Tag Archives: clams

Ate any clams recently? You’ve might have also had a side of microplastics

Whether we realize it or not, microplastics are creeping into every place and organism in the world. These very small pieces of plastic are all over the place, with scientists finding them even in the most remote regions of the world. The most recent example are razor clams in the sparsely populated coast of Washington.

Image credit: Flickr / ConwaySuz

Millions of tons of plastic enter marine ecosystems every year, and quantities are expected to increase in the coming years. Over time, plastic items in the ocean can break down into smaller pieces, known as microplastics. These can be the size of a rice grain or even smaller, making it easy to be ingested by all sorts of sea creature — including one that doesn’t move.

Researchers from Portland State University in the US looked at the concentration of microplastic in razor clams collected from eight beaches in the Olympic National Park in Washington, after surveying clam harvesters. Then, they estimated the annual microplastic exposure of those eating them.

Plastic is everywhere

The razor clam (Siliqua patula) is found on Pacific beaches, on the western coast of North America, from Alaska to southern California. In the State of Washington, razor clams rely on the rich coastal waters to settle and grow, and they’re fortunate enough to not be around too many settlements. They are co-managed by the Department of Fish and Wildlife and by tribal governments living in the area.

The species attracts thousands of visitors to the Olympic Coast’s shores annually, as they try their luck at clamming during one or more recreational fishery openers. The recreational fishery injects what are usually sleepy coastal towns with visitors, filling hotels and restaurants and bringing millions of dollars to the economy.

During the study, the researchers found 799 suspected microplastics in 138 clam samples, 99% of which were microfibers. Each clam had seven pieces of plastic each on average. Those obtained from the Kalaloch Beach, the northernmost site, had significantly more microplastics than clams from the other seven sites.

The researchers didn’t investigate the reasons behind one location having more microplastics than the others, but Britta Baechler, the study’s lead author, said there are no significant differences in land cover types between Kalaloch and the other sites. However, Kalaloch is the closest in the proximity of all sites to the Seattle metropolitan area.

Baechler and her team compared whole clams (minimally processed as if being consumed by an animal predator) and cleaned clams, gutted, cleaned of sand debris and grit, prepared as if being eaten by a person. They found that in cleaned clams the number of microplastics was reduced by half, but was still present.

This is some consolation for people, as 88% of the 107 respondents to the survey done by the researchers said they clean clams before eating them. But it’s bad news for ocean predators, who eat the clams without cleaning them — and subsequently, for people who would eat these predators. This creates a chain of microplastics from the clams to other marine organisms.

The survey allowed the researchers to estimate the average amount of clams eaten per meal and the number of meals with clams eaten every year. They combined this data with the average number of microplastics per clam and estimated the number of microplastics that clam consumers were exposed to per year.

Those that clean their claims before eating them consume between 60 and 3,070 microplastics per year, while those who eat them whole without removing the guts, gills, and other organs consume between 120 and 6,020 microplastics a year. Still, the impact of this on human health isn’t clear yet.

“Our estimates of microplastic exposure from this single seafood item are, for context, far lower than what we likely take in from inhalation, drinking bottled water and other sources, but no amount of plastic in our marine species or seafood items is desirable,” Bachler, a member of Ocean Conservancy, said in a statement.

The presence of microplastics in Washington’s coastal environment and in the food webs raises concern about the potential for ecological harm to Pacific razor clams, their predators, and innumerable other marine species, the researchers said. They urged to address the transmission of microplastics to the marine environment.

Still, this is an enormous task. A study from earlier this year the world’s seafloor is filled with 14 million tons of microplastics, broken down from the masses of rubbish entering the oceans every year. This was 25 times greater than previous estimations from localized studies around the world.

The study was published in the journal Frontiers in Marine Science.

Neanderthals dived underwater for shells to use as tools

The image of Neanderthals has changed quite a lot in the past few decades thanks to new discoveries. We now know that they may have decorated their bodies, buried their dead and created art. Now, we can add another skill to the list, diving under the ocean for shells that they fashioned into tools, according to a new study.

Credit Wikipedia Commons

A group of researchers analyzed clamshells and volcanic rocks from an Italian cave, which showed Neanderthals collected shells and pumice from beaches. Due to specific indicators on some of the shells, the researchers also believe Neanderthals waded and dove into the ocean to retrieve shells, meaning they may have been able to swim.

Only about ten feet above the beach in central Italy’s Latium region, the Grotta dei Moscerini cave was excavated in 1949. Archaeologists recovered 171 clamshells that were modified into sharp tools. They all belonged to a local species called Callista chione, or the smooth clam.

University of Colorado researcher Paolo Villa and colleagues looked at such tools, which had been stored at the Italian Institute of Human Paleontology because the cave itself is no longer accessible. They concluded some must have been gathered from the seafloor by Neanderthals.

“The fact they were exploiting marine resources was something that was known,” said Paola Villa to CNN, study author and curator of the University of Colorado at Boulder’s Museum of Natural History. “But until recently, no one really paid much attention to it.”

Most of the shell tools had abraded surfaces. But nearly a quarter of them had shiny, smooth exteriors, typical of shells picked live from the seafloor. In their study, Villa and her colleagues argued that diving for clams may have been a routine part of Neanderthal life in this region.

The shells were modified to be used as scrapers. These were more efficient than thin flinty rocks, which can’t sustain a sharp edge. It’s possible that stone was hard to come by, which is why they sought out shells. Or perhaps the shells suited their needs better, the researchers said.

The findings align with evidence from a recent study by Prof Erik Trinkaus suggesting that some Neanderthals suffered from “surfer’s ear,” based on bony growths found on the ears belonging to a few Neanderthal skeletons. And previous research has pointed to the fact that Neanderthals engaged in fishing.

The new study “reinforces what is becoming increasingly evident from a variety of different sources of archaeological data: Neanderthals were able to do, and occasionally did, most of these kinds of behaviors that had been considered to be special to modern humans,” said Trinkaus to the Smithsonian Magazine.

Key facts on Neanderthals

Neanderthals are considered the closest extinct human relative. Among the features of their skulls, they had a large middle part of the face, angled cheekbones, and a huge nose for humidifying and warming cold air. They also had shorter and stockier bodies as an adaptation to living in cold environments.

They made and use a diverse set of sophisticated tools, controlled fire, lived in shelters, made and wore clothing, were skilled hunters of large animals and also ate plant foods, and occasionally made symbolic or ornamental objects. Evidence has been found of them burring the dead and marking graves with offering as flowers.