… “When marine mammals strand, the present a unique opportunity to obtain insights into the ecology”….. (Lusher et al. 2015).
It’s not uncommon to see reports on the news and the web about the marine mammals stranding on coastlines around the world. In the most part, their deaths are associated to natural causes. However, in many cases their deaths are attributed to marine debris, specifically large plastic items that have been ingested, caused blockages, malnutrition, starvation and eventually death. Regardless of the route of entry to the marine environment, discarded plastic can be accidently ingested by animals mistaking it for prey.
It is not only large plastic items that could be present in the digestive tracts of these animals. As part of my PhD research and collaborative work with Dr. Gema Hernandez-Milian from University College Cork (UCC) we have been investigating methods for the identification of microplastics in stranded animals on Irish shores.
We were fortunate enough (not fortunate for the animals), to have three True’s beaked whales (Mesoplodon mirus) strand on the west and north coast of Ireland within two weeks of each other. A mother and calf in Co. Donegal, and an adult female in Connemara, Co. Galway.
True’s beaked whale stranded in Co. Galway, May 2013 (Image: Ian O’Connor)
It is important to note that strandings of True’s beaked whales in Ireland are very rare, with only 13 record to date, check out the Irish Whale and Dolphin Group (IWDG) for more details.
A laboratory procedure was developed, to prevent contamination and to search effectively for microplastics in our samples. In short, we looked at each stomach separately, and divided the intestines into 20 equal sections. Rinsing the samples through stacked sieves, we were able to remove remains of prey, for dietary analysis, and the retained material was digested to leave non-biological material.
Any items remaining following digestion were visually analysed under a microscope, and a sub-sample were retained for FTIR analysis to find out which polymer new were looking at. For more information on this technique, read the methodology section of Lusher et al. 2013.
We found microplastics throughout the digestive tract (stomach and intestines) one female whale. We also identified macro plastic items in both the adult whales. The calf had no sign of plastics or food, but did have milk, which suggests it was still feeding from the mother.
Diagram of the stomach of True’s beaked whale (Image: Lusher et al. 2015)
As we are not vets, the cause of death could not be determined. The levels of plastic found did not appear to have caused any significant negative effects on the individuals.
Or you can contact me for a copy of the PDF: amy.lusher@reaserch.gmit.ie
We are carrying out this work on cetaceans stranded in Ireland, so keep an eye out for future research.
Dr. Simon Berrow from IWDG and GMIT was interviewed on TodayFM about a killer whale stranding in Co. Waterford a the beginning of the month. He discusses the work we have been doing form 11. 40 mins on-wards. Take a listen here.
At least once a week a news report will mention the occurrence of plastic waste in our oceans, such as the LEGO pieces washing up on Cornish beaches (BBC News). Beaches might be end-points for larger plastic waste, but what about those that are trapped by ocean currents and circulating the globe? What about the plastic we can’t see, or need the aid of microscope count?
Cutlass on a beach (C) Tracey Williams
A recent study conducted by research from the University of Cadiz, Spain, and the University of Western Australia published in the Proceedings of the National Academy of Sciences set out to describe the levels of plastic pollution around the globe. This study looks as 3,070 samples which have been collected worldwide, including previously published data as well data collected as part of the 2010 Malaspina Science Expedition.
Researchers detected plastics in 88% of samples of the ocean surface during the Malaspina Expedition in 2010 and it demonstrates that the five accumulation gyres in the oceanic surface circulation match with trends of plastics debris. The concentration of plastics ranged over 4 orders of magnitude in the open ocean, matching areas of convergence and divergence in the ocean. They estimated tat the amount of plastic in surfaces waters of the open ocean was between 7,000 and 35,000 tons.
What is interesting about the study is that, yes they identified plastics in the 5 gyres (check out the NGO with the same name), but since the 1980s we have seen plastic production quadruple, and we would think that with all of the wave and wind action, a lot more microplastics would be floating at the sea surface. In reality, a whole lot more particle were predicated than what were actually found.
