Beachcomber’s Paradise

After leaving Washington, we headed for the Coastal Bend of Texas for the rest of the winter. I had been to Corpus Christi a couple times on business and the area looked interesting. The northern Gulf of Mexico is well-known for recreational fishing and the coastal marshes and woodlands are birding meccas. We were ready to leave the cold and wet Pacific Northwest. We rented a house in Rockport, about a half-hour east of Corpus (as the locals refer to it), and became honorary “winter Texans” (the Texas equivalent of "snowbirds" of the Southwest). Here’s the first of a couple posts on the interesting things we learned in this corner of the Lone Star State.

Small (coppice) dune on the beach at Padre Island National Seashore

 “…Texas beaches are public highways and all traffic laws apply, including seat belt regulations …” (link). At 113 miles, Padre Island,between the Gulf of Mexico and Laguna Madre, is the longest undeveloped barrier island in the world (we’re in Texas after all). Padre Island National Seashore protects about 70 miles of the barrier island. Visitors can drive 63 miles on the beach from the end of the paved road south to Mansfield Channel (link), which divides North Padre Island from South Padre Island, the infamous spring-break destination (link). Beachcombing is a popular (and lightly regulated) pastime for many visitors (link), about 500,000 annually. I’ve written about beachcombing in Mexico (link), but here it’s more like a competitive hobby.

Beachcombers at Padre Island

We stopped at the visitor center on our first visit to the national seashore. Inside the entrance was a large table with a hands-on display of shells, fish and mammal bones, seabeans and trash found on Padre beaches. Behind the desk, a woman in street clothes was wearing a necklace of seabeans. Rande is drawn to unusual jewelry and asked about the necklace. She introduced herself as Marian, a park volunteer, and told Rande about seabeans, after which, she was eager to go beachcombing. We drove down the beach six or seven miles. It was mid-afternoon and the tide was coming in and I didn’t want to driver farther without better preparation, like a shovel in case we got stuck. Within minutes, Rande had found a few seabeans and was hooked. We returned several times at low tide to drive 20-30 miles south to an area where, according to another park volunteer, beachcombing was better.

Rande beachcombing at Padre Island National Seashore

Below are a few of the seabeans Rande found (from left to right): Sea heart produced by tropical woody vines that grow on trees on the Caribbean and produce seed pods from four to seven feet long. Tropical walnut from the Caribbean. Pecan in the husk (exocarp) is probably from a domestic orchard; Texas is the second largest pecan producer in U.S. (link). Hamburger bean from a seed pod produced by a climbing,woody tropical vine with bat-pollinated flowers. Mary's bean grows on a woody vine in forests of Central America and the West Indies. Because there is a cross indented on one side, early Christians called it Mary's bean for the Virgin Mary (link). (Identification guides: link; link; link; link)

Seabeans

Seabeans, also known as drift seeds, are produced by flowering trees and vines in tropical forests where floating in water is a dispersal mechanism. Seeds and nuts that fall into waterways can be carried to the ocean and dispersed by ocean currents. Most of the seabeans found on Padre Island come from the Caribbean and Central and South America (link). Beachcombing for seabeans is a serious hobby (link). There are websites and blogs devoted to seabeans (link); seabean guidebooks (link); polished seabeans (link) and seabean jewelry (link). And there’s an Annual International Sea-Bean Symposium and Beachcombers’ Festival. The 21st annual festival will take place in Galveston, Texas, October 14-15, 2016 (link).

Rande's collection of seabeans from Padre Island

Wind is the primary driver of geologic processes on Padre Island and it usually blows from the southeast between 7 and 30 miles per hour. It drives the currents that bring shells, seabeans (drift seeds), driftwood and trash to the island. Wind-blown sand creates the beaches and dunes, and covers paved roads and parking lots. Blowing sand is a “good thing” to park managers; it makes more work for them, but it keeps the island from eroding away. Barrier islands like Padre reduce impacts on the mainland of high winds and waves generated by tropical storms and hurricanes (link).

