1

NOAA Technical Memorandum GLERL-132

TOXICOKINETICS AND TISSUE DISTRIBUTIONS OF NON-POLAR 

CONTAMINANTS FROM AQUEOUS AND DIETARY EXPOSURES FOR THE 

CRAYFISH PACIFASTACUS LENIUSCULUS

Duane C. Gossiaux and Peter F. Landrum

NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI 48105

Great Lakes Environmental Research Laboratory

Ann Arbor, Michigan 

March 2005

UNITED STATES

DEPARTMENT OF COMMERCE

Carlos M. Gutierrez

Secretary

NATIONAL OCEANIC AND

ATMOSPHERIC ADMINISTRATION

Conrad C. Lautenbacher, Jr.

Administrator
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NOTICE

Mention of a commercial company or product does not constitute an endorsement 

by the NOAA. Use of information from this publication concerning proprietary 

products or the tests of such products for publicity or advertising purposes is not 

authorized. This is GLERL Contribution No. 1349.

This publication is available as a PDF file and can be downloaded from GLERLʼs 

web site: www.glerl.noaa.gov. Hard copies can be requested from GLERL, 

Information Services, 2205 Commonwealth Blvd., Ann Arbor, MI 48105.

pubs.glerl@noaa.gov.
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TABLE OF CONTENTS

ABSTRACT ..................................................................................................................................5

INTRODUCTION ........................................................................................................................5

MATERIALS AND METHODS ..................................................................................................6

KINETICS ..................................................................................................................................10

RESULTS ..................................................................................................................................12

REFERENCES ...........................................................................................................................14

LIST OF TABLES

Table 1a. Uptake and elimination rate coefficients and bioconcentration factors for 

 whole body analysis from static aqueous exposures .................................................16

Table 1b. Uptake and elimination rate coefficients and bioconcentration factors for 

 whole body analysis from flow-thru aqueous exposures ..........................................16

Table 2. Uptake rate coefficients from static and flow-thru exposures from pyrene 

 for individual crayfish organs ...................................................................................16

Table 3. Uptake rate coefficients from static and flow-thru exposures from chrysene 

 for individual crayfish organs ...................................................................................16 

Table 4. Uptake rate coefficients from static and flow-thru exposures from 

 benzo(a)pyrene for individual crayfish organs .........................................................17 

Table 5. Uptake rate coefficients from static and flow-thru exposures from 

 hexachlorobiphenyl for individual crayfish organs ...................................................17 

Table 6. Elimination rate coefficients from static and flow-thru exposures from 

 pyrene for individual crayfish organs .......................................................................17 

Table 7. Elimination rate coefficients from static and flow-thru exposures from 

 chrysene for individual crayfish organs ....................................................................17 

Table 8. Elimination rate coefficients from static and flow-thru exposures from 

 benzo(a)pyrene for individual crayfish organs .........................................................18 

Table 9. Elimination rate coefficients from static and flow-thru exposures from 

hexachlorobiphenyl for individual crayfish organs ...................................................18 
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Table 10. Average of bioconcentration factors from static aqueous exposures to crayfish ......18

Table 11. Average of bioconcentration factors from static aqueous exposures to crayfish ......18

Table 12. Absorption efficiencies for crayfish from ingestion of zebra mussel Dreissena 

 polymorpha tissue .....................................................................................................19

Table 13. Percentage of lipid mass for individual crayfish organs ...........................................19

LIST OF FIGURES

Figure 1. Percentage of compounds in crayfish tissues after aqueous exposures ....................20

Figure 2. Percentage of compounds in crayfish tissues after consumption of 

 pre-exposed zebra mussel tissues ..............................................................................21

Figure 3. Lipid normalized concentration of contaminants in crayfish tissues after 

 aqueous exposures ....................................................................................................22

Figure 4. Lipid normalized concentration of contaminants after consumption of 

 pre-exposed zebra mussel tissues ..............................................................................23
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Toxicokinetics and tissue distributions of non-polar contaminants from 

aqueous and dietary exposures for the crayfish Pacifastacus leniusculus.

