INTRODUCTION
There is mounting evidence that human activity re-
sults in localized increases in the environmental levels
of trace metals such as Pb, Hg, Cd, and that such increases
are reflected in higher levels of these metals in organisms
(Patterson, 1965). In order to be able to detect such in-
creases, and to distinquish the effects of human activity
from normal background levels, baseline values must first
be determined in both environment and in representative
species. Hermit crabs of the genus Pagurus are abundant
and ubiquitous on Californian rocky shores and represent
forms that can be studied both in undisturbed regions and
in areas heavily influenced by man. Pagurus samuelis, a
species which lives higher in the intertidal than any
other hermit crab in Central California (Bollay, 1964), was
selected for study. It is more easily obtained than the
local edible crustaceans (eg. Cancer magister, the market
crab or Pandalus jordani, the ocean shrimp; see Frey, 1971).
Analyses were made of six metals (Ag, Cd. Cu, Mn, Pb. Zn).
Specimens from various locations were tested to determine
if the type of location correlates with changes in the
heavy metal concentrations of a Pagurus population.
Previous studies of trace metals in decapods are scanty.
Bowen (1966) lists the following concentrations for Crustacea
in general (in ppm dry animal tissue): Cd, O.15 ppm; Cu.
50 ppm; Mn, 2 ppm; Pb, 0.3 ppm; Zn, 200 ppm. Goldberg
(1967) cites a study in which the zinc level in a Texas
sample of the Blue crab Callinectes sapidus was determined
to be 46 ppm. In another instance he quotes that Cancer
pagurus has 35.0 ug/g (ppm) of Cu. It must be remembered,
however, that differences in concentration factors for a
given element in organisms exist among individuals and
species as well as among families (Goldberg, 1957).
MATERIALS AND METHODS
Pagurus samuelis were collected from eight areas on
the California coast between San Francisco and the Palos
Verdes Peninsula. (Fig. 1)
A) Pacificas latitude 37° 35'; near the San Pedro
Sewage Treatment Plant and outfall.
B) Monterey Harbor: latitude 36° 36', under Fisher-
man's Wharf, Monterey Harbor, and for about 100
meters northwest.
This area is within the Coast
Guard breakwater.
C) Mussel Point, Pacific Grove: latitude 36° 37
east of Hopkins Marine Station of Stanford Univer-
sity.
D) Point Pinos, Pacific Groves latitude 36° 38°
44
within 60 meters of the outfall from the Pacific
Grove Sewage Treatment Plant.
Carmel Mission Point, center of Carmel Bay:
latitude 36° 32', south side of the point, about
500 meters north of the outfall from the Carmel
Sewage Treatment Plant.
Monastery Beach, south end of Carmel Bay: latitude
F)
36° 31', about 700 meters south of the outfall
from the Carmel Sewage Treatment Plant. The cur-
rents run generally southward from the outfall.
Malpaso Creek, Monterey County: latitude 36° 28'
G)
about 500 meters south of the creek on undeveloped
private land which is locked to the general public.
White's Point, Palos Verdes Peninsula: latitude
H)
33° 43' from the beach closest to the Los Angeles
County sewer outfall. This is one of the largest
primary treatment outfalls on the West Coast.
Samples were all taken at low tide near the upper
intertidal limit of the brown alga Egregia. One hundred
Pagurus samuelis were taken from each study area. In the
laboratory, they were removed, without injury, from their
shells by removing the tip of the shell and poking the
crab out. When possible five pooled samples of males and
five pooled samples of females were tested from each area.
Among the females, only ovigerous individuals were used.
and the eggs borne externally were removed before diges-
tion to assure a more uniform population. For each sam-
ple three individuals were pooled to insure adequate dry
weight. The individual crabs used ranged in size from
0.2 to 0.6 grams dry weight.
The method used for digesting the crabs is a modifi-
cation of the Middleton and Stuckey technique (Christian
and Feldman, 1970). Each sample was weighed wet and then
dried at least overnight at 80° C. It was then weighed
dry and pulverized with a ceramic mortar and pestle.
These and all all other glassware used had been previously
cleaned with 4-6 N HNO for 20 minutes. An aliquot (O.5-
0.6g.) of the powder was weighed out to 1.0000g. on a
Sartorius balance and placed in a 30 ml. beaker. To the
powder was added 6 to 8 ml. of 90% HNO3 (dropwise at
first). The beaker was then covered with a watchglass
and simmered, just under boiling, for one to three hours
until the organic matter was well broken down. The watch-
glass was removed and the solution allowed to evaporate
to approximately 4 ml. Four or five ml. of 30% H02 was
added (slowly to avoid bubbling over) and then heat was
applied for another 15 to 30 minutes. Whenever the solu-
tion was still cloudy the last two steps were repeated..
