United States
Environmental Protection
Agency
Environmental Research
Laboratory
Gulf Breeze FL 32561
500 ppm. Sublethal
exposures to drilling fluids resulted in
reductions in growth rates, molting
frequencies, respiration rates, feeding
rates, and growth efficiencies. Re-
duced 0:N ratios and increased
protein:lipid ratios demonstrated a
change in the energetics of the larval
lobsters as a result of drilling fluid
exposure.
Results show that it is primarily the
chemical and not the physical features
of drilling fluids that were responsible
for the detrimental effects observed.
The drilling fluids tested that had a
diesel component were more toxic
than those without this component,
although direct correlations between
percent diesel and relative toxicity
could not be made. The phenol and
metal content of the drilling fluids may
have also contributed to their toxicity.
This Project Summary was devel-
oped by EPA's Environmental Re-
search Laboratory. Gulf Breeze. FL. to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Interest in oil and gas exploration in
the coastal regions of the northwestern
Atlantic has increased in recent years in
efforts to find petroleum resources.
Increased exploitation, however, poses
many unanswered questions concerning
potential toxic effects of drilling and
transport operations on commercially
important species and the resulting
economic impact on established fish-
eries.
The American lobster is found off the
northeastern coast of the United States
and off Atlantic Canada and is of
particular ecological and economic
importance. The life cycle of the lobster
includes both planktonic and benthic
stages and, thus, the lobster may be
exposed to a wide range of stress
conditions as a result of drilling oper-
ations. The lobster has four larval
stages, the larval period extending from
the time of hatching from the egg to the
fifth molt or attainment of the first
postlarval stage (stage V); the duration
of larval development is temperature
dependent and ranges from 2 to 8
weeks. Short-term exposure of these
planktonic larval stages to pollutants
discharged from drilling operations
could result in reduced survival, in-
creased susceptibility of larvae to other
environmental stresses and changes in
the rates of larval growth and develop-
ment. The impact of drilling activities
and the toxicity of drilling fluids to
lobster populations are poorly under-
stood but subtle effects on the physiology
and behavior of lobsters may be expected
-------
with the release of drilling fluids to the
marine environment.
Drilling fluids (or drilling muds) are
complex mixtures of clays and chemical
additives that are used in drilling
operations to equalize hydrostatic
pressure, remove drilled cuttings and
lubricate the drill bit. The components of
drilling fluids may include suspended
solids, chromium compounds, alkaline
compounds, bactericides, organic poly-
mers, dispersants, defoamers, lubricants
and detergents.
The dispersion of discharged drilling
fluids and cuttings has been monitored
in several field studies. In their study of
discharges of drilling fluids in the
Baltimore Canyon, Ayers et al. (1980)
observed the formation of two plumes, a
lower plume that contained solids such
as cuttings and an upper plume that
contained finer materials and remained
as a diffuse cloud in the upper portion of
the water column. Richards (1979)
discussed field observations that indicate
that near surface discharges of drilling
fluids do not disperse uniformly but
concentrate in surface waters above the
thermocline. With these observations,
the impact of drilling fluid exposure to
planktonic organisms, including larval
lobster, becomes an important question.
An understanding of the effects of
drilling fluids on larval lobsters is
needed to assess the impact of this
marine pollutant on lobster populations
and the lobster fishery. The objectives of
this research have been to determine
the comparative effects of various
samples of used, whole drilling fluidson
survival, growth and energetics of larval
lobsters. The specific tasks of this
research were as follows:
• to compare the survival of larval
lobsters exposed to various drilling
fluids and to correlate toxicity with the
chemical composition of drilling
fluids;
• to assess the physiological effects of
sublethal exposure to various drilling
fluids on larval lobsters; and
• to assess alterations in biochemical
and mineral composition of larval
lobsters exposed to various drilling
fluids.
A continuous flow exposure system
was designed to allow uniform distribu-
tion of seawater-drilling fluid mixtures in
thirty-two 500 ml test chambers; four
replicates at seven concentrations and a
control were tested simultaneously.
