U.S. Fish and Wildlife Service
Ecological Services
P.O. Box 33726
Raleigh, North Carolina 27636--3726
Anton M. Wicker
Project Biologist
L.K. Mike Gantt
Project Leader
October 1994
U.S. Fish and Wildlife Service / Southeast Region / Atlanta,
Georgia
Abstract: Samples of sediment, rangia clams (Rangia cuneata),
gizzard shad (Dorosoma cepedianum), and longnose gar (Lepisosteus
osseus) were collected from five sites in the lower Pamlico River and
analyzed for elemental contaminants, organochlorines, aliphatic hydrocarbons,
and polynuclear aromatic hydrocarbons. Most sample concentrations were
either beneath the detection limit or too low to be associated with biological
impacts. However, sediment sample concentrations of cadmium and fluoride
were observed at levels that could be associated with biological impacts
at one of the sites which was located near the discharge from a large phosphate
mining operation.
Key Words: Pamlico River, Fluoride, Cadmium, Sediment, Rangia Clam,Fish
Preface
This draft report addresses work funded and performed under environmental contaminants study identifier 92-4F07 and USFWS contaminants catalog number 4100003.
Questions, comments, and suggestions related to this report are encouraged. Inquires should be directed to the Service at the following address:
U.S. Fish and Wildlife Service
Ecological Services
P.O. Box 33726
Raleigh, North Carolina 27636--3726
The Fish and Wildlife Service requests that no part of this report be
taken out of context, and if reproduced, the document should appear in
its entirety.
Introduction | 1 |
Methods | 2 |
Results and Discussion | 3 |
Summary | 4 |
Literature Cited | 5 |
Figures
Figure 1. Pamlico River sample sites. |
Tables
Table 1. Site water salinity, temperature and sediment composition. | |
Table 2. Trace element contaminant concentrations in sediment composites. | |
Table 3. Trace element contaminant concentrations in rangia clam composites. | |
Table 4. Trace element contaminant concentrations in fish composites. | |
Table 5. Organochlorine concentrations in gizzard shad composites. | |
Table 6. Aliphatic hydrocarbon concentrations in sediment and rangia clam composites. | |
Table 7. Polynuclear aromatic hydrocarbon concentrations in sediment and rangia clam composites. |
1. INTRODUCTION
Work recently conducted has documented heavy metal pollution of sediments
in areas of the Pamlico River (Riggs et al. 1989). Concern exists over
the transfer of heavy metals into fish and shellfish although such mechanisms
are poorly understood. The lower Pamlico River receives discharge from
one of the largest phosphate mining operations in North America and has
been the location of several fish kills and disease outbreaks recently
(Noga et al. 1989). Contaminant data for biota in the AlbemarlePamlico
drainage are limited (NC Division of Environmental Management 1991; Benkert
1992). The objective of this study was to expand the existing contaminants
baseline data in the Albemarle--Pamlico area.
2. METHODS
Sediment samples were collected at a depth of about three feet from October 21-23, 1991 at five sites in the lower Pamlico River. The Chocownity Bay sediment sample was collected of the northeast bank in the first embayment northwest of Fork Point. The Kennedy Creek sample was taken approximately 400 meters southwest of the water tower off the opposite bank. The Broad Creek sample was taken on the west bank approximately 3 km upstream of Mcgotters Marina. Bath Creek was sampled approximately 15 meters offshore from the wooden bulkhead at Archbell Point, across from a group of large pine trees in the hunting preserve field. The Pamlico River sediment was taken approximately 75 meters offshore from the effluent discharge creek just east of the Texasgulf plant. Latitude and longitude coordinates were recorded for each site (Figure 1) so that sites could be accurately revisited using loran navigational equipment. Longnose gar (Lepisosteus osseus) and gizzard shad (Dorosoma cepedianum) were collected with gill nets. Rangia clams (Rangia cuneata) were collected with a clam rake or small dredge. Salinity and temperature were measured mid--water at each site. After collection fish and clams were wrapped in aluminum foil and placed in wet ice. Five core sediment samples were collected at each site with a 5 cm inside diameter PVC core sampler inserted to an approximate depth of 7.5 cm. Core samples were emptied into a stainless steel container and homogenized with a stainless steel spoon. The homogenate was split into two parts; a portion for inorganic analysis was placed in a plastic bag and a portion for organics was placed in a chemically--cleaned glass jar. All sediments were stored on wet ice in the field.
