DDT RESIDUES IN BIRDS AND MAMMALS OF MONTEREY BAY, CALIFORNIA
Paul R. Mascovich
Hopkins Marine Station of Stanford University
Pacific Grove, California
Casual observations by bird watchers in the Monterey Bay area
have indicated an increase in the number of dead birds found along the
beaches during the past year. During the time period of September, 1968.
to May, 1969, regular walks along a stretch of beach near Moss Landing in
Monterey Bay were conducted by James Norris of the Moss Landing Marine
Laboratories in an attempt to détermine rate and cause of deaths of birds.
Preliminary results of these walks are that, oflO birds found, 37%
were oil-covered, 11% were shot, and 49% died of unknown causes.
Monterey Bay is situated in an agricultural region where a great
amount of pesticides is used. Parathion (o,o-diethyl o,p-nitrophenyl
phosphorothioate) is the major pesticide used in Monterey County, with
DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane ranking second.
During the past fifteen years at least 125,000 pounds of technical grade
DDT has been used each year, sprayed on lettuce, broccoli, cauliflower,
and young tomatoes (Scott, 1969). The Monterey Bay area is drained
* See Footnote 1.
20.
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extensively by the Salinas River, the Pajaro River, and Elkhorn Slough.
Early in 1969 heavy rains caused the Salinas River to flood low-lying
farmlands in the Salinas Valley, and it almost certainly leached
quantities of pesticides from the soil, which were carried by the river
into Monterey Bay.
Many of the birds and mammals of Monterey Bay are fish-eaters.
Pesticides are transferred and concentrated in organisms as the food
chain is ascended and may reach the fish-eating birds and mammals at
the end of the food chain in high concentrations. Studies by Risebrough
(1967, 1969), Wurster (1968), and Keith and Hunt (1966) have indicated
the high levels of pesticides and their adverse effects on birds and
other California wildlife.
In order to determine whether the bird deaths were caused by
contamination with DDT residues, selected birds and mammals of
Monterey Bay were examined for concentrations of DDT and its analogs
DDD 1,1-dichloro-2,2-bis(chlorophenyl)ethane and DDE1,1-dichloro-
2,2-bis (chlorophenyl)ethene
Materials and Methods:
A list of birds and mammals analysed and locations and dates of
collection is contained in Table I. Birds were collected by James Norris
of Moss Landing Marine Laboratories, by Verne Yadon of the Pacific Grove
Museum of Natural History, and bymyself. The Steller sea lion was born
prematurely and found by Dr. G. Victor Morejohn of the Moss Landing
Laboratories; the larger California sea lion was found by Ralph Nonella
Resen
of the Pacific Grove Marine Refuge Unit; and the smaller California sea
lion was found by members of the Hopkins Marine Station.
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Great differences in DDT levels can be obtained from different
organs within the same animal (e.g., Keith and Hunt, 1966). The liver
provides a good general index of DDT level and was chosen for analysis
in this study. Whole livers were homogenized before sub-samples were
taken to insure a random sample of the liver. One sample of sub-
cutaneous fat of a loon was used, and a mature ovary of another loon
was used. Duplicate samples were run on the livers of the first two
birds analysed, a cormorant and a gull, in order to check the
reproducibility of the method. These duplicate samples deviated by
less than 10%; thereafter only one sample from each tissue was analysed.
Samples were digested and extracted using the method of Stanley and
LeFavoure (1965), and were analysed quantitatively for DDT and its
analogs with a Beckman GC h gas-liquid chromatograph using a 3 OF 1
column on 80-100 mesh chromosorb W and an electron capture dector. All
chemicals and glassware were checked for possible DDT contamination.
DDE is the only analog reported because the chromatograph
column was unable to separate the DDT and DDD peaks sufficiently from the
DDE peak to be accurately quantitated. In all cases, however, the
combined DDT and DDD concentrations were insignificant in relation
to the DDE concentrations.
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Results and Discussion:
The results of the analysis are summarized in Table I.
Since the Brandt's cormorant, the Western grebe, and the Arctic
loon are reported to feed mainly on fish and small amounts of
crustaceans, mollusks, and aquatic insects and plants (Palmer, 1962).
it might be expected that their levels of DDT residues be approximately
the same. This is not the case. A possible explanation of the
variations among the three species could be differences in ability
to metabolize and excrete DDE. Differences could also be related to
