Correspondence/Rebuttal pubs.acs.org/est
Response to Comment on “Multi-Tissue Molecular, Genomic, and Developmental Effects of the Deepwater Horizon Oil Spill on Resident Gulf Killifish (Fundulus grandis)”
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shared by other species that utilize that same habitat.1 Furthermore, by using oiled sediments collected during August 2010 and 2011, our observations relate findings in the lab to two successive breeding seasons in this spill-impacted bay.1 Pearson’s highlight of other studies that fail to indicate oil spill impacts on juvenile fish from sea grass beds bears little relevance on the implications of our research findings.1,5 The areas in those studies highlighted by Pearson were either not heavily oiled by the DHOS or were not suitable habitats for Fundulus grandis.6,7 In contrast, the locations sampled for our studies included the heavily oiled Grande Terre Island and Barataria Bay marshland of Southern Louisiana that were ideal habitat for Fundulus species, and which experienced some of the most lingering effects of the DHOS measured to date.1,2 Furthermore, chemical analysis of sediment samples used in the exposures was presented, and those data support a relationship between total polyaromatic hydrocarbons (and alkanes) in sediments and biological effects.1 Pearson also chose this forum to debate the relevance of decades of research findings on the Exxon Valdez oil spill (EVOS).5 We decline to debate the effects of the EVOS on fish populations in this forum, other than to highlight much evidence supports population-level impacts to fish, birds, and mammals in the years that followed the EVOS (see8 for review). Though the DHOS is unique in many ways compared to other spills, it is the largest marine oil spill in history, easily dwarfing the EVOS.9 Data from our studies are consistent with sediment contamination from the DHOS adversely affecting fitness parameters in exposed developing Gulf killifish, and such fitness impacts are likely to affect population vital rates.1,2 Whether these impacts ultimately emerge as population-level effects, as was evident in many species following the EVOS,8 remains to be seen. We have observed that industry-hired scientists consistently demand a completely connected chain of causality, from chemical exposure through population measurements, from individual studies, to assent to possible significant effects on natural resources. As a consequence, industry is unlikely to accept the findings of probable damage to fish populations from toxic chemicals, even when existing evidence is clearly consistent with such effects. The Gulf of Mexico holds much aesthetic, ecological, and economic importance for the region and the nation, as do other regions exploited for oil extraction. Because the lives and livelihoods of many people are intimately tied to these environments, the public should expect high standards of environmental stewardship and accountability from the corporations that are granted access to these globally important resources.
n our studies, functional genomic responses clearly indicate exposures of resident and experimental animals to the toxic components of oil spilled from the Deepwater Horizon oil spill (DHOS) disaster, in the field and laboratory.1,2 Such molecular responses are tightly linked with impacts on fitness parameters including embryonic survival and developmental deformities.1 Sublethal effects of crude oil exposure, such as the developmental abnormalities in embryonic and larval fish, can be causally linked to a reduction in fitness and a decrease in survival of the adult fish.1,3,4 As such, Gulf killifish (Fundulus grandis) populations, and other animals that rely on the same coastal marsh for reproduction, likely faced a considerable challenge to reproductive success in field sites heavily oiled during the DHOS.1 Exposure to sediments collected from heavily oiled coastal marsh in Southern Louisiana caused cardiovascular defects in Gulf killifish embryos during controlled laboratory studies, and developmental impacts such as delayed hatch and reduced percent hatch rate, collectively reducing the percent of the total embryos reaching the free-swimming larval stage.1 In fact, of the small percentage of surviving exposed embryonic fish that hatched during exposure to the Grande Terre, Louisiana sediments, all had severe cardiac edema and were significantly smaller and listless after hatch. We concur that no such fish could survive to adulthood in the field. Though we did not directly test for population-level effects, it is perfectly reasonable, contrary to the assertions of Pearson,5 that fitness impacts are likely to affect population vital rates, as we imply in our paper. We agree with much of Pearson’s comment