HEAVY METAL CONCENTRATIONS IN BROWN PELICANS
FROM FLORIDA AND CALIFORNIA
Peter G. Connors, Victor C. Anderlini and Robert W. Risebrough
University of California
Bodega Bay, California
John H. Martin
Stanford University
Pacific Grove, California
Ralph w. Schreiber
University of South Florida
Tampa, Florida
Daniel w. Anderson
Bureau of Sport Fisheries and Wildlife
Davis, California
Abstract. The large nesting population of brown pelicans (Pelecanus occidentalis) on
Anacapa Island, California, has experienced almost total reproductive failure in 1969,
1970, and 1971, apparently the result of thin, easily crushed eggshells, Comparable
populations in Florida are reproducing successfully. The large differences in tissue
concentrations of DDT compounds between the two populations stand as the most probable
explanation of the California failure. We have investigated the occurrence of nine heavy
metals (Ag, Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn) in the tissues of brown pelicans from
Florida and California and in a white pelican (Pelecanus erythrorhynchos) from California
to determine whether elevated levels of these heavy metals might be partly responsible for
the reproductive failure of California pelicans.
Analyses were performed according to established techniques by atomic absorption spectrophotometry.
The concentrations of metals measured in the California birds are about the same or lower
than in the pelicans from Florida. The only metal showing a clear difference between the
two populations is mercury, which is 3-5 times more concentrated in the Florida birds.
INTRODUCTION
Heavy metals are natural components of marine ecosystems. but their levels may be elevated
as a result of increased input into the oceans resulting from man's activities, In some
CAL-NEVA WILDLIFE 1972
56
p·
, 1
cases the concentrations of certain metals in marine waters have reached levels which
caused damage to wildlife populations and created serious human health problems. A large
fish kill on the coast of Holland in 1965 was evidently the result of very high copper
concentrations resulting from copper sulfate which had been deposited on the shore
(Roskam, 1965). Cadmium pollution of a river valley downstream from a zinc mine in Japan
has resulted in the painful "itai-itai" disease in the human populations (Yamagata and
Shigematsu, 1970). In Minamata Bay in Japan, fifty-three persons were killed, and many
more became seriously ill from eating fish with high mercury levels resulting from industrial discharges into the bay (Irukayama, 1966).
Identifying levels in wildlife which are elevated as a result of pollution is difficult,
since very few data have been reported concerning the natural (non-pollutant) levels of
metals in any species of marine vertebrates •. To investigate the extent of heavy metal
pollution in northern oceans, Anderlini et al (in press) measured levels of nine metals in
four populations of petrels: ashy petreTS,-oceanodroma homochroa, from the Farallon
Islands of coastal California; Wilson's petrels, Oceanites oceanicus, nesting in two areas
of Antarctica and wintering in different areas, one population visiting the North Atlantic
and the other visiting the Southern Pacific and Indian Oceans; and snow petrels, Pagodroma
~.
a species confined to the pack-ice region of Antarctica. If concentrations of heavy
metals in marine ecosystems near industrial areas have increased as a result of pollution,
it can be expected that concentrations of metals at corresponding trophic levels in ecosystems remote from the sources of pollution will be lower. The analysis of these different
populations of closely related species would provide a measure of heavy metal pollution in
oceans near industrial areas by comparing levels with those present in Antarctic Seas.
The results of this study indicated a tendency toward higher levels of cadmium, chromium,
mercury, and nickel in petrels feeding in the northern oceans, compa~ed
to those petrels
confined to less industrialized southern oceans. The magnitudes of the differences did
not seem alarming, however, with levels in the same order of magnitude in all four populations. Copper and zinc, essential elements whose tissue concentrations are probably
metabolically regulated, were at similar levels in all populations. Except in the vicinity
of outfalls, it does not appear that pollution by these six metals presents an imminent
hazard to populations of sea birds off the coast of California,
~
f·
In the early 1900's nesting colonies of brown pelicans (Pelecanus occidentalis) existed in
at least five sites in Southern California, and as recently as 1964 it is estimated that
1000 pairs bred successfully on Anacapa Island (Banks, 1966). The nesting success on
Anacapa in 1969 was reported by Risebrough, Sibley, and Kirven (1971) as not more than
four young fledged from a minimum of 1272 nests built. This almost total failure, apparently
the result of thin, easily crushed eggshells, has continued through the two succeeding
nesting seasons.