Drift log on the beach

The landforms of barrier islands are classified based on location and the processes that create them (link; (link). Let’s hike across Padre Island from the Gulf of Mexico to Laguna Madre beginning at the beach. The swash runs up the forebeach after an incoming wave has broken (link); this is where shells accumulate. The backbeach is where trash and debris are deposited by high tides and storms.

Willets feeding on the forebeach

Wind-blown sand creates small dunes around vegetation on the backbeach known as coppice dunes; they’re generally less than three feet high. Rande found most of the seabeans in the wrack line (line of organic debris and trash stranded by the tides) on the backbeach among the coppice dunes.

Trash among the coppice dunes on the backbeach

Ghost crab on a coppice dune

From there we climb the foredune ridge, which in most areas is covered with vegetation, and can be up to 50 feet high and 200-300 feet wide. The foredunes parallel the shoreline and protect rest of the barrier island from the full force of tropical storms.

Foredune ridge

Dew-covered spider webs on foredune grasses...

...and the spider that spins them

Behind the foredunes are the stabilized dunes up to 20 feet high. These elongated and curved dunes were once part of the foredune ridge, but were blown out by storms and migrated inland where they were overgrown with vegetation and stabilized.

Stabilized dunes

Javelina foraging among the stabilized dunes

Prickly pear cactus and Indian blanket in the stabilized dunes

Beyond the dunes are the barrier flats, the most extensive landform of the island and generally less than five feet above sea level. The barrier flats (also called the coastal plain) were at one time sand flats; the more sparsely vegetated flats are where grasses have recently become established. Cattle grazed the barrier flats during the ranching era.

Barrier flats beyond the stabilized dunes

Barrier flats

Freshwater and brackish ponds and wetlands occur in troughs and depressions on the barrier flats. The ponds hold water because mud, plant debris and wind-blown sand seal the bottom. Ponds and wetlands are important habitats and sources of freshwater for the island’s wildlife.

Freshwater pond on the barrier flats

Blue-winged teal and pintail take flight and two American coots and a ruddy duck on the pond

Across the barrier flats are back island dunes, low dunes that can range from barren to vegetation-covered. The blow-out dunes and sand flats are the sources of sand for the back island dunes.

Back island dunes

Finally we arrive at the tidal flats of Laguna Madre (Spanish for Mother Lagoon). About 50 percent of the seagrasses in the U.S. occur in the Gulf of Mexico and the largest seagrass beds in the western Gulf of Mexico occur in Laguna Madre. Seagrass beds are important habitats for invertebrates, fishes, birds (especially migrating waterfowl), sea turtles and marine mammals (link).

Tidal marsh on Laguna Madre

Laguna Madre shoreline with accumulating seagrass debris

Laguna Madre is the largest hypersaline (1.5 to 3 times saltier than seawater; link) estuary in the world. It’s 277 miles long, 4-6 miles wide (10 miles at its widest) and averages less than four feet deep. The lagoon has no freshwater river inputs and is largely isolated from the Gulf of Mexico by Padre Island. It formed about 3,000 years ago with the stabilization of the Texas coast and creation of Padre Island (link). High salinity results from high evaporation rates, lack of freshwater inflows and low inputs of seawater from the Gulf of Mexico (link). High winds can push lagoon waters to one side of the bay for several days leaving behind shallow pools that evaporate in the intense Texas heat. When the winds die, the water moves back to the other side, filling the dry pools and dissolving the salt crystals increasing the salinity.

White and brown pelicans share a small island in Laguna Madre

The winds, currents and tides of the Gulf of Mexico bring trash, shells, seabeans and driftwood to Padre Island from as far away as South America. The amount of trash on the beaches is directly related to the strength, direction and duration of the wind; the height of incoming tides; and the amount of trash dumped into the Gulf of Mexico. Winds and tides move trash across the beach where it can be buried by wind-blown sand. Subsequent storms and high tides can uncover and move the trash down the beach back into the Gulf of Mexico (link). In a long-term study of trash on Padre Island beaches, the park identified the following major sources: Mississippi River, storms, commercial shrimping industry, offshore oil and gas industry and Mexico (link).

