Study Examines Gulf Killifish Rapid Adaptive Resistance to Contaminants

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Story courtesy of the Gulf of Mexico Research Initiative

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Scientists conducted exposure experiments on Gulf killifish populations with known adaptions to common environmental contaminates to determine how rapid adaptation affects future fish health. The researchers found that larvae from killifish that adapted to dioxin-like compounds exhibited higher resistance to oxidative stress and carbamates than did killifish larvae from areas with little-to-no known toxicant exposure. These findings suggest that adaptive toxicant resistance may involve multiple mechanistic pathways.  The team published their findings in Aquatic Toxicology: Cross-resistance in Gulf Killifish (Fundulus grandis) populations resistant to dioxin-like compounds.

Previous research identified that killifish populations in the Houston Ship Channel, which has a long history of industrial pollution, rapidly adapted to resist developmental cardiac deformities caused by a complex mixture of toxicants. The expectation was that the toxin-resistant adaptation passed on to the next generation but came with physiological trade-offs such as increased sensitivity to other environmental stressors, such as hypoxia. However, no such tradeoff could be established.

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Contaminated site along the Houston Ship Channel where elevated levels of toxicants are coincident with resistant populations of Gulf killifish. Here, traps are set in a small tidal cut amid trash and debris to collect resistant fish for study. Photo by Benjamin Dubansky.

Author Benjamin Dubansky noted the significance of the study’s findings, “It is astounding to see not only a fish population that appears to be unbothered by PAHs [polycyclic aromatic hydrocarbons] and other contaminants that would otherwise be lethal, but also that this trait is transmitted from one generation to the next.” He continued, “However, we did observe some interesting differences between populations, which are now driving the research in new directions to help better understand the long-term effects of toxicant exposure on fish populations.”

Author Warren Burggren emphasized the study’s contributions to understanding oil spill impacts and recovery, “In a research area where there are such frequent findings of long-term environmental disruption and damage, it’s encouraging to see that some key organisms can develop resistance to human-induced environmental degradation. This encourages us to think that some effects can be mitigated relatively quickly through the natural characteristics of the organisms.”

The study’s authors are Elias M. Oziolor, Benjamin Dubansky, Warren W. Burggren, and Cole W. Matson.

Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at doi: 10.7266/N7513W6W; doi: 10.7266/N78S4MWF.

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This research was made possible in part by a grant from the Gulf of Mexico Research Initiative (GoMRI) to the Relationship of Effects of Cardiac Outcomes in Fish for Validation of Ecological Risk (RECOVER)consortium. Other funding sources included the Baylor University’s C. Gus Glasscock, Jr. Endowed Fund for Excellence in Environmental Sciences and the Office of the Vice Provost for Research.

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/.


Good Eats and Good Times at the Coconut Grove Seafood Festival

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On Sunday October 16th, Christina Pasparakis, Rachael Heuer, Yadong Wang, Dan DiNicola, and Emma Esch from the RECOVER team participated at the 2016 Coconut Grove Seafood Festival Ecodiscovery Zone presented by Celebration of the Seas Foundation.

“The Coconut Grove Seafood Festival is all about celebrating seafood, waterfront living and giving people their fill of the freshest, tastiest delicacies of the sea. Bushels of shrimp, oysters, crawfish, lobster, clams and fresh fish will soon overflow in Miami, just in time for the opening of stone crab season in October.” The festival also offers live music and local artist exhibitions to draw in the Miami masses.

The event also presented an Ecodiscovery Zone in the center of the festival for visitors to learn about marine and environmental issues pressing to the local communities. Joining RECOVER in this area, was fellow GoMRI consortium CARTHE, along with the University of Miami Shark Tagging and Rescue a Reef programs.

Early morning thunderstorms parted once the gates opened and hundreds of hungry guests came piling in the festival grounds. At the Ecodiscovery Zone, the groups were able to share their research and knowledge with attendees including displaying live samples of mahi embryos and corals and decorating their own drift plates to track ocean currents. For RECOVER, it was a unique opportunity to educate people about a species of fish that was readily available to eat at many of the vendor tents. Visitors at these kinds of outreach activities are always fascinated to learn how fast mahi grow, and as a result, how it contributes to a sustainable fish population.

View some of our photos below!

 


Study Suggests Wider Range of Mahi-Mahi’s Genetic Responses to Oil Exposure

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Story courtesy of the Gulf of Mexico Research Initiative

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Scientists used novel bioinformatics to investigate molecular-level changes over time and toxicity pathways in mahi-mahi embryos and larvae exposed to Deepwater Horizon oil. They observed that weathered oil (collected from slick skimming operations) induced more pronounced gene expression changes than a non-weathered source oil (collected from the subsea containment system directly over the wellhead). The tools predicted impairment of heart rates and increased pericardial edema which the researchers observed in the fish. The method also predicted disturbances in eye and nervous system development. These results suggest new genetic and developmental toxicity pathways targets associated with Deepwater Horizon oil. They published their findings in Environmental Science and Technology: Time- and oil-dependent transcriptomic and physiological responses to Deepwater Horizon oil in mahi-mahi (Coryphaena hippurus) embryos and larvae.

The timing and location of the oil spill coincided with the spawning window for many economically and ecologically important Gulf of Mexico fish species. Natural weathering processes can significantly alter the composition and structure of individual polyaromatic hydrocarbons in the water column possibly increasing oil toxicity. This study builds on recent research about early life stage fish heart health and oil exposure. Researchers conducted exposure experiments with mahi-mahi embryos and water-accommodated fractions of weathered and non-weathered oil at 24, 48, and 96 hours post-fertilization. Using high throughput RNA sequencing and gene signature identification software (On-RAMP; Ingenuity Pathway Analysis), the team analyzed the regulatory directions of gene expression, making it possible to predict additional biochemical, cellular, and tissue pathways targets for the oil.

The researchers observed that both oils induced similar molecular responses at 24 hours, but there were more prominent changes in gene expression in weathered oiled treatments at 48 and 96 hours. The number of genes that were differentially expressed increased from 196 (48 hours) to 1,469 (96 hours) in weathered-oil treatments compared to increases of 128 to 297, respectively, in non-weathered oil treatments. The study provides more detailed genomic responses which indicate affecting specific molecular functions may be altered.

“By understanding how fossil fuels cause toxicity, we can have a better understanding of the risks associated with these contaminants and determine regulatory or management strategies that reduce risks,” commented study co-author Daniel Schlenk. “This experiment was the first to demonstrate that weathered oil more significantly altered gene expression than unweathered oil and suggests that there are multiple targets of oil toxicity to this species at this life stage, including the heart, eye, and neurological systems.”

The researchers noted that their use of rapid genomics annotation analyses coupled with advanced informatics tools may be useful elsewhere to identify species specific molecular and physiological responses to environmental contamination.

Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at https://data.gulfresearchinitiative.org (doi:10.7266/N7BG2M0J).

The study’s authors are Elvis Genbo Xu, Edward M. Mager, Martin Grosell, Christina Pasparakis, Lela S. Schlenker, John D. Stieglitz, Daniel Benetti, E. Starr Hazard, Sean M. Courtney, Graciel Diamante, Juliane Freitas, Gary Hardiman, and Daniel Schlenk.

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This research was made possible in part by a grant from the Gulf of Mexico Research Initiative (GoMRI) to theRelationship of Effects of Cardiac Outcomes in Fish for Validation of Ecological Risk (RECOVER)consortium. Other funding sources included the Medical University of South Carolina College of Medicine and the Genomics Shared Resource, Hollings Cancer Center.

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, visithttp://gulfresearchinitiative.org/.