By Land and Not By Sea: Flying, Creeping, Crawling Critters in Marshes Help Track Oil Impact

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Dr. Sabrina Taylor releases a Seaside Sparrow in its Louisiana marsh home after collecting information about its condition.  (Photo credit: Phil Stouffer)

(Click to enlarge) Dr. Sabrina Taylor releases a Seaside Sparrow in its Louisiana marsh home after collecting information about its condition. (Photo credit: Phil Stouffer)

Birds, crickets, ants, and other insects that live in Louisiana wetlands are helping researchers determine impacts to marsh life from the Deepwater Horizon oil spill.

Collecting and studying these creatures is no easy task as scientists must go deep into the muddy, mucky, grassy, hard-to-reach wetlands to get samples. But these birds and insects are important to study because they are sensitive to environmental hazards and provide signals that indicate the overall health of the marsh system and its food web.

Dr. Sabrina Taylor is an assistant professor of conservation biology in the School of Renewable Natural Resources (RNR) at the Louisiana State University (LSU) Agricultural Center. She leads a team with Dr. Phil Stouffer, also at RNR, and post-doctoral researcher Christy Bergeon Burns to study the Seaside Sparrow.  Dr. Linda Hooper-Bui is an entomologist and associate professor at the LSU Agricultural Center and leads a team studying insects.  These researchers are members of a larger group, the Coastal Waters Consortium (CWC), directed by Dr. Nancy Rabalais. The CWC takes a big-picture perspective of the critically-important area of Louisiana marshes. Their studies include multiple environmental stressors, from hurricanes and flooding to sea-level rise and oil spills on land-based creatures and marine and plant life.

Drs. Taylor, Stouffer, and Burns look closely at animals at the interface between land and water, the wetlands. “We’re studying if the oil from the spill makes its way into animals that live out of water,” explains Dr. Stouffer.  He continues, “We are working with the Seaside Sparrow, a permanent resident of coastal salt marshes that was heavily affected by the spill and our project is to find out if the spill might be affecting these birds.” These researchers’ work includes measuring the abundance of birds, their condition, and their reproduction rates.

This team is also examining the expression of a gene in Seaside Sparrows involved in detoxifying contaminants in oil known as polycyclic aromatic hydrocarbons. Dr. Burns explains, “If the birds’ bodies are focusing on detoxing, or dealing with this physiological stress of oil, then we might see hormonal effects, with elevated stress hormones like corticosterone. Reproductive hormones might be suppressed in Seaside Sparrows in oiled areas, because the birds are directing time, resources and energy away from reproductive success toward dealing with oil stressors.” These researchers are in their 2nd field season and hope to have some initial results soon.

Dr. Hooper-Bui studies the ecology of highly disturbed environments using insects as model organisms since they form the basic level of the food chain. She and her team examine the ability of ants, crickets, and other insects to respond to disasters such as hurricanes, flooding, fire, and pollution. “Our work is focused on insects,” said Hooper-Bui, “mainly on ants, because they are closely associated with the soil and plant life.” Her team has data from both before and after the spill in oiled areas and similar unoiled reference sites, offering a great deal of information on the changes in the marsh ecosystem.

Researchers are following up these field studies with laboratory experiments to test the effects of oil on predator-prey interactions and behavior of representative marsh organisms. Additionally, they are also studying or researching cascading effects through trophic levels. Research that looks at longer-term effects of oiled versus unoiled marsh infauna (animals that live in sediments) and epifauna (animals that live on surfaces) started this year.

Watch how scientists collect seaside sparrows, flushing them from the marsh into nets. Read more about this and other related work on the CWC website and Facebook page.

This research is made possible by a grant from BP/The Gulf of Mexico Research Initiative. The GoMRI is a 10-year, $500 million independent research program established by an agreement between BP and the Gulf of Mexico Alliance to study the effects of the Deepwater Horizon incident and the potential associated impact of this and similar incidents on the environment and public health.

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