ habitat.

Answer 14

In a millennium of habitat loss, residents of this habitat are amongst the very few ‘winners’ as their habitat availability, area and distribution are increasing. Plastic rafts… provid[e] near infinite opportunities for spread of species to new locations. Remote areas with little marine traffic and intact populations of endemic species…are thus highly vulnerable to invasion.”
Barnes et al. 2018

Question 15

Filter-feeding megafauna are susceptible to high levels of microplastic ingestion due to their feeding strategies, target prey, and habitat overlap with microplastic pollution hotspots
Plastic additives and POPs have been found in the muscle of basking sharks, blubber of fin whales, and skin of whale sharks

Answer 15

These can bioaccumulate over decades in long-lived filter-feeding megafauna, leading to a disruption of biological processes (e.g., endocrine disruption)
This might alter reproductive fitness, and toxins can be transferred or offloaded from mother to offspring
Evidence weak at present, but a lack of evidence does not necessarily imply a lack of effect

Question 16

At organismal and ecological (population and assemblage) levels of organization, evidence of demonstrated impacts relative to perceived threats was extremely sparse:

Answer 16

26 examples of non‐correlative demonstrated effects in 17 published studies
Mostly individual organism deaths due to plastic debris (92%)
The remaining 8% were impacts at levels considered ecologically relevant, solely demonstrated for assemblages

Question 17

The most common items of marine debris reported to cause demonstrated effects at the organism or ecological levels were macro-debris: lost fishing gear (e.g., nets) and other items of plastic debris such as rope, bags, straws, and degraded fragments

Answer 17

Of demonstrated impacts on organisms:
63% of deaths were caused by ingestion (2 species marine mammal, one sea turtle, one seabird, two invertebrates)
29% by entanglement (27 species of fish, 10 marine mammals, 49 seabirds, 1 sea snake, 75 invertebrates)
8% by smothering (cord grass, Spartina)

Question 18

Two examples of demonstrated impacts to assemblages:
Derelict fishing gear had a negative ecological impact, smothering a coral assemblage and causing the mortality of several species of corals and associated sessile fauna

Answer 18

Plastic bottles and glass jars increased diversity and abundance in a soft sediment benthic habitat, possibly explained by the debris providing extra hard substratum for some species (including one species each of gastropod, ascidian, and sponge) and acting as a refuge for others (including one species of hermit crab

Question 19

The effects of microplastic exposure do not appear to be consistent across studies
Some organisms may be resilient to stresses induced by microplastic exposure

Answer 19

Egestion of microplastics might mean that cumulative impacts could be minimised
Overall potential impact of microplastic pollution in aquatic systems remains difficult to predict
Foley et al. 2018

Question 20

This study is a meta-analysis of 43 studies which meet these criteria:
The study examined at least one effect of direct exposure to microplastics on fish or aquatic invertebrate consumption, growth, reproduction, or survival
The study was an experiment (field-based mesocosms were allowed)
The study included a “no microplastics” control treatment
The study reported mean, sample size, and measure of variance for controls and treatments

Answer 20

Many aquatic biota have the potential to be negatively impacted by exposure to microplastics
However, trends are not consistent across taxonomic grouping or shape of plastic
Results most strongly support the notion that exposure to microplastics leads to negative effects on consumption of aquatic organisms
Less compelling and consistent evidence that growth, reproduction, or survival of aquatic organisms is negatively affected by exposure to microplastics

Question 21

“Our findings support the scientific and public concern over plastic pollution of aquatic ecosystems:

Answer 21

effects of microplastics were generally negative or neutral across taxa (never positive), with the strongest effects observed on lower trophic level organisms that serve as important linchpins for food web structure”
Foley et al. 2018

Question 22

“Microplastic debris is effectively untraceable to its source and extremely difficult to remove from open ocean environments, suggesting that the most effective mitigation strategies must reduce inputs”

Jambeck et al. 2015

Answer 22

A total ban is proposed for single-use plastic items for which alternatives in other materials are already readily available:
cotton buds, cutlery, plates
straws, drink stirrers, balloon sticks oxo-degradable plastic products
fast food containers made out of polystyrene

Question 23

For the rest, a range of other measures is proposed:
Consumption reduction targets of 25% by 2025 for food containers and 50% by 2025 for cigarette filters containing plastic
Obligations for producers of items such as wrappers, cigarette filters, wet wipes etcetera to cover the costs of waste-management and clean-up (so called extended producer responsibility)
Collection target of 90% by 2025 for drink bottles (for example through deposit refund systems)
Labelling requirements for sanitary towels, wet wipes and balloons to alert users to their correct disposal
Awareness raising

Answer 23

For fishing gear, which accounts for 27% of sea litter:
Producers would need to cover the costs of waste management from port reception facilities
EU countries should also collect at least 50% of lost fishing gear per year and recycle 15% of it by 2025

Question 24

A ban on drinking straws and disposable coffee cups in the UK will not do much for global marine conservation
Plastic pollution in the sea is primarily an issue of poor waste management in major producer countries

Answer 24

But this issue has really engaged people in marine conservation, and provided concrete, achievable things that we can all do
Policy makers are acting on this, and the net result should be less plastic pollution, which is great