Novillo line camp, the last standing remains of the Dunn family cattle operation

Padre Island (Spanish for Father Island) was named for Padre Nicolas Ballí, a Spanish priest and the first permanent settler in 1804. Ballí introduced cattle to the island, and for three decades he and his nephew used the island for grazing. At the end of the United States–Mexican War (1848), Americans replaced Mexicans as island ranchers; by the Civil War, the island supported a small community of cattle ranchers. In 1876, Patrick Dunn, an Irishman, moved to Padre Island, developed a large cattle ranch and ultimately acquired most of the land. The Dunn family enterprise continued until 1971 when the Park Service removed cattle from the island (link).

Corral at the Novillo line camp

The early settlers of Padre Island did not have milled lumber, so they scavenged driftwood, metal objects and ropes from the beaches to build huts, kitchens, fences, corrals and furniture (link). “The [backbeach] is the site of a very large accumulation of flotsam and jetsam…Many of the bottles, boards, trees, shoes, rope, coconuts, and other things that make Padre a beachcomber's paradise have washed ashore after they drift hundreds or thousands of miles across the ocean”  (link). The park encourages beachcombing and allows visitors to remove up to five gallons per person per day (link). The drifting seeds from South America got Rande’s attention and they were the focus of her beachcombing trips, but first, the oceanography that brings them there.

Polypropylene lines and railroad vine

Warm water from the Caribbean Sea flows between the Yucatan Peninsula and Cuba (Yucatan Current) into the Gulf of Mexico. The current flows north before looping east (Loop Current) and exiting the Gulf of Mexico south of the Florida Keys (Florida Current) to become the Gulf Stream in the Atlantic Ocean. The Loop Current can extend as far north as the delta of the Mississippi River, forming a large loop. To return to its direct configuration, a loop pinches off as a clockwise-rotating, warm-core ring, which traps floating debris carrying it west-southwest toward Texas and Mexico (link). Nearshore currents in the northern Gulf of Mexico flow west along the coast from Louisiana toward Texas. Nearshore currents off Mexico flow north along the coast toward Texas. The currents converge at about 27 degrees north latitude (Padre Island). Floating objects are brought ashore by winds, waves and tides where the currents converge (link).

Fishing lures

The beaches of Padre Island are fine quartz sand with lesser amounts of minerals, rock fragments, shells and shell fragments. The highest concentration of shells occurs where the longshore currents from the east and the south converge and waves concentrate sand and shells on the beach. Eventually the finer sand is blown landward leaving large shell-fragment deposits. The park map identifies Little Shell Beach (mile 10-15 from the end of the paved road) and Big Shell Beach (mile 20 to 27). Little Shell Beach is dominated by shells from Donax, a small surf clam. Big Shell Beach is dominated by shell fragments of quahogs and large clams. The shells have been significantly abraded by wave action (link; (link).

Big Shell Beach

Tire tracks on Big Shell Beach

Big Shell Beach details

According to the park service, “Driving on the beach is an incredible adventure, but it takes experience and preparation.” The handout, entitled Traveling Down Island, warns that access by two-wheel is limited to the first five miles, that it costs hundreds to thousands of dollars to for a private wrecker to tow you out if you get stuck (“The National Park Service does not tow vehicles…”) and that driving into vegetated areas is prohibited. Beach-driving is allowed at other national seashores and state and local beaches around the country (link), but it’s not without its problems. It widens beaches, inhibits sand accretion and narrows the barrier island, increases beach erosion and instability during storms, and reduces the natural dune-rebuilding capacity between storms (link).

Driving on the beach at Padre Island

One day, Rande and I were at Big Shell Beach, about mile 26; I was hiking in the dunes and she was beachcombing when she found a small glass bottle with a pink, rolled-up paper inside. There was no cork and, while the paper was laminated, it showed signs of water damage. The message on the long, narrow paper was a poem written to “Poetry Girl” signed by “Alamo” with a phone number and the date (September 2015) next to the name. Did the message float down a river to the Gulf of Mexico? Was it carried by currents and waves to Padre Island?