Larval lobsters were exposed for 96h to
concentrations of drilling fluids ranging
from 1 to 500 ppm. Lobsters exposed to
filtered seawater and suspensions of
barite and sediment collected from
Georges Bank served as control experi-
ments. Five larvae were added to each
test chamber and maintained on a diet
of live Artemia nauplii to reduce can-
nibalism. Larvae were monitored for
survival, growth, respiration rates,
ammonia excretion rates, O.N ratios,
feeding rates and scope for growth
indices at selected times during the 96-
h exposure period. Moribund larvae
were examined microscopically; lack of
heartbeat was the criterion for death.
Control and exposed larvae were rinsed
in distilled water and freeze-dried after
the 96-h exposure period for subse-
quent biochemical and mineral compo-
sition analyses.
Used, whole drilling fluids were
supplied by the U.S. Environmental
Protection Agency (EPA), Gulf Breeze,
Florida. The drilling fluids tested were
water based lignosulfonate type muds.
The J-series fluids (4 through 7) were
collected in July 1980 from aland based
well in Jay, Florida, at drilling depths of
12,257 ft.. 13,399 ft., 13,997 ft. and
14,560 ft., respectively. The Mobile Bay
drilling fluid collected on May 29, 1979
(MB-5-29) had been used in the Gulf of
Mexico at drilling depths of about
14,500 ft. All drilling fluids were stored
at 4°C.
Results
Drilling Fluids
The physical and chemical character-
istics of the J-series and Mobile Bay
drilling fluids are presented in Table 1.
The J-drilling fluids ranged in water
content from 80 to 88 percent. Of the
metals analyzed in the J-series, lead (19
to 42 ppm), chromium (96 to 201 ppm),
and zinc (175 to 271 ppm) were present
in high concentrations. Total barium
concentrations were also high (4 to 12
percent) as is typical of drilling fluids
due to the major clay constituent, barite.
Calcium concentrations ranged from 40
to 140 ppm. The percent diesel content
for J-4, 5, 6 and 7 were 0, 2, 3 and 4,
respectively. MB-5-29 had a No. 2 fuel
oil concentration of 0.27 percent and a
phenol concentration of 1.3 ppm. The
chromium concentration of 1810.0 ppm
reported for MB-5-29 was higher than
the concentrations of any of the J-series
drilling fluids.
Phenol concentrations were 1.3 ppm
in MB-5-29, 0.45 ppm in J-5,0.33 ppm
in J-7, and below the 0.25 ppm
detection limits in J-4 and J-6. Due to
their high toxicity, halogenated phenols
have been banned from use as biocide
additives to drilling fluids used offshore
since 1979 (44 Fed. Reg. 39031, 3 July
1979). It should be noted that mud logs
from the J-series included no record of
such additives. A possible source of
phenols other than biocide additives is
the petroleum products found in the
drilling fluids (J. Farrington, personal
communication).
Toxicity
Four-day LCso values demonstrate
wide variability in the toxicity of the five
drilling fluids tested (Table 2). 96-h LCso
values were 73.8 ppm for J-5 and 88.3
ppm for J-7 exposed stage I larvae. In
contrast, the 96-h LC5o for stage I and
stage IV larvae exposed to J-4 drilling
fluid was greater than the highest
concentration (500 ppm) tested, and
there were no significant differences in
the percent survival for these stages at
concentrations of 10, 50, 100, 250 and
500 ppm. The 96-h LCso for J-6 exposed
stage I larvae, 213.4 ppm, was greater
than for J-5 and J-7 by over a factor of
two. Overall control mortality for these
experiments was 33 percent, largely
attributable to cannabilism.
Results for MB-5-29 exposed stage I
larvae were similar to those obtained for
J-6, with a 96-h LCso of 189.5 ppm. An
estimation of 96-h LCso could not be
determined for stage II larvae with this
drilling fluid because of an insufficient
number of mortality determinations
between 0 and 100 percent. However,
decreased survival rates were observed
at concentrations as low as 50 ppm and
100 ppm. The 96-h LCso was 117.2 ppm
for MB-5-29 exposed stage III larvae.