D.C. Gossiaux and P.F. Landrum

ABSTRACT. The crayfish, Pacifastacus leniusculus, was exposed to dissolved 

polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyls (PCB) 

congeners in short-term static and flow-thru water-only exposures. The uptake and 

elimination rate constants were determined for the total body mass and internal 

organ tissues. The uptake rate coefficient (ku

) for whole crayfish (1–2 g) from 

static water-only exposures ranged from 23.8 to 33.1 ml g-1 h-1 and was negatively 

correlated with log Kow. Uptake rates varied between tissues and compounds. For 

example, the ku from static aqueous exposures for the gill tissue ranged from 37.7 

to 63.8 ml g-1 h-1 and generally increased with increasing log Kow, while ku from 

static aqueous exposures for the hepatopancreas ranged from 357.1 to 37.8 ml g-1

h-1 and decreased with increasing log Kow. The elimination rate constant (ke) for 

whole crayfish ranged from 0.001 to 0.013 h-1 and decreased with increasing log 

Kow. Similarly, the ke values for other individual tissues decreased with increasing 

log Kow. In addition to the aqueous exposures, crayfish were exposed via ingestion 

to zebra mussel, Dreissena polymorpha, tissue pre-exposed to radiolabeled 

contaminants. The percent absorption efficiency (%AE) ranged from 91.2 to 96.5 

%, and the % AE increased with increasing log Kow.

INTRODUCTION

Since the zebra mussel, Dreissena polymorpha, invasion into the Great Lakes (Nalepa et al. 

1989), many biological and ecological changes have occurred (Nalepa and Schloesser 1993). 

Such ecological changes have been attributed to the ability of the zebra mussel to filter large 

volumes of water and compete for food that would normally supply the rest of the benthos (Gossiaux et al. 1997). As a result of the high filtering rates and relatively high lipid content, zebra 

mussels have a high bioaccumulation potential for organic contaminants from the suspended sediments, algae, and water (Gossiaux et al. 1997, Bruner et al. 1995, Fisher et al. 1993), and these 

contaminants become available for trophic transfer. The zebra mussels also have high absorption 

efficiencies for polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) 

congeners from algae (Bruner et al. 1995b). Since zebra mussels are very abundant in the Great 

Lakes (Nalepa et al. 1989), there is an excellent opportunity for predators of zebra mussels to be 

exposed to high levels of contaminants through trophic transfer. One such predator, the crayfish, 

was observed in laboratory studies (Love and Savino 1993) to consume large amounts of zebra 

mussel tissue. Thus, crayfish may be at greater risk of contaminant exposure than organisms that 

do not feed on zebra mussels. This work determined the contaminant uptake through aqueous 

exposures and the absorption of contaminants from ingestion of laboratory-dosed zebra mussel 

tissue by crayfish.
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MATERIALS AND METHODS

Chemicals

The radiolabeled compounds were either purchased from the Sigma Chemical Company (St. 

Louis, MO, USA) or Chemsyn Science Laboratories (Lenexa, KS, USA) and included 3

H-pyrene 

(32.3 Ci/mMol), 3

H-chrysene (340 mCi/mMol), 14C-benzo(a)pyrene (BaP, 26.6 mCi/mMol), 14C3,3’,4,4’-tetrachlorophenyl (TCBP 37.1 mCi/mMol), and 14C-2,2’,4,4’,5,5’-hexachlorobiphenyl 

(HCBP, 12.6 mCi/mMol). The radiopurity was determined by thin layer chromatography (TLC) 

using hexane:benzene (8:2, v:v) and was quantified by liquid scintillation counting (LSC). Samples 

were counted on a LKB 1217 liquid scintillation counter. The data were corrected for quench using 

the external standards ratio method after subtracting for background. Compound radiopurity was 

> 98% for all compounds. Analytical procedures were performed under gold fluorescent light (λ

> 500 nm) to minimize the PAH photodegradation. All compounds were dissolved in an acetone 

carrier. The acetone concentration in the exposure water ranged between 0.005 and 0.01 mL L-1.

Organisms

Crayfish: Crayfish, Pacifastacus leniusculus, were obtained through Carolina Biological Supply 

(Burlington, NC, USA). Upon arrival, crayfish were placed in a shallow 5 gallon aquarium with a 

sand substrate and submerged pieces of PVC pipe for refuge. The crayfish were fed daily ~ 500 mg 

of ground hamburger per organism. Any uneaten food was removed after 1 h and discarded. The 

aquarium was aerated, and the water was renewed by means of a flow-thru system with a flow rate 

of 500 mL h-1. Twenty-four hours prior to the start of the tests, feeding was discontinued.

Zebra Mussels: Adult zebra mussels were collected from Lake St. Clair (42o

20’00’’ N and 

82o

47’30’’ W) at a depth of 5 m using an epibenthic sled. The collected mussels were cleaned with 

lake water, placed in a cooler, covered with wet paper towels, and transported to the laboratory. 