migratory habits.
Map I (Palmer, 1962) shows the migratory routes of the cormorant,
grebe, and loon. The cormorant is a permanent resident of the west
coast of the United States, and is constantly exposed to high pollution.
The Western grebe winters on the west coast, but breeds in the summer
months in fresh water lakes in the northern United States. Many lakes
are contaminated with DDT from insect control spraying, and grebes
feeding there will ingest food which is possibly more contaminated
than on the west coast. The Arctic loon winters on the west coast.
but breeds north of the Arctic Circle. DDT levels are probably low
this far north, explaining the low levels in the loons.
The much higher level of DDE in the sub-cutaneous fat of the loon
as opposed to the liver of the same bird shows the insecticide's
tendency to concentrate in lipid-rich tissues. The loons were the only
birds analysed which contained sub-cutaneous fat. This may be another
explanation for the low DDE values in their livers, since much of their
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total DDE would be contained in their fat instead of their livers.
The loon ovary analysed was much lower in DDE than the liver of the
same bird. This agrees with the findings of Keith and Hunt (1966).
who found 21.00 ppm DDE in the liver of a white pelican, and only 8.87 ppm
in the ovary,
The Ashy and Fork-tailed petrels eat mainly small fish, crustaceans.
and other materials floating on the surface of the water (Palmer, 1962).
The surface of the water receives the aerial fallout of insecticide and
has unique physical-chemical properties which could enable it to
temporarily retain the water-insoluble chlorinated hydrocarbon components
(Risebrough, 1969). This may account for the extremely high DDE levels
in the two petrels.
The large variation in DDE concentrations in the two gulls may be
explained by their feeding habits. Gulls are opportunistic feeders, and
eat almost anything from garbage to fish. Their DDE levels may be
largely a function of where they feed and what they feed on. Differing
migratory habits may also be a factor in causing the different levels in
the two gulls. Map II (Robbins, Bruun, and Zim, 1966) shows the
migratory routes of the two gulls. The Western gull is a permanent
resident of the west coast, but the Ring-billed gull breeds during the
summer months in mountain lakes of southern Canada, where there may be
less DDT pollution than on the west coast.
The differences in DDE levels in the two sea lions may be explained
by the way they obtained their food before dying. The Steller sea lion
had been born prematurely, so its only source of DDT was through the
placenta from the mother. The California sea lions were at the stage of
being weaned from their mothers. The larger one had been tagged by
biologists of the University of California at Santa Cruz and was eleven
09
months old at death. Both readily accepted fish which were offered to
them. Each could have taken up DDT from its mother's bloodstream
while still in the womb, from the mother's milk, and from fish which
it may have caught itself.
The DDE levels found in this analysis are some of the highest
reported to date. Risebrough found 3.3 ppm total DDT residues in the
liver of a Brandt's cormorant (1967), 211 ppm total DDT residues in
the fat of a Western gull (1967), and 59.3 ppm total DDT residues in
the whole body of an Ashy petrel (1969). Most of the birds used in
my analysis were extremely emaciated, having little or no body fat.
This suggests that they had been sick for a prolonged period before
death and were unable to feed. This in turn suggests chronic poisoning
or illness. As the fat was used up while the birds were alive, the DDT
residues contained in the fat would have been released and deposited in
other areas of the body. This would have caused the levels I found in
the livers to be higher than if the birds still had a normal amount of
body fat.
Some of these DDE levels probably approach or exceed lethal doses.
No conclusive statement can be made, however, until IDgo's are
determined for the species analysed. In addition, DDT levels in birds
collected in Monterey Bay while still alive would be valuable.
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Summary:
Pesticidal pollution of Monterey Bay, California has been
suggested as the cause of an unusually large number of bird deaths
reported in the past year. Analyses were performed on a series of
dead or dying birds and mammals taken from the Monterey Bay area.
Concentrations of DDT and its analogs DDD and DDE were determined by
gas chromatography. Results were as follows: 107, 105, and 155 ppm
DDE in livers of three Brandt's cormorants; 192 and 292 ppm DDE in