The percent mortality at 96h for control
larvae and larvae tested with a range of
drilling fluid exposure concentrations is
presented in Figure 1.
Growth Rates and Molting
Significant changes in larval growth
rates and developmental times resulted
from exposures to most of the drilling
fluids tested. Decreases in mean dry
weights of stage I larvae were found
after a 24-h exposure to J-5, 6, and 7 at
the highest concentrations tested and
delayed development to stage II was
evident by the end of the 96-h exposure.
No significant differences in dry weights
of stage I larvae resulted from a 96-h
exposure to concentrations of J-4 as
high as 250 ppm. Larvae at all concen-
trations of J-4 and in the control
seawater group had successfully molted
to stage II at 96h.
2
-------
Tabb 1. Physical and chemical characteristics of the J-series and Mobile Bay (5/29/79) drilling fluids.1
Diesel
Total
Resolved
Total
Resolved
Drilling
Density
Fe
At
Ba
Pb
Cr
In
HzO
Oil
Aliphatics
Aromatics Phenols
Fluid
pH
(lbs/gal)
(%)
(%)
(%)
(ppm)
(ppm)
(ppm)
(%)
(%)
(ug/i)
(ug/i)
(ppm)
J-4
11.0
9.1
3.2
8.0
4.1
40.2
96.4
225
88.3
0
17,000
27,300
<0.25
J-5
11.4
9.3
2.6
6.5
9.3
41.7
201
271
82.6
2
1.320,000
380,000
0.45
J-6
11.0
9.3
2.3
5.9
10.6
41.3
160
250
79.3
3
Not
555,000
<0.25
available
J-7
11.5
9.3
1.1
2.5
11.7
18.5
128
175
79 0
4
1.270,000
376.000
0.33
MB-5-29
11.9
9.1
2.7
6.1
8.2
37.8
1810.0
98.6
80.0
0.27t
1.3
'Analyses performed at Science Applications, Inc., La Jolla, CA; New England Aquarium, Boston, MA; University of West Florida,
Pensacola, FL; and Energy Resources Co., Inc., Cambridge. MA.
tNo. 2 fuel oil.
Table 2. 96-h median lethal concentration (LCso) values (± 95 confidence limits)
for drilling fluid exposed lobster larvae. *
Stage Drilling Fluid LCso (ppm) f± 95 CL)
I
III
I
IV
I
I
/
MB-5-29
MB-5-29
J-4
J-4
J-5
J-6
J-7
189.54 (2.03)
117.17 (4.50)
>500
>500
73.76 (2.43)
213.35 (7.26)
88.29 (2.05)
*Determined by log-probit analysis
1 r-
§
©
99.9
99.0
98.0
95.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
110.0
5.0
2.0
1.0
0.1
A CSW
o CSW
~ CSW
0 csw
V CSW
A MB-5-29
• J-4
¦ J-5
~ J-6
~ J-7
~
~
SO?
_L
10 50 100 250 500 1000
Log concentration, ppm
Figure 1. Percent mortality at 96 h of control and drilling fluid exposed stage /
lobster larvae.
The three larval stages exposed to
MB-5-29 (I, II and III) had decreased 96-
h dry weight values at concentrations of
50 ppm and higher as compared to the
control organisms. Stage I larvae
exposed to the J-series drilling fluids
generally exhibited greater declines in
mean dry weights (as compared to
controls) than did the MB-5-29 exposed
stage I larvae.
Respiration Rates
Respiration rates of stage I larvae
were affected by 24-h and 96-h expo-
sures to concentrations of the J-series
drilling fluids. Significant reductions in
respiration rates (expressed as p\ 02/h)
of J-5 exposed larvae were observed
with exposure to 100 ppm at 24h and 50
ppm at 96 h. Exposure to J-6 and J-7 at
a concentration of 100 ppm also
resulted in significantly decreased
respiration rates after 96 h. There was
no significant difference in respiration
rates of larvae exposed to 100 ppm of J-
4; however, the mean respiration value
was low as compared to the control
seawater and Georges Bank sediment-
100 ppm groups.