At the laboratory, mussels were transferred to an aerated aquarium and maintained at the water 

temperature measured at the site of collection, which ranged from 8 to 15oC. Mussels in culture 

were fed a daily diet of Chlamydomonus spp. The Chlamydomonus was prepared in 2000 mL 

flasks in stock solution using Guillard WC culture medium (Guillard and Lorenzen 1972). This 

algal culture was allowed to grow for 7 d at 15oC with a photoperiod of 16 h light/8 h dark. The 

algae were then added to the mussel cultures at a rate of 200 mL of algal solution per day.

The culture water was renewed once a week by changing half the water of the holding tanks with 

Lake Michigan water at the culture temperature. The culture water was also monitored twice a 

week for ammonia concentration (Aquarium Pharmaceuticals, INC, Chalfont, PA). Throughout the 

course of the mussel culturing, the ammonia concentration never exceeded 2 mg L-1. Furthermore, 

no mussels were used after being held in culture for more than 3 weeks.

Lipid Analysis

Mussels for these studies were 2.5–3.0 cm in length. The lipid content of 10 individual zebra 

mussels was determined for each collection of organisms to monitor health. The lipids were 

measured using a microgravimetric procedure with chloroform/methanol extraction (Gardner et 

al. 1985). Since the crayfish tissues were large, sub-samples of each tissue were taken for lipid 

analysis.
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Crayfish Water-Only Uptake Static Exposures

Crayfish, 3–4 cm in length (1–2 g) were exposed under static conditions to aqueous solutions 

containing two radiolabeled compounds as 3

H and 14C labeled pairs in filtered lake water. Filtered 

lake water (12 L), adjusted to the experimental temperature, was dosed in bulk with radiolabeled 

compounds in the following combinations: 3

H-chrysene/14C-HCBP and 3H-pyrene/14C-BaP. 

The water was allowed to equilibrate for 1 h after dosing. For each set of compounds, crayfish 

were individually housed in 1 L beakers containing 700 mL of exposure solution at 20o

C under 

yellow fluorescent lights, with six crayfish per exposure and an exposure duration of 6 h. Oxygen 

was determined at the beginning and end of the exposure by using an Orion O2

 electrode. 

Water samples (2 mL) and one crayfish were removed every hour to determine contaminant 

concentrations. Each crayfish was dissected into the following parts: hepatopancreas, abdominal 

muscle, thorax muscle, carapace, and a combination of stomach, brain, and adrenal glands 

(viscera). The stomach, brain, and adrenal glands were added together because of their small 

size and the difficulty in separating them cleanly. Tissue samples were removed, weighed, and 

placed in 12 mL of scintillation cocktail (RPI 3a70B). Each tissue was then sonicated for 1 min. 

using a Tekmar 375-watt ultrasonic processor (Tekmar Co., Cincinnati, OH USA). The carapace 

was placed in scintillation cocktail for extraction by the cocktail without sonication for 24 h and 

then removed before counting. Sorption to the beaker was also determined by measuring the 

radioactivity in an acetone rinse of each beaker. At the end of the exposures, the total mass balance 

ranged from 85 to 93%. The 14C and 3

H tracers were counted simultaneously on an LKB 1217 

liquid scintillation counter using dual-label counting. The data were corrected for quench using 

external-standards ratio method after correcting for background. 

Crayfish Water-Only Uptake Flow-Thru Exposures

For comparison with the static exposures, crayfish were exposed under flow-thru conditions for 

6 h at a flow rate of 200 mL h-1 in 250 mL exposure chambers. Two crayfish were added to each 

of the three exposure chambers. Since there were a sufficient number of chambers (6 in total), 

duplicate experiments were performed. The crayfish were not fed during any portion of the uptake 

study. Water samples (2 mL) and one crayfish were removed every hour to determine contaminant 

concentrations. Procedures for determining crayfish concentrations were the same as described 

above.

Crayfish Elimination Studies

Crayfish for the elimination studies were exposed at the same time as each of the static or flowthru experiments were being conducted. The pre-exposure from the static experiment consisted 

of exposing five crayfish to four liters of exposure solution. The pre-exposure for the flow-thru 

experiment involved exposing four crayfish in one flow-thru chamber. For both, static and flowthru experiments, the following protocol was identical. The contaminated crayfish were transferred 

to 4 L of uncontaminated aerated water under the same conditions as those used for uptake studies. 

