Hurricane Harvey more than doubled the acidity of Texas’ Galveston Bay, threatening oyster reefs

Seabirds forage on an oyster shell island on the Texas Gulf Coast. Jon G. Fuller/VW Pics/ Universal Images Group via Getty Images

by Tacey Hicks, Texas A&M University and Kathryn Shamberger, Texas A&M University

Most people associate hurricanes with high winds, intense rain and rapid flooding on land. But these storms can also change the chemistry of coastal waters. Such shifts are less visible than damage on land, but they can have dire consequences for marine life and coastal ocean ecosystems.

We are oceanographers who study the effects of ocean acidification, including on organisms like oysters and corals. In a recent study, we examined how stormwater runoff from Hurricane Harvey in 2017 affected the water chemistry of Galveston Bay and the health of the bay’s oyster reefs. We wanted to understand how extreme rainfall and runoff from hurricanes influenced acidification of bay waters, and how long these changes could last.

Our findings were startling. Hurricane Harvey, which generated massive rainfall in the Houston metropolitan area, delivered a huge pulse of fresh water into Galveston Bay. As a result, the bay was two to four times more acidic than normal for at least three weeks after the storm.

This made bay water corrosive enough to damage oyster shells in the estuary. Because oyster growth and recovery rely on many factors, it is hard to tie specific changes to acidification. However, increased acidification certainly would have made it harder for oyster reefs damaged by Hurricane Harvey to recover. And while our study focused on Galveston Bay, we suspect that similar processes may be occurring in other coastal areas.

Satellite photo of Houston and the gulf coast immediately after Harvey.
This satellite image, taken six days after Harvey made landfall, shows Galveston Bay and other rivers and bays around Houston filled with brown sediment-laden floodwaters. NASA Earth Observatory

Vast quantities of water

Scientists predict that climate change will make hurricanes stronger and increase the amount of rain they produce over the next several decades. Changes in ocean chemistry, caused by runoff from these storms, are becoming an increasing threat to many marine ecosystems, especially coastal reefs built by oysters and corals.

Coastal estuaries like Galveston Bay, where rivers meet the sea, are some of the most productive ecosystems in the world. Galveston Bay is the largest bay on the Texas coast and one of the largest in the U.S.; it covers about 600 square miles, roughly half the size of Rhode Island. Its extensive oyster reefs provide about 9% of the national oyster harvest.

Hurricane Harvey, the wettest tropical cyclone in U.S. history, made landfall on the Texas coast as a Category 4 hurricane on Aug. 26, 2017. Harvey stalled at the coast for four days, sitting over both land and ocean.

Maintaining contact with warm Gulf of Mexico waters fueled the storm with both energy and rainfall, allowing it to persist and drop extreme amounts of rain directly onto Houston and surrounding areas – up to 50 inches in four days. All of that rain and floodwater had to go somewhere, and much of it flowed into Galveston Bay.

These videos show the scale of flooding across Houston from Hurricane Harvey.

Climate change and ocean acidification

The ocean acidification issues that we study are a well-known effect related to climate change. Human activities, mainly burning fossil fuel, emit carbon dioxide into the atmosphere. The ocean absorbs about one-third of these emissions, which alters ocean chemistry, making seawater more acidic.

Acidification can harm many forms of marine life. It is especially dangerous for animals that build their shells and skeletons out of calcium carbonate, such as oysters and corals. As seawater becomes more acidic, it makes these structures harder to build and easier to erode.

Oysters fuse together as they grow, creating large rocklike underwater reefs that protect shorelines from wave erosion. These reefs provide habitat for other creatures, such as barnacles, anemones and mussels, which in turn serve as food sources for many fish species.

Rising atmospheric CO₂ levels are acidifying oceans worldwide. As our study shows, local events like tropical cyclones can add to global acidification.

Stormwater from Harvey caused extreme coastal acidification

The main cause of the unprecedented acidification that occurred after Hurricane Harvey was the excessive amount of rainfall and runoff that entered Galveston Bay. To help manage large-scale flooding in the Houston area, the city released large volumes of water from reservoirs for more than two months after Harvey. These releases extended the time during which stormwater entered Galveston Bay and increased its acidity.

