282
A. NELSON-SMITH
5% after one hour’s immersion in undiluted B P 1002, while that of
topshells and other winkles lay between 75% and 100%. Mortality of
the topshell Monodonta lineata was less than 20% after treatment with
80% BP 1002. Littorina obtusata and Gibbula umbilicalis (da Costa)
were the most sensitive in these tests, with L. saxatilis, G. cineraria (L.)
and the dog-whelk Nucella lapillus (L.) showing an intermediate
response. Simpson offered as a partial explanation of differences in
bivalve sensitivity the “ persistent gape ” of cockles, which do not
close completely as do oysters (Ostrea edulis) and mussels (Mytilus
edulis). Crapp applied the emulsifier to actively crawling gastropods,
but noted that mortalities are much lower if they are first shaken to
make them close tightly. Spooner (1968a) suggested that a heavy dose
of emulsifier might have less effect than a light one, because it stimulates those animals which can to close up quickly. Crapp also reported
marked seasonal changes ; for example, L. obtusata collected at the end
of the winter were exceptionally sensitive.
Perkins (1968a) also studied the effect of brief exposure to a high
concentration (25%) of various emulsifiers which only some winkles
and whelks survived. He found that the median lethal concentration
of BP 1002 over 24 h is greater than 3 000 p.p.m. for Littorina saxatilis,
greater than 2 000 p.p.m. for L. littorea, 1 000 p.p.m. for Nucella and
250 p.p.m. for L. obtusata. Mytilus is fairly resistant a t 90 p.p.m. over
24 h, but in a 96 h test its LC,, dropped to 2.5 p.p.m. ; the sea-star
Asterias rubens survived 40 p.p.m. and the shore-crab Carcinus maenas,
about 30 p.p.m. The other common shore animals which he tested are
even less resistant. Portmann and Connor showed much the same
results. Hermit crabs Eupagurus bernhardus (L.), brown shrimps
Crangon crangon and pink shrimps Pandalus montagui are particularly
sensitive (LC,, about 5 p.p.m.). Tests at the Plymouth laboratory
(Smith, 1968) revealed that a variety of sublittoral crabs are killed by
BP 1002 at 5-25 p.p.m., bpt molluscs failed to survive one-tenth these
concentrations. Wilson (1968a) found that larvae of the tubeworm
Sabellaria spinulosa Leuckart were killed within a day or two by 2.5
p.p.m. of this emulsifier. Although irritated by 0.5-1.0 p.p.m. they
apparently survived, but later became unhealthy and died in 4-6
weeks. Corner et al. (1968) found that adults of the barnacle Elminius
modestus are killed by 10-100 p.p.m., although 5-10 p.p.m. slows down
their feeding; 3p.p.m. slows down the swimming of the settling
(cypris) larvae but, again, only 0.5-1.0 p.p.m. inhibits the development
of younger (nauplius) larvae. Developing his earlier work, Perkins
(1968b) showed that whelks Buccinum undatum, which had apparently
recovered from brief immersion in 25% emulsifier, died as much as four
A. NELSON-SMITH
5% after one hour’s immersion in undiluted B P 1002, while that of
topshells and other winkles lay between 75% and 100%. Mortality of
the topshell Monodonta lineata was less than 20% after treatment with
80% BP 1002. Littorina obtusata and Gibbula umbilicalis (da Costa)
were the most sensitive in these tests, with L. saxatilis, G. cineraria (L.)
and the dog-whelk Nucella lapillus (L.) showing an intermediate
response. Simpson offered as a partial explanation of differences in
bivalve sensitivity the “ persistent gape ” of cockles, which do not
close completely as do oysters (Ostrea edulis) and mussels (Mytilus
edulis). Crapp applied the emulsifier to actively crawling gastropods,
but noted that mortalities are much lower if they are first shaken to
make them close tightly. Spooner (1968a) suggested that a heavy dose
of emulsifier might have less effect than a light one, because it stimulates those animals which can to close up quickly. Crapp also reported
marked seasonal changes ; for example, L. obtusata collected at the end
of the winter were exceptionally sensitive.
Perkins (1968a) also studied the effect of brief exposure to a high
concentration (25%) of various emulsifiers which only some winkles
and whelks survived. He found that the median lethal concentration
of BP 1002 over 24 h is greater than 3 000 p.p.m. for Littorina saxatilis,
greater than 2 000 p.p.m. for L. littorea, 1 000 p.p.m. for Nucella and
250 p.p.m. for L. obtusata. Mytilus is fairly resistant a t 90 p.p.m. over
24 h, but in a 96 h test its LC,, dropped to 2.5 p.p.m. ; the sea-star
Asterias rubens survived 40 p.p.m. and the shore-crab Carcinus maenas,
about 30 p.p.m. The other common shore animals which he tested are
even less resistant. Portmann and Connor showed much the same
results. Hermit crabs Eupagurus bernhardus (L.), brown shrimps
Crangon crangon and pink shrimps Pandalus montagui are particularly
sensitive (LC,, about 5 p.p.m.). Tests at the Plymouth laboratory
(Smith, 1968) revealed that a variety of sublittoral crabs are killed by
BP 1002 at 5-25 p.p.m., bpt molluscs failed to survive one-tenth these
concentrations. Wilson (1968a) found that larvae of the tubeworm
Sabellaria spinulosa Leuckart were killed within a day or two by 2.5
p.p.m. of this emulsifier. Although irritated by 0.5-1.0 p.p.m. they
apparently survived, but later became unhealthy and died in 4-6
weeks. Corner et al. (1968) found that adults of the barnacle Elminius
modestus are killed by 10-100 p.p.m., although 5-10 p.p.m. slows down
their feeding; 3p.p.m. slows down the swimming of the settling
(cypris) larvae but, again, only 0.5-1.0 p.p.m. inhibits the development
of younger (nauplius) larvae. Developing his earlier work, Perkins
(1968b) showed that whelks Buccinum undatum, which had apparently
recovered from brief immersion in 25% emulsifier, died as much as four