The rates of elimination were determined by sampling over a 10 d period post-exposure (24, 144, 

192, 288, and 360 h for crayfish from the static exposure and 24, 96, 216, and 360 h for crayfish 

from the flow-thru exposure). During this time, the water was continuously exchanged by using a 

flow-thru system exchanging at least 100% of the water daily. The crayfish were fed as described 

for the culture conditions. At each of the time points, one crayfish was removed at each time point, 

dissected and the tissue residues determined as described above.
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Kinetics

Accumulation for the static exposures was modeled through a mass balance model (Equation 

1, Landrum et al. 1992). Using the initial rates assumptions, the model assumed that during 

the uptake phase, elimination was not significant, and the total mass of contaminants remained 

constant throughout the exposure and could be found either in the water or the organism. The mass 

balance indicated that the amount sorbed to the beaker was 0.8 ± 0.2% for PY (mean ± SD, n=6 in 

all cases), 8.1 ± 3.2% for Ch, 9.5 ± 1.6% for BaP, and 18.1 ± 8.2% for HCBP. The amount in the 

system was corrected for the amount bound to the beaker for HCBP only, because past experience 

suggested that losses of less than 10% have little impact on kinetic calculations (Landrum et al.

2003). The initial rate assumption was supported by the relatively slow elimination (half-life = 

53-693 h) compared to the duration of exposure (6 h).

(1)

where 

Qa = amount of contaminant in tissue (μg) 

A = total amount of contaminant in a treatment beaker at t=o (μg)

t = time (h)

Solving for k1

 (2) 

k1 is a conditional rate constant, which is a system dependent value, and must be converted to a 

system independent clearance (ku

) by the following equation (Landrum 1983)

ku = k1 (volume of water (mL) /wet mass of tissue (g)) (3)

The uptake clearance, ku

, describes the amount of water scavenged of contaminant per amount of 

tissue per time (mL g-1 wet tissue h-1).

The elimination rate coefficient, ke

, was determined using a first-order elimination model.

(4)

where:

ke = fraction of material eliminated with time (h-1)

Ca = amount of contaminant in the tissue (μg g -1wet tissue)

log Bioconcentration Factors (BCF, mL g-1) were calculated from uptake and elimination rate 

constants (Bailer et al. 2000):

(5)

The hat (^

) above the BCF, ku, and ke is a notion that indicates that we are referencing an estimator 

or estimate and not a known parameter.
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The standard errors (SE) of the BCF were estimated by applying the delta method to the BCF

estimates, which yielded an appropriate SE associated with the estimated BCF.

(6)

where the variance associated with the ku estimator is σ u

2

, the variance associated with the ke

estimator is σ 2

e

, and the covariance between these two estimators is denoted σ ue. 

For the flow-thru studies, a constant infusion (2 compartment) model is used because the water 

concentration did not change over the time course of the experiment. The variability in the water 

concentrations for pyrene and chrysene was 2-4%.

(7)

where

ku= uptake rate coefficient (mL g-1 h-1)

ke= the elimination rate coefficient calculated by equation 4

Ca= concentration in the crayfish (μg g-1)

t = time (h)

Cw = concentration in the water (μg ml-1)

In all kinetic studies, Ca

 is determined as the sum of the amount of compound in each tissue 

divided by the total wet weight.

Absorption Efficiencies: 

Zebra mussels were added to an exposure solution containing either radiolabeled 3

H-chrysene/14CHCBP or 3

H-pyrene/14C-TCBP at water concentrations of 10,000 dpm mL-1 for the 3H compounds 

and 1000 dpm mL-1 for the 14C labeled compounds. The mussels were removed after 3 h, and the 

soft tissues were dissected. To obtain an estimate for the amount of activity in each piece of zebra 

mussel tissue fed to the crayfish, six zebra mussels exposed to treated water were dissected and 

the radioactivity determined by the same procedure as for crayfish tissues. The average amount of 

contaminant per zebra mussel (pyrene 0.17 μg ± 0.003, chrysene 0.52 μg ± 0.21, TCBP 25.8 μg 

± 0.5, HCBP 2.91 μg ± 1.2) was used to set the amount ingested by the crayfish. Tissue from one 

mussel was then fed to one crayfish, which was housed in a 600 mL beaker covered with black 

paper to prevent startling the crayfish. Any crayfish that did not ingest the tissue within 10 minutes 

was removed from the experiment. Only crayfish that ingested the entire mussel tissue, were 

sampled for contaminant distribution. The crayfish were allowed to digest the tissue for 1 hr prior 

to sampling. After exposure, the crayfish were removed from the water and sacrificed by dipping 

them in liquid nitrogen. The same organs as described above were removed, weighed, placed in 

scintillation cocktail, and analyzed after 24 h by LSC.
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Absorption Efficiencies were calculated by:

% AE = ((Amti – Amte) / Amti)* 100 (8)

where:

Amti = the amount ingested by the crayfish (dpm) based on the average amounts determined 

above

Amte = the amount eliminated in the feces (dpm)

Statistics

Student’s t-tests were performed with SYSTAT® version 10.0 (SPSS, Chicago, IL, USA) to 

determine statistical differences between means. Differences were considered significant when 

p<0.05. The regression package in Scientist® (Micromath Inc, St. Louis, MO, USA 1995), was 

used for non-linear regressions. 