Results of analyses of 65 eggs from this colony have been reported by Risebrough (in press)
with a mean value for total DDT compounds of 1223 parts per million of the lipid weight.
This value is extremely high in comparison to measured concentrations in brown pelican
eggs from successful nesting colonies in the Gulf of California and in Florida. The mean
level of total DDT compounds in 87 eggs from four Florida colonies was only 34 ppm, approximately 36 times lower than the Anacapa level. The concentration of polychlorinated biphenyls
(PCB) was also higher in the California eggs, but only by about three times (Schreiber and
Risebrough, in press). Coupled with the results of several feeding experiments relating
thinning of eggshells to DDT compounds in the diets of birds (Heath et al 1969; Wiemeyer
and Porter, 1970; Risebrough and Anderson, in prep.), this evidence B;e;s clearly to
implicate the high levels of DDT compounds as the most probably cause of the reproductive
failure of the Anacapa pelicans.
During some of the controversy which has surrounded this problem, it has been suggested
that perhaps pollution of California's coastal waters with heavy metals is responsible for
the continuing loss of Anacapa's pelicans. In an effort to ascertain the extent of heavy
metal pollution in brown pelicans of California, we have investigated the levels of nine
heavy metals in tissues of adult birds from California, and for comparison, corresponding
data were collected for brown pelicans from a colony'in Florida which is reproducing
successfully.
CAL-NEVA WILDLIFE 1972
57
Research was supported by National Institute of Health Postdoctoral Fellowship l-F02-ES51971-0l
(Connors) from the National Institute of Environmental Health Sciences; by the Division of
Ecology and Systematics of the National Science Foundation, grant GB-11649; and by the
International Decade of Oceanic Exploration program of the National Science Foundation,
grant GX-28743. We thank George Knauer, Carolyn Connors, and Seddon Bennington for assistance in the laboratory, and Arthur Bischoff and Dick Bauer for assistance in obtaining
specimens.
~fiTHODS
Five brown pelicans were obtained in California, all found dead or dying: one adult on
Anacapa Island, August 1970; one adult and one first year bird in Monterey County,
October 1970; one adult and one second year bird in Los Angeles County, August 1971. Five
adult brown pelicans were collected near Tarpon Key and Tampa Bay, Florida, August 1969.
In addition, one white pelican (Pelecanus erythrorhynchos) found dead in the Sacramento
National Wildlife Refuge, California, in November 1971, was analyzed with the brown pelicans.
Five addled eggs of the brown pelican were taken for analysis from Anacapa Island after
the breeding season in 1971.
Duplicate samples of liver, breast muscle, and mid-section of one femur were dissected
for analysis and prepared according to the procedures described in Anderlini et al (in
press). Liver and breast tissue were not available in two of the California br~
pelicans
when the specimens were received in our laboratory. The entire contents of the eggs
(exclusive of shell) were analyzed.
All analyses were performed on a Perkin-Elmer Model #303 Atomic Absorption Spectrophotometer
according to standard conditions for Ag, Cd, Co, Cr, Cu, Ni, Pb, and Zn. Analyses for Hg
were performed on the same equipment by flameless spectorphotometry following the techniques
of Uthe
al (1970) and Stainton (1971).
RESULTS
Table 1 presents a summary of the data obtained for mercury levels in the pelican tissues.