Scientists use the pH scale to measure how acidic or basic (alkaline) water is. A pH value of 7 is neutral; higher values are basic, and lower values are acidic. The pH scale is logarithmic, so a decrease of one full unit – say, from 8 to 7 – represents a tenfold increase in acidity.

Rainwater is more acidic than either river water or seawater, which pick up minerals from soil that are slightly basic and can balance out absorbed carbon dioxide from the atmosphere. Rainwater’s pH is around 5.6, compared with between 6.5 and 8.2 for rivers and about 8.1 for seawater.

Th pH scale with values for common substances.
The pH scale shows how acidic or basic substances are. USEPA

Galveston Bay contains a mix of fresh water from rivers and salty seawater from the Gulf of Mexico – oysters’ preferred habitat. We collected water samples in the bay two weeks after Harvey and found that the bay was made up almost entirely of river water and rainwater from the storm.

Since rainwater, river water and seawater all have different chemistries, we were able to calculate that rainwater made up almost 50% of the water in the bay. This means that acidic rainwater from Harvey replaced the basic seawater within the bay after the storm. The average bay water pH had dropped from 8 to 7.6, a 2.5-fold increase in acidity. Some zones had pH even as low as 7.4 – four times more acidic than normal.

Bar charts showing combinations of seawater, river water and rainwater in Galveston Bay before and after Hurricane Harvey.
These charts show how rainfall and runoff from Hurricane Harvey altered the composition of Galveston Bay after the storm made landfall on August 25, 2017. Tacey Hicks, modified from Hicks et al., 2022, CC BY-ND

This extreme acidification lasted for more than three weeks. Bay waters became corrosive not only to more sensitive larval and juvenile oyster shells, but to adult oyster shells as well. Scientists had predicted that increasing CO₂ could cause this scale of coastal acidification but did not expect to see it until around the year 2100.

The fresh water from Harvey also caused a severe oyster die-off in the bay because oysters need slightly salty water to survive. Harvey struck in the middle of oyster spawning season, and acidification may have slowed reef recovery by making it harder for young oysters to form new shells. Officials at the Texas Parks and Wildlife Department have told us that four years later, in late 2021, some Galveston Bay oyster reefs still showed very low additions of new oysters.

Other coastal areas at risk

Only a few studies, including ours, have analyzed how tropical cyclones affect coastal acidification. In our view, however, it is highly possible that other storms have caused the kind of extreme acidification that we detected in the wake of Harvey.

We reviewed the 10 wettest tropical cyclones in the U.S. since 1900 and found that nine, including Harvey, caused large amounts of rain and flooding in coastal areas with bay or estuary ecosystems. Other storms didn’t produce as much rainfall as Harvey, but some of the affected bays were much smaller than Galveston Bay, so less rain would have been needed to replace seawater in the bay and cause a similar level of acidification to what Harvey produced.

We think that this likely has already occurred in other places struck by hurricanes but went unrecorded because scientists weren’t able to measure acidification before and after the storms. As climate change continues to make tropical cyclones larger and wetter, we see storm-induced acidification as a significant threat to coastal ecosystems.

Tacey Hicks, PhD Candidate in Oceanography, Texas A&M University and Kathryn Shamberger, Associate Professor of Oceanography, Texas A&M University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Measuring societal impact: how to go beyond standard publication metrics

Read the full story in Nature.

Approaches to capturing the benefits of research on society are improving — but huge challenges remain.

A chat may help convert a peer to a pro-sustainability stance

Read the full story from Ohio State University.

Changing the mind of someone who is dismissive of efforts to protect the planet could be accomplished by sharing a pro-sustainability point of view during a conversation, new research suggests.

How waste-eating bacteria digest complex carbons

Read the full story from Northwestern University.

For the first time, researchers mapped the metabolic mechanisms in a Comamonas bacterium that digests chemicals from plastic and plant waste. This new information could potentially lead to novel biotechnology platforms that harness the bacteria to help recycle plastic waste.