Upon returning from the field, clam soft tissues were removed, placed
in a stainless steel container and homogenized with a
stainless steel spoon. The clam sample homogenate was then split into two chemically cleaned glass jars and frozen. Clam composites consisted of 17 to 50 individuals per site. The fish were measured to the nearest mm total length and weighed to the nearest gram. Samples were stored in a freezer prior to shipment on dry ice for laboratory analysis.
Elemental contaminant analyses were conducted at the Environmental Trace Substance Research Center, Columbia, Missouri and organic analyses were conducted at the Mississippi State Chemical Laboratory, Mississippi State, Mississippi. Organochlorine scans used electron capture capillary gas chromatography, and PCB results were confirmed by mass spectrometry. Lower levels of detection were 0.01 ppm except for toxaphene and PCBs which were 0.05 ppm. Aliphatic hydrocarbons were quantified by capillary column flame ionization gas chromatography and aromatic hydrocarbon quantification utilized capillary flame ionization gas chromatography and fluorescence high pressure liquid chromatography.
Metals were extracted by strong acid digestion with a mixture of nitric
and perchloric acids. This digestion yields very low results (< 50%
recovery) on standard reference materials for Al, Ba, Sr, and V; low results
(> 50% & < 80% recovery) for As, Cr, Fe, and Mg; and results close
to the certified value (> 80% recovery) for Se, Hg, Cd, Cu, Mn, Ni, Pb,
and Zn. Standard reference material was not available for B, Be or Mo,
but based on spike recovery data they are probably in the low result range.
Strong acid digestion gives a measure of the maximum potential bioavailablity
of the metal in the sample. An inductively coupled plasma emission spectroscopy
scan was used for metals. Mercury content was determined by cold vapor
reduction atomic aborption spectroscopy and arsenic by graphite furnace.
Fluoride samples were mixed with ion selective electrode buffer and mineral
oil as a combustion aid, combused in a Parr Oxygen Bomb and analyzed with
an ion selective electrode. Lower levels of detection were variable for
different metal samples. Quality assurance/quality control (QA/QC) samples,
including blanks, spiked samples, reference material analyses, and duplicate
analyses, were performed for all analytes. Review of QA/QC samples indicated
precision and accuracy were acceptable for all analytes.
3. RESULTS and DISCUSSION
Site salinities ranged from 0.8 ppt at Kennedy Creek to 5.8 ppt at Bath
Creek. The sediment samples from Broad Creek, Bath Creek, and Pamlico River
near Texasgulf had a very low percent composition of clay and total organic
carbon (Table 1) which is where any contaminants are going to be. The sand
and silt fractions which were the major constituents of sediment sampled
from Broad Creek, Bath Creek and Pamlico River at Texasgulf are mostly
inert quartz. In general elemental contaminants, organochlorines, aliphatic
hydrocarbon, and polynuclear aromatic hydrocarbon sample concentrations
of sediment, rangia clams, gizzard shad, and longnose gar (Tables 2--7)
were either beneath the detection limit or too low to be associated with
biological impacts (Long and Morgan 1990). However, sediment concentrations
of cadmium and fluoride were elevated for the Texasgulf site when compared
to the other sites sampled, and were observed at levels that could be associated
with biological impacts (Long and Morgan 1990). Values observed for cadmium
and fluoride are discussed separately in the text following the tables.
Table 1. Site water salinity, temperature and sediment composition.
Sample Site | Salinity (ppt) | Temp.(degrees C) | %Sand | %Silt | %Clay | %TOC |
Kennedy Creek | 0.8 | 19.9 | 42 | 44 | 15 | 16 |
Chocowinity Bay | 2.8 | 22.5 | 30 | 45 | 25 | 15 |
Broad creek | 4.1 | 19.0 | 95 | 3 | 2 | 0.4 |
Bath Creek | 5.8 | 18.3 | 88 | 6 | 6 | 0.2 |
Pamlico River ( at Texasgulf) | 3.8 | 18.0 | 59 | 34 | 8 | 0.1 |
Table 2. Trace element concentrations in sediment composites (ppm dry weight).
