The RECOVER team is hard at work determine the effects of crude oil on fish in the Gulf of Mexico. Conference presentations of our research will appear here as they become available.
Grosell, M. Sublethal and often subtle impacts of oil exposure on aquatic animals can inform us of modes of action and long term effects. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Abstract: Crude oil toxicity can manifest in obvious deleterious effects in birds and aquatic fauna even following short term exposures. However, sublethal and often seemingly subtle effects may arise from exposure to low levels of crude oil derived water soluble compounds and such effects may have delayed and/or long term effects on individuals, populations and thus ecosystems. For all fish examined to date, exposure of early life stages to low levels of PAHs (low µg/L range total PAHs) results in cardiac dysfunction and malformation. When severe enough, this phenotype results in mortality shortly after hatch. However, less pronounced impacts evident from altered gene expression, altered metabolic rates and alterations to cardiac performance still allows for survival and seemingly normal growth and development under laboratory conditions. However, such early sublethal impacts have been demonstrated to result in reduced swim performance in juvenile as well as young adult survivors and have been proposed to be the source of reduced juvenile to adult survival in the wild. These observations of delayed higher level effects have been ascribed to impairment of cardiac function and oxygen delivery but other factors likely contribute to reduced fitness following early life stage sublethal exposures. A detailed understanding of the physiological mechanisms underlying sublethal oil toxicity will greatly improve our ability to predict long term impacts of recent and future oil spills. Grosell is supported by funding provided by the Gulf of Mexico Research Initiative
Esbaugh, A. Eco-physiological implication of early life cardiotoxicity in a coastal fish species, Sciaenops ocellatus. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Abstract: Pelagic larval fish have been shown to be some of the most sensitive organisms to oil exposure via water accommodated fractions. These fast developing species also represent a large portion of the commercial fisheries found in the Gulf of Mexico and elsewhere. The available evidence suggests that toxicity is driven by the relative concentration of polycyclic aromatic hydrocarbons (PAHs), and more specifically the concentration of 3-ring PAHs, which result in a characteristic cardiotoxic phenotype. This phenotype consists of a malformed heart, and in some instances extra-cardiac abnormalities, which can lead to reduced swim performance, aerobic performance and survival. While much is known regarding the developmental impacts on pelagic species, relatively little is known of coastal species that are generally more tolerant of environmental perturbations. Red drum is a fast growing species that spawns off shore and recruit to estuaries early in development, making them an ideal coastal comparison. Here we will describe on-going research examining the sensitivity of embryonic, larval and juvenile red drum to acute oil exposure with a specific emphasis on integrating early life cardiotoxicity, eco-physiological performance and recovery. The specific eco-physiological performance indices will include measures of aerobic and swim performance, foraging activity and prey capture ability as well as conspecific competition. Funding for this work was provided by the Gulf of Mexico Research Initiative through the RECOVER consortium.
Sweet, L. Exposure to ultraviolet radiation increases the toxicity of oil to mahi mahi (Coryphaena hippurus) embryos. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Abstract: The timing of the Deepwater Horizon oil spill in 2010 overlapped with the spawning of several ecologically and economically important fish species, including the mahi mahi (Coryphaena hippurus). Polycyclic aromatic hydrocarbons (PAHs) released into the marine environment during this oil spill have been shown to cause photo-enhanced toxicity under ultraviolet (UV) radiation. Mahi mahi eggs are positively buoyant and transparent, making these embryos at risk for photo-enhanced toxicity. In this study, mahi mahi embryos were exposed to high-energy water accommodated fractions (HEWAF) of source oil a (SOA), source oil b (SOB), and the Massachusetts source oil (MASS) for 48 h. The timing of the co-exposure with UV radiation varied between an early UV exposure at 7 hpf for 8 h and a late UV exposure at 27 hpf for 8 h. Hatching success was documented at approximately 48 h and samples were collected for oxidative stress gene expression analysis. The early UV exposure had a photo-enhanced toxic effect on embryo mortality in all three oil types. The early UV exposure LC50 values were 5.9% HEWAF for SOA, 4.2% HEWAF for SOB, and 2.0% HEWAF for MASS, which were all five-fold lower than the non-UV controls. The late UV exposures were significantly more phototoxic than the early UV exposures, with a seven-fold decrease in the LC50 values. This study provides evidence that the developmental window when UV exposure occurs has a significant effect on the degree of photo-enhanced toxicity of oil. Funding for this research was provided by GOMRI.