This resulted in a clear sample. Finally the solution
was diluted to 25 ml. with distilled water. At this
point the solution was tested for Ag, Cd, Cu, Mn, Pb, and
Zn with a Perkin-Elmer 303 Atomic Absorption Spectro-
photometer (Perkin-Elmer, 1968, 1971).
Many problems were incurred in attempting to get
reliable values for concentrations of lead. In all cases
the samples were measured at a wavelength of 285) which is
a very steady, easily readable line. Many of the samples
were also run at 218.5/, a line which fluctuated a great
deal on the a. a. spectrophotometer. In some instances
the machine could not be zeroed adequately and measurements
of the same sample taken two minutes apart differed radi-
cally. In the cases where measurements at 218.5 were
completed the concentration levels measured were about one-
third to one-half those measured at 285). Probably the
best assumption is that the true concentration value in
each lies somewhere between the two.
RESULTS AND DISCUSSION
Concentrations of the six heavy metals considered are
shown in Table 1 and Figs. 2-6. The results show that
Pagurus samuelis ooncentrates the six metals to differing
degrees and that levels of occurrence varied with the loca-
tion. Significance of the differences between means of
the sample populations were determined with the Student's
t-test (Simpson, et. al., 1960). The graphs of Figs. 2-7
0
are based on the data of Table 1.
The females were compared to the males at each loca-
tion (Figs. 8 & 9).. In most cases the differences be-
tween sexes were not statistically significant.
Lead (Fig, 2)
Lead acts as a cumulative poison in mammals where it
is moderately toxic (Bowen, 1966). While absolute values
are to be regarded as approximate the relative amounts at
the various locations are probabCly reliable. The Mussel
Point and Monterey Harbor samples are not significantly
different; however, the Mussel Point results differ signi-
ficantly from those at the remaining six locations, which
are similar.
Cadmium (Fig. 3)
Cadmium is a cumulative poison in mammals and moderately
toxic to all organisms (Bowen, 1966). Mean levels of Cd
in P. samuelis were highest at Pacifica, and (contrary to
expectations) lowest at White's Point. The latter was
significantly lower than all the others at the,Ol level.
Cadmium may precipitate readily and the Los Angeles out-
fall is a mile offshore with another mile of diffuser pipe
beyond that. It may be that the Cd is precipitating out
before reaching the intertidal zone.
Voe
Manganese (Fig, 1
Manganese is only moderately toxic, and in small
amounts is essential to all organisms. It is known to
activate numerous enzymes (Bowen, 1966), and is necessary
for normal growth, skeletal development, reproductive
performance, and functioning of the central nervous sys-
tem (Christian and Feldman, 1970). The levels of man-
ganese found at Pacifica and at White's Point are signi-
ficantly different from one another at the.Ol level and
both are much higher than the levels found at the other
six locations. The Monterey Harbor and Point Pinos values
are similar but differ significantly from the level for
Mussel Point which geographically lies in between them.
Carmel Mission Point and Malpaso Creek have similar levels
but differ significantly from Monastery Beach values.
Silver (Fig, 5)
Silver may be accumulated as an environmental contami-
nant. It can inhibit or inactivate a number of enzymes by
reacting with thiol groups on the enzyme at or near the ac-
tive site. Silver is rarely found in plants (Christian
and Feldman, 1970) so probably is not entering the Pagurus
through the algal part of their omnivorous diet. Point
Pinos shows the highest levels of silver while Carmel
Mission Point shows the lowest. The Point Pinos, Pacifica.
and Carmel Mission Point samples represent populations
which differ at the.Ol level of significance. The
samples from the Mussel Point and White's Point popula-
tions are not significantly different; the same is true
of the populations at Monterey Harbor, Malpaso Creek, and
Monastery Beach with regard to silver concentrations.
Zinc (Fig, 6)
Zinc has a low toxicity to mammals and is an essential
nutrient for all plants and animals (Bowen, 1966; Christian
and Feldman, 1970). The levels of zinc at Monterey Harbor
were significantly higher than those at all other loca-
tions (.Ol level). These high readings at the Harbor are
probably being influenced by the Monterey sewage plant
effluent which on May, 1971 put into Monterey Bay about
7500 grams/day of Zn (Vieth, 1971). This effluent is
dumped into the Bay approximately 2000 meters from the
Harbor, and periodically the currents run from the out-
fall toward the Harbor. Another major source of zinc in
the Harbor is probably the zinc used externally on small
ships to prevent electrolysis of the shaft and propellor.
Point Pinos, White's Point, Carmel Mission Point, and
Pacifica were statistically similar and ranked second
highest in Zn concentrations. All four are fairly close
to sewage outfalls.
