A three year study of metal levels in skin biopsies of whales in the Gulf of Mexico after the Deepwater Horizon oil crisis

Abstract

In response to the explosion of the Deepwater Horizon and the massive release of oil that followed, we conducted three annual research voyages to investigate how the oil spill would impact the marine offshore environment. Most investigations into the ecological and toxicological impacts of the Deepwater Horizon Oil crisis have mainly focused on the fate of the oil and dispersants, but few have considered the release of metals into the environment. From studies of previous oil spills, other marine oil industries, and analyses of oil compositions, it is evident that metals are frequently encountered. Several metals have been reported in the MC252 oil from the Deepwater Horizon oil spill, including the nonessential metals aluminum, arsenic, chromium, nickel, and lead; genotoxic metals, such as these are able to damage DNA and can bioaccumulate in organisms resulting in persistent exposure. In the Gulf of Mexico, whales are the apex species; hence we collected skin biopsies from sperm whales (Physeter macrocephalus), short-finned pilot whales (Globicephala macrorhynchus), and Bryde's whales (Balaenoptera edeni). The results from our three-year study of monitoring metal levels in whale skin show (1) genotoxic metals at concentrations higher than global averages previously reported and (2) patterns for MC252-relevant metal concentrations decreasing with time from the oil spill.

One Environmental Health: an emerging perspective in toxicology

“…The expedition collected samples of resident Bryde’s whales ( Balaenoptera edeni ) and resident sperm whales. These data showed oil-related metals (including Cr) were elevated in 2010 and declined over a three-year period after the spill 50 , 51 , implicating the marine oil industry as one potential anthropogenic source of metal pollution in the marine ecosystem.…”

“…Data show increasing levels of pollution in tissues from marine mammals. Metals, in particular, are a growing concern, and data show whales are exposed to high levels of metals, such as chromium (Cr), as shown by skin tissue concentrations obtained from biopsies of healthy free-ranging whales 50 – 54 . Metal toxicology in whales is generally poorly understood, largely because of a lack of controlled toxicology studies in whale-specific models and difficulty in accessing the animals themselves.…”

“…For example, the research vessel Odyssey provided a global baseline for metal levels based on biopsies collected from the skin of free-ranging sperm whales. This pioneering work found metals are ubiquitous in all 16 regions surveyed across the ocean 50 – 54 . The data show variability in levels by region and metal.…”

“…A subsequent voyage by the research vessel Odyssey also tested the levels of Cr in the aftermath of the Deepwater Horizon oil rig explosion on 20 April 2010 that released over 779 million liters of crude oil into the Gulf of Mexico over the course of 87 days 50 , 51 . The expedition collected samples of resident Bryde’s whales ( Balaenoptera edeni ) and resident sperm whales.…”

Metal Levels in Whales from the Gulf of Maine: A One Environmental Health approach

“…Biopsies were collected as previously described [10]. Briefly, biopsies were collected from the flank of the whale's back using a stainless steel tip approximately 20 mm in length and 6 mm in diameter.…”