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Oil Spills and the Marine Environment
thereof, of the release of petroleum on fishery productivity as
reflected in commercial catch statistics. Notable among these was a
study undertaken along the coast of Louisiana, which supports very
large and important commercial fisheries as well as a highly
developed petroleum industry. Statistics show no decline in catches
of shrimp, crabs, and fish concommitant with the development of the
petroleum industry (). A decline in the oyster harvest coincident
with the expansion of the petroleum industry in the 1940s has been
attributed to an oyster disease and not oil. While it is tempting
to seize upon this as evidence that oil is not detrimental to the
productivity of a large coastal area, several shortcomings in
fishery catch statistics need to be pointed out. They do not
represent precise reporting, because they fail to take into account
the changing effort and technological advances of fisheries and are
generally not available for the localized areas in which pollution
may be intense. On the other hand, field surveys in Texas indicate
that the production of fish and shrimp is reduced in waters
polluted by large oil-producing operations ().
It is
certainly apparent that the long history of oil production on the
Gulf Coast has not resulted in large scale devastation of
fisheries, but data are inconclusive on the possibility of
important local effects.
PLANKTON
Few
observable effects of oil spills on the small, passively drifting
plants and animals composing the plankton have been uncovered in
post-spill investigations. Some kills were observed during the
Torrey Canyon spill among phytoplankton (plant plankton),
but none among the zooplankton (animal plankton) (). In any case,
the heavy use of chemical dispersants complicates the issue.
Studies following the Santa Barbara blowout could detect no harmful
effects on phytoplanktonic productivity () or zooplankton
populations (). However, because plankton is passively carried
about by water currents, it would be very difficult to discern
effects in the field, especially in open waters like the English or
Santa Barbara Channels.
Laboratory
experiments have generally produced more tangible results, although
the degree to which these results may be extrapolated to natural
conditions is open to question. As early as 1935, Galtsoff et al ()
found that growth in cultures of diatoms, which are important
components of the phytoplankton, was inhibited by high
concentrations of oil. Russian workers have also found that various
diatom species are sensitive to kerosene and fuel oils ().
Recently, researchers have found that water extracts of various
crude and fuel oils and dispersants may inhibit growth of
phytoplankters (), or affect the rate of photosynthesis ().
However, it is difficult to relate the results of most of these
studies to what might actually be experienced in the marine
environment, because either the actual concentrations of
hydrocarbons in the experimental water was unreported or the
concentrations used in the