(AP) — Floating fences in India. Whimsical water-and solar-driven conveyor belts with googly eyes in Baltimore. Rechargeable aquatic drones and a bubble barrier in The Netherlands.

These are some of the sophisticated and at times low-tech inventions being deployed to capture plastic trash in rivers and streams before it can pollute the world’s oceans.

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The devices are fledgling attempts to dent an estimated 8.8 million tons (8 metric tons) of plastic that gets into the ocean every year. Once there, it maims or kills marine plants and animals including whales, dolphins, and seabirds and accumulates in the Great Pacific Garbage Patch and other vast swirls of currents.

Trash-gobbling traps on rivers and other waterways won’t eliminate ocean plastic but can help reduce it, say officials with the National Oceanic and Atmospheric Administration’s Marine Debris Program.

“It’s just hard to get out to our big open oceans and collect the trash there. We’d much rather collect that trash closer to shore, which is easier, it’s less costly, and we can have that impact before it gets into the ocean,” director Nancy Walker said.

Trash is blown, washed, or thrown into waterways nearly everywhere. Storm drains funnel in litter tossed onto streets. In places without refuse collection, people use convenient waters to carry the trash away.

The science of plastic pollution is new and almost as much in flux as the waters it studies. For instance, a scientist who reported in 2017 that rivers might carry anywhere from 450,000 to 4.4 million tons (410,000 to 4 million metric tons) of plastic a year into the sea was part of a 2021 study that narrowed the range considerably, with an upper limit of nearly 3 million tons (2.7 million metric tons).

D.C. Sekhar of Bengaluru, India, designed a low-tech trap for rivers in his country after he left a career in commercial shipping.

Wanting something modular, inexpensive, easy to maintain and able to withstand monsoons, he designed stainless steel mesh fences that extend above and below aluminum floats 3.9 feet (1.2 meters) long.

Sekhar’s AlphaMERS Ltd. has installed big floating barriers across rivers in eight southern cities from Hyderabad to Tuticorin. Each is angled to guide trash to a riverbank where excavators pile it into dump trucks.

The system with the biggest fan base may be the anthropomorphized Trash Wheels at the mouths of four Baltimore watersheds.

The devices use ancient and modern technology to run rakes and a conveyor belt that moves floating trash into barge-mounted dumpsters. Usually, the current-carrying bottles and cigarette butts also turn a water wheel for power. When the current slows, a solar-powered water pump spins the wheel.

The WasteShark, a boxy 5-foot, 2-inch long (157 centimeters) aquatic drone, was developed about 35 miles (57 kilometers) away in Rotterdam. A drone’s hold can accommodate 42 gallons (160 liters) of trash, floating plants and algae, according to RanMarine Technology. They can operate for up to eight hours on a charge.

Forty-two have been sold worldwide to buyers in a dozen countries including the U.K, U.S., Nigeria and Singapore, chief operating officer Esther Lokhorst said in an email. Prices start at 23,500 euros (about $25,600) for manually controlled models, and more for programmable versions.

Osprey Initiative LLC, of Mobile, Alabama, works on an even smaller scale, setting up floating traps on creeks, canals and rivers in the U.S. Southeast and training local crews to empty the traps, then sort, analyze and dispose of trash.

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The company employs about eight to 10 people full-time, with about 30 part-time local workers at projects across nine states, said owner and founder Don Bates.