ABSTRAC
In an effort to determine the effectiveness of the sand
crab, Emerita analoga, as an indicator species of DDT levels
in the California coastal marine environment, specimens were
collected from different beaches on Monterey Bay and analyzed
using gas-liquid chromatography (GLC). After all initial
samples were analyed, it was found that ovigerous animals
contained much lower levels of DDT than non-ovigerous animals.
Since the bulk of the samples from the different beaches had
differing proportions of ovigerous to non-ovigerous animals.
and this difference was not recorded, the effectiveness of this
species as an indicator of DDT was not fully demonstrated.
However, the specimens collected do represent natural populations
from the various beaches, and a rough comparison is possible.
Since DDE is reported to increase with time in a biological
system, the relative amount of DDE to the total residues of DDT
was determined for each beach and the data was analyzed for
possible trends. Sand samples were also collected at each beach
when the Emerita were collected, and comparison of DDT levels
in the sand with those in the animals was made.
25
INTRODUCTION
The presence of p.p'-DDT and its principal metabolites,
p.p'-DDD, and p,p'-DDE (hereafter referred to as sDDT) in the
global ecosystem (Risebrough, et. al., 1967; Woodwell, etl. al.,
1967; Tatton and Ruzicka, 1967), its affinity for and con-
centration in biological systems (Woodwell, et. al., 1967;
Robinson, 1967; West, 1967), and its relative stability within
these systems (Cox, 1971: Risebrough, et. al., 1967; Nash and
Woolson, 1967) has been widely documented. Since DDT tends to
be concentrated by organisms at the upper trophic levels of
a given food web (Rudd, 1964; Woodwell, et. al., 1967; West,
1966), special concern is warranted when considering levels of
sDDT at the bottom of such food webs. Emerita analoga, the
common sand crab of exposed sandy beaches on the West Coast,
is a filter-feeding primary consumer (predominantly) which
has been found to contain a mean sDDT level of 7200 ppb (wet
weight) near a point source of heavy sDDT input into the marine
environment (Burnett, 1971) and up to 252 ppb in an area of
apparently more subtle input, Monterey Bay, California, the
geographical focus of this study (King, 1969). Burnett (1971)
found the sand crab to be a good biological indicator of sDDT
concentrations since: 1.) It is readily available on nearly
all exposed sandy beaches from San Francisco to Ensenada, Mexico.
2.) In a survey of that stretch of coastline he found it to
exhibit marked gradients of sDDT concentrations relative toand
indicating point sources of sDDT input. 3.) It is the main food
source for a variety of marine and maritime organisms. For
example, it represents 90% of food, by volume, of the Barred
260
-2-
Surfperch (Carlisle, et. al., 1960), and 75 of the diets of
the Western Sandpiper, Semipalmated Plover, Snowy Plover
and sanderling (Reeder, 1951).
Monterey Bay is the focus of drainage for three rivers
draining an area in excess of 6000 square miles. The Salinas
River with a drainage of 43000square miles, covering essentially
the entire basin of the agriculturally rich Salinas Valley
and having an annual average flow of 320,000 acre feet, is by
far the largest surface water input into the bay. The Pajaro
River (1400 square miles, 120,000 acre feet) also drains a large
agricultural area. The San Lorenzo River, with a drainage
area of only 140 square miles drains a predominantly non-
agricultural, mountainous area, but nevertheless yields 106,000
acre feet per year. (Yancey, 1968).
Although air transport of sDDT-ladened dust particles has
been reported to be the greatest input source of these particular
chlorinated hydrocarbons into the pelagic marine environment
(Risebrough, et. al., 1968), input into littoral and estuarine
waters is influenced most by surface runoff as evidenced by
substantially higher residue concentrations found along inhabited
coastlines as compared to those found in the open ocean. Since
DDT usage in Monterey County (encompassing the Salinas Valley)
alone averaged about 125,000 pounds per year during the period
1959-1969 (Scott, 1969) and as per acre agricultural usage of
DDT does not differ markedly over the watershed being considered,
the Salinas River is clearly the main source of sDDT input into
the bay.
26
l
-3-
The study reported herein represents an effort to substantiate
the effectiveness of Emerita as an indicator of subtle changes
of sDDT in the littoral marine environment. In order to try to
pinpoint areas of high sDDT levels and possible sources of sDDT
in Monterey Bay, sand crabs were collected from 22 beaches
around the Bay, and analyzed for sDDT.