Because of the small number of_individuals sampled and the uncertainty of the distribution
of values in the population, no confidence limits about the mean can be given. The range
of values for each category is shown. Duplicate samples of tissue were prepared and
analyzed independently, and the two measurements, which were usually in close agreement,
were averaged. Thus, the high value of 17.36 ppm mercury in the liver of one Florida brown
pelican cannot be considered a spurious result due to contamination during the analysis.
It is clear from these data that the levels of mercury in the sample of the Florida brown
pelican population are higher than in the California sample, by 3-5 times. In comparison
with levels of mercury in other sea birds, the values in the Florida population are
surprisingly high. The maximum concentration of mercury in liver measured in our laboratory
for any of 10 ashy petrels, 20 Wilson's petrels, 10 snow petrels and 16 common terns
(Sterna hirundo) from Long Island Sound and Lake Ontario was 4.74 ppm. Common terns
feeding in polluted Lake St. Clair in Canada have been measured at values as high as
39 ppm mercury in liver (Dustman et al, 1970), but in mercury feeding experiments, redtailed hawks (~
jamaicensis) had-only 17-20 ppm mercury in the liver at death
(Fimreite and Karstad, 1971). In view of this, a value of 17 ppm in the liver of a
Florida brown pelican can be considered potentially dangerous. This population is presently
being carefully monitored, however, and no unusual mortality associated with high pollutant
levels has been observed (Schreiber and Risebrough, in press). The single white pelican
analyzed has values slightly higher than the California brown pelican levels.
None of the other eight metals investigated showed such clear differences in levels between
the two brown pelican populations. Tables 2 and 3 present the nickel and chromium
results. For each of these metals the liver and breast values are comparable, but the
bone values are higher in the Florida population. In view of the small sample size,
this should not be considered as indicative of significant differences between the levels
in the two populations. The white pelican values are slightly lower than the brown pelican
values for both metals.
CAL-NEVA WILDLIFE 1972
58
Concentrations of cadmium, copper, and zinc showed no differences judged significant
between the Florida and Califo~n
populations. The data are summarized in Tables 4, 5,
and 6. One individual brown pelican found dead near Monterey Bay had an unusually high
level of cadmium in the liver, probably indicating that it had recently been feeding on
fish containing a high concentration of this metal. Other west coast pelicans had much
lower levels. Petrels from Antarctic and California ocean waters had liver cadmium levels
considerably higher than the miximum pelican value (Anderli~
al, in press).
Concentrations of these metals in the white pelican analyzed tend to_ be comparable or
slightly below the mean values for the brown pelicans, except for a very high level of
zinc in the liver. Zinc, an essential element, usually shows a narrow Gaussian distribution
in a population, probably indicating metabolic control of the concentration. Mean liver
levels in populations of common terns, brown pelicans and three species of petrels have
ranged from 92 ppm to 176 ppm. Thus, the level of 275 ppm found in this bird is surprising,
and may indicate greatly elevated levels in the food of this individual. It will be informative to investigate other white pelicans.
In Table 7 the results of analyses for silver, cobalt, and lead are presented. Only the
bone samples had concentrations great enough for measurement, and the values listed should
be regarded as maximum values. All samples were treated equivalently, so comparisons are
valid, but because of a large, not precisely determined background correction (especially
for cobalt and lead), these values should not be considered as accurate estimates of the
actual concentrations. Improvements in the methodology used will provide more accurate
determinations in the future. No appreciable differences in concentrations of these
metals are noted.
Results of the analyses of the brown pelican eggs are included in 1able 8. Concentrations of the metals in eggs tend to be low compared to adult body tissue levels, and by
the methodology employed in these analyses, accurate concentration determinations could be
made only for chromium, copper, mercury, and zinc,
DISCUSSION
In conclusion, the possibility that elevated levels of any of these nine metals in the
coastal waters of Southern California might account for the overwhelming reproductive
failure of brown pelicans in that area seems to be ruled out by these data. The concentrations of metals in California birds appear to be about the same or lower than in brown
pelicans from the Florida colony which is reproducing satisfactorily. The only metal
showing a clear difference in levels between the Florida and California populations is
mercury, which, in the samples analyzed in this study, is 3·5 times more concentrated in
the Florida birds.