Respiration rates calculated on a
weight specific basis were generally not
different for the various groups of
control and exposed stage I larvae.
Significant reductions in the dry weights
of drilling fluid exposed larvae were
responsible for the observed differences
between the absolute respiration rates
and the weight specific respiration rates
of control and experimental groups.
In exposures conducted with 10 ppm
MB-5-29 drilling fluid, stage I larvae
exhibited significant differences in
absolute and weight-specific respiration
rates (p <0.05) at 24 h and 96 h.
Respiration rates measured for 1 ppm
exposed larvae were not different from
control larvae.
Respiration rates (absolute and
weight specific) for stage I larvae
exposed to 50, 100 or 500 ppm of
Georges Bank sediment or to 500 ppm
barite were not significantly different
from the control seawater values.
3
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Feeding Rates
After 24 h, stage I larvae exposed to
50 ppm of J-5 consumed an average of
15.5 Artemia nauplii per h, whereas the
control seawater group and the Georges
Bank sediment exposed group consumed
an average of 27.3 and 32.8, respectively.
A statistical comparison demonstrates a
highly significant difference (p <0.001)
between control and drilling fluid
groups, but no significant difference
between the control seawater and
Georges Bank sediment groups.
Data from the feeding experiments
were converted from the number of
Artemia consumed to calories using
average dry weight and caloric content
for Artemia nauplii. Growth rates of
larvae were also converted to hourly
caloric values and growth efficiencies
(Og/Oc) were calculated. Growth effi-
ciency for larvae exposed to 50 ppm of
J-5 was reduced by 75 percent in
comparison with control groups.
Ammonia Excretion Rates
and 0:N Ratios
Ammonia excretion rates of stage I
larval lobsters were significantly in-
creased with a 96-h exposure to J-5 and
J-7 drilling fluids. Values for J-6
exposed larvae were also greater than
the control values, but not significantly
higher. Exposure to J-4 drilling fluid
resulted in no differences between
exposed and control larvae for both stage
I and IV, with the exception of a
significant increase in the 72-h ammo-
nia excretion rates of stage IV larvae
exposed to 500 ppm of J-4.
For J-5, 6 and 7 exposed stage I
larvae, 0:N values were significantly
lower after 96-h exposure to J-4
resulted in no such difference (Figure 2).
The average 0:N ratio of the control lar-
vae was 21.7 and is within the range
previously reported by Capuzzo and Lan-
caster (1979). Comparisons of ammonia
excretion rates and 0:N ratios for
Georges Bank-500 ppm, barite-500
ppm and control seawater groups de-
monstrated no significant differences.
Biochemical composition
Biochemical compositions of stage I
and IV larval lobsters are presented in
Table 3. Significant increases (p <0.01)
in protein content were found in stage I
larvae exposed to 50 ppm of J-5, which
is below the 96-h LCso (73.76) Earlier
studies by Capuzzo and Lancaster
(1981) on oil-exposed larval lobsters
have shown similar results. Protein:lipid
ratios were also significantly greater
30
20
5:
ci
10
I *
*
_i_
CSW J-4-IOOppm J-5-50ppm J-6-100ppm J-7-t00ppm
Exposure groups
Figure 2. Mean 0:N ratios (+ 1 S. E.) at 96 h of control and J-series drilling fluid
exposed stage / lobster larvae.
(p <0.05) in exposed stage I larvae,
whereas no significant differences
were observed among control and ex-
posed larvae for percent ash, carbohy-
drate, and lipid values.
Biochemical determinations were
made on stage IV larvae after a 96-h
exposure to 100 ppm of J-4 drilling fluid.
A significant increase (p<0.05) in lipid
content was observed in the exposed
animals. Protein, carbohydrate, and ash
contents of the stage IV larvae were not
different from the controls. Both control
and exposed stage IV larvae had higher
ash, carbohydrate, and lipid contents
than stage I larvae.
