Texas Gulf dead zone caused by excessive rainfall, unlike Louisiana's, Texas Gulf area affected by rains,not pollutants (Houston Chronicle)

Headlines this month bring grim news of a massive "dead zone" in the Gulf of Mexico. Is this something Houston should be worried about?

bottle with hypoxia, bottle without hypoxia
Yes and no.

Most of those headlines refer to a recent study from Louisiana State University, which forecast a dead zone in the Gulf one-third larger than average this summer. That's big. It forms from chemical runoff in the Mississippi River, and it kills a lot of marine life.

But that's Louisiana. Texas is different. It has a different kind of dead zone, said Steve DiMarco, an oceanographer and veteran dead zone researcher with Texas A&M, and it's also hitting record size this year after a rainy spring. When you put the two contiguous zones together, that's a 600-mile swath of uninhabitable sea from Gulfport, Miss., to south of Corpus Christi.

"The dead zone that's off Texas right now has nothing to do with the Mississippi," DiMarco said. "It has everything to do with the Brazos, the Colorado, the Guadalupe, the Trinity."

As the name suggests, it's an area of the ocean where life withers for lack of oxygen. Specifically, it happens in the bottom 6 to 9 feet of shallow coastal waters for various reasons.

Runoff drains into Gulf

In Louisiana, it's largely due to the runoff of chemical fertilizers from the vast central swath of the country that drains into the Mississippi River. The high-tech, nutrient-rich fertilizers farmers spray over tens of thousands of square miles of Midwestern farms eventually wash into the Gulf.

There, hungry algae have a feeding frenzy on the nutritious muck, and their population explodes. Until the food is gone, that is. Then they all die together and sink to the bottom, where microbes await to decay them.

Microbes, unlike algae, breathe oxygen. Like the algae, their population booms when a food source - algae - becomes rapidly abundant. But eventually the microbes breathe all the oxygen. Then they also all die. And so do most other creatures down there without oxygen to breathe.

Unlike the Louisiana zone, DiMarco said, Texas' has much less to do with pollution runoff and more to do with rain. And Texas has sure had a lot of rain this season.

Almost everything that falls on the state then flows out to sea, and floods on the land became floods atop the water, which are harder for people to see.

Saltwater and freshwater, though similar in appearance, don't mix. They just stack like water and oil.

So when billions of gallons pour down Texas rivers and into the Gulf, it smothers the saltwater beneath, blocking it from the oxygen in the air above. Then a dead zone - also called hypoxia - begins to form, and it stays in place until late summer storms bring waves to mix the water.

The National Oceanographic and Atmospheric Administration sends vessels out to track these zones. Nelson May helped lead the most recent expedition in June, when researchers found dead zone oxygen levels (less than 2 milligrams of oxygen per liter of water) more than 55 miles south of Corpus Christi.

"This is the farthest south that we've detected hypoxia since the beginning (2001) of the Hypoxia Watch Project," he said.

The Texas dead zone was first described in the 1970s, DiMarco said, though evidence suggests it's been occurring for more than 100 years, which predates most chemical fertilizers and many chemical pollutants.

Varying noxious effects

Still, it has effects. DiMarco said dead bottom-feeding sea life is washing ashore along parts of the Texas coast now, creating bad smells and offending tourists.

Peter Thomas, a marine scientist at the University of Texas Marine Science Institute in Port Aransas, said, "We have found that a very large dead zone causes widespread reproductive impairment in Atlantic croaker, an indicator species, with potential long-term serious impact on their populations."

Atlantic croaker are studied to assess the broader health of their environment.

Thomas' research showed that croaker populations in dead zones experienced "masculinization." Male reproductive cells were found in female reproductive parts, and the overall population saw a greater ratio of males to females. The reasons are complicated.

Research by the Smithsonian Institution in 2014 found that dead zones worldwide were increasing in frequency and severity. Researchers attributed that mostly to an increase in fertilizer runoff, like in the Louisiana case.

But they also cautioned that a warming climate - the planet broke annual temperature records for both of the last two years - would exacerbate the problem. Warm water becomes more buoyant than cool water.

So as a warmer atmosphere slowly heats the ocean surface, the top layer, rich with oxygen, will become less likely to mix into the depths beneath, where the dead zone occurs.

