Following our previous post “why our plastic consumption is also a conservation issue“, where we took endangered turtles as an example, this week we are delighted to interview an expert not only in turtles but also in the impacts that plastics are having on these charismatic species.
Sarah Nelms is a PhD student at Plymouth Marine Laboratory and University of Exeter who is studying the impacts of plastic on marine organisms. She recently published the paper “Plastic and marine turtles: a review and a call for research” where she affirms that all seven turtle species are ingesting or becoming entangled in marine debris.
<<The key to preventing marine litter becoming a problem for animals such as turtles is to stop it getting there in the first place.>> Sarah Nelms
The number one characteristic that differs turtles from other marine animals is that turtles migrate between foraging and nesting grounds, which often means very long-distance movements. Does this make turtles particularly vulnerable to marine pollution among other marine animals?
Sarah Nelms – Perhaps but it may also give them an advantage. For example, if they were restricted to one area that was heavily polluted they wouldn’t have a choice but to stay there. Turtles are highly mobile which allows them to move to optimal sites. Their susceptibility is more likely due to their foraging ecology and presence in highly polluted habitats, such as coastal regions and frontal zones.
Taken that the majority of marine debris are plastics, which are the impacts that they are having on species such as turtles?
Sarah – Synthetic material, such as plastic, is highly persistent. It may break down into smaller fragments but it never goes away. This is what makes it so dangerous, particularly as approximately 4–12 million tonnes enters the oceans each year. For animals such as turtles, plastic debris poses a considerable risk. If ingested, it can cause internal injuries, such as lacerations to the intestinal wall, and blockages as well as malnutrition and starvation. It may also get tangled around the animals limbs or head, hindering its swimming ability, potentially preventing it from foraging properly on reaching the surface to breath. Sadly it could lead to a slow and painful death.
Regarding the previous questions; we know that turtles visit different areas throughout different stages in their lives. Is there a particular stage of their life in which they could be more affected by this issue?
Sarah – It’s difficult to say as some age-classes have been more heavily studied than others but I would be interested to know what happens to turtles during their ‘lost-years’, the stage when juveniles spend time in the open ocean before heading back to coastal areas to breed. Very little is known about this time but it appears that some turtles inhabit frontal areas, where oceanic currents meet. These areas can be high in food and so attract feeding turtles. But the currents also draw in debris and mix it with the turtles food. This could make the turtles more likely to accidentally ingest plastic and their small size may mean that they are more at risk from the impacts, i.e. they are more likely to suffer from internal injuries or blockages than an adult that may be able to pass the obstruction. We need more research to know whether this is the case though.
On your paper, you also cite indirect impacts on nesting beaches and ecosystems. Tell us more about these.
Sarah – Nesting beaches are very important for turtles as the females nearly always return to lay their eggs on the beach from which they hatched. This means that if the beach is changed or polluted, they are not able to easily find a new place to nest. Worldwide, turtle nesting beaches are under threat from human impacts such as coastal development, light pollution and sea-level rise. When beaches are contaminated with marine litter, nesting females are hampered by debris as it obstructs their path up the beach and can stop them from digging the hole for the nest.
It can also trap hatchlings below the surface of the sand when they try to emerge and may slow them down when they race towards the sea, exposing them to predators and drying out in the sun.
Other ecosystems, such as coral reefs and sea grass beds are vital to turtles for food and shelter from predators. They can become degraded by marine debris, making them less able to support species like turtles.
Finally, we have discussed the impacts that plastic pollution can have on turtles. Now, tell us more about what needs to be done.
Sarah – I think the key to preventing marine litter becoming a problem for animals such as turtles is to stop it getting there in the first place. Approximately 70% of marine debris originates from land-based sources so it’s clear that the solutions lie on land too.
There are things that governments can do, such as improving waste management, but I feel the onus lies on us, as individuals, to reduce the amount of plastic we consume. Part of the problem is that many products are designed to be disposable, suitable for one or two uses before being thrown away. Stopping using plastic entirely is difficult but reducing our plastic consumption is actually pretty easy, especially if we focus on saying no to single-use plastic items. For example, when I go shopping I take cloth bags. I try to only buy food that has no or little plastic packaging. I always carry a re-fillable metal water bottle so I don’t need to buy plastic ones and if I have to buy plastic I recycle it. Also, when I buy cosmetics, I always check the label for microbeads, which are listed in the ingredients as polyethylene and polypropylene.
We just need to think a little and make small efforts to change our behaviour. If everyone did this, it would make a big difference.
Nelms SE, Duncan EM, Broderick AC, Galloway TS, Godfrey MH, Hamann M, Lindeque PK, Godley BJ (2015) Plastic and marine turtles: A review and call for research. ICES Journal of Marine Science. Doi: 10.1093/icesjms/fsv165