Tag Archives: mollusk

Deep-sea mining could push many delicate species to extinction

There are hundreds of mollusk species living in the deep sea and about two-thirds of them could face extinction if the plans to mine the seabed continue as planned, a new study reports. The findings already triggered reactions, with 184 mollusk species living near hydrothermal vents added to the global list of threatened species.

Image credit: Flickr / Klaus Stiefel

The seabed is home not only to a wide array of living organisms but also to vast amounts of commercially valuable minerals such as copper, nickel, and manganese. These are found in specific structures such as polymetallic nodules lying on the seafloor. Of course, a lot of people want to get their hands on them.

Countries and companies are currently discussing mining these deep-sea environments and their resources, as demand for minerals grows and supply is becoming scarcer. From smartphones to electric vehicles, practically every tech device needs minerals for its manufacture, and some people are increasingly looking to the sea to find new sources of minerals.

But the problem is that deep-sea mining can be devastating to the environment.

Several studies have found deep-sea mining would have adverse and irreversible effects on biodiversity, but only a few conservation measures have been implemented to date. Still, mining hasn’t officially started yet, as countries have to agree on an international mining code – which falls under the International Seabed Authority.

A group of researchers from the UK, the US, Germany, and Canada wanted to further understand the impacts of deep-sea mining on hydrothermal vents. These occupy small areas (just 50 squared kilometers of the seafloor globally) but host a multitude of unique species due to their unique environment. Mollusks are the dominant group in vents, so likely the ones to be most affected.

“As important members of the vent community, they inhabit an array of niches including hosting endosymbiotic bacteria in specialized organs, forming dense aggregations that provide substrate for other species and exhibit unique ecological traits,” the researchers wrote in their paper, referring to the role of mollusks. 

Mining vs mollusks

The researchers assessed 184 vent-endemic mollusk species from around the world and listed over 60% of them as threatened (vulnerable, endangered, or critically endangered) by deep-sea mining. A further 45 species (24%) were listed as near threatened, with only 13% of all species of mollusks classified under a low level of risk. 

Among the nine biogeographical regions examined, vent-mollusks located in the Indian Ocean were considered to be under the greatest extinction risk – with all species there listed in threatened categories. This matches with the distribution of mining licenses across vent sites in the Central and Southwest Indian Ridges in the Indian Ocean. 

The researchers called for “real conservation measures” to be implemented to mitigate the effects of deep-sea mining to vent species. One approach is the implementation of marine protected areas (MPAs). In fact, the reason why some mollusk species were classified as low risk is that they are at locations with MPAs.

However, MPAs don’t necessarily guarantee the protection of biodiversity, as the outcome depends on how the protected area is managed. Simply put, classifying an area as ‘protected’ and actually ensuring it is protected are two different things, and enforcing this protection at sea can be challenging. Another possibility, the researchers said, is implementing a moratorium on deep-sea mining to allow further research into the biodiversity, resilience, and connectivity of vent communities.

Ultimately, it’s crucial that society has a real discussion about what deep-sea mining actually entails and ensure that it doesn’t just happen while the world is busy with something else. As it so often happens, this involves a balancing act between exploiting natural resources and protecting the natural environment, and we’d be wise not to merely forego the latter.

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

Mollusks are the most plastic-filled seafood in the world

New research found that marine mollusks such as mussels, oysters, and scallops, contain the highest levels of microplastic contamination of all seafood.

Image credits Pixabay.

The team, led by members from the Hull York Medical School and the University of Hull has analyzed over 50 studies on the topic of microplastic contamination in seafood. These were published between 2014 and 2020 and worked with species ranging from fish to shellfish all around the world.

Food with a little extras

“A critical step in understanding the full impact on human consumption [of plastics] is in first fully establishing what levels of microplastics [MPs] humans are ingesting,” says Evangelos Danopoulos, a postgraduate student at Hull York Medical School and co-author of the paper. “We can start to do this by looking at how much seafood and fish is eaten and measuring the number of MPs in these creatures.”

Microplastics are produced by the breakdown of larger plastic particles as they decompose slowly; some are produced outright, as additives for cleaning or beauty products. Eventually, they make their way into waterways and the ocean through wastewater. Once there, MPs often become ingested by wildlife that confuses it for bits of food. Microplastics resist digestion and build-up in the animals’ bodies.

Whenever we eat seafood, then, we’re also taking in the plastics they ingested over their lifetimes. MP contamination is not limited to seafood, but it is more pronounced here than in any other type of environment. The team found microplastic content ranged between 0-10.5 microplastics per gram (MPs/g) in mollusks, 0.1-8.6 MPs/g in crustaceans, 0-2.9 MPs/g in fish.

“Microplastics have been found in various parts of organisms such as the intestines and the liver,” says Danopoulos. “Seafood species like oysters, mussels, and scallops are consumed whole whereas in larger fish and mammals only parts are consumed. Therefore, understanding the microplastic contamination of specific body parts, and their consumption by humans, is key.”

