Texas Parks & Wildlife Magazine   


The Salty Lagoon

By Claudia Kolker

Its isolation, shallowness and wind-whipped tides have spared Laguna Madre many of the problems of urban development.

The gulls sound like they’re laughing at me. It’s a hushed, drizzly morning on Upper Laguna Madre. The fishermen have stayed at home, and even windsurfers are scarce. So out here by the water, it’s just me, biologist Kyle Spiller and the flock of gulls. In my neon yellow waders, I’m an obvious outsider in this landscape of pale grass and flint-colored clouds. The laughing gulls, meanwhile, are in their element. Flapping wings in the damp wind, they peck each other, groom and bark with that unnerving laugh. There’s no question why a gull might like Laguna Madre. What I want to know is why so many humans — duck hunters, fishermen, conservationists and scientists — love this slim saltwater bay as well.

Five years ago, the Nature Conservancy of Texas named Laguna Madre one of its half-dozen top priorities for conservation. Fishermen and hunters stream to the laguna’s shores from other states; biologists make pilgrimages to its salt waters from different continents. But when I first stand on these austere flats of grass and scrub, with few creatures visible except the gulls, I wonder what it is so many people see.

I do have some guidance from John “Wes” Tunnell, director of the Center for Coastal Studies at the Corpus Christi branch of Texas A&M University. Laguna Madre, he has told me, is one of only half a dozen lagoons in the world whose water is hypersaline — saltier than seawater. Like a desert, this landscape might appear incompatible with life. In fact, Tunnell tells me, it nourishes some of the most vigorous species anywhere.

Christopher Onuf, a seagrass expert with the U.S. Geological Survey, has given me another hint. Get into the water, he advises. If you want to see why Laguna Madre is unique, Onuf tells me, you need to look at it up close.

When the U.S. Army Corps of Engineers toiled on the laguna during World War II, up close was not a top priority. Instead, they looked straight down. Peering from helicopters, they saw two elongated bays stretched along the Texas Coast. Both lacked major inflows from rivers or the Gulf.

Budding near the JFK Causeway in Corpus Christi and reaching 227 miles south into La Pesca, Mexico, Laguna Madre of Texas and Laguna Madre of Tamaulipas are mirror images, wedged between the mainland and a rim of barrier islands. In its Texas incarnation, the system is divided into Upper and Lower Laguna Madre. Below, in Mexico, the system splits into the Northern Laguna and Southern Laguna. The whole eel-shaped complex belongs to one water system that for centuries routinely has been saltier than the ocean.

It is also extremely shallow, 4 feet deep or less in most spots. Midway between Corpus Christi and Brownsville, the water simply fades into tidal flats that often are dry enough to tramp across on foot. This geography, to the chagrin of Corpus Christi oil refiners, made commercial shipping through Laguna Madre out of the question.

So in the 1940s, at the urging of the refiners wanting to transport gasoline to Brownsville, the corps started an extension of the Gulf Intracoastal Waterway (GIWW), which had stopped at the laguna’s northern end. By 1949 the corps had dredged a canal 12 feet deep and 125 feet wide straight down the lagoon. The channel carved through the land bridge that divides the Upper and Lower Laguna; today this channel is known as the Land Cut. In 1954 the corps dredged another channel across Lower Laguna and through the barrier island at Mansfield Pass.

While the digging improved commercial transport in the region, it also refashioned the laguna’s ecosystem. Before the dredging, salinity levels routinely hit two or three times those found in the oceans. Vast fish kills would cyclically signal that salt had reached a concentration that was unlivable for many organisms. Then, also cyclically, hurricanes would storm in from the Gulf and flush the system with fresher water.

The GIWW and other channel-building projects stabilized that boom-and-bust fish population and freshened the laguna’s water overall. Nevertheless, it’s still a hypersaline environment, so challenging that only a handful of fish and plant species can live there.

And therein lies Laguna Madre’s paradox — the one that makes it so compelling to biologists. Rather than compete with other plants and animals, the creatures here compete only with their habitat. Those that are successful — whether they are shoalgrasses, red-headed ducks or spotted seatrout — thrive in an unlikely, almost Edenic abundance.

But Christopher Onuf, the seagrass specialist, was right. It’s only when I start looking closely that I really begin to understand the life here.

The Upper Laguna’s most famous feature makes its appearance in spring. When the air grows calm and bright, the waters sparkle with sublime transparency. Shallowness is the secret for gin-clear water. Fill a vast, shallow basin with water undisturbed by inflows from rivers or the sea, and you get Laguna Madre — a bay whose sandy, grass-swept bottom is visible as far as you can see. For sight fishermen, it rates among the classic fishing destinations in North America.

