NEWPORT BEACH, California - With a navy pink- and- blue-flowered baseball cap pulled over her forehead, purple boots and a plastic grabbing tool in hand, 4-year-old Amelia Jones set off down the marsh's dirt road.

Her parents, Erin and Chris, both biologists, and her uncle, Andrew Hardison, were not far behind.

As Amelia scoured the ground for trash, Erin, who works for the U.S. Army Corps of Engineers Los Angeles District, pointed to a plastic water bottle hidden in the brush. Amelia seemed pleased with her find, as she picked up the bottle with her grabber and dropped it into her lime-green bucket.

"When we told her we were going to help clean up trash today to protect animals, she was so excited about it," Erin said. "She loves animals."

The family was among more than 25 volunteers who traveled to the Santa Ana River Marsh Sept. 15 to participate in California's Coastal Cleanup Day. This was the second year of cleanup efforts at the 92-acre marsh.

In its 34th year, California Coastal Cleanup Day is one of the state's largest annual volunteer events, organized by the California Coastal Commission. It is part of the International Coastal Cleanup, organized by the Ocean Conservancy.

This year, more than more than 53,000 volunteers picked up about 367 tons of trash and recyclable materials across the state, according to the California Coastal Cleanup Commission's website.

One of the biggest contributors to ocean pollution: single-use disposable plastics, like straws, cups, spoons, take-out containers and water bottles.

"Trash tends to blend with its surroundings for a number of reasons - the sun bleaches its color, dust covers it over time, gravity sinks it or humans push it deeper into its surroundings," said Hoiyin Ip, Sierra Club Angeles Chapter Zero Waste Subcommittee chair. "As it gets less visible, its harm to the environment increases. Plastic breaks into microplastic and becomes basically impossible to pick up. Wind blows it into the water, the fish eat it, and then, we eat the fish. The chemicals in plastic have a definite impact to our health."

More than 90 bird species winter in and around the Santa Ana River Marsh, and several endangered species, like the Belding's savannah sparrow, California least tern and the light-footed Ridgeway's rail, forage and live in the marsh. Vegetation, like cordgrass and pickleweed, provide important habitat for the birds nesting and foraging there.

"Trash impacts the water quality, tends to get caught up on the water's edge and accumulates in the grass," Erin said. "It eliminates some of the nesting opportunities, if the birds can't find a decent site to nest."

A portion of the marsh includes an island the Corps built to allow California least terns to nest.

"You have to keep the vegetation clear on the island for the most part," Erin said. "If it's not kept clear, it's difficult to attract the California least terns to come and nest."

Last year, volunteers cleaned up more than 3,000 pounds of trash out of the marsh, she said. This year, the group's efforts concentrated on picking up more of the microplastics.

"The thing with plastics is when they sit out in the sun for months or years, the plastic degrades, cracks and breaks up into tiny pieces," Erin said. "That's when you have microplastics that get into waterways and are ingested by wildlife. Microplastics are difficult to remove because it's easier to find large pieces of trash, but the tiny pieces of plastic, it's a lot harder to pick those up. So once they're in the environment, they're really difficult to get out."

Ed Andrews, a retired Corps' employee and one of the original senior project managers of the lower Santa Ana River, traveled with his wife from Pacific Palisades to help with the cleanup.

At the time he was the project manager - from 1990 to 2000 - it was a $1.4-billion project.

"This was all degraded salt marsh and abandoned oil pits," he said. "We cleaned it up, re-graded it, built the (California least) tern island, put a fence around it and put in flood-control gates. It was $500 million just for the channelization. The channel is 23 miles. It provides flood-control benefits to millions of people. It was a real career opportunity for me."

Andrews said he was hoping to see the light-footed Ridgeway's rail while helping to clean the marsh.

Many of the volunteers participating in the event live nearby and recreate in the area.

One of those families is Gary and Olga Reynolds, and their daughter, Arlis, who serves as vice chair of the Costa Mesa Parks and Recreation Commission.

Arlis said she developed a love of nature and the outdoors from her parents, who met while studying plant chemistry at the University of California-Irvine.

"Growing up, they were both public school teachers," Arlis said. "For a while, my mom stayed home and my dad was a (doctorate degree) student, so we didn't have a lot. We weren't going to Disneyland or Sea World; we were going to parks, spending our time outdoors. We didn't have a TV at home, so being with nature is how we were raised. I think we are realizing these kinds of spaces are becoming more and more precious."

The family enjoys participating in events like this, Arlis said, because it's a way to meet like-minded people, like Jill Prunella, who was at the event with her son, Kody Wells.

The Reynolds and Prunella are part of a group that meets monthly at Fairview Park in Costa Mesa to educate children and community members about environmental stewardship.

"They have literally spent their entire lifetime dedicated to the community and to the environment," Prunella said about the Reynolds' family. "I've never seen them not giving of themselves, every day. They're my heroes."

The Santa Ana River Marsh Cleanup Day was organized by the Sierra Club and Orange County Earth Stewards, and hosted by the U.S. Army Corps of Engineers Los Angeles District. Some of the other organizations and participants included volunteers from Drains to Ocean, Orange County Coastkeeper, Fairview Park Alliance, Newport Bay Conservancy and the Sea & Sage Audubon Society.

Oftentimes, Erin said, organizations that focus on natural resources may view the Corps as not having the same mission, which is not necessarily true. She's hoping by participating in community events like this that view may change.

"The most exciting part of my job is participating in events like this, where I feel like I am really making a difference," Erin said. "I work on a lot of restoration projects - planting, weeding and trying to restore native habitat. When I get an opportunity to work with the community, it's a bonus."