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Some shores in Cornwalll following the Torrey Canvon oil spill in 1967 ,
where rocks
previously covered with barnacles , and limpets ,
became dominated by seeweeds , FUCUS, and this change persisted
for several years . This change was not caused by the stranded oil , but
by the very toxic oil spill dispesrants then in use .
Most critically , limpets were eliminated . In the absence of these
dominant herbivores , diatoms and algae colonized the rocks and an
algal succession continued unchecked during the summer following
the oil spill . More than ten years after the spill , although barnacles
domination of the rocky shore community had been restored , the
associated fauna appeared to be less rich and varied than before.
Soft substate :
Oil does not penetrate finely compacted sediments , except down
worm or clam burrows . It may penetrate coarse mobile beaches , but it
is rapidly washed out again by wave action . Oil does penetrate gravel
and coarse sandy beaches , and is likely to remain buried indefinitely
where it may form asphalte layers , but such habitats have a small
fauna and the biological consequences are minor.
Subtidal sediments may become contaminated by oil if it is carried to
the seabed attached to sediment particles , there it may remain ,
undegraded , and continue to cause damage for along time.
Plankton :
Plankton, and especially the nuston living in the top few centimetres of
the sea, might be supposed to be particularly at risk because it is
exposd to the highest
concentration of water-solubl constituents
leaching from floating oil.
Fixed vegetation :
Salt marshes , sea grass beds , and in the tropics , mangrove swamps
are low energy areas likely to trap oil , and the plants that form the
basis for these ecosystems suffer accordingly.