New species of bivalves discovered on mangroves in Brazil

On coasts and in estuaries around the world, mangroves are facing rising sea temperatures, plastic and oil pollution and destruction due to development.

The green tops of the tropical trees adorn the top of the water, while the intricate root system twists and turns beneath the surface, creating a protected haven for all kinds of aquatic creatures.

The submerged networks of mangroves act as nature’s water filters and have been the subject of more specific studies, as environmental factors threaten the trees’ survival.

But for a research team in Brazil, a closer look at mangroves led to another discovery: a new species.

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Along the northern Atlantic Ocean coast, researchers in the Ceará River estuary noticed small, white bivalves clinging to mangrove roots in the muddy sand, according to a study published May 14 in the journal Zoosystematics and Evolution.

According to the research, the shells are only a quarter inch long, have a glossy white finish and ridges that create ‘C’ shapes along the surface.

The shell itself, which protects the fleshy animal inside, has “thin” walls, which are considered particularly “fragile,” the researchers said.

Inside the shell, the bivalve’s body consists of a muscular system and a large “foot,” which protrudes from the shell to help the bivalve move, the study said.

The muscles are gray and light cream-colored, and the foot has a “blunt, swollen” shape that is about half the size of the shell, the researchers said.

The shape of its shell and its fragility, compared to other bivalves in the genus that burrow deep into muddy sediment, distinguish it as a new species, the study said.

The new species was named Cyrenoida simplexa, the latter referring to the Latin word for ‘ensnared’ in reference to their home on mangrove roots.

According to the National Oceanic and Atmospheric Administration, bivalves, like fish, have gills that filter the water for oxygen and food.

They also have an internal organ called the mantle that produces calcium carbonate that the animal then uses to build its own shell, allowing them to enlarge their shell as the animal grows inside, NOAA says.

Bivalve harvesting, an industry that NOAA estimates contributes $1 billion annually in the U.S. alone, is also under threat as the ecosystem they call home faces existential threats.

But they could serve a greater purpose.

Researchers have proposed introducing bivalves into polluted water because their “filters” are self-cleaning and can operate for more than 12 hours a day, according to a March 2021 press release from the University of Connecticut.

It is estimated that there are more than 15,000 species of bivalves, including clams, oysters, mussels, scallops and molluscs.

The new species is found in multiple locations along Brazil’s Atlantic coast and was first discovered outside the city of Fortaleza, on Brazil’s northeastern tip.