There appear to be 5 distinct areas where plastic accumulates :
Pacific Ocean: to the west of the United states (AKA the North Pacific Central Gyre-add link)
Although these areas tend to receive the most research, there are other areas of the ocean are likely to have plastics as well. From my own research we are finding microplastics throughout the Irish marine and coastal environment (watch this space – publication coming soon).
Nearly 300 million tons of plastic is produced every year, worldwide we do our best to recycle and reuse a large quantity of this, but it has been estimated about 10% (by mass) will eventually find its way into the marine environment. Once there is can be transported on currents, slowly breaking down into smaller and smaller pieces (processes include wave action and UV degradation). Microplastics are also input directly through the use of cosmetics, air blasting and loss of pre-production pellets at sea.
It’s not just these floating garbage patches that accumulate plastics, they only appear to account for 1 percent of what is expected to be found. So where could this plastic have gone? Plastics could end up sinking to the sea floor, washing up on beaches, or interacting with marine biota (take a look at my previous posts about this). If ingestion is the case, and chemical effects are associated with microplastics, this could have wide-ranging environmental impact, because so many different species living on the earth live in or eat from the oceans. It might even find its way onto our plates.
I guess the step forward is to continue looking for the sources and sinks of microplastics in the marine environment, to begin to understand their pathways around the globe and their eventual fate in the marine environment, be it interacting with marine organisms of burying deep in sediment.
What is known is that microplastics are certainly ubiquitous in the marine environment, and they will be there for many decades and centuries to come.
Published by Amy Lusher
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If you want to read the full articles from PNAS you can access it here. I have copied the abstract below:
There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.
Authors: Andrés Cózar, Fidel Echevarría, Juan I. González-Gordillo, Xabier Irigoien, Bárbara Úbeda, Santiago Hernández-León, Álvaro Palma, Sandra Navarro, Juan García-de-Lomas, Andrea Ruiz, María L. Fernández-de-Puelles, and Carlos M. Duarte. Plastic debris in the open ocean. PNAS, 2014; DOI: 10.1073/pnas.1314705111
In my last post I discussed the range of different species that ingest microplastics, and the potential consequences of this ingestion.
Last week (27/7/14), a new study was published in Environmental Science and Technology on the route of microplastics uptake in crabs, which discusses a new mechanisms for uptake. You can find a link to the paper here. (You will need access to ES&T though).
The team of researchers at the University of Exeter (funded through the CleanSea* research project) have been looking at the mechanisms of microplastic uptake and retention in the common shore crab, Carcinus maenas. Their aim was to test the hypothesis that shore crabs can uptake microplastics across the gill surface during inspiration as well as ingestion from pre-exposed food (in this case, the common mussel, Mytilus edulis). They found that polystyrene microspheres (8-10µm) were retained in the body tissues of crabs, both following ingestion and inspiration. Interestingly they observed significantly higher uptake in the posterior gills than the anterior gills, the Watts et al. suggest that:
Crabs appear to uptake microspheres in two ways:
Ventilation: a masked breathing study found microplastics were uptaken from the water column. All exposed crabs had plastic on their gills.
Ingestion of prey: dietary exposure also resulted in crabs having microspheres in their stomach. This suggests that trophic transfer of microspheres is possible within the marine food chain, especially at the lower levels.
What happened with the microspheres:
They were NOT translocated to the haemolymph system.
They were excreted in the form of faecel pellets.
Microspheres take over 6 times longer to leave the body compared to the average excretory phase for food waste.
Now the study of microplastic ingestion by wild and laboratory exposed animals is not uncommon (previous post), what makes this research different is that it looks at the mechanism behind the uptake of microplastics, going beyond the usual ingestion studies.