Mager, E. Effects of Deepwater Horizon crude oil exposure on the intestinal transport physiology of the Gulf toadfish (Opsanus beta). 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Abstract: Marine teleosts are faced with the continuous challenge of diffusive water loss, primarily through the gills, due to the high osmolarity of the surrounding seawater. To combat this diffusive water loss, marine teleosts must drink seawater to maintain hydration and excrete the absorbed salts through their gills. Thus, the gastrointestinal tract of marine fish represents a potentially significant route of exposure to waterborne pollutants such as those found in crude oil, most notably polycyclic aromatic hydrocarbons (PAHs). To investigate the potential osmoregulatory responses of the marine teleost intestine to crude oil exposure, short-circuit current (Isc) and conductance were measured in isolated intestinal epithelia from the Gulf toadfish exposed to various dilutions of high energy water accommodated fractions (HEWAF) of Deepwater Horizon slick oil using Ussing chambers. Results showed a dose-responsive decrease in the absorptive Isc with increasing %HEWAF dilution in the anterior intestine but no significant effects in the middle and posterior intestine. These findings suggest that crude oil exposure may impair the osmoregulatory function of the marine teleost intestine. Future efforts will focus on utilizing Ussing chamber exposures with individual PAHs or PAH classes in an attempt to identify the primary components of crude oil that account for the observed effects. This research was made possible by a grant from BP/The Gulf of Mexico Research Initiative to the RECOVER Consortium.
Xu, G. Genome-wide transcriptional responses to Deepwater Horizon oil in mahi-mahi (Coryhaena hippurus) embryos. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Abstract: The Deepwater Horizon (DH) oil spill contaminated the spawning habitats for pelagic fish. Exposure to water accommodated fraction (WAF) of oil from the spill is known to result in cardiotoxicity across fish species. The syndrome is consistently characterized by defects in heart formation and function. Unraveling the potentially diverse molecular mechanism of cardiotoxicity is essential for understanding the hazard posed by complex DH oil mixtures present in the environment. We analyzed the time-course (24, 48 and 96 hpf) transcriptional responses to field-collected DH oil, prepared as a WAF exposure in Mahi-Mahi (Coryhaena hippurus) embryos. The mRNA expression was quantified using high-throughput Illumina RNA sequencing (RNA-Seq) on a HiSeq2500. To analyze the Mahi-Mahi RNA sequencing data, a data analysis pipeline was developed. Reads were mapped to reference transcriptomes using the Diamond Basic Local Alignment Search Tool (Diamond Blast) and subsequently counted using a custom perl script, and subsequent translation of the RNA ID’s to gene ID’s was performed using the NCBI database. RNAseq was analyzed using DEseq2. Significantly up-/down-regulated mRNAs were identified, and the selected targets were verified by quantitative real-time PCR (qRT-PCR). Downstream gene ontology enrichment analysis was performed using the DAVID Bioinformatics Resources, and network analysis and biomarker identification performed using Ingenuity Pathway Analysis software (Ingenuity Systems, Inc.). Hypothesized transcriptomic responses include AHR-mediated response, HIF1 signaling, immune signaling, Ca2+-cycling and cardiac-associated genes. This RNA-Seq experiment was successfully applied to a non-model wild, and ecologically significant organism affected by the DH oil spill, and may reveal the molecular mechanisms of cardiotoxicity of DH oil mixtures (Grant No: SA-1520; Name: Relationship of Effects of Cardiac Outcomes in fish for Validation of Ecological Risk (RECOVER)).
