Pollution on Mytilus edulis — Schafer 
the free amino acids of transfer from a clean 
area to a polluted one. 
ACKNOWLEDGMENTS 
The author is indebted to the administration 
of the Allan Hancock Foundation for the use 
of laboratory facilities. This study was supported 
by a research grant from the United States Pub- 
lic Health Service of the National Institute of 
Health, no. RG-491L 
MATERIALS AND METHODS 
In the present study the wharf mussel, Mytilus 
edulis , was selected for investigation. Its wide 
occurrence made it easily available from a vari- 
ety of areas of varying environmental condi- 
tions. Because of its sessile nature and presence 
on floats, it was possible to use specimens which 
had been constantly subjected to the conditions 
prevailing in the area from which it was taken. 
No attempt was made to differentiate sexes or 
size of specimens, as preliminary tests showed 
no amino acid differences in these respects in 
this species. 
Comparisons of free amino acids were made 
on muscle tissue of animals from ( 1 ) different 
polluted areas, (2) an area considered free of 
pollution, and (3) from animals transferred 
from a nonpolluted area to areas of pollution. 
In addition, muscle tissue hydrolysates of speci- 
mens from the clean area were compared with 
hydrolysates of individuals from the polluted 
areas. 
The sites chosen for study were a small yacht 
marina in the Los Angeles Harbor, designated 
here and in previous studies of water pollution 
as LA. 7; a dock in slip I of the main channel, 
identified as LA. 39; and a third area of pollu- 
tion in Cerritos Channel of Long Beach Harbor, 
LB. 23 (Fig. 1). 
Specimens from a nonpolluted area were 
taken at Tomales Bay, north of San Francisco. 
To establish the normal free amino acid pat- 
tern of M. edulis , specimens were taken from 
the Tomales Bay area, returned to the laboratory 
alive where muscle tissue was excised, quick 
frozen with dry ice, lyophilized, and extracted 
with 70'% cold ethanol. Hydrolysates were pre- 
pared by hydrolysis of excised muscle with 6 N 
247 
Fig. 1. Areas of pollution from which collections 
were made. 
HC1 and desalted with 70% cold ethanol. Best 
results were obtained by serial studies using dif- 
ferent amounts of a given extract. By limiting 
the amount of extract on one paper to a minimal 
quantity necessary for resolution, those amino 
acids ordinarily present in quantities so large 
that adjacent spots tended to merge upon de- 
velopment remained distinct and compact. By 
placing large amounts of extract on a second 
paper those amino acids present in trace quanti- 
ties could be detected upon development, while 
those present in large amounts, already deter- 
mined in the first run, merged and became in- 
distinguishable. 
To determine whether or not differences in 
free amino acid metabolism existed in M. edulis 
under conditions of pollution, specimens were 
collected from polluted areas mentioned above, 
and treated in an identical manner. 
Assuming that a difference might exist be- 
tween these two groups with respect to free 
amino acids, as it had in other forms, an attempt 
was made to learn whether a change would occur 
following transfer from the nonpolluted to the 
polluted areas. Specimens from Tomales Bay 
were tagged for identification, placed in plastic 
containers through which a free exchange of 
water was possible, and placed in the polluted 