What are the consequences of this form of microplastic uptake
The mechanism of uptake may play a role in which organisms are more susceptible to microplastic pollution. In the case of the shore crab its ventilation rate is less than that of the common mussel. Watts et al. discuss this in much more detail, but in summary, they suggest that in reference to ventilation rates alone, mussels may be more susceptible to higher levels of pollutants. further research is required on levels of ingestion via feeding and predation
*CleanSea is a multidisciplinary and collaborative research project addressing marine litter from different perspectives. It aims at providing Member States and other stakeholders with improved knowledge, methods and tools to be able to better define, monitor and achieve a marine environment free of harmful litter levels by 2020 (Good Environmental Status -GES- as required by the Marine Strategy Framework Directive -MSFD). In doing so, it will deliver a set of integrated results that will provide transparent and useful guidance to policy makers and stakeholders dealing with marine litter mitigation. http://www.cleansea-project.eu/ ——————————————————————————————————————————————————————————– Paper title: Uptake and retention of microplastics by the shore crab Carcinus maenasAuthors: Andrew Watts, Ceri Lewis, Rhys Goodhead, Stephen Beckett, Julian Moger, Charles Tyler, and Tamara Galloway
Abstract: Microplastics, plastics particles <5mm in length, are a widespread pollutant of the marine environment. Oral ingestion of microplastics has been reported for a wide range of marine biota, but uptake into the body by other routes has received less attention. Here, we test the hypothesis that the shore crab (Carcinus maenas) can take up microplastics through inspiration across the gills as well as ingestion of pre-exposed food (common mussel Mytilus edulis). We used fluorescently labelled polystyrene microspheres (8-10 µm) to show that ingested microspheres were retained within the body tissues of the crabs for up to 14 days following ingestion and up to 21 days following inspiration across the gill, with uptake significantly higher into the posterior versus anterior gills. Multi-photon imaging suggested that most microspheres were retained in the foregut after dietary exposure due to adherence to the hair like setae and were found on the external surface of gills following aqueous exposures. Results were used to construct a simple conceptual model of particle flow for the gills and the gut. These results identify ventilation as a route of uptake of microplastics into a common marine non-filter feeding species.
For those of you who are currently sitting at a desk chewing on their plastic pen (or other plastic object). Stop. Think carefully about what you are doing (I have to remind myself about this on a daily basis). You are currently/potentially breaking off teeny tiny pieces of plastics which, if you are unlucky, will find their way into your mouth, and end up in your stomach. You know the old fable that if you swallow chewing gum it will say in your stomach for several years (It’s a myth). Well the same could be said about plastic. In fact it will more than likely exit your body given a day or two. Lets face it, gum and plastic pieces are small, your body cant dissolve or utilize it, so it will try to get rid of it. However, what if the plastic gets stuck, or you eat enough plastic that it has a nasty effect on your body?
#MyStrangeAddiction
This is the basis for theory behind microplastic ingestion in the wild. In most cases ingestion is accidental and plastic is mistaken for food, although some studies have found that plastics can be targeted specifically by animals (more about this later). In some extremely polluted areas, the numbers of microplastic may outweigh natural prey items.
There are so many studies which look at microplastics ingestion in the wild. Most studies of microplastic come from the analysis of stomach contents. Below I am going to discuss are a few highlights, once you start getting into the material you will see that there are several other studies, these are some of the more recent ones. Some of the links you have to have access to journals, although most are available free online. I might be biasing your reading a little with two of them….
So we cut up all of these organisms (normally by-catch species, or those washed up on beaches), and find microplastic in their stomachs but what does this mean? The more species we look at, the more we find ingestion plastic. Is this a case of seek and you shall find? On a positive note: in all of the papers I have mentioned above, microplastics are not the cause of death.
Were the organisms feeding directly on microplastics?
This is often hard to determine from wild studies, in the case of the Humbolt squid (Dosidicus gigas) plastic pellets were found in their stomachs (Braid et al. 2012). However they are a predatory species which feeds at depths >200 m. The route of ingestion is unknown, they could have been feeding directly on pellets that had sunk, or they ate organisms that had already eaten pellets.
What’s great about laboratory studies is you can control for the plastics you are looking for and directly expose organisms. However sometimes the levels of exposure are greater than the microplastic level in the wild. Laboratory studies have shown ingestion in marine species. For example:
So why is the study of microplastic uptake important?