Element | Kennedy Creek | Chowcow. Bay | Broad Creek | Bath Creek | Pamlico River (at Texasgulf) |
Al | 27800 | 43600 | 4820 | 7290 | 13300 |
As | 2.2 | 3.6 | 0.42 | <0.1 | 4.3 |
B | 7.8 | <20 | <2 | 3 | 17 |
Ba | 95.5 | 89 | 56.1 | 15.4 | 50.4 |
Be | 1.4 | 1 | 0.1 | 0.2 | 0.71 |
Cd | <0.4 | <3 | <0.4 | <0.3 | 8.8 |
Cr | 19 | <30 | 4 | 8 | 36 |
Cu | 9.3 | 14 | 2.9 | 1.9 | 8.9 |
F | 109 | 54.1 | <8.8 | 11.6 | 475 |
Fe | 17300 | 23600 | 1970 | 3760 | 11000 |
Hg | 0.063 | 0.085 | 0.01 | 0.018 | 0.027 |
Mg | 3300 | 5070 | 333 | 609 | 6430 |
Mn | 166 | 160 | 63.8 | 40 | 204 |
Mo | 3 | <10 | <1 | <1 | 2 |
Ni | 13 | <20 | 2 | 2 | 8.6 |
Pb | 21 | <40 | 6 | 7 | 14 |
Se | 0.4 | 1.1 | <0.2 | <0.2 | 0.3 |
Sr | 62.4 | 78 | 17 | 6.9 | 311 |
V | 40.8 | 62 | 5.4 | 13 | 37.9 |
Zn | 34.3 | 23 | 7.4 | 10 | 98.5 |
Table 3. Trace element concentrations in rangia clam composites (ppm wet weight).
Element | Kennedy Creek | Chowcow. Bay | Broad Creek | Bath Creek | Pamlico River (at Texasgulf) |
Al | 62.3 | 27 | 41 | 47 | 52.7 |
As | 0.91 | 0.69 | 1.2 | 0.78 | 0.55 |
B | <0.3 | <0.2 | 0.3 | 0.8 | 0.6 |
Ba | 4.73 | 9.93 | 1.4 | 0.57 | 0.74 |
Be | 0.006 | 0.005 | <0.007 | 0.0060 | 0.007 |
Cd | 0.026 | 0.01 | 0.062 | 0.07 | 0.17 |
Cr | 0.1 | 0.09 | 0.62 | <0.1 | 0.1 |
Cu | 2.71 | 1.1 | 5.77 | 1.8 | 1.8 |
F | <1.00 | <1.26 | <1.33 | 1.93 | 13.6 |
Fe | 82.4 | 70.3 | 92.9 | 61 | 68.7 |
Hg | 0.036 | 0.014 | 0.036 | 0.0160 | 0.007 |
Mg | 205 | 249 | 268 | 312 | 321 |
Mn | 3.16 | 12.1 | 27.5 | 19.8 | 14.3 |
Mo | <0.1 | <0.1 | <0.2 | <0.2 | <0.1 |
Ni | 0.86 | 1.1 | 0.56 | 0.68 | 2.1 |
Pb | <0.1 | <0.1 | <0.2 | <0.2 | <0.1 |
Se | <0.23 | 0.17 | 0.31 | 0.4 | 0.34 |
Sr | 2.71 | 4.65 | 5.18 | 4.7 | 5.85 |
V | 0.09 | 0.07 | 0.1 | 0.16 | 0.17 |
Zn | 16.2 | 8.82 | 13.5 | 12.7 | 11.4 |
Table 4. Trace element concentrations in fish composites (ppm wet weight).
Element | Kennedy | Chocow. | Broad | Bath | Texasgulf |
Al (shad) | 57 | 6.7 | 5.4 | 318 | 32 |
(gar) | 14 | ND | ND | ND | 3.5 |
As (shad) | 0.24 | 0.26 | 0.19 | 0.19 | 0.21 |
(gar) | 0.35 | ND | ND | ND | 0.82 |
B (shad) | -0.5 | -0.5 | -0.5 | -0.6 | -0.6 |
(gar) | -0.6 | ND | ND | ND | -0.7 |
Ba (shad) | 1.2 | 0.8 | 0.54 | 1.5 | 0.38 |
(gar) | 4.05 | ND | ND | ND | 0.85 |
Be (shad) | -0.01 | -0.01 | 0.01 | 0.02 | -0.009 |
(gar) | -0.01 | ND | ND | ND | -0.01 |
Cd (shad) | -0.02 | -0.02 | -0.02 | -0.02 | 0.03 |
(gar) | -0.02 | ND | ND | ND | -0.02 |
Cr (shad) | -0.2 | -0.2 | 0.5 | 2 | 1.3 |
(gar) | 3.2 | ND | ND | ND | 5 |
Cu (shad) | 0.46 | 0.83 | 1.5 | 1.1 | 0.82 |
(gar) | 0.71 | ND | ND | ND | 1.2 |
F (shad) | 2.87 | 2.39 | -1.59 | -2.9 | 3.56 |
(gar) | 6.36 | ND | ND | ND | 8.44 |
Fe (shad) | 69.8 | 79.7 | 44.7 | 306 | 70.3 |
(gar) | 50.5 | ND | ND | ND | 53 |
Hg (shad) | 0.021 | 0.015 | 0.014 | 0.013 | 0.01 |
(gar) | 0.15 | ND | ND | ND | 0.82 |