MATERIALS AND METHODS
All specimens were collected within a five day period
(April 18-22, 1971) from 23 beaches encompassing the entire.
configuration of Monterey Bay (Fig. 1). Onlyfemale animals
were taken and these were easily determined by size alone
(Eickstaedt, 1969). Ovigerous females had their eggs removed
at the collection site and these were placed in a glass test
tube until analyzed (All glassware used was heated overnight
at 400 C to remove impurities). These eggs were found to be
at about the same stage of development, as determined by
color (Lee and Gilchrist, 1971), which coincided nicely with
Eickstaedt's (1969) findings that the mean developmental
stage of eggs for any given month of the year should be approx-
imately the same for different animals from the same general
area. Whole animals were wrapped in aluminum foil. Burnett
(1971) noticed that smaller specimens of E.analoga tend to
accumulate higher sDDT concentrations than larger animals and
Cox (1971) noticed the same thing in Euphausia pacifica,
a large zooplankter. An attempt was thus made to use only
specimens weighing more than two grams, above which sDDT
levels are not significantly affected by body weight (Burnett.1971).
263
-4-
Only one of the 145 animals analyzed weighed less than two
grams. Sand samples were obtained by skimming the surface
sand with a test tube at the point of collection. Eggs, animals
and sand were immediately frozen, until needed for analysis.
The wet weight of frozen animals was determined by allowing
each animal to thaw for five minutes, removing excess water and
ice and weighing to the nearest.Ol gram. Individual animals
were digested overnight in a 50% mixture of glacial acetic
acid in perchloric acid. Three extractions with nanograde
hexane removed lipids, pigments and chlorinated hydrocarbons.
An additional cleanup was carried out be running an aliquot
of the hexane (about one ml) through a microcolumn (5 3/4" L. X
7.0-7.5 mm.) of silica gel (60-200 mesh, grade 950) and eluting
with 8 ml of 20-80% mixture of benzene and hexane (both nanograde).
The cleaned sample was either used directly or concentrated
under reduced pressure, if necessary.
A Beckman GC 4 gas-liquid chromatograph with an electron
capture detector was used for all analysis. DDT and all its
detectable congeners were determined using a mixed 62 OFi.
5% DC200 cloumn on 80-100 mesh chromosorb W (acid washed and
DMCS treated).
Wet wet weight of eggs was determined by allowing the
frozen seawater around the eggs to melt, removing eggs and
weighing them immediately. Cleanup was with silica gel mixed
with nuchar-attaclay mixture (K-3213, Kensco, Oakland, California).
Otherwise, the procedure was as described above. Sand samples
were automatically shaken with hexane (nanograde) for 20
hours and cleanup was the same as with the whole animals.
-5-
RESULTS
The actual mean levels of sDDT found at each beach tested
is given be Fig. 2. The highest value was found at Monterey
Wharf + 2,(site 5), which had a significantly higher value than
the next four highest peaks, Asilomar (3), Cannery Row (4).
Zumdoski State Beach (14) and Natural Bridges State Beach (23).
It is interesting to note that Carmel (city) Beach had a level
commensurate with some of those found in Monterey Bay. Big Sur
(BS) also exhibited a level similar to those in the Bay. Seacliff
State Beach (20) had the lowest level, and it should be noted
that that beach had had most of its sand scoured away--a
situation not found at any other beach.
Fig. 3, which illustrates the relative levels of DDT and
its metabolites, DDE and DDD, shows parallel distributions for
DDD and DDT, but an erratic distribution of DDE. For this and
other reasons ratios of DDE to sDDT were calculated (Fig. 4)
and their possible significance considered. It can be seen
that the highest values are found in the region of the Salinas
River (10), Elkhorn Slough (13) and Pajaro River (15).
sDDT levels in the sand samples collected are given in
Fig. 5. Definite peaks exist at the Elkhorn Slough (13), Pajaro
River (15), Manresa State Beach (17) and the San Lorenzo River
(22) areas. A low level at the Salinas River may be due to the
fact that a sand bar blocks the mouth of the river during most
of the year (including the period when the sample was taken
there). These values are particularily vulnerable to exper-
imental error, since only one sample from each beach was analyzed.
264
68
-6-
Perhaps the most significant data obtained is presented
in Table 1. Cox (1971) suggested that a possibly significant
amount of sDDT might be lost through the gonads of the particular
organsim he was studying (Euphausia pacifica). Unfortunately,
all collections and analysis were already completed before
this hypothesis was tested in Emerita analoga. It is obvious
from the table, that ovigerous females that had their eggs
removed contained significantly lower levels of sDDT than the
non-ovigerous animals. The eggs that were removed were analyzed
and it was determined that although they had higher levels of
SDDT than did the whole animals from which they were removed,
this did not make up for the large discrepancy. Values for
DDE were found to vary by only 118 in the two groups. It
SDDT
can be seen that DDE seems to be disproportionately accumulated
in the eggs, relative to both ovigerous and non-ovigerous female
Emerita.