Barium and calcium
composition
Barium and calcium concentrations
for control, barite-500 ppm exposed and
J-4-250 ppm and 500 ppm exposed
stage I larvae are given in Table 4. A
barium concentration of 1.43 //g/mg
dried tissue was found for the barite-ex-
posed larvae; barium was not detected
in the other groups. The 250 ppm and
500 ppm drilling fluid exposed larvae
had the highest calcium concentrations,
43.8 and 33.0 ^rg/mg, respectively.
Control larvae values were 29.2 //g/mg
Ca, and barite-exposed values were
24.4 pg/mg Ca.
Discussion
Different drilling fluids can vary
markedly in their toxicity to larval stages
of the lobster, Homarus americanus, as
shown in the present study. The 96-h
LCso values for the five drilling fluids
tested ranged from 74 ppm to greater
than 500 ppm. Other investigations on
the toxic effects of used, whole drilling
fluids and water-soluble fractions of
drilling fluids on marine crustaceans
have also shown wide variations in their
toxicity. Conklin et al. (1980) demon-
strated a 96-h median lethal concentra-
tion of drilling fluid tested, whereas a
concentration of drilling fluid >25,000
ppm was the reported 96-h LCso for
Mysidopsis by Carr et al. (1980). The
larval stages of lobsters are particularly
sensitive to drilling fluid exposure, as
has also been shown for the early
developmental stages of other crust-
aceans (Derby and Capuzzo, in press).
4
-------
Protein:
Lipidf Lipid]
11.6 ±0.9 5.0
11.9 ±0.3 5.1
11.4 ±0.3 5.6
17.1 ±0.2 2.2
18.3 ±0.2] 1.9
Table 3. Biochemical analyses of control and drilling fluid exposed lobster larvae.
Component
Ash*
Protein]
Carbohydrate]
Stage Group
/ Control
GB-50 ppm
J-5-50 ppm
IV Control
J-4-100 ppm
21.5 ± 1.7
23.6 ±1.6
22.8 ±2.2
31.2 ±0.9
31.6 ± 0.2
57.8 ± 1.4
60.2 ±0.7
63.7 ± 1.2]
37.4 ± 1.3
35.6 ± 1.4
1.4 ± 0.2
1.2 ±0.2
1.2 ±0.1
3.5 ± 0.2
3.2 ± 0.1
*dry weight basis; mean values of a sample size of 5 with 3 replicates/sample ± 1 S.E.
]ash-free dry weight basis.
} p <0.01
Table 4. Barium and calcium analyses of control, barite-500ppm exposed and J-4
drilling fluid*exposed stage / larvae at 96 h. *
Group Ba (pg/mgj Ca (pg/mg)
CSW
Bar-500 ppm
J-4-250 ppm
J-4-500 ppm
0.0
1.4
0.0
0.0
29.2
24.4
43.8
33.0
*Analyses performed by A. Fleer, R. Belastock. P. Brewer of Woods Hole Oceano-
graphic Institution, Woods Hole, MA.
Reductions in growth rates, molting
frequencies, respiration rates, and
feeding rates of larval lobstersfollowing
sublethal exposures to certain drilling
fluids were also observed in this study.
Growth efficiencies (Ki) determined
from these physiological measure-
ments indicate a significant degree of
stress as a result of drilling fluid expo-
sure. Decreased food consumption was
a major contributing factor in the re-
duced growth efficiency of lobster lar-
vae exposed to drilling fluids. Lower
food consumption may be attributed to
numerous variables, such as a weak-
ened condition of the larvae exposed to
drilling fluids, interference of chemo-
sensory processes, or change in pay-
ability of the food source. A recent inves-
tigation has demonstrated that low con-
centrations (10 to 100 ppm) of drilling
fluids interfere with the normal physio-
logical response of primary chemosen-
sory cells of adult lobsters to food odors
(Derby and Atema, 1981).
The reduced respiration rates of the
drilling fluid exposed larvae represent
an interference of a metabolic process
that could result in inefficient utilization
of food and subsequent reductions in
growth. Disruption in energy flow,
manifested specifically in impairment of
growth and development, may be the
most serious consequence of drilling
fluid exposure. Several investigators
have reported similar patterns in the
respiration rates and energetics of other
marine crustaceans as a result of
pollutant exposure.
