OIL AND RELATED CHEMICALS - Marine Pollution: What Everyone Needs to Know - page 75

mucus production, smaller gonads, and dead areas on cor-
als, even in reefs that had not been in direct contact with the
oil. Hydrocarbons in reef sediments were correlated with
the degree of injury and with reduced growth. The probable
cause of high injury was chronic exposure to sediments mixed
with partially degraded oil that had moved from mangroves
onto reefs. There was no evidence of recovery five years after
the spill. Years later, reduced colony size and decreased size
of gonads were seen, which can reduce the number of repro-
ductive colonies. Oil damages the coral reproductive system
resulting in fewer breeding colonies, fewer ovaries per animal,
fewer larvae, premature release of larvae, abnormal behav-
ior of larvae, and lower growth rates. Dispersants appear to
increase the damage done by the oil.
Fish and Crabs
Oil has major impacts on fish embryos that may produce
delayed effects when they become adults. Pink salmon that
had been exposed as embryos to Exxon Valdez oil and survived
to migrate to the ocean, returned from the sea at only half
the normal rate. These adults showed reproductive impair-
ment and their embryos had reduced survival. Thus, the
second generation was affected by the exposures their par-
ents had had as embryos. Oil spill effects on fish eggs have
been intensively studied, with studies initially focusing on
the water-soluble fraction (WSF) containing mostly one- and
two-ringed aromatic hydrocarbons. After the Exxon Valdez
spill, which occurred during the breeding season of many
fish, fish embryos were exposed to partially weathered oil
including the larger three-, four-, and five-ringed hydrocar-
bons, which had been thought to be less toxic than the WSF.
These PAHs affected pink salmon and herring eggs at concen-
trations far lower than had been previously known to be toxic.
Ronald Heintz and colleagues found more deformities and
chromosomal abnormalities in embryos from oiled than from