Burggren, W. Epigenetic transgenerational inheritance and its implications for organismal resilience to oil spills. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Abstract: Phenotypic modification in the face of environmental stressors has long been an area of focus for biologists. Recently, epigenetic studies are becoming of increasing interest the context of the mid- to long-term effects of environmental stressors, including substances released from oil spills. Yet, “epigenetics” means different things to different life scientists. Most agree that this term generally refers to the processes whereby stressors lead to altered gene expression and modified phenotype, typically through DNA methylation, histone modification and/or the actions of small RNAs. However, many life scientists focus on the phenotypic modifications that occur during a single animal’s lifetime, especially because such effects are often maladaptive (e.g. the “epigenetics of cancer”). Less emphasis has been placed on epigenetic inheritance of modified molecular, morphological or physiological phenotypes across generations. Such phenotypic modifications can be maladaptive, but can also be highly adaptive, enhancing survival in the face of dynamic environmental stressors. This presentation reviews some of the key studies examining the epigenetic inheritance of modified phenotypes in fishes as a response to polycyclic aromatic hydrocarbons (PAHs) and other pollutants released from oil spills. Some epigenetically inherited traits appear maladaptive (e.g. morphological malformations such as edema in the F1 and beyond), while positive effects on fitness (enhanced hypoxia tolerance) have yet to be assessed. Additionally, “epigenetic dynamics” (e.g. wash in and wash out of modified phenotypes over multiple generations) results in a complex suite of interactions between stressor dose and generation (e.g. F1, F2, etc.), the full implications of which have yet to be determined in the context of the lingering effects of oil spills. (Financial support to RECOVER Consortium provided by Gulf of Mexico Research Initiative)
Perrichon, P.; Khursigara, A.; Pasparakis, C.; Martinez, N.; Mager, E.; Steiglitz, J.; Esbaugh, A.; Grosell, M.; Benetti, D.; and Burggren, W. Deepwater Horizon Oil Spill in early life stages impairs cardiac development of three Gulf of Mexico fishes (Gulf killfish, redfish and mahi-mahi. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Khursigara, A.; Perrichon, P.; Bautista, N.; Burggren, W.; and Esbaugh, A. Early life sensitivity of red drum, Sciaenops ocellatus, to source and naturally weathered oil. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Johansen, J.; and Esbaugh, A. Immediate and prolonged changes to swim performance of red drum (Sciaenops ocellatus) following acute exposure to naturally weathered crude oil. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Nelson, D.; Heuer, R.; Stieglitz, J.; Hoenig, R.; Mager, E.; Allmon, E.; Esbaugh, A.; Benetti, D.; Grosell, M.; and Crossley, D. Hemodynamics throughout recovery from polycyclic aromatic hydrocarbon exposure in juvenile mahi mahi (Coryphaena hippurus). 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Reynolds, A.; Heuer, R.; Hoenig, R.; Stieglitz, J.; Grosell, M.; Bennetti, D.; and Crossley, D. OXPHOS capacity in mahi mahi (Coryphaena hippurus) and sheepshead minnows (Cyprinodon variegatus variegatus) after crude oil exposure. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Schlenker, L.; Stieglitz, J.; Benetti, D.; and Grosell, M. Foraging behavior and predator prey interactions of mahi mahi (Coryphaena hippurus) exposed to crude oil from the Deep Water Horizon event. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Pasparakis, C.; Mager, E.; Stieglitz, J.; and Grosell, M. Combined effects of Deepwater Horizon crude oil exposure, temperature and developmental stage on oxygen consumption of embryonic and larval mahi mahi. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Magnuson, J.; Sweet, L.E.; Garner, T.R.; Alloy, M.; Stieglitz, J.D.; Mager, E.M.; Grosell, M.; Benetti, D.; and Roberts, A. Mollecular characterization of antioxidant response in mahi mahi (Coryphaena hippurus) embryos co-exposed to Oil and ultraviolet radiation. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Diamante, G.; Silva Muller, G.; Dias Bainy, A.; and Schlenk, D. Effects of 2- and 6- hydroxylated Chrysene on the development of Danio rerio embryos. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Rojas, M.; Wood, A.; Martinez, N.; Perrichon, P.; Dubansky, B.; and Burggren, W. Exposure to PAHs during early stages of development of the chicken (Gallus gallus) affects cardiovascular structure. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.
Dubansky, B.; Rojas, M.; Perichon, P.; Tazawa, H.; Mach, P.; Verbeck, G.; and Burggren, W. Oil vapors from Deepwater Horizon oil and altered development of avian embryos. 2016 Gulf of Mexico Oil Spill & Ecosystem Science Conference. Tampa, FL. February 1-4, 2016.