OIL AND RELATED CHEMICALS - Marine Pollution: What Everyone Needs to Know - page 72

over the leaking well. Thus, water that already had a bacterial
community got a second input of hydrocarbons, and the micro-
organisms that had already bloomed and degraded hydrocar-
bons immediately attacked and degraded the new oil.
In addition to the one-fourth of the oil that was degraded,
the Unified Command, led by the US Coast Guard, physi-
cally removed about a third of it, and burning at the surface
removed another 5%. However, the oil budget they published
was criticized as incomplete. Samantha Joye of the University
of Georgia said that data she collected showed that oil at depth,
as well as gas, lingered much longer than the oil budget sug-
gested. There was also the residual oil unaccounted for, some
of which is still out there—on or under beaches, in marshes,
down on the bottom, or floating as tar balls.
What were the overall impacts to the ecology of the Gulf?
At the time this topic is being written, mostly in 2012 and 2013
there have been relatively few published reports on effects,
as many scientists are not permitted to publish their findings
and it is too early to say anything about long-term effects on
the Gulf ecosystems. Three years after the accident, fish in
the Gulf were found with high levels of petroleum hydrocar-
bons in their tissues, presumably because dispersants made
them more available. The floating brown alga Sargassum is an
oasis of biodiversity and productivity, functioning as habitat
for a diverse collection of attached and mobile animals. The
Deepwater Horizon oil contacted much of the Gulf of Mexico's
Sargassum . Aerial surveys during and after the spill showed
loss and subsequent recovery of the seaweed. Dispersant
and dispersed oil caused it to sink and reduced the local dis-
solved oxygen. Sargassum accumulated oil, exposing animals
to toxicants; application of dispersant sank the Sargassum ,
thus removing the habitat and transporting oil and dispersant
deeper; and low oxygen levels around the algae stressed the
resident animals.