The reported reduction of 0:N ratios
in drilling fluid exposed lobster larvae is
a further indication of an altered
physiological state. The 0:N ratio has
been used as an index of the catabolic
balance between protein, carbohydrate
and lipid substrates (Capuzzo and
Lancaster, 1979, 1981) and has been
shown to vary under conditions of
physiological stress. The reduction in
0:N ratios of exposed larvae indicates
an increased dependence on protein
catabolism for energy production. The
ratio of biochemical constituents may
provide further information on alter-
ations in energy cycles associated with
pollutant stress. Protein and lipids are
the major energy substrates utilized by
lobsters during larval development
(Capuzzo and Lancaster, 1979) and
alterations in the protein: lipid ratio
were observed with exposure of larval
lobsters to South Louisiana crude oil
as a result of interference with lipid
metabolism (Capuzzo and Lancaster,
1981). In the present study, changes in
protein cpntent and the protein:lipid
ratio also denote significant shifts in
both energy storage and utilization due
to drilling fluid exposure. Simultaneous
increases in protein catabolism and
protein content along with reductions in
protein:lipid ratios of drilling fluid
exposed stage I larvae suggest that
protein is being metabolized for imme-
diate energy needs while less protein is
being utilized for de novo synthesis of
lipid reserves. Such a change in
energetics as a result of drilling fluid
exposure may alter the likelihood of
successful completion of larval devel-
opment. In addition, the delayed devel-
opment shown here would also keep the
lobsters in a planktonic stage for a
longer period, increasing their exposure
to predators and other environmental
stresses.
Although high concentrations of
barite were found in the drilling fluids
tested, barium was not detected in the
drilling fluid exposed larvae. Barite (500
ppm) exposed lobster larvae had a 0.14
percent barium concentration with
these exposure periods. Brannon and
Rao (1979) have reported even greater
shifts in the total barium concentration
of barite exposed Palaemonetespugio (a
benthic-inhabiting shrimp). The level of
Ba in whole shrimp exposed to only 50
ppm barite was 1 percent (for controls-
0.003 percent) after a one-week expo-
sure period. This suggests that exposure
to the clay components of drilling fluids
may become more important to post-
larval lobsters that live in the benthos.
The toxicity of used, whole drilling
fluids has been shown by other investi-
gators to be primarily due to the soluble
chemical constituents. The present
study includes experiments with barite
and a Georges Bank sediment as well as
drilling fluids in an effort to isolate
physical from chemical factors affecting
larval lobsters exposed to drilling fluids.
Grain size analyses show that barite
has a similar grain size distribution as
two of the drilling fluids (MB-5-29 and
j-5), but is somewhat coarser than the
other drilling fluids (J-4, J-6, and J-7).
Georges Bank sediment is coarser than
the drilling fluids and the barite. Because
barite and Georges Bank sediment had
no effect even at very high concentra-
tions, (500 ppm) and some of thedrilling
fluids had an effect on survival, growth,
respiration, excretion, 0:N ratios, and
biochemical composition at compara-
tively low concentrations (50 ppm), it
can be concluded that it is primarily the
chemical and not physical features of
5
-------
drilling fluids that are responsible for
the harmful effects observed here. It
should be noted, however, that histo-
pathological evidence of perturbations
in the midgut epithelium has been
shown in another crustacean, Palae-
monetes pugio, exposed to concentra-
tions of barite comparable to this study.
It is probable that the chemically based
toxicity demonstrated with these drilling
fluids acts in combination with such
perturbations as those resulting from
the physical properties of the clays in
drilling fluid.
Whole used drilling fluids were used
in this study in order to simulate as
closely as possible the chemicals that
lobsters will be exposed to with ocean
discharges. There are two factors that
make it difficult to identify which
classes of constituents are primarily
responsible for the toxicity of each
drilling fluid used in this study. The
chemical compositions of the drilling
fluids are incompletely known and there is
the possibility of synergistic interactions
among the many constituents. Never-
theless, certain chemicals that are
known to be toxic to some marine
crustaceans are present in the drilling
fluids studied here; these chemicals
include petroleum products, metals,
and phenols.
