Is Exposure to Macondo Oil Reflected in the Otolith Chemistry of Marsh-Resident Fish?

Abstract

Genomic and physiological responses in Gulf killifish (Fundulus grandis) in the northern Gulf of Mexico have confirmed oil exposure of resident marsh fish following the Macondo blowout in 2010. Using these same fish, we evaluated otolith microchemistry as a method for assessing oil exposure history. Laser-ablation inductively-coupled-plasma mass spectrometry was used to analyze the chemical composition of sagittal otoliths to assess whether a trace metal signature could be detected in the otoliths of F. grandis collected from a Macondo-oil impacted site in 2010, post-spill relative to pre-spill, as well as versus fish from areas not impacted by the spill. We found no evidence of increased concentrations of two elements associated with oil contamination (nickel and vanadium) in F. grandis otoliths regardless of Macondo oil exposure history. One potential explanation for this is that Macondo oil is relatively depleted of those metals compared to other crude oils globally. During and after the spill, however, elevated levels of barium, lead, and to a lesser degree, copper were detected in killifish otoliths at the oil-impacted collection site in coastal Louisiana. This may reflect oil contact or other environmental perturbations that occurred concomitant with oiling. For example, increases in barium in otoliths from oil-exposed fish followed (temporally) freshwater diversions in Louisiana in 2010. This implicates (but does not conclusively demonstrate) freshwater diversions from the Mississippi River (with previously recorded higher concentrations of lead and copper), designed to halt the ingress of oil, as a mechanism for elevated elemental uptake in otoliths of Louisiana marsh fishes. These results highlight the potentially complex and indirect effects of the Macondo oil spill and human responses to it on Gulf of Mexico ecosystems, and emphasize the need to consider the multiple stressors acting simultaneously on inshore fish communities.

Fishery closures, more than predator release, increased persistence of nearshore fishes and invertebrates to the Deepwater Horizon oil spill

“…However, none of these pathways are mutually exclusive, and the impacts of the oil spill itself were mediated through other stressors like oil redistribution by storms and changes in freshwater discharge to keep oil out of marshes and bays (Able et al 2015;López-Duarte et al 2016). For species that are targets of major fisheries (menhaden, blue crab, shrimp), fishing cessation likely played a key role in stability because it is a major component of total mortality.…”

Past and Contemporaneous Otolith Fingerprints Reveal Potential Anthropogenic Interferences and Allows Refinement of the Population Structure of Isopisthus parvipinnis in the South Brazil Bight

“…Those temporal variations in Pb concentration were also registered in sediment cores: a reduction in SSP and PR from the 1970s to 2000–2010s [ 87 , 88 ] in contrast to an increase in CSP [ 89 ]. The literature also shows the anthropogenic impacts of oil exposure, industrial, gasoline, sewage, and agriculture input not only in Pb concentration in otoliths but also in Ba, Mg, Mn, Na, Sr, and Zn [ 90 , 91 , 92 , 93 , 94 ]. Anthropogenic climate changes, mainly after the 1950s, are also affecting marine biodiversity, ecosystems, fisheries, and ecosystem services [ 95 , 96 , 97 ].…”