“No-one yet fully understands the full impact of microplastics on the human body, but early evidence from other studies suggest they do cause harm.”

China, Australia, and Canada are the largest global consumers of mollusks, the team also found, followed by Japan, the US, Europe, and the UK. Those captured off the coasts of Asia tended to see the highest levels of contamination, suggesting these areas are the most heavily polluted with plastics and microplastics.

The findings showcase the sheer extent of the plastic pollution problem facing our planet. Production of such materials is expected to triple by 2060, meaning it will only get worse and worse in the future unless steps are taken soon. For that to happen, however, we need to get a clearer image of the problem, and the team explains that we need standardized methods of measuring microplastic contamination levels, and more on-the-ground data to see how different oceans and waterways are impacted by them.

The paper, “Microplastic contamination of seafood intended for human consumption: a systematic review and meta-analysis” has been published in the journal Environmental Health Perspectives.

Scientists finally place mysterious Cambrian fossils in the tree of life

This strange creature lived on the bottom of the ocean some 530 million years ago during the Cambrian explosion. They were among the first animals to develop external mineralized skeletons but until recently – we didn’t really know what they were.

This illustration shows the hyolith extending the tentacles of its feeding organ (lophophore) from between its shells. The paired spines, or ‘helens’, are rotated downwards to prop the animal up off the ocean floor. Credit: Artist: Danielle Dufault. Image credits: Royal Ontario Museum

They’re called hyoliths, and we previously thought they belonged to the same family as snails, squid, and many other molluscs. But Joseph Moysiuk of the University of Toronto found otherwise. After analyzing more than 1,500 specimens dug out of rocks in Canada and the US, he believes they are more related to brachiopods, a distinct group of which few members survive.

“Hyoliths are small cone-shaped sea dwelling animals. They are known from all around the world, mostly from fossils of their shells,” he told BBC News. “They appear in the fossil record about 530 million years ago and survived until about 250 million years ago. But the question of where hyoliths actually fit into the tree of life has been somewhat of a mystery for the last 175 years, since they were first described.”

Brachiopods somewhat resemble oysters, featuring hard “valves” (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve mollusks. They open their valve at the front when feeding but otherwise keep them closed to protect their inner organs. The structure of their body is what gave the hyoliths away, Moysiuk says.

“Our most important and surprising discovery is the hyolith feeding structure, which is a row of flexible tentacles extending away from the mouth, contained within the cavity between the lower conical shell and upper cap-like shell,” said Moysiuk. “Only one group of living animals — the brachiopods — has a comparable feeding structure enclosed by a pair of valves. This finding demonstrates that brachiopods, and not molluscs, are the closest surviving relatives of hyoliths.

“It suggests that these hyoliths fed on organic material suspended in water as living brachiopods do today, sweeping food into their mouths with their tentacles,” Moysiuk said.

The new fossils were found in Canada. Image credits: Royal Ontario Museum.

Brachiopods have inhabited the Earth for over 500 million years, although fewer species survive to this day. They are very well represented in the fossil record and in fact, hyoliths are too, although they became extinct some 250 million years ago. It’s not that there were no fossils available, it’s that these fossils didn’t preserve vital information about their soft tissues. Just the mineral shells were preserved. This breakthrough in this study was due to findings made in the renowned Burgess Shale, an exceptional fossil-bearing deposit exposed in the Canadian Rockies of British Columbia. Jean-Bernard Caron at the Royal Ontario Museum, who also participated in the study, explains:

“Burgess Shale fossils are exceptional because they show preservation of soft tissues which are not usually preserved in normal conditions,” said Caron, Moysiuk’s research supervisor, who is the senior curator of invertebrate palaeontology at the ROM and an associate professor in U of T’s Departments of Earth Sciences and Ecology & Evolutionary Biology.

Journal Reference: Joseph Moysiuk, Martin R. Smith, Jean-Bernard Caron. Hyoliths are Palaeozoic lophophorates. Nature, 2017; DOI: 10.1038/nature20804

Scientists find the smallest snail

As far as titles go, ‘smallest snail’ isn’t really the one you’d like, but that’e exactly what Acmella nana will have to settle for. The tiny mollusk measures only 0.033 inches (0.86 mm) on average.

A tiny snail from Borneo is the smallest ever found, smaller than a period on a printed page. Identifying the shells in the wild required a microscope, researchers say.
(Photo : Menno Schilthuizen, Naturalis Biodiversity Center

When the biologists set out to find small snails, they knew exactly where to go; the limestone hills of Borneo area ideal because the shells of snails are built from calcium carbonate, the main component of limestone. The collection process is actually pretty crude.

“When we go to a limestone hill, we just bring some strong plastic bags, and we collect a lot of soil and litter and dirt from underneath the limestone cliffs,” said co-researcher Menno Schilthuizen, a professor of evolution at Leiden University in the Netherlands.

They sieve the contents, throwing away the larger objects into a bucket of water.

“We stir it around a lot so that the sand and clay sinks to the bottom, but the shells— which contain a bubble of air — float,” Schilthuizen said.