Gopper (Eig.2
While oopper is essential to all organisms, abnor-
mally high levels may be highly toxic to invertebrates
and moderately toxic to mammals (Bowen, 1966). Pagurus
contains copper in its hemocyanin. Levels of Cu obtained
at Carmel Mission Point, Monastery Beach, and Malpaso
Creek were statistically similar and were the lowest.
If this level is accepted as a general indication of the
level necessary for Pagurus samuelis, then the other val-
ues are much in excess of this. White's Point and the
Monterey Harbor were not significantly different and showed
the highest levels; with Mussel Point not far below.
Pacifica and Point Pinos showed intermediate levels of
Cu that were still very high. The high levels at Mussel
Point and Monterey Harbor are probably affected by the
effluent from the Monterey Sewage Treatment Plant, which
on May, 1971 contained about 2500 grams/day of copper
(Vieth, 1971).. Also copper is contained in the anti-
fouling paiht used for many boat hulls. Some of the cop-
per found may represent the local use of fungicides con-
taining Cu and the use of copper sulfate to control fresh-
water algae.
SUMMARY
Amounts of Ag, Cd, Cu, Mn, Pb, and Zn were measured
in the hermit crab Pagurus samuelis from eight locations
on the California coast between San Francisco and the
Palos Verdes Peninsula. Highest and lowest average
values obtained were: Ag (5.0-1.5), Cd (3.1-1.2).
Cu (200.7-44.6), Mn (24.2-6.5), Pb (23.4-14.8), and
Zn (108.8-76.4). Females did not differ significantly
from males for most metals in most areas. High levels of
zino and copper in Pagurus samuelis show some relation to
possible local sources in the environment.
ACKNOWLEDGMENTS
1 would like to thank my advisors Drs. D. P. Abbott
and J. H. Martin, and Sue Swarbrick for their help during
this research project. This work was made possible by
Grant GY8950 of the Undergraduate Research Participation
Program of the National Soience Foundation.
82
REFERENCES CITED
Bollay, M. 1964. Distribution and utilization of
gastropod shells by the hermit crabs Pagurus
samuelis, Pagurus granosimanus, and Pagurus
hirsutiusculus at Pacific Grove, California.
Veliger 6 (Supplement). 71-76.
Bowen, H. J. M. 1966. Trace elements in biochemistry,
Academic Press. 241 p.
Christian, G. D., and F. J. Feldman. 1970. Atomic absorp-
tion spectroscopys: applications in agriculture.
biology, and medioine. John Wiley & Sons, New York.
490 p.
Frey, H. W. 1971. California's living marine resources
and their utilization. State of California, Depart-
ment of Fish and Game, California. 148 p.
Goldberg, E. D. 1957. Biogeochemistry of trace metals.
p. 345-358. In J. W. Hedgpeth (ed.), Treatise on
marine ecology and paleoecology, V. 1. Ecology.
Geol. Soc. Am. Mem. 67.
1967. Review of trace element concen-
trations in marine organisms. Puerto Rico Nuclear
Center. 535 p.
Patterson, C. C. 1965. Contaminated and natural lead
environments of man. Arch. Environ. Health 11. 344-
360.
Perkin-Elmer. 1968. Analytical methods for atomic ab-
sorption spectrophotometry. Perkin-Elmer Corp..
Norwalk, Conneoticut.
1971. Analytical methods for atomic ab-
sorption spectrophotometry. Perkin-Elmer Corp..
Norwalk, Connecticut.
1760
Simpson, G. G., Roe, A., and R. C. Lewontin, Quantita-
tive Zoology. Harcourt, Brace, & Co., New York.
440 p.
Vieth, R. 1971. Trace metals in Monterey Peninsula
sewerage. Unpublished MS. on file at Hopkins Marine
Station Library.
Vinogradov, A. P. 1953. The elementary chemical composi-
tion of marine organisms. Sears Foundation Mar. Res.
Mem. 2, New Haven. 647 p.
PIGURE CAPTIONS
Figure 1: A map of the eight collection sites. The
location letters are referred to in figs. 2-7.
Map of the relative amounts of lead present in
Figure 21
the P. samuelis population at each location.
Map of the relative amounts of manganese pre-
Figure 3.
sent in the P. samuelis population at each
location.
Figure 4.
Map of the relative amounts of cadmium present
in the P. samuelis population at each location.
Figure 51: Map of the relative amounts of silver present
in the P. samuelis population at each location.
Figure 6: Map of the relative amounts of zinc present in
the P. samuelis population at each location.
Figure 7.
Map of the relative amounts of manganese present
in the P. samuelis population at each location.
Figures
8 & 91: Means and standard deviations for females versus
males by metal content level at each location.
Note: Female value at White's Point (H) is
based on one sample only and therefore has no
standard deviation.
7
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MANGANESE
(ppm dry wt.)
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20-
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10-
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ZINC
(ppm dry wt.)
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85
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(ppm dry wt.)
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