Marsh Madness Is Seldom in March

Paola Lopez-Duarte and Brian Roberts use a seine to collect nekton next to a marsh. (Photo provided by CWC)

(Click to enlarge) Paola Lopez-Duarte and Brian Roberts use a seine to collect nekton next to a marsh. (Photo provided by CWC)

Scientists Converge Seasonally to Conduct Oil Spill Research

It’s a catchy name. But, Marsh Madness rarely starts in March (as implied by the NCAA basketball playoffs reference) and the scientists are not crazy-mad, just crazy-busy. “Marsh Madness” is the name of the Coastal Waters Consortium’s (CWC) multi-investigator ‘all hands to the field’ coordinated collection of marine samples.

CWC scientists are sampling oiled and unoiled sites in Louisiana marshes as part of long-term marsh ecosystem monitoring studies after the Deepwater Horizon oil spill. Researchers gather at the Louisiana Universities Marine Consortium (LUMCON) facility and travel by boat to upper Terrebonne Bay, western Barataria Bay, and eastern Barataria Bay. There they collect samples to measure wetland biogeochemistry, plant health, plant photosynthetic activity, greenhouse gas flux, microbial community composition, subtidal invertebrates, and fish.

The field work requires much advanced and on-site coordination as it is a complex, integrated effort that physically challenges participants over many days and nights. The most recent field trip, in May 2015, brought together 18 participants from 8 institutions. The timing of marsh sampling depends on certain conditions such as insects being present, weather, and when researchers conducting different aspects of this large project are at a point that they can benefit from a coordinated, simultaneous effort.

Having this group of specialists working together has its benefits. “The fun part of these marsh field trips – other than getting physical exercise – are the evening meals, where we discuss the day’s events and the science,” said marine ecologist Nancy Rabalais, Director of LUMCON and CWC. “Wendy Morrison and I also had some quality time sorting living benthic infauna from marsh debris and putting tiny marine organisms into feeding modes.”

A research focus this year is microphytobenthos (benthic diatoms) and other phytoplankton living on the sediment surface. These tiny organisms are part of the food web base and are consumed by marine animals such as fiddler crabs, worms, snails, and small crustaceans. The team’s hypothesis is that as summer air heats, microphytobenthos may be affected when temperatures reach 29°C, a point that can be lethal to some insects. Thus, the researchers collect field data on the microphytobenthos community in spring, summer, and fall to cover various temperature ranges. Scientists use the same collection-timing philosophy for subtidal macrofauna, which also may be susceptible to summer heat.

A comprehensive food web study is another focus this year. Long hours collecting samples are followed by even longer hours preparing tissues or sorting out organisms in the subtidal benthic samples. Researchers analyze tissues from small animals, microbes, and several primary producers to build a food web diagram. Their analyses include bulk tissue carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) stable isotopes, fatty acid profiles, and compound-specific stable isotopes (δ13C) in amino acids. Fish stomach content analyses will provide information on marsh nekton prey. Research teams also collect samples for the insect/spider and bird/rodent studies.

Scientists are not only learning more about marsh ecology but also their research strategies. “One thing we discovered trying to sample all components of the food web over a broad geographic area is that we were overly ambitious,” remarked Joel Fodrie, a biological oceanographer. “We had to pare back our geographic breadth.”

Five years after the Deepwater Horizon oiling, these scientists are finding that the oil signal is declining but is still much above background concentrations. Their combined efforts contribute to a better holistic understanding of marsh ecosystems with multiple stressors, including oil, as context for studying potential future oiling impacts.

Visit the CWC website to learn more about their research.

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The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.

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