Large Dead Zone Growing in the Gulf of Mexico (page not found)

MCH begins 2010 Field Year
  • A group of 12 scientists from Texas A&M University, Texas A&M University at Galveston, Dalhousie University (Canada), and the Louisiana Universities Marine Consortium (LUMCON) embarked Apr. 5, 2010 for a six-day cruise in the Louisiana Deadzone.
  • The Deadzone is an area of the coastal ocean in the northern Gulf of Mexico south of Louisiana that experiences low oxygen concentrations each summer. The purpose of this cruise is to determine the relationship between the physical, biological, chemical and geological oceanographic processes that contribute to the onset, severity and duration of the deadzone. Ultimately, the data collected and insight gained will be used in the development of numerical models that can simulate the processes and lead to better management practices for the region.
  • Scientists include Cheif Scientist Dr. Thomas Bianchi and Dr. Heath Mills (TAMU), and Dr. Michael Dagg (LUMCON).
  • For more information concerning this cruise please contact Project Lead Dr. Steven DiMarco.
  • From time to time the investigators of this study have released information concerning this project that is of general interest to the public.Information concerning continued funding on this project expected Aug. 2009.
Gulf Deadzone Stretches More than 400 Miles

With unprecedented coverage and resolution, a team of Texas A&M University and Texas A&M University at Galveston researchers aboard the NOAA R/V Manta has just completed the most intensive survey of the northern Gulf of Mexico Deadzone ever. The team leader, Dr. Steven F. DiMarco, associate professor of oceanography at Texas A&M University says that hypoxia was observed from Port O’Connor, Texas, to south of Atchafalaya Bay, La. The total area of hypoxic area observed was 10,352 square km. A team of researchers from Louisiana reported on August 2 an area of 20,000 square km between High Island, Texas and the Mississippi River delta. The discrepancy between the two numbers is due to the differences in the area covered by the two cruises; the cruises overlap between Galveston and Terrebonne Bay, La. The TAMU cruise extended west to Corpus Christi. Also, the TAMU team has the ability to sample with ultrahigh spatial resolution, 200 m spacing, and the use of an extremely fast vessel, capable of 20+ knots. The team collected more than 19,000 near bottom observations across the coastal ocean in less than five days. When the findings of the two cruises are combined, the hypoxic zone of the northern Gulf of Mexico stretches, with a couple of short breaks, along nearly 700 km of coastal Louisiana and Texas from Port O’Connor to the Mississippi River delta at Southwest Pass, La.

Figure 1 (below). Map of dissolved oxygen concentration derived through objective analysis/optimal interpolation (OI) of near bottom observations on MS2 cruise, 2-7 August 2010.

Hypoxia is the ocean condition where oxygen concentrations in the water can fall below levels that most marine life need for healthy life. If levels fall low enough, marine life can be seriously affected. The principal driving factors causing the hypoxia in the coastal waters of the Louisiana Shelf are the combined inputs of freshwater and nutrients of the Mississippi River. However, other sources such as organic material from coastal wetlands also contribute and environmental conditions such as winds, waves, and currents also impact the size, severity, and duration of the deadzone each summer. Hypoxia off of coastal Texas is likely the result of several additional factors including local freshwater sources flowing onto the coast and summer upwelling and the accompanying algal blooms. This year’s hypoxia was observed in total water depths of 8-30 m and was usually confined to the lower part of the water column from 1-8 m above the ocean floor.

The researchers report hypoxia off of Texas at High Island, Crystal Beach, Galveston, Freeport, and Port O’Connor. Near Port Aransas and Corpus Christi, Texas, oxygen concentrations were depleted to 50% of normal, but were not hypoxic. Extremely low oxygen values were seen in the offshore region south of Sabine and Lake Charles, La.

Figure 2 (below left). Vertical profile of dissolved oxygen concentration as a function of depth and distance offshore observed with Acrobat towfish vehicle.

Location is line L11, which is south of Atchafalaya Bay, La. (see basemap). Graphic produced by Bo Li, TAMU Graduate Student.

The NOAA vessel R/V Manta is a 83-foot twin hull catamaran operated by the NOAA Flower Garden Banks National Marine Sanctuary Program Office in Galveston, Texas. The vessel has five crew and is captained by Capt. Darrell Walker.The study is funded by the NOAA Center for Sponsored Coastal Ocean Research. More information including a blog during the cruise can be found at the project website or contact lead Principal Investigator, Dr. Steven F. DiMarco. Other Scientists aboard the ship were Dr. Piers Chapman, Head of Oceanography, TAMU; Dr. Norman Guinasso, Director of the Geochemical and Environmental Research Group, TAMU, and Postdoctoral Researchers Drs. Yuelu Jiang and Zhankun Wang. Graduate students, Ruth Mullins and Li Bo and TAMUG Undergraduate Lexie Denby. Two marine technicians, Andrew Dancer and Eddie Webb, complete the science party.

Figure 3. Basemap of planned station locations for MS2 cruise.

