A loggerhead turtle swims in the Two Oceans Aquarium in Cape Town, South Africa. (Photo by Jeff Overs/BBC News & Current Affairs via Getty Images)
Over the past six weeks, 47 of the 124 rescued turtle hatchlings in the care of the Two Oceans Aquarium in Cape Town have excreted plastic.
That’s a worrying sign for the health of our oceans, says Talitha Noble, the conservation co-ordinator at the Two Oceans Aquarium Education Foundation. During this period, the hatchlings —121 loggerhead turtles and three leatherback turtles — excreted 218 pieces of plastic, which they had mistaken for food in the ocean.
“The largest amount from one turtle was 22 pieces that were passed by hatchling 19,” said Noble, who manages the turtle rescue, rehabilitation and release programme. “It’s only the beginning of our season so this [figure of 47] is a very preliminary statistic.
“In May and June, we still get a lot of turtles coming in and then, because they have got a slow digestive system, it often takes a long time for the plastic to pass … Unfortunately, for the ones that pass away, we often also on post-mortem find plastic. We’ve got about 10 hatchlings that we haven’t managed to post-mortem yet and it’s very likely that we’ll find plastic in a good number of those as well.”
Microplastic peril
The turtles hatch on the North Coast of KwaZulu-Natal and enter the warm Agulhas current that runs down the coastline. “They’re small and the current is warm and fast so they’re just drifting along and as the current reaches our South Coast, it slows down and the little hatchlings are thrown out of the current into our cooler surrounding waters.
“Then they go into thermal shock from that change of temperature and also at this point, they have often got injuries, they’re dehydrated and they’ve been eating whatever they’re been floating with and that’s where the plastic comes in.
“So, there’s a huge amount of microplastic that they’re eating that’s floating with them and so that’s why that’s such a huge problem for them. Normally at that stage of their life, they would be finding a floating bed of algae, or a log and they would drift with that and eat things around it … but it just happens to be plastic.”
Winter storms and onshore winds push the hatchlings onto the beach “and that’s where our rescue network comes in”.
Dramatic increase in plastic ingestion
Turtles are opportunistic feeders and although they will “pretty much eat anything”, stool samples and analysis have shown that the baby turtles have a preference for white and blue pieces of plastic, which they could be mistaking for blue bottles and jelly fish.
The microplastic is typically between 1mm and 3mm to 4mm in size. “The size of their gut is 2mm. So, it’s quite large pieces of plastic. Some are round, some are soft and some are hard.”
Last year, 75% of the aquarium’s rescue hatchlings excreted more than 500 individual pieces of plastic. Noble has been working in turtle rehabilitation at the aquarium for the past six years and, in the past two to three years, she and her colleagues have documented a huge number of turtles excreting plastic. “It’s increasing quite dramatically,” she said.
Harm at multiple levels
This plastic ingestion harms baby turtles at multiple levels. “In the best case scenario, they consume it, it will make them feel a little bit full and they will pass it, feel fine and eat something that’s wholesome.
“But most of the time, what happens is because the plastic is large and hard, it causes perforation in their gut or cloaca and causes a point of infection that leads to secondary issues. So, you’ve got this already immuno-compromised turtle that now has to fight an infection and it’s too weak to do that so that’s often a big problem.”
It can cause blockages in the throat, stomach, in their gut and leave them with a “fake feeling” of being full. “One thing we haven’t looked into yet, which would be quite interesting, is whether any chemicals in the plastic are possibly leaching out into the body.”
Months, sometimes years, of rehabilitation
Bob, the Green Turtle, one of the aquarium’s most notable rescues, might be released within the next year, Noble said. He was brought to the aquarium in November 2014 after he was discovered stranded on rocks at the De Hoop Nature Reserve.
Wounds on the underside of his shell became infected and caused meningitis. Bob became blind and suffered brain damage. Three months after his arrival, he pooped out a pile of plastic — pieces of balloons with their strings still attached, ribbon and black bags that he had mistaken for food in the ocean.
“We’re talking about different ways that we can release him and what would be best for him,” she explained. “We had someone do an incredible fundraising run to raise money for the tag that Bob is going to have. His rehabilitation and enrichment have really improved over the last year and made him behave more like a turtle, a bit more wild and exploratory, so it’s really given us a lot of confidence towards his release.”
An average stay for a hatchling patient is between six and nine months — at a cost of about R8 000 each. But each patient is different, Noble said. “We’ve had a little hatchling that’s been with us for over two years with consistent issues and turtles like Bob, who’s been with us since 2014.
“What’s exciting is for each turtle there’s that progress, that movement towards release, it’s very motivating for us.”
Messengers of the ocean
People are disconnected from the life-sustaining oceans, and “between our realisation that what we do on land impacts on the oceans”, she said. “We don’t realise that littering on land is not littering on land, that it’s going to end up in the ocean. With our use of single-use plastics, even if we’re kind of trying to be responsible with it, it will all eventually end up in the ocean.
“What’s amazing about turtles is that they are indicators of ocean health. Because they’re drifting in this current, which is out of sight and out of mind for us, they’re coming in and they’ve got plastic inside of them and it’s giving us a very clear message and indication of what the health of the ocean is.”
As little messengers, the turtles are “unfortunately incurring this message, always to their own detriment. But we need to listen and learn from that message and recognise our connection to the sea and how our behaviour impacts on the sea and then change it.”
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