“It’s not like shallow-water redfish drives [elsewhere] when anglers in tunnel hulls churn up mud and sea grass while rounding up fish against a shoreline,” writes David Sikes, outdoors columnist for the Corpus Christi Caller-Times. “In the clear green water, schooling reds appear as an orange or pinkish haze.” On a recent trip, Sikes writes, “I scurried to the bow and cast… into about 200 reds, mostly bulls over 30 inches… I could see fleeing redfish, shoulder to shoulder, under and around the boat.”

But when it’s windy, or when it rains, the Upper Laguna’s waters grow obscure. Its paradoxes, though, grow more apparent. That’s how it is this morning, as Kyle Spiller and I set out in a Texas Parks and Wildlife Department boat. Lined by agrassy shore, the water is a flat, slow-breathing field of gray. There is almost no moon-driven tide here, Spiller tells me. Instead, it’s wind that sweeps the water to and from the shorelines. “It’s not uncommon,” he says, pointing to a cozy-looking curve of beach, “for a duck hunter to anchor his boat in a little tertiary bay and have the water blown out from under him. If you’re not careful which way the wind is blowing, it can leave you high and dry.”

I mull this as our flat-bottomed boat proceeds, once bogging down in waters only a few inches deep. I’ve always thought of tides — the kind pulled by gravity — as the life force of a bay. In Laguna Madre, though, it’s wind-driven tides that catalyze astounding bursts of life.

Laguna Madre houses North America’s biggest expanse of wind-tidal flats — parched, barren-looking sand patches that are engulfed periodically by wind-pushed water. When this flooding occurs, these apparent scraps of desert leap to life so fiercely you see it happen. Within hours of being inundated, the bleached-bone flat begins to bubble like a stew. Microalgae — invisible during months of dryness — synthesize wildly, transforming the packed sand into a lush, blue-green vegetative mat. Sometimes, bubbles lift the whole top off a flat, setting it adrift as if it were a fuzzy ice floe.

The new habitat lures hordes of birds, hungry not for algae, but for the bugs and baby fish now coursing through it. Depending on the water’s depth, the tidal flat pulses with piping plovers, dunlin, sandpipers, roseate spoonbills and egrets.

Today, since it’s been raining on and off for weeks, the tidal flats sit underwater. As we whoosh over the dark surface, we see water birds resting in more permanent haunts: humps of sand in the middle of the lagoon, often marked with signs warning boaters to leave the birds alone.

At first a big grass-colored blur, the shoreline slowly separates into individuated plants. Their variety now stuns me: millions of brushstrokes in cinnamon, taupe, tan, wheat, flax and ash. And though there are few trees onshore, there are no people, either. The only creatures in the grass are white pelicans, huddled against the chill.

It would be difficult indeed to see so little on another stretch of U.S. bay. As a whole, Laguna Madre is the least-developed bay in the country. In addition to its physical remoteness from urban centers, about 70 percent of Laguna Madre in Texas is protected by the federal government in the form of nature preserves; by private groups such as the Nature Conservancy; and by a handful of historic ranches, including the Armstrong Ranch, Kenedy Ranch, King Ranch and Yturria Ranch.

Harsh-looking at first, Laguna Madre’s empty shoreline ends up entrancing visitors, says local fishing guide Walt Kittelberger.

“To a lot of people the appeal of the laguna is its remoteness,” Kittelberger says. “There is a certain value in just not seeing the reflective glass of a condominium as the background of your fishing experience.”

The great ranches that border Laguna Madre have acted as barriers to such development. At the same time, outfits such as the King Ranch have also kept their shorelines pristine and wild. As we approach the shore, it gains definition, with mesquite trees crenellating its top edge. Even closer, one section of the horizon seems to shatter. It’s a flock of redheads, rising like a cinder cloud over the beach.

Of all creatures in the laguna, the redhead reflects the amazing vitality that a hypersaline habitat can breed. About 80 percent of all redheads in North America spend their winters on these shores. In the winter of 1997-1998, federal surveys counted 2.4 million of them in the region. Despite the lack of fresh water, the ducks flourish because they eat the rhizomes of a single plant: shoalgrass. And shoalgrass coats three-fourths of the floor of Upper Laguna Madre.

These meadows are an underwater reflection of the abundance overhead. More than 80 percent of all the seagrass meadows in Texas wave underneath the laguna’s surface. On a clear day, you can see the thick, jade-colored fronds stretching like a great lawn across the lagoon. The grass looks scratchy, indestructible. In fact, it’s fragile — vulnerable to at least two threats distinctive to the very habitat that also makes it so abundant.