Microplastic exposure doesn’t just stop at the individual that has eaten the microplastics. There have been a number of studies addressing the fate of ingested microplastics, and research is still continuing. Below are a quick run down of the fate of microplastics.
1) The first option for microplastics is to pass directly out of the organism, either by excretion or the production of pseudofaeces (think of it like the animals make themselves sick). If this happens then it can be assumed that microplastics are not having any long-lasting effect on the individual.
2) Microplastics might stay within the animal and transfer between tissues, as Browne et al (2008) and von Moos et al (2012) found in mussels. Further work is required in this area.
3) Micropalstics might have negative effects on organisms. Adverse effects of microplastic ingestion have been noticed in laboratory studies. Microplastics can reduce feeding activity and compromise the fitness of a invertebrates. Stephanie Wright’s PhD research has been based around this topic. Her paper on laboratory exposure of worms to microplastic is extremely interesting.
3) Animals with microplastics inside them, may subsequently be eaten by animals from higher in the food chain. Microplastics can therefore pass to other animals.
Microplastics moving in the food chain.From: Ivar do Sul, J. A., & Costa, M. F. (2014). The present and future of microplastic pollution in the marine environment. Environmental Pollution, 185, 352-364. DOI: 10.1016/j.envpol.2013.10.036
A question for you:
If microplastics are ingested by fish and bivalves that we, as humans, consume on a regular basis….does this mean microplastics could end up inside us? From here on in: what I say needs to be taken lightly, until we can provide results.
– The answer is technically, Yes. However this is assuming that microplastics are present in the tissue of individuals that we eat. In the case of most fish species, we gut them before eating. The risk is practically non-existent. Although there are some species of fish and mollusc that we eat whole (mussels, pilchard etc). Microplastics might be in there tissues. The word MIGHT is important, because for all we know microplastics may have been egested (as laboratory studies have already shown), and the presence of microplastics will be related to how recently the individual has fed. Gut passage time for fish is relatively fast, and the likelihood of plastics hanging around in the gut of healthy fish is minimum. Furthermore, most shellfish are depurated before sold to the consumer, depuration would in theory allow for microplastics to be passed out of individuals.
-But what if the microplastics have transferred into tissues that we do eat, like skin….well currently there are no conclusive reports in this respect. It is more than likely the plastics will pass through our digestive system in the same way as the chewing gum and plastic example I gave earlier. So there is no need to worry ………. YET.
…..I will come back to the issue of chemicals associated with plastics in another post.
After reading a recently published journal article (Koushal et al. 2014), I realised we haven’t actually explained the plastic issue on our blog in great detail. I guess we were assuming everyone has a similar knowledge and understanding about marine litter.
With reference to Koushal et al. (2014) I am going to give a quick overview of plastics and why they are an environmental issue.
If you want to read the paper yourself you can find it in the International Journal of Waste Resources. An online Open Access and peer-reviewed journal: plastics: issues, challenges and remediation.
Fantastic plastic? Plastics have become a fundamental part of our day to day lives. They are inexpensive, durable, convenient and have multiple uses. Having a look at the desk in front of me, my computer, mouse, keyboard, phone, stapler, scissors, pens and ruler are all made of plastic. We use plastic every day to carry out simple tasks. Food items are more often than not packages in plastic. This functionality provided by plastic has made our lives simpler. They have replaced metals, glass, paper and cardboard, offering benefits over these alternative materials. Cost is reduced because plastics can be mass produced. They are robust and can probably last hundreds of years. Our use of plastics is expected to continue to rise to meet consumer demands.
So what’s wrong with plastic? Over the years research and technological advancement has led to new, safer forms of plastics, but this comes at a cost, both to human health and the environment. Plastics are non-biodegradable, they build up in the environment adding to the ever growing rubbish piles and land-fills. As plastics do not break down naturally, they will remain in the environment as waste for a very long time. As more plastics are made to replace old and discarded plastic, there is a never ending cycle of plastic production and disposal.
