have recovered within a few years. This resistance and
resilience is due to () the hardiness of intertidal organisms, ()
their rapid reproduction, and () the relatively rapid removal of
oil from the intertidal zone by waves. The use of cosmetic clean-up
techniques—such as toxic dispersants and steam
cleaning—on oiled shores often does more harm than good and
should be stringently controlled and generally discouraged. Most
biologists who have experience with the effects of such techniques
recommend no attempt at removal unless clearly necessary, and then
only with absorbents or by scraping away oily sand.
SEABED
ORGANISMS
Oil has a
distinct affinity for sediment particles, especially clay minerals
and particles coated with organic matter. Thus, much of the oil
spilled at Santa Barbara met with water masses made turbid by heavy
land run-off, formed denser-than-water, oil-sediment aggregates,
and sank to the bottom of Santa Barbara Channel (). Subtidal
bottoms were the ultimate depository of much of the oil spilled at
Santa Barbara (), at West Falmouth (), in the English Channel (),
and in Chedabucto Bay, Canada ().
While the
British worsened the littoral pollution from Torrey Canyon
through excessive application of toxic detergents, the French sank
the oil before most of it reached shore, thus eliminating obvious
intertidal pollution, but doing potentially serious if not obvious
harm to bottom life. Unfortunately, the seabed organisms' subtidal
habitat, especially soft, sediment-covered bottoms, has been
largely ignored in most post-spill studies. Instead, concern and
research effort has concentrated on the intertidal habitat.
Observations
on the subtidal effects of oil spills were made on larger benthic
(seabed) organisms by skin divers after the Tampico Maru and
Torrey Canyon spills. Extensive kills of Pismo clams,
abalones, starfish, sea urchins, lobsters, and other subtidal
benthic invertebrates occurred within the small cove into which
Tampico oil was spilled (). The persistence of oil in the
cove and the ecological imbalance resulting from the reduction of
grazing invertebrates (mainly sea urchins) and predators altered
the ecology of the cove such that complete recovery could not be
reported seven years after the spill.
Large numbers
of dead and moribund clams, snails, crustaceans, and echinoderms
were noted by divers just off shores oiled by the Torrey
Canyon spill (). The effect of oil itself on the benthic
organisms is impossible to assess because of the overwhelming
effects of toxic dispersants applied to nearby shores.
Approximately 23,500 tons of Torrey Canyon oil was sunk off
the coast of Brittany by the application of 3,000 tons of chalk in
order to prevent it from reaching shore (). Virtually nothing is
known about the effects of this oil on bottom life or its
persistence in the bottom sediments. Large masses of oil on the
bottom have subsequently fouled fishing gear and contaminated
catches off the French coast ().