that there is much to be learned about the causal links between organismallevel effects seen in the field and laboratory and ecosystem level impacts, or to the impacts on fisheries.5 We do not dispute that it remains a challenge to link biological effects at the organism level to the biology and economics of fisheries, considering the complexity of natural systems and the pragmatism that dictates our experimental reality. As such, we contend that efforts should continue well after this publication to monitor oiled sites in the northern Gulf of Mexico for evidence of population level effects; impacts that could take years to emerge. To this extent, integrated field-based and laboratory-based experiments that link molecular responses through to fitness end points represent the state-of-the-art for environmental impact assessment; such approaches identify regions and particular sediments oiled by the DHOS that are of potential concern to the health of resident individuals and populations. In our studies, sediments collected from Gulf killifish breeding habitat in regions directly oiled by the DHOS, were used in laboratory exposures. By using the same sediments that Gulf killifish were exposed to during the peak summer months of development in the field, our laboratory observations can be linked to the field, and the impacts that we observe in killifish are likely to be © 2014 American Chemical Society
Benjamin Dubansky*,†,∥ Andrew Whitehead‡
Published: June 19, 2014 7679
dx.doi.org/10.1021/es501185a | Environ. Sci. Technol. 2014, 48, 7679−7680
Environmental Science & Technology
Correspondence/Rebuttal
Charles D. Rice§ Fernando Galvez∥ †
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University of North Texas, Department of Biological Sciences, Developmental Integrative Biology Research Cluster, 225B Life Sciences Building, Denton, Texas 76203, United States ‡ University of California, Davis, Department of Environmental Toxicology, 4121 Meyer Hall, Davis, California 95616, United States § Clemson University, Department of Biological Sciences, 132 Long Hall, Clemson, South Carolina 29634, United States ∥ Louisiana State University, Department of Biological Sciences, 216 Life Sciences Building, Baton Rouge, Louisiana 70803, United States
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Dubansky, B.; Whitehead, A.; Miller, J.; Rice, C. D.; Galvez, F. Multi-tissue molecular, genomic, and developmental effects of the Deepwater Horizon oil spill on resident Gulf killifish (Fundulus grandis). Environ. Sci. Technol. 2013, 47, 5074−5082. (2) Whitehead, A.; Dubansky, B.; Bodinier, C.; Garcia, T. I.; Miles, S.; Pilley, C.; Raghunathan, V.; Roach, J. L.; Walker, N.; Walter, R. B.; Rice, C. D.; Galvez, F. Genomic and physiological footprint of the Deepwater Horizon oil spill on resident marsh fishes. Proc. Natl. Acad. Sci. U. S. A. 2012, 109 (50), 20298−20302. (3) Hicken, C. E.; Linbo, T. L.; Baldwin, D. H.; Willis, M. L.; Myers, M. S.; Holland, L.; Larsen, M.; Stekoll, M. S.; Rice, S. D.; Collier, T. K.; Scholz, N. L.; Incardona, J. P. Sublethal exposure to crude oil during embryonic development alters cardiac morphology and reduces aerobic capacity in adult fish. Proc. Natl. Acad. Sci. U. S. A. 2011, 108 (17), 7086−7090. (4) Heintz, R. A.; Rice, S. D.; Wertheimer, A. C.; Bradshaw, R. F.; Thrower, F. P.; Joyce, J. E.; Short, J. W. Delayed effects on growth and marine survival of pink salmon (Oncorhynchus gorbuscha) after exposure to crude oil during embryonic development. Mar. Ecol.Prog. Ser. 2000, 208, 205−216. (5) Pearson, W. H. Comment on “Multitissue Molecular, Genomic, and Developmental Effects of the Deepwater Horizon Oil Spill on Resident Gulf Killifish (Fundulus grandis)”. Environ. Sci. Technol. 2014, DOI: 10.1021/es405220v. (6) Moody, R. M.; Cebrian, J.; Heck, K. L., Jr. Interannual recruitment dynamics for resident and transient marsh species: Evidence for a lack of impact by the Macondo Oil Spill. PLoS One 2013, 8 (3), e58376. (7) Fodrie, J. F., Heck, K. L. Jr., Response of coastal fishes to the Gulf of Mexico oil disaster. PLoS One 2011, 6 (7). (8) Peterson, C. H.; Rice, S. D.; Short, J. W.; Esler, D.; Bodkin, J. L.; Ballachey, B. E.; Irons, D. B. Long-term ecosystem response to the Exxon Valdez oil spill. Science 2003, 302 (5653), 2082−2086. (9) Peterson, C. H.; Anderson, S. S.; Cherr, G. N.; Ambrose, R. F.; Anghera, S.; Bay, S.; Blum, M.; Condon, R.; Dean, T. A.; Graham, M.; Guzy, M.; Hampton, S.; Joye, S.; Lambrinos, J.; Mate, B.; Meffert, D.; Powers, S. P.; Somasundaran, P.; Spies, R. B.; Taylor, C. M.; Tjeerdema, R.; Adams, E. E. A tale of two spills: Novel science and policy implications of an emerging new oil spill model. Bioscience 2012, 62 (5), 461−469.
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