Alamo's bottle and message to Poetry Girl

Rande shared the poem with several of her new friends, including the staff of the park visitor center. The women thought it was romantic and wanted to know more. Three men read the poem; one said “look what you started!”; one said Alamo should move on with his life; and one, an older volunteer at Padre Island National Seashore, said that he was going to put a message with his phone number in a bottle and throw it in the ocean for Rande to find so she would call him.

Could she miss

the love letters

that I tear up

and throw away?

A week later, Rande called the phone number in Arkansas and left a message on the answering machine that she had found a bottle on the beach at Padre Island with the message to Poetry Girl from Alamo and asked her to call if she wanted to know more.

She broadcasts

her seeds in my

soul and waters

them oh so well.

A week later, Poetry Girl called Rande and began to reveal the story of Alamo. Poetry Girl lives in Arkansas and dated Alamo, who lives in San Antonio, in high school, after which they went their separate ways, married other people and raised families. Rande sent her the poem and some seabeans and sea glass she found nearby.

I can never lose

hope as

my flame still

burns brightly for

her…

Poetry Girl shared Rande’s emails with Alamo, who then added to the story in emails to Rande. Poetry Girl was his muse. Over the years they've exchanged poems and emails. Every year when Alamo goes duck hunting in Aransas Bay north of Corpus Christi, he walks across the Matagorda Island and throws a bottle with a poem to Poetry Girl into the Gulf of Mexico. He hopes that it will be blown offshore and carried east by currents, maybe into the Atlantic Ocean. The bottle that Rande found traveled about 70 miles in a straight line. It was the first time the finder contacted Poetry Girl.

Picnic table near the visitor center at Padre Island National Seashore

It’s not unusual to find a message in a bottle on Coastal Bend beaches. Tony Amos, a researcher at the University of Texas Marine Science Institute in Port Aransas, has found more than 100 messages in bottles, including two thrown overboard from the same ship more than a year apart. The first one traveled 438 days and 3,500 miles; the second one traveled 530 days and 4,000 miles; both ended up on Mustang Island, a barrier island north of Padre Island. The 74-year old Amos estimated that he’s traveled 16,000 miles up and down the island over the years – that’s one message every 160 miles; clearly you have to work to find them (link). You can read more message-in-a-bottle stories here (link) and beachcombing stories, including the saga of yellow rubber duckies lost off a ship in the Pacific Ocean, here (link).

A word about climate change. Barrier islands are the first line of mainland defense against coastal storms and hurricanes. As ocean water warms it expands causing sea levels to rise (thermal expansion), and the extra heat is fuel for more intense storms. If (when?) the ice sheets of Antarctica and Greenland melt, sea levels will rise more and faster.

Since 1958, relative sea level at South Padre Island has risen 0.14 inches per year. Relative sea level includes changes in worldwide sea level (eustatic) plus changes due to land adjustments (tectonic). Sea level rise in south Texas is consistent with the worldwide eustatic rate of 0.12 inches per year (link). The Geological Survey estimated that 45% of Padre Island National Seashore is highly vulnerable to sea level rise, which means it is more susceptible to shoreline erosion (land loss), saltwater intrusion into freshwater aquifers and inundation of freshwater wetlands and estuaries. Twenty-six percent of the national seashore’s beaches has low vulnerability to sea level rise (link).

The Texas Bureau of Economic Geology estimated that 80% of Texas beaches on the Gulf of Mexico retreated between 1930 and 2012 (based on areal and ground surveys). The average rate of shoreline retreat was 4.1 feet per year, or 178 acres per year. From 1920 to 2012, average retreat was 2.7 feet per year at North Padre Island (3.7 feet per year from 2000 to 2012) and 7.5 feet per year at South Padre Island (5.2 feet per year from 2000 to 2012) (link). With higher sea level and storm surges, sand dunes and wetlands will migrate inland and park managers will have to decide whether to move buildings, roads and parking lots farther inland (retreat); protect infrastructure with barriers (adapt) (link); or abandon the barrier island.

Want to read more about the vulnerability of U.S. coasts to climate change? Here are two links to news articles (link; link) and a more technical assessment (link).