The most toxic drilling fluids in the
present study were those with a high
diesel content. Although direct correla-
tions between percent diesel content
and relative toxicity cannot be made, the
diesel oil was apparently an important
contributing factor. The biochemical
changes that occurred with drilling fluid
exposure parallel findings reported on
oil-exposed larval lobsters (Capuzzoand
Lancaster, 1981). Oil-exposed larvae al-
so had significantly reduced 0:N ratios
as was shown for the larvae exposed to
drilling fluids with high hydrocarbon
contents.
The likelihood that lobster larvae in
the natural environment will encounter
concentrations of drilling fluids com-
parable to those used in these experi-
ments is an important question. Disper-
sion rates and distribution patterns of
drilling fluids released into oceanic
waters will depend on the specific
location of the drilling site in terms of
local atmospheric and hydrographic
conditions. Although dispersion studies
have indicated that particulate compo-
nents of drilling fluids may be detected
at a distance of 1000 m or more from the
discharge source, no information is
available on dispersion of the soluble
6
components. The present study has
shown that it is these fractions that are
of greatest concern in terms of causing
detrimental effects to the early life
stages of a marine organism. Since it is
likely that the soluble fractions are
dispersed further from the drilling sites
than the heavier fractions, the area of
exposure may actually be much larger
than that indicated in current dispersion
studies.
References
Ayers, R.C., T.C. Sauer, R.P. Meek, and
G. Bowers. 1980. An environmental
study to assess the impact of drilling
discharges in the mid-Atlantic. In:
Water Quality Monitoringi Mid-
Atlantic Outer Continental Shelf Area,
EG and G, Environmental Consul-
tants, pp. 7-58.
Brannon, A.C. and K.R. Rao. 1979.
Barium, strontium and calcium levels
in the exoskeleton, hepatopancreas
and abdominal muscle of the grass
shrimp Palaemonetes pugio: Relation
to molting and exposure to barite.
Comp. Biochem. Physiol., 63A: 261 -
274.
Capuzzo, J.M. and B.A. Lancaster.
1979. Some physiological and bio-
chemical considerations of larval
development in the American lobster,
Homarus americanus Milne Edwards.
J. Exp. Mar. Biol. Ecol. 40. 53-62.
Capuzzo, J.M. and B.A. Lancaster.
1981. The physiological effects of
South Louisiana crude oil on larvae of
the American lobster (Homarus
americanus). In: F.J. Vernberg, A.
Calabrese, F.P. Thurberg and W.B.
Vernberg (eds.), Biological Monitoring
of Marine Pollutants, Academic
Press, New York, pp. 405-423.
Derby, C D. and J. Atema. 1981.
Influence of drilling muds on the
primary chemosensory neurons in
walking legs of the lobster, Homarus
americanus. Can. J. Fish. Aquat. Sci.
38: 268-274.
Derby, J.G.S. and J.M. Capuzzo. (In
Press). The effects of drilling fluids on
marine crustaceans: A review of
bioassay techniques and physiological
and behavioral responses. In: I.W.
Duedall, D.R. Kester, P.K. Park and
B.H. Ketchum (eds.), Wastes in the
Ocean, Vol. 4: Energy Wastes in the
Ocean. Wiley Interscience, New York.
Richards, N.L. 1979. Effects of chem-
icals used in oil and gas well-drilling
operations in aquatic environments.
In: Fourth National Conference,
Interagency Energy/Environment
Research and Development Program.
U.S. Environmental Protection Agency
Office of Energy, Minerals and
Industry, Washington, D.C., pp. 1-12.
Judith M. Capuzzo and Jennifer G. Smith Derby are with Woods Hole Oceano-
graphic Institution, Woods Hole, MA 02S43.
Charles McKenney is the EPA Project Officer (see below).
The complete report, entitled "Drilling Fluid Effects to Developmental Stages of
the American Lobster," (Order No. PB 82-220 740; Cost: $9.00. subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487 4650
The EPA Project Officer can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
Gulf Breeze. FL 32561
*U$ QPO:1 M2-&59-092-454
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