DISCUSSION
After all collections and analysis had been made it was
discovered that ovigerous specimens contained significantly
lower levels of sDDT than non-ovigerous females (Table 1).
While this, in itself is very interesting, it also means that
most of the sDDT data that was collected must be qualified.
The fact that eggs were removed at the collection sites and
ovigerous females with eggs removed were not marked or seperated
from non-ovigerous females introduces a possibly significant
error in the results. Essentially, different beaches may
contain different levels of sDDT, but the results of any analysis
266
-7-
might depend totally on the proportion of ovigeroussto non-
ovigerous animals collected from each beach. Hence, if the sand
crab is to be used as an indicator of actual relative levels of
sDDT, only animals at the same reproductive stage should be
used. Since the female Emerita, once she begins to reproduce
continues to lay eggs until the end of the season (usually
about eight months of reproductive activity) it is reasonable
to hypothesize that there might be a continual loss of sDDT
throughout the reproductive season. If this were the case,
only non-reproductive animals should be used as indicators of
SDDT levels, since the length of the reproductive season is
functionally related to environmental parameters (Eickstaedt, 1969)
which are likely to be different at different beaches. In
short, it is highly unlikely that female Emerita at the same
reproductive stage would be collected at two different beaches
at the same time.
While Fig.2 can be considered as representative of naturall
levels of sDDT in populations of Emerita the data from these
samples cannot be used for a systematic comparison between
populations. For example, animals from site 5 have significantly
higher levels than those from any other site. Yet, this may
be due to the fact that all animals from that site were non-
ovigerous. However, Swarbrick (1971) also found high sDDT
levels in that area (Monterey Wharf + 2) when analyzing hermit
crabs (Pagurus samuelis) during the same period. Therefore,
it seems that this graph may,in fact, offer a rough estimation
only of the relative sDDT levels. Clarification of the anomalous
-8-
results results obtained between ovigerous and non-ovigerous
females would allow for an acceptable interpretation.
There seems to be relatively low levels between the Pajaro
and San Lorenzo River (sites 15-22) and at the Salinas River
mouth (site 10, Fig. 2). Since sDDT levels in the sand
samples (Fig. 5) showed peaks at the major drainage outlets
(except the Salinas River which was blocked by a sand bar at the
time of collection), and the aforementioned low sDDT levels
exist at all the drainage outlets, it seems reasonable to
hypothesize that sDDT input must first get into the marine
ecosystem--adherred to particulate matter and/or ingested by
marine plankton-before its presence is revealed in the Emerita,
If, during low runoff periods, most of the sDDT is deposited
on the beach adjacent to the drainage outlet, rather than
dispersed in the ocean (as would occur during a flood), it
is unlikely that the Emerita would accumulate much of it since
they do not actively ingest sand while feeding (Efford, 1965).
Analysis of organic detritus and phytoplankton in the surf
zone would probably offer a better correllation, since the
sand crab's food is comprised of this material, and since body¬
weight concentrations of sDDT have been found to be a function
of daily intake of sDDT in many animals (Robinson, 1967).
Examination of Fig.3 shows a fairly good relationship
between the distribution of DDT and DDD, but an erratic trend
for DDE distribution. Since DDE is thought to increase with
time in a biological systim (Cox, 1971) and values for DDE may
SDDT
be an indicator of that time, (lower values corresponing to a
6
26d
-9-
shorter presence in a biological system) it could be valuable
to consider the ratio of DDE to sDDT. Such a comparison between
DDE and sDDT is presented in Fig. 4. The results show a
definite trend towards lower DDE values away from the Salinas
SDDT
River, a trend seemingly contradictory to the argument developed
above. One would expect a shorter "system time" near a point
source of input. However, since recent usage of DDT in the
area has decreased sharply and the Salinas River has not flooded
in over two years, it is likely that the last significant input
of sDDT (mostly DDT) into the bay (at least from this river)
occurred in Feb., 1969, when the river flooded thousands of
acres of farmland. Since it is now established that the majority
of the sDDT being translocated in such a river is adsorbed
to fine sediment particles rather than sand-sized particles
(Routh, 1971; Lee, 1971) and since the heavier sand particles
have faster sedimentation rates than the finer material, the
majority of sDDT would be washed out into the ocean instead of
settling on the beach (as it would if adsorbed to sand particles).