They then scoop the floating shells and sort them by size, using a microscope; usually, there’s a lot of them.

“You can sometimes get thousands or tens of thousands of shells from a few liters of soil, including these very tiny ones,” he said.

Researchers hand’t observed the species in the wild, so they don’t know what they eat or their breeding habits. However, they likely do many of the things that other small snails do – foraging on thin films of bacteria and fungi that grow on wet limestone surfaces in caves.

Due to its favorable conditions, Borneo boasts a large mollusk diversity, with over 500 snail species, but they are all very vulnerable to external influences, especially human influences. For example, a species can be limited to one limestone massif, and this limestone is quarried intensely. Scientists have already documented at least one species destroyed because its entire habitat was mined.

In addition to Acmella nana, researchers discovered another 47 snail species.

The research is published in Zoo Keys.


Ocean Acidification Threatens to Destroy Shellfish Populations

Mollusks such as oysters, clams and scallops are highly vulnerable to the increasing acidification of the world’s oceans. A new study concluded that the acidification is so intense that the mollusks aren’t able to properly produce a hard shell, putting them in peril.

Image via Seattle Mag.

Water, Acid, and carbon emissions

Mollusks are the largest phyllum of invertebrate marine animas; 1 in 4 marine animals is a mollusk. Mollusks like oysters generate a calcium carbonate shell which surrounds and protects their bodies. Under normal conditions, they don’t dissolve – well, technically speaking they do, but slow enough so that oysters can continuously generate enough calcium carbonate. But here’s when you add carbon dioxide (CO2) to the water (H2O) and calcium carbonate(CaCO3), they simply aren’t able to form their hard shell. Here’s what happens from a chemical point of view:

The calcum starts to dissolve, and therefore the oysters’ shells start to dissolve. So When we’re spewing out greenhouse gases like carbon dioxide, we’re making our oceans more acidic, and this is destorying marine wildlife. In other words, ocean acidification makes it harder and harder for shellfish to form hard structures, making them vulnerable, especially in their larval stages.

Today, the world’s oceans are absorbing carbon dioxide at an unprecedented rate and the resulting acidification is reaching alarming levels – that’s the conclusion of a study published today in the peer-reviewed journal Nature Climate Change. The study analyzed the situation in shellfisheries across the US.

Image via Pangea Shellfisheries.

According to the study, previous models, which stated that acidification caused by carbon dioxide in the atmosphere will not affect the local oyster crop until 2100 are wrong – they haven’t taken into consideration river runoffs and algae blooms – and those are significant factors. It’s also not only carbon we have to worry about – other greenhouse gases can have significant negative effects too.

“Messages from global models to date are that the Gulf will experience changes later on, but with these other local factors enhancing it, things can be moving at a much shorter timeline than that,” said Sarah Cooley, the Ocean Conservancy acidification program’s science outreach manager and a co-author of the study.

This is the first nationwide vulnerability assessment, and aside for the environmental damage, the economic damage is also huge – millions of dollars and hundreds of jobs are lost every year due to ocean acidification.

“Ocean acidification has already cost the oyster industry in the Pacific Northwest nearly $110 million and jeopardized about 3,200 jobs,” said Julie Ekstrom, who was lead author on the study while with the Natural Resources Defense Council. She is now at the University of California at Davis.

Scientists reviewed data from multiple fields, and managed to identify which are the most vulnerable areas in the US:


  • The Pacific Northwest. Oregon and Washington coasts seem to be affected by a multitude of factors which favorize acidification, including including cold waters, upwelling currents that bring corrosive waters closer to the surface, corrosive rivers, and nutrient pollution from land runoff.
  • New England. The product ports of Maine and southern New Hampshire are the main drivers here; they feature poorly buffered rivers running into cold New England waters which are especially rich in carbon dioxide.
  • Mid-Atlantic. Nitrogen pollution (mostly from agriculture) is the main issue there.
  • Gulf of Mexico. The conditions in this area are not particularly difficult, but some communities in the area rely greatly on shellfish, and are highly vulnerable. Should this source of income disappear or be reduced, they would be left with very little alternatives.

The study shows just how vulnerable marine wildlife really is – and as we continue to emit more and more greenhouse gases, the oceans will become more and more acidic, and the problem may spiral out of control. This is a problem we have to deal with, and deal with fast.

“There’s not a lot of room for error,” said Mike Rice, professor of fisheries and aquaculture at the University of Rhode Island, who was not associated with the report.

However, no matter how much we improve our resilience and how many adaptation strategies we implement, the bottom line is the same – as long as we continue to emit greenhouse gases, the problem is only going to get worse. From an economic point of view, the situation is even more acute – 95 percent of the U.S. shellfish revenue comes from only 10 species, and we don’t know how those species will react to the new conditions.

“We need a fuller understanding of those species to understand the economic impact,” Ekstrom concluded.

You can read the full scientific article, for free, from the link below.

Journal Reference: Julia A. Ekstrom et al. Vulnerability and adaptation of US shellfisheries to ocean acidification.