News Update
  • The South Marsh mooring is in place and is reporting data from 3 CTDs, 2 NO3 sensors and one ADCP. GERG is in the process of restarting the website at and getting the data graphically for us to look at. Thanks to GERG and divers for getting this done.
  • The M15 cruise seems like it was highly successful and has sparked interesting discussion as to the plan for future cruises. Kudos to the Science team on the ship led by Bianchi, Dagg, and Mills.
  • The third annual report for the NGOMEX 2006 Award is due May 31, 2010. Please provide your inputs. Include papers, presentations, and other materials (graphics and text) that can contribute to the report. The reporting period for this report is May 1, 2009 - April 30, 2010. The M15 Cruise is NOT included in this report.
  • The Year One Report for the NGOMEX 2009 Award is due June 30, 2010. The M15 cruise IS included in this report. The reporting period is Sept. 1, 2009 - May 31, 2010. This report will be much shorter than the year 3 report, however, we should have a new section on the statistical modeling that we are doing.

Second Process cruise to embark Saturday night

The second MCH Process cruise is set to mobilize Saturday August, 14 2010 for its six-day investigation of the processes responsible for controlling and maintaining the deadzone of the Louisiana continental Shelf. The Science Party, led by Dr. Mike Dagg of LUMCON, is made up of 12 scientists from LUMCON, Texas A&M University, Texas A&M University at Galveston, Carolina Coastal University, and Hong Kong University. Dr. Heath Mills will lead the microbial aspect of the cruise; Dr. Antonietta Quigg will lead the phytoplankton component. The cruise is part of the Mechanisms Controlling Hypoxia Project funded by NOAA CSCOR.

This cruise will examine short-term biogeochemical processes at three stations located on the inner Louisiana shelf and how they with relate to physical processes. This is the first time in the history of the MCH program that such an emphasis will be made on the biogeochemical flux and rate measurements. The main objective of this research is to investigate the mechanisms that control the onset hypoxia, which occurs off of coastal Louisiana each summer, by examining dissolved and particulate organic matter (DOM and POM) cycling rates and sources in the region between the Atchafalaya and Mississippi River Plumes. The methods include deployment of real-time reporting instrument systems, an extensive coupled biological/physical/sediment numerical modeling effort, and shipboard process studies (to complement the real-time observations). Sampling on this cruise will consist of CTD/bottle casts and box-cores. Depending on time and weather considerations, we have planned biogeochemical sampling for 24-hour at each of the 4 anchored stations, the 3 we did in April 2010, and an additional one at the mouth of the Atchafalaya River. A test station will be done on the transit to the first CTD station to train graduate students on CTD and rosette sampling and test scientific apparatus. The ship's flow-through system will be run for the duration of the cruise. Bucket nutrients and salinity may be done between planned stations to best locate the river plume. A bottom-tripped frame containing 10 L Niskin bottles, CTD, and transmissometer will be deployed at each station in addition to the 12-bottle rosette. An RDCP current profiler and short-term sediment trap will be deployed at the start of the station. A shipboard 600-kHz ADCP will run throughout the cruise. We will also conduct a number of additional complementary and related experiments during the course of this cruise. These experiments involve the collection of additional water and sediment samples for analysis both at sea and on shore.

A combined molecular and geochemical approach will provide a better understanding of the prokaryotic community ecology. Building upon data from previous cruises, sediment associated prokaryotic activity will be assessed by observing transitions in sulfur and iron valence states and concentrations. Supporting anion and cation measurements will provide a more complete view of the potential nutrient cycling. The inorganic chemistry will be compared to the organic chemistry and the physical sediment characteristics. The focal point of the sediment biogeochemistry will be high-resolution sampling and sequencing of the active prokaryotic populations (i.e., Bacteria and Archaea domains). Structural and functional gene targets will be used to determine active metabolic processes within the sediment. Data collected on this cruise will be compared to previous cruises to identify potential trends in population distribution and activity.

For the first time on an MCH cruise, the water column prokaryotic populations will also be subjected comprehensive molecular analysis. Focus will shift from sulfur and iron to nitriogen related populations and processes. Again, active populations will be observed through both structure and function based comparisons. Geochemistry obtained via shipboard operation will be used to support molecular analysis. Data collected will provide baseline assessment of water column prokaryotic ecology prior to the onset of summer hypoxia. Alkalinity and DIC: The inorganic carbon measurements serve two purposes. We need data in this region for our project where we are trying to model alkalinity and the carbonic acid system in the Gulf of Mexico and Caribbean Sea. The northern Gulf of Mexico is one of the areas where we need more data. This is one of the reasons for the higher density surface water sampling (a sample ever 25km) using buckets and possibly water from the flow through system if a bucket cannot be done.

The second purpose is in direct relation to the biogeochemical process stations. We can examine the changes in the carbonic acid system relative to the microbial processing under the different salinity conditions experienced at the 4 process stations.