Current patterns off the mouth of the Salinas River are seasonally
variable, but in general, offshore bottom currents off the
mouth of the river tend to move in a northerly and southerly
direction parallel to the shore (Wolf, 1968). The majority
of sDDT input, having moved out into the bay, would be distrib-
uted throughout the bay by surface and bottom currents, where
longshore currents which run in a northerly and southerly
direction parallel to the southern and northern parts of the
bay respectively before turning seaward just south of the
269
-10
Salinas River (Wolf, 1968), may recirculate the sDDT, increasing
the relative amounts of DDE all the while. After the 1969 flood,
King (1969) found levels of sDDT in Emerita at the mouth of the
river with higher values for DDT than DDE, which is reasonable,
SDDT
SDDT
since extreme local effects would necessarily contaminate the
immediate area with sDDT (adsorbed in part to the fraction of
fine sediments that were not washed out to sea immediately) and
a short "system time" for sDDT to reach the Emerita resulted.
Animals tested from the same site in this study (two years
later) showed considerably higher values for DDE than for DD
SDDT
SDDT
It is doubtful that sDDT that has remained in the sediments of
the riverbed over a period of time (and are thus mostly DDE)
contribute a relative significant amount of DDE to the runoff
during a flood, since according to usage figures the vast majority
of sDDT being translocated would be in the form of technical
grade DDT that had been recently applied to agricultural lands
of the watershed.
The trend seen in Fig. 4, therefore, is
not unreasonable.
Of course, it is possible that Fig. 4 merely represents
the effect of differential ecological parameters in different
parts of the bay such as standing crop density, trophic level
interchange (and concommitant differential accumulation of
sDDT). Any pattern that exists may either be coincidental or
directly related to the river runoff.
Since DDE values of ovigerous to non-ovigerous animals
SUDT
differs by only 11% (Table 1), the data presented in Fig.4
needs little qualification.
27
-11
Unfortunately,time considerations and lipid cleanup problems
prevented a thorough analysis of all of the egg samples. How-
ever, those that were tested showed a considerable concentration
of sbpT compared to animals they were taken from. However.
egg removal alone does not account for the discrepancy
between non-productive animals and ovigerous ones with eggs
removed (Table 1).
This suggests that ovigerous females have at some point
lost a considerable amount of sDDT. Without further study, one
can only speculate as to the mechanism involved. Since it is
quite unlikely that all of the six non-ovigerous animals tested
(Table i) were non-reproductive (they all had noticeable
ovaries)and some may have just lost their eggs) and there was no
overlap of sDDT values for ovigerous versus non-ovigerous animals.
a rapid but short-lived elimination of the sDDT is suggested. A
plausible time for this to occur would be when the rate of lipid
translocation from the female to the eggs is greatest. If, in
fact, all the non-ovigerous animals were also non-reproductive.
then a more uniform elimination of the sDDT is suggested. It has
been reported that Emerita may build up lipid reserves prior
to the energy-consuming egg laying season, and used them up
during the season (Lee and Gilchrist, 1971; Eickstaedt, 1969).
Because the largest animals, which would tend to store more
lipid, are the first to become reproductive (Eickstaedt, 1969).
this hypothesis seems reasonable. It is doubtful that the
hydrophobic, lipid-soluble sDDT would be lost from the eggs, which
-12
are exposed to the seawater, via some diffusion mechanism
across the egg membrane. All these hypothesis could be tested
without too much difficulty.
Whether or not Emerita analoga is, in fact, a good
systematic indicator of comparative sDOT levels has not been
fully demonstrated in this study, principally because it was
found that sDDT levels differ markedly between ovigerous and
non-ovigerous animals. This difference could not be attributed
entirely to the amount of sDDT lost in the egas when they were
experimentally removed from the animals. It is therefore
suggested that the pertinent difference occurs between
reproductive and non-reproductive animals rather than between
ovigerous and nen-ovigerous specimens. In order to determine
the effectiveness of Emerita as an indicator species, then,
perhaps only non-reproductive animals should be used. Until
further information is gained concerning the stage of reproduction
in relation to loss of uptake of sDDT the problem must necessarily
remain unresolved.
27
elt
Good J

KNOWEDGE
TS

ppe
t a
or
ank you, everybody, f
1 Mrs.
sof
ugave
wa
27.