LITERATURE CITED
Anderlini, V. C., P. G. Connors, R. W. Risebrough, and J. H. Martin. Concentrations of
heavy metals in some Antarctic and North American sea birds. Proceedings of the Symposium: Conservation on the Seventh Continent, Antarctica. B. Parker, editor. In
press.
Banks, R. c. 1966. Terrestrial vertebrates of Anacapa Island, California.
Society Natural History Trans. 14:179.
San Diego
Dustman, E. H., L. F. Stickel, and J. B. Elder. 1970. Mercury in wild animals, Lake
St. Clair, 1970. International Conference on Environmental Mercury Contamination,
September 1970. Ann Arbor, Michigan.
Fimreite, N. and L. Karstad. 1971. Effects of dietary methyl mercury on red-tailed
hawks. J. Wildl. Mgmt. 35(2):293-300.
Heath, R. G., J. W. Spann and J. F. Kreitzer. 1969.
reproduction in controlled studies. Nature 24~7-8.
Marked DDT impairment of mallard
Irukayama, K. 1966. Third International Conference Water Pollution Research.
Pollution Control Federation, Washington, D. C. p. 153.
CAL-NEVA WILDLIFE 1972
59
Water
Risebrough, R. W. Effects of environmental pollutants upon animals other than man.
Berkeley Symposium on Mathematical Statistics and Probability. Proc. 6:(in press).
Risebrough, R. W. and D. W. Anderson. Synergistic effects of DDT and PCB upon the
reproduction of mallards. CManuscript in preparation.)
Risebrough, R. W., F. C. Sibley, and M. N. Kirven. 1971. Reproductive failure of the
brown pelican on Anacapa Island in 1969. American Birds 25:8-9.
Roskam, R. T. 1965. A case of copper pollution along the Dutch shore. In: C. M. Council
Meeting. Int. Council for the Exploration of the Sea, Sect. C. Near NOrthern Seas
Committee, Amsterdam, Holland.
Schreiber, R. W., and R. W. Risebrough.
Wilson Bulletin (in press).
Studies of the brown
occidentalis.
pelican.~us
Stainton, M. P. 1971. Syringe proced\lie for transfer of nan()gram .quantities of mercury
vapor for flame less atomic absorption spectrophotometry. Anal_. Chent. 43:625-627.
Uthe, J. F., F. A. J. Armstrong, and M.P. Stainton, 1970.
fish samples by wet digestion and flameless atomic absorp~icm
J. Fish. Res. Bd. Canada 27:805-811.
Wiemeyer, s. and R. Porter.
Nature 227:737-738.
1970.
Yamagata, N. and I. Shigematsu.
Publ. Health 19(1):1-27.
~;eAryct.'E!linao
in
.spectrophotometry.
DDT thins eggshells of captive American kestrels.
1970.
Cadmium pollution in ..persct~v.
Bull. Inst,
,..
CAL-NEVA WILDLIFE 1972
60
.~·
Table 1.
Mercury concentrations in tisauea of pelicana, parta per
aillion vet weight. Arithaetic aeans • nuaber of
iadividuals analyzed, and range of values.
Species
locality
Liver
Breast
Bone
Brown Pelican
florida
9.74 (5)
5.14-17.36
1.85 (5)
1.04-2.27
.278 (5)
.148-.407
Brown Pelican
california
1.54 (3)
1.20-1.88
.66 (3)
.26-.89
.095 (5)
.064-.134
White Pelican
california
4.13 (1)
Table 2.
1.04 (1)
~064
(1)
Bickel concentration. 'in tissuea of pelicens, parts per
aillion clry veipt. Arit-.tic aesus, nuaber of
individuals anslyaed, and rense of valu...
