The Lagoons : Biologists Revere Rich Tidal Soup Berated by Many as Murky Swamp

It was a cool, blustery day on the shore of Carlsbad’s Agua Hedionda Lagoon, and biologist Jack Bradshaw was kneeling reverently in the mud beside a scruffy plant the color of rusting Brillo pads.

Sunglasses resting on the tip of his nose, Bradshaw plucked a sprig laden with cylindrical, orange and green nodules from the plant and solemnly declared: “This is Salicornia, better known as pickleweed, and it is the very precious foundation of the entire coastal food chain.�

Rising to move closer to the waves rolling quietly over the soggy shore, Bradshaw pointed into the salty water and continued.

“When the plants die, they fall into the lagoon and decompose with the help of fungi and bacteria. In this way they become the nucleus of a highly nutritious whole--a sort of ham sandwich. Then any of the invertebrates--maybe a clam, a worm, a snail--comes along and eats the package. Those creatures in turn provide food for birds and fish.�

Jack Bradshaw looks at a lagoon and sees beauty in its murky waters. For him, a lagoon is a resource brimming with life, a cradle for the planet’s oceans, a farm belt for the aquatic world.

To those unaware of their role, wetlands appear to be drab, useless wastelands--smelly, mucky swamps that breed mosquitoes and are badly in need of some sprucing up. The wetlands’ unspectacular, grayish-brown vegetation, muddy floor and stale, briny smell discourage closer investigation, thus concealing the biological wonders of the areas.

“The name, Agua Hedionda, means ‘stinking water,’ and that about says it all,� said Bradshaw, who teaches marine biology at the University of San Diego and has written a report on the natural resources of Agua Hedionda Lagoon. “Most people probably drive by here and say to themselves, ‘Why doesn’t somebody do something with that thing?’ �

Biologists say that perception, which lingers despite the popularization of the environmental movement, is unfortunate because it masks the organic marvels of the marsh. They say wetlands are a rare and valuable natural resource--highly productive ecosystems teeming with life.

Their rich tidal soup is not only brimming with the seeds of a complex food chain, but also acts as a nursery for many of the nation’s commercial and sport fisheries.

Hundreds of thousands of birds, including many migratory ducks and four federally listed endangered species, depend on the lagoons as resting, feeding and nesting spots. Mice, raccoons, rabbits and other small mammals frequent their shore.

“A lot of people overlook these areas because they don’t resemble the stereotypical blue lagoons of the South Pacific,� said Joan Jackson, a Carlsbad resident who heads the San Diego Sierra Club chapter’s conservation committee. “But the very health of our oceans, which determine the health of our planet, depends on these lagoons, and I think they’re fabulous.�

The lagoons’ leading value depends, to a large degree, on one’s perspective. Bird lovers, for example, treasure their role as sanctuaries for migratory birds along the Pacific Flyway--the major western route connecting the nesting grounds of Alaska and Canada with wintering grounds in California and points south.

“If you take a look at how little habitat is left north of San Diego, it quickly becomes clear why these remaining bits of wetlands in North County must be protected,� said Elizabeth Copper, a bird watcher and a biological consultant who is an expert on least terns. “Many of these birds have a very tenuous hold and their population is very small. Eventually, by reducing habitat, we’ll deplete their numbers to a level they just can’t tolerate, and they’ll vanish.�

All six North County lagoons have been known to host the elegant and endangered California least tern. The secretive light-footed clapper rail, an endangered bird that feeds in the mud flats and hides in the adjoining salt marsh, can still be spotted at San Elijo, Agua Hedionda and occasionally at Los Penasquitos Lagoon, Copper said.

San Elijo and Batiquitos lagoons host the greatest diversity of bird species, Copper said. Batiquitos is popular among shore birds favoring a shallow-water and mud flat environment, while San Elijo--where as many as 100 species can be spotted on an average day--features marsh vegetation attractive to herons, white-faced ibis and two endangered birds, the California brown pelican and the Belding’s savannah sparrow.

Buena Vista, once a birder’s paradise, lost many species when it was dredged in 1981, Copper said, and the infrequent tidal action at Los Penasquitos has gradually thinned that lagoon’s mix of species. Birders are hopeful a restoration project that reintroduced tidal flow to San Dieguito--for years little more than a stagnant pond--will encourage least terns and other birds to return.

Unfortunately, birders say, many of North County’s lagoons are also home to domestic ducks. These ducks, Easter pets dumped by their owners when they get too large, crowd the lagoon, compete with threatened species for food and can spread disease.

Last summer, an outbreak of botulism killed hundreds of ducks and shore birds at San Elijo Lagoon, one of many episodes that have created biologists’ fears that migratory birds will contract a disease and carry it to other wetlands.

While birds are the most conspicuous of the lagoons’ inhabitants and tend to inspire the most ardent support, coastal wetlands also are spawning grounds for many species of fish.

Some species, including the commercially popular Pacific herring, seasonally migrate from the open ocean into estuaries and marshes to feed and to lay their eggs on submerged rocks or among algae covering the tidal mud flats.

Halibut, bass, anchovy and diamond turbot have different habits. These species lay their eggs offshore, and young fish travel with the tide into nutrient-rich lagoons to feed and mature.

Further, “these wetlands are ideal and heavily used as quiet, safe places where fish can elude predators,� said Eric Metz, of the National Audobon Society, former wetlands coordinator for the Coastal Commission. “Many lagoons provide beds of eelgrass--an important hiding place--and are often inaccessible to bigger fish that can’t make it up the narrow tidal channels.�

In North County, Agua Hedionda Lagoon and San Dieguito Lagoon are most useful to fish because their mouths are kept open to the sea.

Finally, there are those--Bradshaw among them--who believe the swirl of sea creatures invisible to the eye are the lagoons’ most intriguing feature.

“As a marine biologist, I’m most fascinated by the tiny single-cell organisms,� Bradshaw said. “Take the diatoms, for instance. There are thousands of them in a cubic inch of water! They’re so cute. They look like miniature kayaks under a microscope.�

A foot resting on a mattress dumped atop a bed of the pickleweed that laces Aqua Hedionda’s shore, Bradshaw reflected on why some people overlook the ecological significance of lagoons--and the price lagoons pay for that oversight.

If local residents were encouraged to investigate the wetlands and learn about their biology and inhabitants through interpretive centers and nature walks, the lagoons would undoubtedly gain new allies badly needed in the fight to preserve them, Bradshaw said.

“My feeling is that if you encourage human access to the resource, maybe put in a bike path or hiking trail, more people will realize what’s in a lagoon and will appreciate it,� he said. “Unless people are encouraged to enjoy lagoons and learn about them, they’ll continue to see them as junkyards.