Disappearing coastal mud flats are ‘the habitat of the overlooked’

When it comes to nature’s ugly ducklings, coastal mud flats are probably near the top of the list.

The land is marshy, the vegetation scrubby and the brackish water isn’t anything people would care to take a dip in. The mud flats are replete with decaying materials and carry a distinctive smell.

“I’ll be honest about it. They stink,” said Ed Mastro, exhibit curator at the Cabrillo Marine Museum in San Pedro.

But, though they’re not pretty, mud flats are a vital part of the coastal life system, Mastro said. And that is the point that a new permanent exhibit at the museum tries to make.

As visitors learn, mud flats are cradles of life for more than 50 species of fish, including fingerlings of the common halibut and turbot, which live there for the first three years of their lives.

Also called wetlands or estuaries, mud flats provide a feeding ground for 100 species of birds, including migratory birds that winter there and permanent residents such as gulls, sandpipers, terns, plovers and others.

Flying birds leave no doubt that mud flats support life, but many other creatures that call them home--the burrowing clams, worms, snails, sea slugs, crabs and shrimp--are all but invisible.

“It’s the habitat of the overlooked,” said Mastro, standing in the midst of the exhibit, which tells the story of mud flats through examples of the birds and other animals that live there. Various displays show the spawning and food systems of fish and birds, and one explains how burrowing creatures exist beneath the surface.

Mastro confesses that some of the critters aren’t exactly beautiful, noting that one sea slug in the exhibit is downright disgusting in the way it digests entire snails for nourishment.

A highlight of the exhibit is “Mud Flat Metropolis,” a revamped aquarium that simulates the shore and watery areas of a mud flat, complete with old bottles and tennis shoes like those that people toss into the water. Fish swim amid strands of eel grass, foraging for food.

Mastro said that for many people, the exhibit is an introduction to the richness and complexity of mud flats: “Most people think there’s nothing there.”

Dennis Lamantia, a visitor from Sacramento, was one who discovered something new about his world. “I never realized how many living things there are down there, how many things are alive,” he said. “It makes you afraid to take a step.”

Mud flats occur at points where rivers carrying sediment flow into oceans, creating a marsh sheltered from the waves. They once dotted the coastline of Los Angeles and Orange counties, but according to the museum, mud flats have been reduced since 1900 to one-fifth of their original area, through various kinds of development.

“They’re the kinds of places people like to cover over with boat slips and parking lots,” Mastro said.

The largest remaining nearby mud flats, he said, are 750 acres in Upper Newport Bay and 900 acres within the Naval Weapons Station in Seal Beach.

Wilmington once had a 3,500-acre estuary, Mastro said, but it was destroyed to develop Los Angeles Harbor. A 3.5-acre example of what once existed has been restored near the museum, but it has not yet been opened to the public.

The museum will present a special program built around the mud flats exhibit on Feb. 10 from 8 a.m. to 2 p.m. A talk at the museum will be followed by a field trip to the Newport mud flat. The cost is $12.

Mastro said the decades-long destruction of mud flats has played havoc with creatures that depend on them. The light-footed clapper rail, Belding’s savannah sparrow and the California least tern are all on the federal endangered species list because of this destruction. But he said the ecology movement has prompted people to support preservation and enhancement of the habitats that remain.

“Hopefully, we have a role in that,” Mastro said. “Our goal is to show that there’s a lot of stuff living in mud flats.”