Species
locality
Liver
Brown Pelican
Florida
C2.0
Brown Pelican
california
<2.0
White Pelican
california
Breast
Bone
4.41 (5)
3.73-5.25
14.6-26.0
3.08 (3)
1.85-4.00
10.8 (5)
8.9-13.7
1.60 (1)
CAL-NEVA WILDLIFE 1972
61
2o.J'
<5>
7. 70 (1)
Table 3.
ChrOJDiUIIl concentrations in tissues of pelicans, parts per
million dry weight. Arithmetic means, ll1Diber of
individuals analyzed; and range of values.
Species
locality
Liver
Brown Pelican
Florida
.92 (5)
.80-1.20
4.01 (5)
2.65-4.71
Brown Pelican
California
1.37 (3)
.7o-1.80
3.57 (3)
1.45-6.27
White Pelican
california
.10 (1)
1.19 (1)
Table
4.
Bone
Breast
15~40
(5)
8.82-22.89
6~03
(5)
4.65-8.68
. 3.83 (5)
cadaiua concentrations in tissues of pelicans, parts per
million dry weight. Aritluletic means, .DUIIlter. of
individuals analyzed, and range of values ..
Species,
locality
Liver
Breast
.Bone
Brown Pelican
Florida
1.80 (5)
1.32-2.39
.275 (5)
.252-.324
1.66 (5)
1.38-1.86
Brown Pelican
california
4.97 (3)
.62-13.62
.392 (3)
.242-.644
1.52 (5)
1.08-1.96
White Pelican
california
1.69 (1)
.194 (1)
1.19 (1)
CAL-NEVA WILDLIFE 1972
62
Table 5.
Copper concentrations in tiaauea of pelicana, parta per
aillion dry veigbt. Aritbaetic aeana, nuaber of
individual• analyzed, aad range of valuea.
Speciea
locality
Liver
Breast
Bone
Brown Pelican
nor ida
26.3 (5)
18.6-48.0
17.4 (5)
14.2-23.0
2. 78 (5)
0.3o-6.20
Brown Pelican
california
so.s (3)
17.8-98.0
19.0 (3)
16.8-21.0
2.88 (5)
1.6o-3.80
White Pelican
california
20.1 (1)
24.0 (1)
2.40 (1)
Table 6.
Zinc concentrations in tiaauea of pelicana, parta per
aillion dry veiaht. Arithaetic aeana. nuaber of
individuala analyzed, and range of va1uea.
Speciea
locality
Liver
Breast
Bone
Brown Pelican
Florida
120.9 (5)
107.3-144.9
57.8 (5)
47.2-69.9
157.4 (5)
140.3-172.6
Browo Pelican
california
124.1 (3)
79.6-171.7
70.2 (3)
52.6-99.9
128.5 (5)
104.1-162.1
White Pelican
california
274.8 (1)
65.0 (1)
95.1 (1)
CAL-NEVA WILDLIFE 1972
63
Table 7.
Maximum concentrations of silver, cobalt and lead in femurs
of pelicans, parts per million dry weight. Arithmetic
means, number of individuals analyzed, and range of values.
Species
locality
Ag
Co
Pb
Brown Pelican
Florida
2.51 (5)
2.03 3.12
6.08 (5)
4.77-7.28
23.1 (5)
20.4-26.4
Brown Pelican
California
2.32 (5)
1.95-2.75
5.73 (5)
4.13-6.90
. 23.1 (5)
19.2-26.9
White Pelican
California
1.92 (1)
4.48 (1)
Table 8.
16.3 (1)
Concentrations of metals in cOiteal'"!~of
Brown Pelicans fr011 Anacapa Island. c.a,U.ta, p~ts
per
million dry weight (Hg in.. ·Jilllll wet'. . . .th ~tic
means with range of values. eoac..a;'-"'..._. of· Ag, Cd,
Co, Ni, and Pb were less the 1 ij':~,
....~·"'
Cr
Cu
1.04
.57-1.51
7.66
7.04-8.85
Zn
.083
.051-.145
CAL-NEVA WILDLIFE 1972
64
45.9
39.9-49.4