livers of two Western grebes; 2.35 ppm DDE in the liver and 121 ppm DDE
in the sub-cutaneous fat of an Arctic loon; 1.25 ppm DEE in the liver
and O.61 ppm DDE in the ovary of a second Arctic loon; 373 ppm DDE in
the liver of a Fork-tailed petrel; 112 ppm DDE in the liver of an
Ashy petrel; 805 ppm DDE in the liver of a Western gull; hl.5 ppm DDE
in the liver of a Ring-billed gull; 1.2 ppm DDE in the liver of an aborted
Steller sea lion pup; and 3.94 and 89 ppm DDE in the livers of two
immature California sea lions.
Acknowledgments:
For their guidance and assistance throughout my project, I would
like to sincerely thank the following people: Dr. G. Victor Morejohn
and Mr. James Norris of the Moss Landing Marine Laboratories; Mr. Verne
Yadon of the Pacific Grove Museum of Natural History; the faculty and
staff of Hopkins Marine Station, and in particular,Dr. Donald P. Abbott,
Mr. Phillip Murphy, and Mr. Alan Baldridge.
This work was supported in part by the Undergraduate Research
Participation Program of the National Science Foundation, Grant + GY-5878.
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BIBLIOGRAPHY
Hickey, Joseph J., and James E. Roelle. 1968. Conference Summary and
Conclusions, p.553-567. In Joseph J. Hickey (ed.), Peregrine
Falcon Populations: Their Biology and Decline. University of
Wisconsin Press, Madison.
Hunt, E.G., and A.I. Bischoff. 1960. Inimical Effects on Wildlife of
Periodic DDD Applications to Clear Lake. California Fish and Game,
16: 91-106.
Keith, J.O., and E.G. Hunt. 1966.
Levels of Insecticide Residues in Fish
and Wildlife in California.
In Transactions of the 3lst North
American Wildlife Conference. p.150-177.
Norris, James. April 23, 1969. Personal Communication.
Palmer, Ralph S. (ed.). 1962. Handbook of North American Birds. p.
Yale University Press, New Haven, Connecticut.
Risebrough, R.W. 1967. DDT Residues in Pacific Sea Birds: a Persistent
Insedticide in Marine Food Chains. Nature, 216: 589-590.
Risebrough, R.W. 1968.
Chlorinated Hydrocarbons in Marine Ecosystems.
Chapter 1, p.5-23.
In Chemical Fallout: Current Research on
Persistent Pesticides. Charles C. Thomas, Springfield, Illinois.
Risebrough, R.W. 1969.
Thin Eggshells are Causing Reproductive Failure
of Brown Pelicans in California. Preliminary Report (mineo), 2 pgs.
Risebrough, R.W. 1969. Artifacts of Man: Pesticides. Unpublished Report
(mimeo).
Robbins, Chandler S., Bertel Bruun, and Herbert S. Zim. 1966.
Birds of North America. Golden Press; Inc., NewaYork New York.
Scott, David, June 2, 1969. Employed at Soil Serv, Inc. Personal
Communication.
Stanley, R.L., and H.T. LeFavoure. 1965. Rapid Digestion and Cleanup of
Animal Tissues for Pesticide Residue Analysis. Journal of the
Association of Official Agricultural Chemists, 18: 666-667.
Wurster, C.F. 1968. DDT Residues and Declining Repeoduction in the
Bermuda Petrel. Science, 159: 979-981.
86
Species
1.Brandt's Cormorant
(Phalacrocorax penicillatus
2. Brandt's Cormorant
andt's Cormerant
3. Brandt's Cormorant
1. Western Grebe
(Aechmophorus
occidentalis)
5. Western Grebe
6. Arctic Loon
(Gavia arctica)
7. Arctic Löon
8. Fork-tailed Petrel
(Oceanodroma furcata)
shy Petrel
Oceanodroma homochroa)
10. Western Gull
(Larus occidentalis)
11. Ring-billed Gull
(Larus delawarensis)
12. Steller Sea Lion
(Eumetopias jubata)
13. California Sea Lion
(Zalophus californianus)
1. California Sea Lion
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TABLE I
Total
Tissue
Location & Date
Wet Weight Analysed
of Collection
Liver
H.M.S. Beach
1816 gm.
Liver
1-11-69
2110
Liver
Moss Landing
1-26-69
Monterey
Liver
1832
5-7-69
976
Liver
Moss Landing
5-8-69
Monterey
2645
Liver
1-30-69
Liver
Monterey
2130
11-30-69
Fat
Monterey
Liver
Ovary
5-9-69
Monterey
Liver
5-3-69
Monterey
Liver
5-1-69
Moss Landing
870
Liver
1-26-69
Liver
230
Moss Landing
Liver
5-8-69
Ano Nuevo Is.
Liver
1-27-69
Pacific Grove 40 lbs. Liver
5-25-69
Pacific Grove 28 lbs. Liver
5-17-69
Wet Weight
of Tissue
5.139 gm.
5.150
5.161
5.274
5.219
5.134
5.527
1.hl
5.558
1.058
1.260
0.820
5.161
5.132
1.680
5.109
5.082
5.393
2
DDE PPM
Wet Weight
112
102
155
105
192
292
2.5.
121
1.25
0.61
373
112
818
11.5
1.2
3.91
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MAP I
Migratory Routes of the Brandt's Cormorant, Western Gull,

and Western Grebe.
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Mg
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WESTERN GRESE
Beavoris Cemaenvr
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MAP II
Migratory Routes of the Western Gull and the
Ring-billed Gull
L
dese

d



L






2
59

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kue-Brred Gult

Wesreer Gltt
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FOOTNOTES
1. Please send requests for reprints to:
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