Mg (shad) | 270 | 291 | 286 | 398 | 327 |
(gar) | 2960 | ND | ND | ND | 2840 |
Mn (shad) | 4.9 | 4.3 | 3.3 | 16.6 | 3.2 |
(gar) | 7.52 | ND | ND | ND | 5.7 |
Mo (shad) | -0.3 | -0.3 | -0.3 | -0.3 | -0.3 |
(gar) | -0.3 | ND | ND | ND | -0.4 |
Ni (shad) | 0.1 | 0.2 | 0.36 | 2 | 0.61 |
(gar) | 1.6 | ND | ND | ND | 2.3 |
Pb (shad) | -0.3 | -0.3 | 0.5 | 0.88 | -0.3 |
(gar) | -0.3 | ND | ND | ND | -0.4 |
Se (shad) | 0.28 | 0.29 | 0.33 | 0.1 | 0.32 |
(gar) | 0.2 | ND | ND | ND | 0.2 |
Sr (shad) | 17.6 | 22.2 | 21.4 | 37.1 | 19.9 |
(gar) | 56.9 | ND | ND | ND | 78.6 |
V (shad) | 0.2 | -0.08 | -0.08 | 3.5 | 0.1 |
(gar) | <0.1 | ND | ND | ND | <0.1 |
Zn (shad) | 9.14 | 9.39 | 10.2 | 13.4 | 9.83 |
(gar) | 23.2 | ND | ND | ND | 20.7 |
Table 5. Organochiorine concentrations in gizzard shad composites (ppm wet weight).
Analyte | Kennedy | Chocow. | Broad | Bath | Texasgulf |
HOB | NDa | ND | ND | ND | ND |
a-BHC | ND | ND | ND | ND | ND |
r-BHC | ND | 0.01 | ND | ND | ND |
ß-BHC | ND | 0.01 | ND | 0.01 | ND |
ð-BHC | ND | ND | ND | ND | ND |
Oxyclordane | ND | ND | ND | ND | ND |
Hept. Epox. | ND | ND | 0.01 | ND | 0.01 |
r-Chlohlordane | ND | 0.01 | ND | ND | 0.01 |
T-Nonachlor | 0.01 | 0.02 | 0.01 | 0.01 | 0.01 |
Toxaphene | ND | 0.45 | ND | ND | ND |
PCB's(total) | ND | ND | ND | ND | ND |
o,p'-DDE | ND | ND | 0.01 | ND | ND |
p,p?-DDE | 0.09 | 0.16 | 0.08 | 0.09 | 0.18 |
Dieldrin | 0.02 | 0.02 | 0.02 | ND | 0.02 |
o,p?-DDD | 0.01 | 0.02 | 0.01 | ND | 0.01 |
Endrin | ND | ND | ND | ND | ND |
cis-nonach. | 0.01 | 0.02 | 0.01 | ND | 0.02 |
o,p?-DDT | ND | 0.01 | ND | ND | ND |
p,p?-DDD | 0.05 | 0.08 | 0.04 | 0.03 | 0.09 |
p,p?-DDT | 0.01 | 0.02 | 0.01 | 0.01 | 0.01 |
Mirex | ND | 0.01 | ND | ND | ND |
Analyte | Kennedy | Chocow. | Broad | Bath | Texasgulf |
n-dodecane | |||||
sediment | 0.01 | ND | ND | ND | 0.01 |
clams | 0.01 | ND | 0.01 | ND | ND |
n-tridecane | |||||
sediment | ND | ND | ND | ND | 0.01 |
clam | ND | ND | ND | ND | ND |
n-tetradecane | |||||
sediment | ND | 0.01 | 0.32 | ND | 0.01 |
clam | 0.01 | ND | ND | ND | 0.01 |
octycyclohexane | |||||
sediment | 0.01 | ND | 0.02 | ND | 0.01 |
clam | 0.02 | ND | ND | ND | 0.01 |
n-pentadecane | |||||
sediment | 0.04 | 0.01 | 0.03 | 0.02 | 0.02 |
clam | 0.02 | 0.02 | 0.06 | 0.16 | 0.1 |
nonylcyclohexane | |||||
sediment | 0.01 | ND | ND | 0.01 | 0.02 |
clam | 0.01 | ND | ND | ND | 0.02 |
n-hexadecane | |||||
sediment | 0.03 | ND | 0.01 | 0.01 | 0.01 |
clam | 0.02 | 0.02 | 0.02 | 0.02 | 0.02 |
n-heptadecane | |||||
sediment | 0.3 | 0.05 | 0.16 | 0.13 | 0.04 |
clam | 0.04 | 0.07 | 0.13 | 0.19 | 0.09 |
pristane | |||||
sediment | ND | 0.01 | ND | ND | 0.03 |
clam | 0.01 | ND | ND | ND | ND |
n-octadecane | |||||
sediment | 0.02 | 0.01 | 0.01 | 0.01 | 0.02 |
clam | 0.01 | 0.01 | 0.01 | ND | 0.02 |
phytane | |||||
sediment | 0.01 | 0.01 | ND | 0.01 | 0.04 |
