Collaborative Research: Nematostella as an estuarine indicator species for assessing molecular and physiological impacts of the Deepwater Horizon oil spill. Dr. Matthew J. Jenny (PI), Dept. Biological Sciences, University of Alabama Dr. Ann M. Tarrant (Co-PI), Biology Dept., Woods Hole Oceanographic Institution
As a result of the Deepwater Horizon oil spill, millions of gallons of oil have leaked into the Gulf of Mexico and much of that oil has and will continue to wash up along the Gulf Coast of the United States. In an attempt to minimize the amount of oil to reach the coast, an unprecedented of amount of dispersant has been used both on surface oil and at the source of the leak. The impact of this unprecedented use of dispersant on the marine environment, food webs and the bioavailability of oil remains to be investigated. Furthermore, the microbial degradation of oil and dispersed oil in the marine environment or estuarine marshes can produce very low oxygen levels (hypoxia) that will further stress marine and estuarine invertebrates. Unfortunately, very little information is available on the impact of oil or dispersed oil and additional abiotic stressors (hypoxia) on the physiology of marine and estuarine invertebrates. Nematostella vectensis is a sea anemone (an organism related to reef-building corals) found in salt marshes along the Gulf of Mexico and Atlantic coast of the United States. This project will use Nematostella as a model to address the urgent need to understand the physiological responses of estuarine invertebrates to oil exposure, combined exposure of oil and dispersant and possible synergism between oil exposure and hypoxia (low oxygen). First, Nematostella will be collected from Gulf Coast populations. Contaminant load, energetic stores and reproductive status will be quantified. Molecular techniques will be used to determine which genes are affected (?turned on? or ?turned off?) in anemones from oil-exposed sites. Second, laboratory experiments will be conducted to determine the effects of oil exposure and combined exposure to oil and dispersant under normal oxygen (normoxic) and hypoxic conditions. Brine shrimp will be reared in the presence of a range of concentrations of oil, dispersant, and oil with dispersant. These shrimp will be fed to Nematostella under normoxic and hypoxic conditions. Effects of exposure will be characterized by assessing changes in gene expression, lipid analysis, histological examination and biochemical assays. The results of these experiments will provide insight into the different molecular and cellular processes that are used to protect the organism from combinations of stressors that are associated with the oil spill and exposure to oil or dispersed oil. This project will also enable development of biomarkers that can be used to assess responses of organisms collected in the field.
Broader Impacts: This project will provide insight into the ecological consequences of the Deepwater Horizon oil spill. Results from field sampling will be posted and linked with other emerging results (e.g., EPA sediment analysis). Gene expression and sequence data will be curated, and posted to publicly accessible databases. Two PhD students will be trained in lipid analysis and ecological genomics. This project will identify cellular and molecular responses of a cnidarian (sea anemone, related to reef-building corals) to oil exposure through an understudied route of exposure (feeding). In addition this project will provide direct measurements of gene expression, lipid stores and contaminant burdens an indicator species of anemones from potentially impacted populations along the Gulf Coast. The identification and characterization of various pathways being affected by oil exposure and related stressors (e.g., hypoxia) will assist in development of ecological forecasting tools to predict the physiological responses of organisms and subsequent impacts on local populations and ecosystems.
Project overview: Nematostella vectensis is a sea anemone that is native to salt marshes on the Atlantic coast of the United States. Sea anemones are part of an ecologically important group of animals called cnidarians (stinging?celled animals) that also includes corals and jellyfish. Relatively little is known about how these organisms are able to defend themselves against chemical pollutants like those released during an oil spill. This project is aimed at using molecular techniques and other more classical approaches to determine how Nematostella responds to exposure to crude oil, dispersed oil, and toxic chemicals found within oil (such as benzo[a]pyrene). We also examined the combined effects of oil and ultraviolet light. It is useful and important to study effects of oil on Nematostella because (1) Nematostella is relatively easy to work with in the lab and can provide insight into the biology of related organisms, such as reef?building corals, and (2) Nematostella inhabits shallow coastal environments, environments where contaminants can accumulate following oil spills and where chemical exposure may be combined with exposure to other stressors such as ultraviolet light. Major scientific results: We learned that crude oil and some polycyclic aromatic hydrocarbons (PAHs, a class of chemicals that is found within oil) become more toxic to Nematostella when the animals are exposed to the chemicals and ultraviolet (UV) light at the same time. This is most likely because the UV light causes photoactivation of the chemicals, making them more damaging within the animals (phototoxicity). This finding is important because organisms living in shallow environments are often exposed to chemical stresses and UV at the same time, but when determining the potential toxicity of chemicals, scientists often don’t consider these kinds of interactions. We identified specific genes respond to oil exposure (by "responding" we mean that the cells produce more of the RNA that corresponds to a given gene). Some of these genes code for antioxidant enzymes (which help to neutralize the oxidative stress produced by chemicals), as well as other enzymes that most likely help to break down the chemicals and move them out of the cells. These responsive genes can serve as biomarkers, allowing scientists to better understand the "health" of animals in natural environments. These results are particularly important because the cellular and molecular responses of vertebrate animals (like fish and mammals) to oil are relatively well known, but many responses by many invertebrates, including anemones are poorly understood. We have generated evidence in support of distinct cellular and molecular responses. Broader Impacts and Additional Public Benefits: Through this collaborative project, our two labs provided training and research experience for one postdoctoral researcher, three graduate students, two undergraduates and one high school student. To give some examples of success of this training, the postdoctoral researcher has since gone on to a faculty position at another university, where he is conducting research and training students of his own. The high school student conducted a highly successful science fair project (placed second in a regional competition). In addition to presentations at scientific conferences, we gave at least seven public presentations of this research, which included presentations targeted toward students (department seminars and a science honor society induction), journalists (participants in a journalism fellowship program), and the general public (public seminar series). This project was featured within the non?technical magazine Oceanus (available online: www.whoi.edu/oceanus )and in a non?technical documentary about the oil spill response by researchers at WHOI ("Science in a Time of Crisis, available online: www.whoi.edu/deepwaterhorizon/ , our work is featured within part 6 "Assessing the Impacts").