Empowering first generation scientists with Gabriel Reyes

Read the full post from the Federation of American Scientists.

For many students in the U.S. a career in science is out of reach. Too often young people interested in science never get the chance to pursue their dreams simply because they come from low-income families or live in parts of the country where opportunities to engage in scientific research are limited. This leads to a critical lack of diversity in the scientific community that stifles creativity, innovation and progress. 

FLi Sci, short for first-generation/low-income scientists, is an education nonprofit that addresses the root causes of lack of diversity in the scientific profession. The organization provides financial support for high school and college students in poverty to access, pursue, and engage in scientific opportunities. The flagship program is a two-year paid fellowship during which students are able to conduct their own independent research projects.  

FLi Sci recently became a member of FAS’s Fiscal Sponsorship Program which identifies burgeoning entrepreneurs in science and technology policy and supports their philanthropic endeavors. Gabriel Reyes, FLi Sci’s founder and Executive Director, sat down with us to discuss his organization’s pioneering work and how his own experiences as a scientist inspired him to make a difference.

What Lego—yes, Lego—can teach us about avoiding energy project boondoggles

Read the full story at Inside Climate News.

A new book looks at why big projects fail and finds that solar, wind and transmission lines are some of the best kinds of big projects, while nuclear power is among the worst.

Water crises due to climate change: more severe than previously thought

Read the full story from the Vienna University of Technology.

New data analyses indicate that previous models systematically underestimate how sensitively water availability reacts to certain changing climate parameters. An analysis of measurement data from over 9,500 hydrological catchments from all over the world shows that climate change can lead to local water crises to an even greater extent than previously expected.

Environmental Resilience Institute, IU Press announce environmental change book series

Read the full story from Indiana University.

As Indiana communities, businesses, and residents increasingly recognize the threat posed by climate change to Hoosiers’ health and livelihood, Indiana University Press and the Environmental Resilience Institute are teaming up on a new book series focused on environmental change—its challenges as well as solutions.

James Shanahan, a professor in The Media School at IU and former ERI associate director, announced the collaboration during a Jan. 18 event at IU Bloomington celebrating the publication of Climate Change and Resilience in Indiana and Beyond (IU Press), a book detailing how the Hoosier State can navigate the stresses posed by environmental change. The volume, released in November 2022, served as inspiration for the new book series.

Webinar: A New Era for ESG and Climate Disclosure: How Your Business Should Prepare

Mar 9, 2023, noon CT
Register here.

ESG and climate reporting is a must-do for any business. Yet we’re currently experiencing a surge of new frameworks and policies – as a business, it can be challenging to keep track of these changes. Which apply to you? What does it mean for your company? Join leaders from Point B, Radisson Hotel Group, and Duke Energy as they discuss how businesses around the world should respond to this new wave of ESG frameworks and regulations, both stateside and in the EU. You’ll get the answers you need on topics like:

  • How frameworks and rulings like the SEC, ISSB, CSRD, and Federal Supplier Disclosure Rule are converging
  • Which frameworks and regulations to pay attention to
  • What actions your business should take to prepare
  • How to create a “no regrets” approach to the SEC’s Climate Disclosure Ruling
  • Where the ESG and climate disclosure landscape is headed


  • Joel Makower, Co-Founder & Chairman, GreenBiz Group


  • Kevin Wilhelm, Senior Principal, Point B
  • Inge Huijbrechts, Global Senior VP of Sustainability, Security and Corporate Communications, Radisson Hotel Group
  • Katherine Neebe, Vice President, National Engagement and Strategy & Chief Sustainability and Philanthropy Officer, Duke Energy

If you can’t tune in live, please register and GreenBiz will email you a link to access the webcast recording and resources, available to you on-demand after the live webcast.

‘My kids are being poisoned’: How aviators escaped America’s war on lead

Read the full story at Politico.

Lead was removed from gasoline decades ago. So why is aviation fuel still laced with the metal — a neurotoxin tied to developmental problems in children?