Study Estimates Sharks And Manta Rays Consuming Up To 137 Plastic Pieces Per Hour
According to a new study published on Tuesday in Frontiers in Marine Science, manta rays and whale sharks in Indonesia are consuming between 63 and 137 pieces of plastic pollution per hour.
A team of scientists from Marine Megafauna Foundation and Murdoch University, determined this number by collecting and counting plastic waste fragments in the water around reefs across Indonesia, where whale sharks and mantas are known to feed. Then they took their samples back to the lab to find out how much plastic pollution was in these feeding areas.
Marine biologist Elitza Germanov, who led the study, says that they used a fine-meshed plankton net to collect the plastic waste from the feeding areas.
“We separate the plankton and other natural material from the plastic using gravity and sea water. Basically, plankton sinks and plastic floats,” Germanov told Earther.
The team also examined fecal and vomit samples from both species, and found a large number of plastic pieces in every sample, confirming the estimations that were made from the waste collected from the feeding zones.
“We enlisted the help of the local SCUBA diving communities who visit the manta ray aggregation sites regularly and asked them to carry ‘poo tubes’ in their [dive gear] pockets while diving just in case they saw the manta rays egest poo or vomit. There are already several examples of plastic being found in the digestive tracts of stranded and deceased whale sharks in Brazil, Thailand, Philippines and Malaysia,” Germanov explained.
Germanov fears that plastic pollution could threaten the existence of many different species in the ocean, because it can interfere with their mating and reproduction, possibly leading to a reduction in birth rates for species with population numbers that are already dangerously low. Many plastics contain an additive called Phthalates to make the material more flexible, but this additive causes massive disruptions to the endocrine system, which can cause reproductive problems.
“In other organisms, including fish, we know that exposure to some of the plastic associated pollutants can disrupt the regular functioning of the endocrine system, the system responsible for controlling growth and reproduction. As threatened species, neither manta rays nor whale sharks can afford to have any dips in reproductive rates,” Germanov said.
Luckily, the researchers also learned some interesting information that gives insight into how this problem can be managed. The data from the study showed that most of the plastic waste were fragments from single-use shopping bags and food wrappers. They also learned that plastic waste increase by more than 40-fold during the rainy season, when plastic from streets and riverbeds are washed out to sea.
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Earlier this year, Truth Theory reported on a disturbing study which found that we are absorbing tens of thousands of plastic particles each year, just in the food we eat and the air that we breathe. It was also noted in the study, that drinking a lot of bottled water can nearly double the presence of toxins in our bodies.
IMAGE CREDIT: sergemi