RESULTS

Uptake Rate Coefficients

Uptake rate coefficients for the whole crayfish, from static water exposures, were not significantly 

different between all compounds, but uptake rate coefficients did decrease linearly with increasing 

octonal-water partition coefficient (Kow), ku

 = -4.32 (1.45 SE) (log Kow) + 54.03 (8.52 SE), r2=0.65, 

n=24 (Table 1a). In the static exposures, the uptake coefficient for pyrene for all tissues except gills 

was larger than for the gill tissue with other compounds. The gill tissues exhibited relatively large 

uptake coefficients for all compounds, which is reasonable as they represent the major route of 

accumulation for these materials (Table 2-5). Although not significant, gill tissue also exhibited a 

general increase in the uptake coefficient with increasing log Kow except that the ku

 for HCBP was 

somewhat lower than that for BaP.

Uptake rate coefficients for the whole crayfish, from flow-thru water exposures, were not 

significantly different between all compounds with the exception of pyrene (Table 1b). The ku

 for 

pyrene was statistically larger than for the remaining three compounds. Uptake rate coefficients for 

the various tissues from flow-thru water exposures were significantly different between compounds 

(Tables 2-5) and were similar between replicated flow-thru tests.

Uptake rate coefficients between the two different experimental designs were statistically different 

for all compounds tested; specifically the ku

 values were generally larger for the static experiments 

except for pyrene. The ku

 from the various tissues for the two different experimental designs varied, 

and no particular experimental design proved to generate higher or lower ku

 values with respect to 

the other design.

One dynamic feature from both experimental designs is that the ku for the hepatopancreus, 

thorax, viscera, and abdominal muscle changed by more than a factor of 10 from the low log 

Kow compound pyrene to the highest log Kow compound HCBP (Table 2-5). While for the gills, 

a maximum change in the ku

 was only a factor of two. This likely reflects the rapid flushing rate 

for the gills and the absence of restrictive barriers to accumulation. All other tissues depend both 
11

on circulation rate, which governs redistribution within the crayfish, and gill transfer rate, both of 

which serve as kinetic barriers. 

Comparing the uptake rates of Pacifastacus leniusculus with other species of similar size, the 

zebra mussel Dreissena polymorpha has a very high clearance rates relative to the crayfish (pyrene 

350 mL g-1 h-1 ,BaP 760 mL g-1 h-1 and, HCBP 900 mL g-1 h-1, Bruner et al. 1993). This reflects the 

high pumping volumes of the mussels, which is required because they are filter feeders. However, 

the uptake clearance of the crayfish is more similar to that for small bluegill sunfish 67 ml g-1 h-1

for anthracene and 62 ml g-1 h-1 for BaP (Spacie et al. 1983). The bluegill and the crayfish are more 

similar physiologically as they do not use filtration as a feeding mechanism.

Elimination Rate Coefficients

The elimination rate coefficients for the whole crayfish from static water-only exposures decreased 

linearly with respect to the log Kow and ke

 values are significantly different between each compound 

(Table 1a). The ke values for static water-only exposures for the whole crayfish were substantially 

different from the ke

 values for the individual tissues (Table 6-9). For pyrene and chrysene, the ke

values for the tissues were generally similar to the whole body values, while for BaP and HCBP, 

the tissue values were generally larger than that determined for whole organisms. Further, for 

HCBP and BaP, all the tissues exhibited significantly larger ke values than the whole body ke. The 

lower ke

 values for the whole animal verses specific tissues may reflect distribution limitations 

from the tissue to the gill.

There are also statistical differences in ke values between the static and flow-thru water exposures 

for chrysene and BaP in whole crayfish. The ke

 values were generally larger for the flow-thru 

studies perhaps representing better maintenance of an activity gradient between the organism 

and the water (Table 6-9). For pyrene, flow-thru conditions yielded the higher ke

 values in the 

abdominal mussel, gills, hepatopancreas, and thorax muscle but not in the viscera. In the case of 

chrysene, BaP, and HCBP, all ke

 values were higher in the flow-thru conditions. There are also 

statistical differences between replicate tests for both the static and flow-thru exposures for pyrene, 

chrysene, and BaP (Table 6-9). As with the static experiments, the individual tissues exhibited 

larger ke values than the whole organism.

