Drones survey waning red tide at South Padre Island

SOUTH PADRE ISLAND — Scientists from Texas A&M AgriLife, the University of Texas Rio Grande Valley and Texas A&M Corpus Christi have collaborated on unmanned aerial vehicle flyovers of the red tide algae bloom off the South Texas coast, according to experts.

The red tide seems to be fading at this time, the experts said.

“We’ve actually flown three unmanned aerial vehicles, or drones, over the Gulf of Mexico affected by red tide in South Texas,” said Tony Reisinger, Texas A&M AgriLife Extension Service agent for coastal and marine resources in Cameron County and with Texas Sea Grant.

They each flew for about 20 minutes along the coast and over the jetties at Santiago Brazos Pass, Reisinger said.

Red tides occur naturally and are caused by high concentrations or blooms of microscopic algae called Karenia brevis, Reisinger said. The algae produce a toxin that can affect the central nervous systems of fish, birds, mammals and other animals. In high enough concentrations, it can cause water discoloration, making it appear red, green or brown.

While it’s not life-threatening for humans, red tide aerosol can cause temporary symptoms, including burning eyes, coughing, sneezing, skin irritation and respiratory problems, he said. People with asthma or other respiratory problems should avoid exposure.

“Using UAVs may eventually be an excellent way to monitor these red tide algal blooms,” Reisinger said. “It has potential to save state and federal agencies lots of time and money by tracking the movement and concentration of the bloom, and conducting fish-kill counts along the shore, which are measurements now taken by hand, so to speak. All that takes lots of man hours and resources.”

Reisinger said much research still needs to be done to enable UAVs to collect red tide data, but the potential is obvious.

“Right now, we track red tide movement with satellite flyovers,” he said. “Not only is that very expensive, but data collection is sometimes limited by cloud cover. We currently determine red tide concentrations by manually taking hundreds of water samples to measure red tide cell concentrations. A multi-spectral equipped UAV could quickly do all that from the air in a fraction of the time and expense if concentrations can be correlated with color change.”

Reisinger said the Texas Parks and Wildlife Department currently invests significant resources to drive along the shore documenting fish kills due to red tide to assess the impact on fish populations.

The satellite flyovers are currently conducted by the National Oceanic and Atmospheric Administration in Maryland. And water samples to measure red tide cell counts are taken by the Red Tide Rangers, volunteers trained by AgriLife Extension and the University of Texas Rio Grande Valley Coastal Studies Laboratory at South Padre Island. Brigette Goza, senior program coordinator, coordinates their efforts.

But UAVs may be a more efficient way to go, Reisinger said. The UAV flights made over red tide waters last week were flown by Dr. Jude Benavides, UT Rio Grande Valley, and Dr. Jinha Jung and Joe Fox, both with Texas AgriLife

“The good news is that this red tide seems to be slowly winding down,” Reisinger said. “Cell counts at South Padre Island have been declining over time. This occurrence of red tide started in Corpus Christi in mid-September and was pushed south into our area by northerly winds. Cell counts here peaked about two weeks ago, and in Corpus Christi, their red tide is now pretty much confined to Corpus Christi Bay.”

Reisinger said this red tide event has been unusual in two respects.

“Texas red tides originate in Mexico’s Bay of Campeche and move north along the coast to Texas,” he said. “This one seems to have started offshore in the Bay of Campeche, moved north to the Texas Coastal Bend then south again into Mexico as far south as Tampico.”

The other oddity of this red tide is the marine life it has affected.

“This red tide has killed more invertebrates,” Reisinger said. “It’s a mystery. We don’t know why, but this red tide has killed mole crabs, hermit crabs and ghost shrimp. Bivalves have also been affected. This is marine life that lives in what’s called the ‘slosh zone’ on beaches where there’s wave action. It will take more research to determine why this is occurring.”

Reisinger said fishing guides are still taking anglers to the Lower Laguna Madre and catching lots of fish.

“The cell counts in the bay are variable and patchy,” he said. “And they’re out there catching the foraging fish, including redfish, trout, flounder and snook. We had a report of one man catching and releasing a beautiful 32-inch snook recently.”

While red tide has taken its toll on tourism at South Texas beaches, Reisinger advised wearing a dust mask to reduce adverse effects of red tide.

“But by all means, I encourage those who like to fish to get out into the bay because anglers are reporting excellent catches.”

Reisinger said it’s difficult to predict what the current red tide bloom will do, but depending on weather and wind currents, he suspects its declining trend will continue.

Red tide status can be monitored online at https://tpwd.texas.gov/.