LITERATURE CITED
Burnett, R. (1971). DDT residues: Distribution along coastal
California of concentrations in Emerita. Submitted
to Science, June, 1971.
Carlisle.
J.G., Schott, J.W., Agramson, N.J. (1960). The Barred
Surperch (Amphistichus argenteus Agassiz)in Southern
California. State of California Department of Fish
and Game Marine Resources Operation. Fish Bulletin
No. 109, 48-52.
Cox, J.L. (1971). DDT residues in coastal marine phytoplankton
and their transfer in pelagic food chains. (PhD
Thesis, Stanford University).
Efford, I.E. (1965). Feeding in the sand crab, Emerita analoga
(Stimpson) (Decapoda, Anomura). Crustaceana. 10(2), 167-82.
Eickstaedt, L.L. (1969). The reproductive biology of the sand
crab Emerita analoga (Stimpson). (PhD thesis, Stanford
University).
King, R.E. (1969). DDT uptake in Emerita analoga and levels
of DOT residues in populations from Asilomar Beach
and near the mouth of the Salinas River. Spring
Quarter report, Hopkins Marine Station, Pacific Grove.
California.
Lee, W.L.
(1971). Hopkins Marine Station, Pacific Grove,
California. Personal communication.
Lee, W.L. and Gilchrist, B.M. (1971). Carotenoid metabolism
and reproduction in the sand crab Emerita analoga
Decapoda, Anomura). In preperation.
Nash, R.G.. and Woolson, E.A. (1967). Persistance of chlorinated
hydrocarbon pesticides in soils. Science. 157 924-7.
Reeder, W.G. (1951). Stomach analysis of a group of shorebirds.
The Condor. 53, 43-5.
Risebrough, R.W., Menzel, D.J., Martin, D.J. and Olcott, H.S.
(1967). DDT residues in Pacific sea birds: A
persistant insecticide in marine food chains. Nature
216, 589-90.
Risebrough, R.W., Reiche, T., Peakall, D.B., Herman, S.G.,
Kirven, M.N. (1968). Polychlorinated biphenyls in
the global ecosystem. Nature. 220 (5172), 1098-1102.
I. (1967). Dynamics of organochlorine insecticides
Robinson,
in vertebrates. Nature. 215, 33-5
(1971). DDT residues in Salinas River sediments.
Routh, J.
Spring Quarter report. Hopkins Marine Station,
Pacific Grove, California.
Rudd, R.L. (1964). Pesticides and the Living Landscape, Chapter
20. University of Wisconsin Press, Madison.
Swarbrick, S. (1971). DDT residues in the marine intertidal
hermit crab (Pagurus samuelis) (Crustecea, Decapoda)
in California waters. Spring Quarter report. Hopkins
Marine Station, Pacific Grove, California.
Tatton, J.O'G., and Ruzicka, J.H.A. (1967). Organochlorine
pesticides in Antarctica. Nature. 215, 346-8.
West, I. (1966). Biological effects of pesticides in the
environment. In Organic Pesticides in the Environment
(American Chemical Society). 309 pages.
274
Wolf,
oodwel
Yancey, T
or
re
SO
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In
go
Co
residue:
DDT
—


ide.
persi
iene.

ents
fornia.
versity of California
raulic Engineering Labor
ratory.
Site Number
2.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
BS
COLLECTION SITI
Location
Carmel (city) Beach
Not listed: Too few and too small
animals collected.
Asilomar State Beach
Cannery Row, Monterey
Wharf + 2, Monterey
Del Monte Beach
Beach near Seaside sewage outfall
Beach near Ft. Ord sewage outfall
Beach near county animal shelter
Mouth of Salinas River
Moss Landing State Beach
Beach behind Moss Landing marine
research station
Mouth of Elkhorn Slough
Zumdoski State Beach
Mouth of Pajaro River
Northern Boundry of Sunset State Beach
Manresa State Beach
Beach half way between sites 17 and 19
Mouth of Aptos Creek
Seacliff State Beach
Twin Lakes State Beach
Mouth of San Lorenzo River
Natural Bridges State Beach
Point Sur
ig.1
analog

Collection
sites fre
whi
were collected
April
22
I


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22
N
27.
rsid
ea
(SDD
Tota
110
the loatic
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.
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collected and anal
Site 2 1:
abse
rom the graph becau
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o0
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type point marks
represent st
different
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stands f
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a
Comparis
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erita analoga
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Asiloma
h, May 2.
tate B
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mation is giv
the eggs that were
removed f
athe ovigerous animal
Si
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