As with the uptake rates, the elimination rate constants can be compared between aquatic 

organisms of similar size. The elimination rate constant for P. leniusculus are smaller than those 

for D. polymorpha where ke was pyrene 0.021 h-1, BaP 0.009 h-1, HCBP 0.005 h-1 despite the 

fact that the lipid content of the two species was similar (Bruner et al. 1994). The faster rates for 

elimination in the zebra mussels also reflect the high filtration rates. As with the uptake rates, 

the elimination rates for small bluegill sunfish are more similar but are still faster than for the 

crayfish, 0.040 h-1 for anthrancene and 0.010 h-1 for BaP. Some of the difference in this case may 

be differences in the biostransformation capacity of the fish. While biotransformation was not 

determined in the crayfish, bluegill were able to readily biotransform the PAH congeners.

Bioconcentration Factors

In general there was no trend in BCF verses log Kow for whole crayfish exposed either in static 

or flow-thru experiments (Tables 1a and 1b)

.

 In general, the calculated BCF was greater from 

the static tests except for pyrene. As with the whole organism, there were no trends in the log 
12

BCF from static water exposures for the individual tissues (Table 10). In contrast, the log BCF

for the individual tissues from flow-thru exposures, with the exception of pyrene, increased with 

increasing log Kow (Table 11). This may result from the pyrene ku

 in the hepatopancreas being a 

factor of 10 greater than the other three compounds in the same tissue.

Absorption Efficiencies 

Crayfish absorption efficiencies were high and increased linearly with respect to the contaminant’s 

log Kow (Table 12). Absorption efficiencies ranged from 91.2 to 96.1%. These efficiencies are 

similar to those of zebra mussels, which ranged from 91.5 to 97.6%, when exposed to radiolabeled 

algae with the same contaminants (Gossiaux et al. 1998). The high absorption efficiencies for 

accumulation from food likely reflects the high digestibility of the food for both the crayfish and 

the zebra mussel.

Lipid Analysis

The percent lipid within the crayfish ranged from 1.55% in the abdominal mussel to 15.57% in the 

hepatopancreas on a dry weight basis (Table 13). Lipid normalized concentrations in crayfish for 

both aqueous and feeding exposures were larger for pyrene in all tissues than all other compounds 

(Figures 3 and 4). However, the concentration of pyrene remained roughly the same for the viscera 

whether the crayfish were exposed to the contaminants in aqueous exposures or feeding exposures.

Contaminant Distributions

From the water-only exposures, the fraction of contaminant in tissue increased linearly with 

increasing log Kow for the carapace and gills and decreased for the rest of the tissues, likely 

reflecting distribution limitations relative to the log Kow across the four compounds (Figure 1). The 

fraction of pyrene, which has the smallest log Kow, was greatest in the hepatopancreas and lowest 

in the gill tissue. While the fraction of HCBP with the largest log Kow, was greatest on the carapace 

and smallest in the viscera (Figure 1).

Fractional contaminant distributions after the ingestion of pre-exposed zebra mussels, exhibited a 

linear increase for the hepatopancreas and decreases for most of the other tissues relative to the log 

Kow (Figure 2). While HCBP was found at smallest percent accumulation in the hepatopancreas 

following water-only exposures, it had the greatest percent accumulation when exposure occurred 

via ingestion (Figures 1 and 2). Similarly, while HCBP exhibited the largest fraction on the 

carapace following the aqueous exposures, it had the smallest concentrations following the 

ingestion exposures (Figures 1 and 2). The decline in the importance of the carapace is clear in that 

the carapace would serve as a site of sorption for HCBP with aqueous exposure. For the exposure 

via feeding, the hepatopancreas is apparently kinetically closer to the site of uptake. In mammals, 

the bloods flow carries materials from the GI tract through the portal vein almost directly to the 

liver. Apparently, a similar flow occurs in the crayfish based on the greater accumulation in the 

hepatopancreas when exposed via feeding compared to exposure via an aqueous solution.

SUMMARY

In summary, whole crayfish had higher uptake rates for pyrene in both static and flow-thru 

exposures, while HCBP yielded uptake rates that were the lowest for both experimental designs. 

