THE PROBLEM O F OIL POLLUTION O F T H E SEA
255
(Schaeffer). Larger molecules have a greater anaesthetic effect whe
inhaled by mammals, but they are less soluble in water ; C , X I 4 paraffins were narcotic, but above C,, they were iiisufficiently soluble to
have an effect. Goldacre (1968) extended these experiments to include
cycloparaffins and aromatic hydrocarbons, which in low concentrations
have the same effects. With rising concentration, these are increased
irritability followed by anaesthesia, swelling of the plasma membrane,
contraction of the granular cytoplasm, bursting of the membrane and
death. Even after considerable swelling of the membrane, the process
is reversible; the action seems to be due to solubility of the hydrocarbons in the lipid phase of the membrane.
6. Larger plants
Unlike all but the simplest animals, a considerable portion of most
marine plants can be damaged without necessarily destroying their
capacity to recover. Thus the algae affected by a large oil spill are
likely to show less long-term damage, even without the advantageous
elimination of grazing animals which usually follows such an incident
and will be discussed below. The larger brown algae are covered with
a coat of mucilage which is not readily wetted by fresh oils. Topshore
forms which have been emersed for long enough to dry out (for example,
during neap tides) are more readily oiled, especially Pelvetia canaliculata
(L.) Decne. & Thur., which occurs at the highest intertidal levels.
Emulsified oils or " mousses " will cling more readily still and may
cause the overweighted plants to be torn off by waves. On Santa Cruz
Island in the Santa Barbara Channel, spilt crude oil covering the surface
canopy of the kelp Macrocystis pyrifera (L.) Ag. was easily washed of€
by water movement, whereas the heavily oiled smaller alga Hesperophycus harveyanus (Decne.) Setchell & Gardner quickly disappeared
from the rocks (California Department of Fish and Game, 196913, c).
Macrocystis was more seriously affected in the " Tampico Maru "
wreck and toxicity studies carried out with the diesel oil concerned
(North et al., 1964) showed that a 0.1% emulsion almost completely
inhibited photosynthesis in young blades. The effect appeared in three
days, although irreversible damage is caused by exposure to the oil for
6-12 h. A 0.01% emulsion inhibited photosynthesis after a delay of
seven days. Fuel-oil was even more toxic. I n another study, Clendenning and North (1960) showed that 10-100 p.p.m. caused 50% inactivation of photosynthesis in four days, compared with 5-10 p.p.m. cresol
and 10 p.p.ni. phenol. Crosby et al. (1954) investigated the growths of
bacteria, fungi and lower algae in a brackish oil-refinery effluent. They
found that 25-50 p.p.m. naphthenic acid, introduced in an attempt to
255
(Schaeffer). Larger molecules have a greater anaesthetic effect whe
inhaled by mammals, but they are less soluble in water ; C , X I 4 paraffins were narcotic, but above C,, they were iiisufficiently soluble to
have an effect. Goldacre (1968) extended these experiments to include
cycloparaffins and aromatic hydrocarbons, which in low concentrations
have the same effects. With rising concentration, these are increased
irritability followed by anaesthesia, swelling of the plasma membrane,
contraction of the granular cytoplasm, bursting of the membrane and
death. Even after considerable swelling of the membrane, the process
is reversible; the action seems to be due to solubility of the hydrocarbons in the lipid phase of the membrane.
6. Larger plants
Unlike all but the simplest animals, a considerable portion of most
marine plants can be damaged without necessarily destroying their
capacity to recover. Thus the algae affected by a large oil spill are
likely to show less long-term damage, even without the advantageous
elimination of grazing animals which usually follows such an incident
and will be discussed below. The larger brown algae are covered with
a coat of mucilage which is not readily wetted by fresh oils. Topshore
forms which have been emersed for long enough to dry out (for example,
during neap tides) are more readily oiled, especially Pelvetia canaliculata
(L.) Decne. & Thur., which occurs at the highest intertidal levels.
Emulsified oils or " mousses " will cling more readily still and may
cause the overweighted plants to be torn off by waves. On Santa Cruz
Island in the Santa Barbara Channel, spilt crude oil covering the surface
canopy of the kelp Macrocystis pyrifera (L.) Ag. was easily washed of€
by water movement, whereas the heavily oiled smaller alga Hesperophycus harveyanus (Decne.) Setchell & Gardner quickly disappeared
from the rocks (California Department of Fish and Game, 196913, c).
Macrocystis was more seriously affected in the " Tampico Maru "
wreck and toxicity studies carried out with the diesel oil concerned
(North et al., 1964) showed that a 0.1% emulsion almost completely
inhibited photosynthesis in young blades. The effect appeared in three
days, although irreversible damage is caused by exposure to the oil for
6-12 h. A 0.01% emulsion inhibited photosynthesis after a delay of
seven days. Fuel-oil was even more toxic. I n another study, Clendenning and North (1960) showed that 10-100 p.p.m. caused 50% inactivation of photosynthesis in four days, compared with 5-10 p.p.m. cresol
and 10 p.p.ni. phenol. Crosby et al. (1954) investigated the growths of
bacteria, fungi and lower algae in a brackish oil-refinery effluent. They
found that 25-50 p.p.m. naphthenic acid, introduced in an attempt to