Location: Padre Island National Seashore, Texas
Automobile Traffic on Texas Beaches
Padre Island National Seashore is located on a barrier island between the Gulf of Mexico and the Laguna Madre. The island is sandy, ranging from surf-swept beaches through extensive dune fields to tidal flats along the Laguna. Except for a paved road running to the headquarters and adjacent facilities, access to most of the island is by boat, four-wheel drive vehicle, or on foot.
At Malaquite Beach, near the headquarters, the beach sand is highly compacted and suitable for passage of regular automobiles, trucks, and recreational vehicles. A set of posts divides the beach into a southern area (South Beach), used for camping, fishing, etc. and a northern area (North Beach) in which driving, except by seashore personnel, is prohibited. At first glance, the two areas look identical. Both consist of fine sand sloping to the ripples and sand bars of the surf zone of the Gulf of Mexico. Laughing gulls, Caspian terns, and other shore birds frequent the area.
Appearances are deceiving. Biologists have studied the small invertebrates that inhabit Malaquite Beach by taking core samples-known volumes of sand and the organisms in it. Equal numbers of core samples were taken from the edges of the dunes to below the water line on both sides of the posts. The results were startling. At North Beach, samples could contain more than 300 animals. The animals were divisible into an upper beach community, consisting of rove beetles (Bledius spp.), beach hoppers (Talitrus sp.), and beach flies; a middle beach community, containing digging amphipods (family Haustoriidae) and polychaete worms (Scolelepsis sp.); and a lower beach community, dominated by the ghost shrimp (Callichirus islagrande). Seasonally, the small clam Donax variabilis was abundant. Ghost crabs (Ocypode quadrata) ranged across the beach. At South Beach, animals of the upper beach were almost completely absent. Those of the middle beach were significantly fewer than at North Beach. Only at the lower beach were the numbers similar.
At present, there are few studies indicating how the loss of beach animals affects the local ecosystem. Tiny animals of the upper beach are abundant among decaying algae, suggesting that they play a role in breaking down and recycling debris that is cast ashore. Beach birds such as sanderlings, willets, plovers, and others feed on beach invertebrates.
Beach invertebrates dig into the sand, where they hide from predators, stay moist, and avoid the heat and glare of sunlight. Vehicular traffic kills beach invertebrates directly by crushing them. It causes the sand to become compacted, thereby destroying burrows or hiding places and forcing moisture out of the sand. Traffic indirectly leads to loss of habitat by flattening the beach, crushing vegetation, and allowing storm waves to cut away the edge of the dunes. Aerial photographs show that small dunes and vegetation extend farther seaward at North Beach than at South Beach, which is flattened by traffic. Birds and sea turtles generally avoid beaches with heavy traffic.
It is becoming increasingly difficult to collect small beach invertebrates along the coast of Texas. The depletion of the beach fauna has many causes. Oil spills, industrial pollutants, and toxic algal blooms have affected the beach biota. Texas beaches have become badly eroded due to hurricanes, storms, and diversion of sand by structures that cut off the flow of replenishing sand. There may be effects of rising sea levels due to global warming.
For many years, environmentalists, biologists, bird watchers, and beach-goers commented on beach erosion, to little notice. As building and development of private property have increased, so has the alarm over the erosion. The city of Galveston built expensive breakwaters and pumped sand from offshore to build up beaches and retard erosion. Yet driving on the beaches continues, not just at the park, but along many of the beaches near urban areas. During holiday periods, stretches of beach may become heavily used roads. Some cities and counties use huge mechanized rakes every day to sift out garbage from the beaches, leaving the beach clean but totally devoid of life.
What should a beach be? Should it be a flat piece of sand to be used for recreation? Should it offer scenic vistas of surf, sand, and dunes in a natural state? Should traffic be prohibited in certain areas to preserve an ecosystem, protect endangered species, or save protective dunes in front of private property? How can public access to the beaches be ensured if vehicular traffic is restricted?
Mary K. Wicksten
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