Upon examination of tissue uptake rates, it was discovered that the uptake rates varied between 
13

tissues and compounds. However, from static exposures, ku values for the gill tissues generally 

increased with increasing log Kow, while ku

 values for the hepatopancreas decreased with increasing 

log Kow. Elimination rate constants for whole crayfish from static-exposures decreased with 

increasing log Kow and were lower than ke

 values for individual tissues exposed to the same 

contaminants. Elimination rate constants for tissue from flow-thru exposures were statistically 

greater than those from static exposures. The ke

 values from flow-thru exposures were also larger 

than ke valuesfrom whole crayfish flow-thru exposures. Absorption efficiencies were high (>91%) 

and increased linearly with respect to the contaminants log Kow. Fractional contaminant distribution 

from aqueous exposures was greatest for the contaminant with the lowest log Kow, pyrene, in the 

abdomen, hepatopancreaus, thorax, and viscera tissues, while the contaminant with the great log 

Kow, HCBP was greatest in the gills and carapace. When these fractions were lipid-normalized, 

pyrene was in the greatest concentration for all tissues. Fractional contaminant distributions for 

crayfish after consumption of zebra mussel tissues revealed variable distribution for each tissue. 

However, HCBP was found in the greatest percent in the hepatopancreaus, while pyrene was 

greatest in carapace and viscera. When contaminant concentrations were lipid-normalized, pyrene 

again was in the greatest concentration for all tissues.
14

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16

Table 1a. Uptake, elimination rate coefficients and log bioconcentration factors (BCF) for whole 

body analysis from static aqueous exposures. Numbers in parentheses are standard deviations.

Compound log Kow ku 

(mL g-1 h-1) ke (h-1) log BCF

Pyrene 5.2 33.1 (4.3) 0.013 (0.001) 3.41 (0.09)

Chrysene 5.8 31.4 (2.7) 0.008 (0.002) 3.60 (0.25)

Benzo(a)pyrene 5.9 25.9 (3.9) 0.003 (0.0004) 3.94 (0.16)

Hexachlorobiphenyl 6.7 23.8 (2.6) 0.001 (0.0005) 3.30 (0.50)

Table 1b. Uptake, elimination rate coefficients and log bioconcentration factors (BCF) for 

whole body analysis from flow-thru aqueous exposures. Numbers in parentheses are standard 

deviations.

Compound log Kow ku 

(mL g-1 h-1) ke (h-1) log BCF

Pyrene 5.2 60.5 (10.7) 0.016 (0.007) 3.58 (0.47)

Chrysene 5.8 12.0 (1.7) 0.033 (0.001) 2.56 (0.15)

Benzo(a)pyrene 5.9 13.9 (1.4) 0.019 (0.001) 2.86 (0.11)

Hexachlorobiphenyl 6.7 11.7 (0.6) 0.001 (0.0002) 4.07 (0.21)

Table 2. Uptake rate coefficients (ku

 ml g-1 h-1) for pyrene from aqueous exposures. Numbers in 

parenthesis are standard deviations.

Exp Type Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Static 20.9 (1.8) 37.7 (18.3) 357.9 (140.1) 88.3 (50.3) 32.6 (10.1)

Flow-thru 18.8 (4.7) 21.2 (5.1) 573.1 (125.3) 66.6 (5.9) 24.9 (3.1)

Flow-thru 18.9 (1.7) 23.5 (4.4) 335.2 (20.1) 77.8 (22.5) 17.3 (1.9)

Table 3. Uptake rate coefficients (ku

 ml g-1 h-1) for chrysene from aqueous exposures. Numbers in 

parenthesis are standard deviations.

Exp Type Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Static 0.8 (0.7) 26.2 (20.1) 69.3 (25.9) 12.6 (10.4) 5.2 (2.1)

Flow-thru 3.7 (0.4) 14.4 (3.3) 52.3 (5.4) 4.5 (0.3) 4.4 (0.4)

Flow-thru 5.4 (0.2) 36.2 (7.4) 63.1 (12.6) 11.1 (1.6) 6.8 (0.4)
17

Table 4. Uptake rate coefficients (ku ml g-1 h-1) for BaP from aqueous exposures. Numbers in 

parenthesis are standard deviations.

Exp Type Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Static 3.6 (1.0) 63.8 (42.5) 37.8 (18.8) 15.9 (11.9) 5.2 (2.6)

Flow-thru 4.4 (0.4) 11.3 (1.6) 84.2 (19.1) 13.2 (1.2) 5.6 (0.4)

Flow-thru 1.1 (1.1) 41.1 (4.4) 57.8 (22.9) 5.0 (1.0) 7.1 (6.2)

Table 5. Uptake rate coefficients (ku ml g-1 h-1) for HCBP from aqueous exposures. Numbers in 

parenthesis are standard deviations.

Exp Type Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Static 6.8 (5.2) 60.9 (34.5) 58.5 (48.1) 2.3 (2.1) 7.5 (5.7)

Flow-thru 2.0 (0.3) 34.4 (7.2) 48.2 (3.8) 3.4 (0.4) 3.1 (0.2)

Flow-thru 2.0 (0.6) 69.4 (12.2) 41.3 (24.9) 3.8 (1.5) 3.8 (1.7)

Table 6. Elimination rate coefficients (ke

 h-1) for pyrene after aqueous exposure. Numbers in 

parenthesis are standard deviations.