But we recycle plastic: Yes, this is a convenient and easy way to reduce the amount of plastics that end up in land fill. This requires smart sorting, and efficient ways to separate the different types of plastic. The picture below lists the different types of plastic that can be recycled. Often if you look on the bottom of plastic products, you can see the triangle with a number indication the main constituent polymer in the plastic.
What about biodegradable plastics? These are very similar to conventional plastics, however they have the natural ability to decompose, breaking into natural and safe byproducts. Bio-plastics, which are naturally derived plastics, come from biological sources including cellulose. They degrade in open air, or compost using fungi, bacteria and enzymes.
What are the impact of plastic on the environment? As there is no “safe” way to dispose of plastic, there are several ways it can have an effect on the environment.
1. During plastic production chemicals additives are incorporated into the polymer matrix to give plastics their desirable qualities. These chemicals, can also be released during the manufacture process, adding another significant source of environmental pollution.
Additives include:
carcinpogenic chemicals
neurotoxic chemicals
hormone (endocrine) disrupting chemicals
Many of these chemical additives are classed as persistent organic pollutants or POPs, which are a consider harmful under the Stockholm Convention. For example: PVC often contains vinyl chloride, dioxins, phalates and other plasticisers; Polystyrene contains benzene; formaldehyde and Bisphenol-A are found in poly-carbonates.
2. Plastic can also affect the environment during their use. An example of this is through the release of toxic gases or dust, during installation and use.
3. Plastic disposal is possibly the most problematic area, and where the environment is most at risk. Plastics’ durability and resistance to degradation is one of the reasons it poses a large environmental threat. If plastics are not recycled (even then only 10% is recycled effectively) they are sent to land fill. Synthetic polymers do not break down and as a result plastic will persist in the environment. Plastics are also sent to incinerators where toxic compounds are released into the atmosphere where they can accumulate in the ecosystem. If plastics are lucky, they might escape land-fill and find themselves in one of the many waterways leading to the sea. The density of plastics is often less than seawater, and plastics can float around on currents and accumulate in areas such as the Great Pacific Garbage Patch in the North Pacific Ocean. This is not the only area plastic accumulates, there are similar gyres in all of the worlds oceans
Over time plastics can break down into smaller and smaller pieces through the process of fragmentation and UV exposure, but the tiny pieces or microplastic will never full break down and disappear (out of sight, but not out of mind).
What are the impact of plastic on organisms? Many reports of plastic debris in the environment have focused on larger items known as macroplastics. infact most of the information we have on plastic debris comes from the marine environment. Numerous reviews have commented on the impacts and effects of their presence in the marine environment so I wont go into great detail here (e.g. Derraik 2002,Gregory 2009). Macroplastic is commonly reported due to large size and visible implications which are regularly depicted in reports such as those by the United Nations Environment Programme (UNEP 2011).Birds, sea turtles and marine mammals are among the groups of organisms known to be affected by entanglement and ingestion of macroplastic. The consequences of this interaction includes impaired movement, reduced feeding ability, decreased reproductive output, lacerations and ulcerations, and death. Below is a video that I find really interesting, photogrpaher Chris Jordan discusses his Midway Project; which documents the ingestion of plastic and subsequent death of albatross.
The Marine Strategy Framework Directive has identified understanding the ecological implications of plastics to monitor the environmental status of the marine environment. Plastic size will play a key part in the effects it will have on different marine species and as it breaks down into smaller and smaller pieces the effects are still being determined.
Plastic can contain a number of chemicals that are toxic, and have been used to give the polymers specific properties. An example of one such chemical is Bisphenol-A. It is a plasticiser which is known to have negative effects on the endocrine system of humans and animals. Toxic monomers have also been linked to caner and reproductive problems.
Plastics can also attract chemicals, such as POPs from surrounding sea water. As a result plastics could act as transport vectors of contaminants to “clean” environments, or marine organisms.