One of these is propeller scarring — wear and tear from boats just like the one we’re riding in today. It’s ironic, Spiller tells me. For decades, Laguna Madre was remote enough that relatively few people boated or fished on it, and so shallow that many parts of it were unnavigable. In recent years, though, more and more Americans have been drawn to live nearcoasts; shallow-water hulls and stronger engines have enabled them to travel to once-pristine parts of the bay. When boats run aground, as inevitably happens in the shallowest parts, their propellers dig apart the seagrass beds below.

Dredging of the GIWW creates another set of problems. A half-century after its creation, the GIWW is more than a commercial structure. It shapes its very environment, freshening the Upper Laguna’s water through the land cut and staving off the fish kills that occurred regularly when the salinity was more intense. But the maintenance of the canal is continuing to affect the ecosystem, Onuf says.

Mainly for economic reasons, the U.S. Army Corps of Engineers dumps the superfine sand and clay called dredge spoil onto islands or designated spots in the laguna every year. Dredge spoil isn’t toxic, but it tends to hang suspended in laguna waters. When the water gets too murky, light can’t get in to the underwater meadows. The grasses die, the laguna floor becomes less stable -— and more and more particles churn up to make the water darker.

And if the shoalgrass meadows smother, or simply are replaced by other grasses? It’s starting to happen already. For reasons that are not completely clear, some of the shoalgrass in Lower Laguna Madre has been replaced with manatee grass, a sturdier species but one that offers fewer nutrients to sea creatures. Slowly, shoalgrass in some patches of the Upper Laguna Madre is ceding way to other grasses, too.

In response to a 1994 environmental lawsuit, state and federal agencies have prepared a long-term management plan for the disposal of dredge spoil. Their draft, released this winter, recommended against the current practice of dumping in the open bay. But it also noted that the corps doesn’t have the money to perform the best practice: dumping the spoil offshore in the Gulf.

Onuf, who is one of the world’s authorities on seagrass, points out that dredging is not the only culprit behind murkier waters. From 1990 through 1997, Laguna Madre was invaded by brown tide, an algal bloom that darkened the water and killed whole seagrass meadows. No one is really sure what triggered the brown tide, but agricultural and oil industry runoff may have played a role.

So far, though, shoalgrass still dominates the Upper Laguna. Despite gradual arrival of new seagrass species, the shoalgrass-loving redhead population is extravagantly healthy. Red drum, black drum and spotted seatrout also abound, to the joy of visiting sight fishermen and their paid guides. In the past 10 years, in fact, the number of fishing guides in the laguna has more than doubled, Kittelberger says.

As we veer away from the King Ranch, I see another cloud of cinders, and now recognize them as redheads. I ask Spiller to stop the boat near a point where the laguna is only a few inches deep, and I get out to look. Clumsy in my yellow waders, I peer into the pure water. In a few more weeks, the whole laguna will be this clear.

I stand there in the water, watching the grass fronds arc around my boots. Nothing, I think, could look less natural than my two neon feet in this transparent water. And yet — probably no other wild place is more thoroughly enmeshed with human handiwork than Laguna Madre. Sixty years ago, people resculpted and remixed this bay into what it is today. In the years after, commercial, private and governmental interests combined to keep it among the most pristine coastal environment in the country.

So questions of intervention, evolution and conservancy all have special shadings here. What parts of this harsh, grassy place should be preserved — and why? Take the laguna’s transparent water, for example: It’s good for shoalgrass, which is good for ducks and, not unimportantly, duck hunters. It’s also simply good for human souls to look at.

But what about other links in this humanly influenced wilderness? What do people owe Laguna Madre? What does it owe to us? I don’t know the answer, and most scientists and managers I meet don’t purport to either. The one thing I’m convinced of is that, like a feral creature fed by humans, the laguna must be nurtured on its own terms, not those of something tamed and owned.

“So many people,” fishing guide Kittelberger says, “look at our system through the narrow perspective of one species or another. If you’re a trout fisherman, you might say dredging must be OK because we’re catching a lot of trout. But it’s not really good management to ignore any species. The first rule in environmental management is to keep all the components intact until you understand their role.”

Spiller steers us toward the shore. As we approach, the gulls, still gathered by the water, burst out with their unnerving jeers. But it never pays to anthropomorphize, I reflect. The gulls belong to this pale landscape, yes. To keep Laguna Madre wild, though, humans now have to be a part of it as well. The gulls laugh on and I climb from the boat. We are in this together.

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