Exp Type Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Static 0.0123 (0.0012) 0.0390 (0.0002) 0.0125 (0.0024) 0.0148 (0.0024) 0.0098 (0.0016)

Static 0.0191 (0.0029) 0.0212 (0.0033) 0.0164 (0.0018) 0.0158 (0.0008) 0.0155 (0.0019)

Flow-thru 0.0192 (0.0043) 0.0167 (0.0064) 0.0232 (0.0042) 0.0131 (0.0022) 0.0198 (0.0054)

Flow-thru 0.0692 (0.0017) 0.0654 (0.0265) 0.0183 (0.0112) 0.0086 (0.0017) 0.0117 (0.0031)

Exp Type Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Static 0.012 (0.002) 0.010 (0.003) 0.007 (0.001) 0.012 (0.001) 0.012 (0.008)

Flow-thru 0.077 (0.002) 0.105 (0.016) 0.032 (0.002) 0.042 (0.005) 0.025 (0.002)

Flow-thru 0.067 (0.003) 0.114(0.012) 0.039(0.002) 0.063(0.010) 0.011 (0.003)

Table 7 Elimination rate coefficients (ke h-1) for chrysene after aqueous exposure. Numbers in 

parenthesis are standard deviations.
18

Table 8. Elimination rate coefficients (ke h-1) for BaP after aqueous exposure. Numbers in 

parenthesis are standard deviations.

Exp Type Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Static 0.0089 (0.0015) 0.0074 (0.0013) 0.0093 (0.0012) 0.0087 (0.0012) 0.0078 (0.0014)

Static 0.0149 (0.0029) 0.0066 (0.0016) 0.0049 (0.0013) 0.0109 (0.0019) 0.012 (0.0021)

Flow-thru 0.0442 (0.0044) 0.0444 (0.0113) 0.0238 (0.0030) 0.0103 (0.0012) 0.0452 (0.0077)

Flow-thru 0.0826 (0.0041) 0.0651 (0.0082) 0.0253 (0.0025) 0.0188 (0.0032) 0.0223 (0.0021)

Table 9. Elimination rate coefficients (ke h-1) for HCBP after aqueous exposure. Numbers in 

parenthesis are standard deviations.

Exp Type Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Static 0.0032 (0.0026) 0.0061 (0.0044) 0.0004 (0.0002) 0.0021 (0.0005) 0.0027 (0.0002)

Flow-thru 0.0118 (0.0034) 0.0529 (0.0122) 0.0009 (0.0001) 0.0052 (0.0005) 0.0037 (0.0001)

Table 10. Average bioconcentration factors BCF (ku

/ke) from static aqueous exposures.

Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Pyrene 1396 5722 25164 5779 2714

Chrysene 66 3500 9760 1033 448

BaP 323 9144 5889 1644 549

HCBP 219 9393 52750 1667 703

Table 11. Average bioconcentration factors BCF (ku

/ke) from flow-thru aqueous exposures.

Abdominal Muscle Gills Hepatopancreas Viscera Thorax Muscle

Pyrene 626 814 21663 3139 1369

Chrysene 64 227 1626 142 397

BaP 57 443 2911 774 221

HCBP 169 980 49722 1385 933
19

Table 13. Percent lipid in crayfish.

Tissue % Lipid S.E.

Abdominal Muscle 1.55 0.43

Gills 11.85 2.85

Hepatopancreas 15.57 3.95

Thorax Muscle 3.40 0.58

Viscera 4.34 0.89

Table 12. Crayfish absorption efficiencies from ingestion of zebra mussel tissue.

Compound % Absorption Efficiency Standard Deviation

Pyrene 91.21 6.13

Chrysene 92.78 6.86

Tetrachlorobiphenyl 95.95 1.10

Hexachlorobiphenyl 96.05 4.17

n=10

n=4
20

Figure 1. Percent of total contaminants (with stand errors bars, n=6) in crayfish tissues after 

aqueous exposures.
21

Figure 2. Percent of total contaminants (with stand errors bars, n=6) in crayfish tissues after 

consumption of contaminated zebra mussel tissue. 
22

Figure 3. Lipid normalized contaminant concentrations in crayfish tissues after aqueous 

exposures.
23

Figure 4. Lipid normalized contaminant concentrations in crayfish tissues after consumption of 

contaminated zebra mussel tissue.