The most likely route of exposure to these chemicals is through ingestion of contaminated chemicals. Studies have been conducted to understand how chemicals could transfer from plastics to organisms, and the current level of understanding (based on models) may indicate that the chemical transfer from plastics might not be significant as first thought.
Toxicity is an issue for single use plastics. Phthalates and Bisphenol-A can leach form plastics into food and water. This type of plastic, when discarded can end up in waterways where they can continue to leach chemicals into the environment. Bisphenol A used to be found in a lot of polycarbonate food grade plastics, but has a strong oestorogenic effect. To put things bluntly, it make things more feminine and has been linked to effects on pregnancy.
Koushal et al. conclude stating that it’s not the plastics to blame, but the misuse of plastics. Maybe with a little at source reduction (reduce and reuse of plastic) and by altering the design, manufacture and use of plastic we might be able to start reducing the effects plastic debris can have on the environment.
I am interested to hear your opinions on the topic. If you have an comments or want to add further to this, please feel free to leave a comment, or contact me on our email: plastictides@gmail.com
Welcome to our blog! Christmas is getting closer and closer, so why not start our blog with a Christmas post?
A few weeks ago I was asked to write short piece about my research in relation to Christmas. It was to be part of the Irish Independent’s Christmas supplement, called ‘Science of Christmas’ in partnership with the Irish Research Council. So I put together a little story about how Santa was trying to minimise the impact of Christmas on planet Earth. The piece was published last Wednesday (11/12/13), complete with cheesy Christmas picture. You can find the full text below.
– Does Santa care about planet Earth?
His annual trip around the world gives Santa a great view of any changes on planet earth. Over the years, one of the things he notices is the growing amount of plastic in the sea.
Plastics have only been around since the early 1990s with the introduction of Bakelite in 1970 while mass production began in the 1040s. Now, the use of plastic for packing and in industry is widespread.
Even though many plastic items are recycled, about 10% of what is produced will end up in the ocean where it can accumulate and persist for hundreds of years.
This accumulation in the marine environment I a worrying trend and one that is being studied by scientists internationally.
Plastics build up on shorelines, in seawater and on the sea bed. Along with the unsightly impact, they also affect the environment in a number of ways. Marine animals can become entangled in them. Sea birds, marine mammals and sea turtles can swallow plastics items, both accidentally and mistakenly targeting them for food items. Ingestion can lead to malnutrition- because it can cause a blockage and decrease the nutritional intake- starvation and sometimes death.
It is not only the large items of plastic that cause problems; over time, larger plastic break down into smaller and smaller pieces, making it easier for smaller organisms to mistake them for items of prey or accidentally eat them. These microplastics are less than 5mm in size- about the size of half a grain of rice- and fish, invertebrates, such as mussels and prawns, as well as sea bird have been found to ingest them. By the way, polyester and acrylic fibres can also separate from clothes during washing and eventually find their way into the sea, while certain cosmetic products contain microplastic scrubbers. These also contribute to the accumulation of microplastics.
The effect of ingestion of microplastics still needs to be fully understood, but it has been suggested that they can cause the same damage as larger items of debris.
I am currently involved in research at Galway-Mayo Institute of Technology (GMIT), where I am investigating the effect of microplastics on the marine environment in the North Atlantic and Irish waters. I have spent a lot of time on the Marine Institute’s research vessel, the R.V. Celtic Explorer, to collect water and biological samples. On these trips, balloon yoga mats, washing up gloves and bottles are among the many plastic items you see bobbing around on the sea.
Wisely, Santa decided it was time to do his best to minimise the impact of Christmas on the marine environment. He told his elves to reduce the amount of plastic packaging used in his workshop, so that he leaves less unnecessary and potentially damaging packaging in home.
That, in turn, reduces the amount of rubbish to be disposed of at the end of the Christmas period. The less plastic packaging use, the less that can end up in the sea. Plastic is a convenient and widely use produced and it is impossible to eliminate it completely, however by reducing its use, Santa is doing his bit to help preserve the environment for future generations
Plastic Tides 
