MIAMI - A new study showed that several Gulf of Mexico fish embryos developed serious defects in
heart development following exposure to crude oil from the Deepwater Horizon oil spill. The study is the
first to analyze the effects of the primary toxic agents released from crude oil on several commercially
important pelagic fish species that spawn in the Gulf of Mexico.
The research team, which included five researchers from the University of Miami (UM) Rosenstiel
School of Marine and Atmospheric Science, concluded that, “losses of early life stages were therefore
likely for Gulf populations of tunas, amberjack, swordfish, billfish, and other large predators that
spawned in oiled surface habitats.”
“This study is the first to understand the impacts of the Deepwater Horizon oil spill on the early life
development of commercially important fish in the Gulf of Mexico,” said Daniel Benetti, UM Rosenstiel
School professor of marine affairs and policy and director of the Aquaculture Program. “The findings can
be applied to fisheries management questions in marine regions where crude oil extraction is prevalent.”
The study, published in the March 25 issue in the journal of the Proceedings of the National Academy of
Science (PNAS), assessed the impacts of polycyclic aromatic hydrocarbons (PAHs), a toxic agent
released from crude oil, from Deepwater Horizon oil samples on embryos of bluefin tuna, yellowfin tuna,
and amberjack. Embryos were exposed to two different oil samples, one collected from surface skimming
operations in the Gulf of Mexico and another from the source pipe attached to the damaged Deepwater
A vast number of the water samples collected at the Deepwater Horizon oil spill site had PAH
concentrations exceeding the toxicity thresholds observed in the study, therefore researchers
demonstrated the potential for losses of pelagic fish larvae during the 2010 Deepwater Horizon disaster.
“Having access to the aquaculture facility and expertise at The Rosenstiel School positioned our team of
UM scientists to address questions regarding the impacts of the 2010 Deep Water Horizon oil spill on
these important pelagic top predators.” said Martin Grosell, Maytag professor of ichthyology at The UM
Rosenstiel School. “The present study is the first of several on the topic to emerge from efforts by
scientists and graduate students at The UM Rosenstiel School.”
The embryos used in the study were collected from research broodstock located at land-based fish
hatcheries in Australia and Panama. Test methods were developed and designed by Dr. Grosell and Dr.
Benetti’s team at The UM Rosenstiel School’s experimental hatchery facility.
Exposure to each oil type produced virtually identical defects in embryos of all three tested species. For
each species, oil exposures caused serious defects in heart development, and abnormalities in cardiac
function, indicating crude oil cardiotoxicity. Bluefin tuna showed the highest percentage of larvae with
the entire suite of defects, and their populations are currently listed by the IUCN as endangered due to
historically low levels.
The Deepwater Horizon oil spill in the northern Gulf of Mexico released more than four million barrels
of crude oil into the surrounding waters during the seasonal spawning window for bluefin and yellowfin
tunas, mahi mahi, king and Spanish mackerels, greater and lesser amberjack, sailfish, blue marlin, and
cobia, all commercially and ecologically important open-ocean fish species.
“Vulnerability assessments in other ocean habitats, including the Arctic, should focus on the developing
heart of resident fish species as an exceptionally sensitive and consistent indicator of crude oil impacts,”
said the paper’s authors.
The paper is titled “Deepwater Horizon Crude Oil Impacts the Developing Hearts of Large Predatory
Pelagic Fish.” The co-authors include Andrew J. Esbaugh, Edward M. Mager, John D. Stieglitz, Daniel
D. Benetti and Martin Grosell from The UM Rosenstiel School of Atmospheric Science; and scientists
from the NOAA Northwest Fisheries Science Center in Seattle, Stanford University’s Hopkins Marine
Lab, and University of the Sunshine Coast in Australia.
Mahi-mahi embryos approximately 8 hours post-fertilization
Mahi-mahi broodstock at the University of Miami Rosenstiel Experimental Hatchery
Mahi-Mahi embryo approximately 36 hours post-fertilization
Photo Credits: John Stieglitz, UM Rosenstiel School of Marine & Atmospheric Science
About the University of Miami’s Rosenstiel School
The University of Miami is the largest private research institution in the southeastern United States. The University’s mission is to provide quality education, attract and retain outstanding students, support the faculty and their research, and build an endowment for University initiatives. Founded in the 1940’s, the Rosenstiel School of Marine & Atmospheric Science has grown into one of the world’s premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. For more information, please visit www.rsmas.miami.edu.