Study shows Gulf salinity increasing red tide occurrence

Images like these with hundreds of dead fish washing up on the Gulf of Mexico shores are the result of red tides.

CORPUS CHRISTI – According to a new paper from Harte Research Institute (HRI) for Gulf of Mexico Studies at Texas A&M University-Corpus Christi doctoral candidate Sarah Tominack, red tides are occurring in Coastal Bend bays with increasing frequency. Red tides are algal blooms that form in the Gulf of Mexico which can cause fish to die by the hundreds while also releasing toxins in the air that irritate people’s eyes, skin and respiratory systems.

Tominack delved into decades of data from state environmental agencies and historic reports from area newspapers to piece together patterns of red tide occurrences and compared it to environmental data collected over the same period. Her findings suggest that not only are red tides increasing in the Corpus Christi area, but they may be tied to documented long-term increases in salinity levels in the Nueces Estuary system. 

She published a paper about her research, “An assessment of trends in the frequency and duration of Karenia brevis red tide blooms on the South Texas coast (western Gulf of Mexico),” in the journal PLOS ONE.

HRI Chair for Coastal Ecosystem Processes and one of the co-authors of Tominack’s paper Dr. Michael Wetz added, “What I can say is our data indicates that pretty much anything we do that leads to an increase in the salinity of the bay has the potential to create more conducive conditions for red tide.”

Tominack dug into the historical archive of the newspapers dating back to the 1950s to get a picture of red tide recurrence along the Coastal Bend area that spanned decades before the state was collecting regular data on the harmful algal blooms. She said that regular agency monitoring of red tides was not done until the 1990s, with some spotty data dating back to the 1980s – so the best way to understand the phenomenon was studying news mentions.

Tominack also said that it was interesting to see how newspapers documented the phenomenon over time, from small blips in coverage to several stories per day during a major Corpus Christi bloom in 1986 that spanned months and killed millions of fish.

“From my perspective, the bigger picture from things I see is that over the past half century to the past century, we’ve really turned this bay from sort of a brackish bay – meaning it has a good mix of salt and freshwater – to now, almost an arm of the ocean,” Wetz added.

“We’ve definitely been able to change the bay without some of these other factors coming into play.”

Wetz said that one of the important aspects of Tominack’s study gave them was some more information in terms of helping to move towards more predictive capabilities for red tide.

He said, “With some additional studies we might be able to start predicting when these things are going happen, and that will just help people in general.”



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