(a) to conduct 24-hour microbial, zooplankton, phytoplankton, DOC/POC, sediment, and biomarker process measurements at four stations;
(b) to obtain a series of box-cores for GUST sediment erodibility measurements;
(c) to obtain zooplankton and phytoplankton flux measurements;
(d) to obtain microzooplankton DNA data
(e) to obtain alkalinity and DIC data to estimate CO2 fluxes
(f) to collect hydrography data


Dr. Mike Dagg, LUMCON: Chief Scientist, Zooplankton Leader
Dr. Heath Mills, TAMU: Microbial Process Leader
Dr. Antonietta Quigg, TAMUG: Phytoplankton Leader
Dr. Hongbin Liu, Hong Kong University: non-Co-PI Invited by M. Dagg to do water column DNA work
Dr. Kehui Xu, Carolina Coastal University: Sediment Dynamics Leader
2 LUMCON techs

Li Shen: TAMU, CO Graduate Student (female)
Mike Shields : TAMU, Undergraduate Student (male)
Li Bo: TAMU, PO Graduate Student (male)
Sarah Stryker: TAMU, PO Graduate Student (female)
Brandi Reese: TAMU, CO Graduate Student (female)
Jiang Yuelu - TAMUG, postdoc (female)
Fennix Garcia Tigreros - TAMU, CO Graduate Student (female)
Winch Operators
Two provided by LUMCOM
Participating Institutions
TAMU - College Station, Dept. of Oceanography
TAMUG - Marine Biology Department
Dalhousie University
University of Texas Institute for Geophysics
Louisiana State University: Dept. of Ocean. and Coastal Studies (remote sensing)
Coastal Carolina University

Project Website:

Record Dead Zone predicted for the Gulf

Texas A&M researchers to examine scope and scale of Gulf "dead zone" page not found

Oceanography Graduate Student Seeing the World One Wave at a Time page not found

Massive fishkill reports off Galveston, Texas page not found

Twenty-first MCH Process Cruise Underway

A group of 14 scientists and students boarded the R/V Pelican in Cocodrie, Louisiana, for the 21st MCH Process cruise. Led by Chief Scientist Dr. Antonietta Quigg, of the Department of Oceanography (TAMU) and Department of Marine Biology (TAMUG) and Dr. Heath Mills of the Department of Oceanography, the objective of this cruise is collect data to investigate the oceanographic processes responsible for coastal hypoxia. The cruise was at sea from 7-12 August 2012. The cruise is funded by the NOAA Center for Sponsored Coastal Ocean Research. Seven institutions are contributing to the cruise efforts: Texas A&M University, Texas A&M University at Galveston, Coastal Carolina University, Louisiana State University, the Louisiana Universities Marine Consortium, Dalhousie University (Canada). Graduate students include: Yan Zhou and Tyra Booe, Fenix Garcia Tigeros, Mike Shields, RC Mickey. Shore based scientists include Dr. Thomas Bianchi, Dr. Shari Yvon-Lewis (TAMU), Dr. Nan Walker (LSU), Dr. Kevin Xu (CCU). Marine Technicians Paul Clark and Erik Quiroz also participated.

Sixth MCH Survey Cruise Brings TV's' Water Brothers

The second cruise of the 2012 field year mobilizes on 13-14 August 2012. The cruise is led by Chief Scientist, Dr. Steven DiMarco, of the Department of Oceanography. Also participating on the cruise are scientists Dr. Piers Chapman, Dr. Matthew Howard (TAMU), and Dr. Chris Shank (UT). Four graduate students will participate on the cruise: Ruth Mullins-Perry, Laura Harred, Emma Cochran (TAMU), and Allyson Burgess-Lucchese (TAMUG). Marine Technicians Andrew Dancer and Eddie Webb will also participate on the cruise. Shore based participants include: Dr. Lisa Campbell , Dr. Ethan Grossman (TAMU), and Dr. Antonietta Quigg (TAMUG). The science party also includes Alex and Tyler Mifflin from Canadian TV's the Water Brothers ( ).

The cruise is the sixth survey cruise of the MCH project; the objective of the cruise is to map the spatial extent of the hypoxic zone of the northern Gulf of Mexico. The cruises are conducted twice per year: once in June and once in August; the cruises bracket the yearly shelfwide survey performed in late July by the Louisiana Universities Marine Consortium. This year the MCH group found very little hypoxia in June on the Texas-Louisiana Shelf, as did the LUMCON group in July. The participants will blog their experiences from the ship ( ). The cruise is funded by the NOAA Center for Sponsored Coastal Ocean Research. The NOAA ship R/V Manta is a twin hull catamaran operated by the NOAA Flower Garden Banks National Marine Sanctuary.