clam | 0.01 | ND | ND | ND | 0.01 |
n-nonadecane | |||||
sediment | 0.03 | 0.03 | 0.02 | 0.03 | 0.03 |
clam | 0.01 | 0.01 | 0.01 | 0.01 | 0.03 |
n-eicosane | |||||
sediment | 0.02 | 0.01 | 0.01 | 0.03 | 0.02 |
clam | 0.02 | ND | ND | ND | 0.01 |
Analyte | Kennedy | Chocow. | Broad | Bath | Texasgulf |
napthalene | |||||
sediment | ND | ND | ND | ND | ND |
clam | 0.02 | ND | ND | ND | ND |
fluorene | |||||
sediment | ND | ND | ND | ND | ND |
clam | ND | ND | ND | ND | ND |
phenanthrene | |||||
sediment | 0.01 | ND | ND | ND | ND |
clam | 0.06 | ND | ND | ND | 0.02 |
anthracene | |||||
sediment | ND | ND | ND | ND | ND |
clam | ND | ND | ND | ND | ND |
flouranthene | |||||
sediment | ND | ND | ND | ND | 0.05 |
clam | ND | ND | ND | ND | ND |
pyrene | |||||
sediment | ND | ND | ND | ND | ND |
clam | ND | ND | ND | ND | ND |
1, 2-benzanthracene | |||||
sediment | ND | ND | ND | ND | ND |
clam | ND | ND | ND | ND | ND |
chrysene | |||||
sediment | ND | ND | ND | ND | ND |
clam | ND | ND | ND | ND | ND |
benzo (b) fluoranthene | |||||
sediment | 0.01 | ND | ND | ND | 0.01 |
clam | ND | ND | ND | ND | ND |
benzo (k) fluoranthene | |||||
sediment | ND | ND | ND | ND | 0.01 |
clam | ND | ND | ND | ND | ND |
benzo(e)pyrene | |||||
sediment | ND | ND | ND | ND | ND |
clam | ND | ND | ND | ND | ND |
1,2,5, 6-dibenzanthracene | |||||
sediment | ND | ND | ND | ND | ND |
clam | ND | ND | ND | ND | ND |
benzo(g, h, i)perylene | |||||
sediment | ND | ND | ND | ND | ND |
clam | ND | ND | ND | ND | ND |
Cadmium
The composite concentration of cadmium in sediment observed at the
Texasgulf site was 8.8 ppm dry weight. This value is above the concentration
(5 ppm) at the low end of the range in which biological effects have been
observed and slightly less than concentration (9 ppm) approximately midway
in the range of reported values associated with biological effects (Long
and Morgan 1990). All other site concentrations were beneath detection
levels (Table 2). The potential for biological effect of cadmium at Texasgulf
may be underestimated by the observed concentration because the sediment
sampled at Texasgulf had a low percent total organic carbon (0.1) and thereby
a low pollutant binding affinity. The highest observed cadmium concentrations
for rangia clam tissue and gizzard shad tissue were also observed at the
Texasgulf site although the difference between site values for gizzard
shad is very small. Fertilizer production is one of several anthropogenic
sources of cadmium which include smelter fumes and dust, incineration of
cadmium--bearing materials and fossil fuels, and municipal wastewater and
sludge discharges (Eisler 1985)
Fluoride
Sediment
Sediment fluoride concentration at the Texasgulf site appeared to be
elevated when compared to other Pamlico River sample locations (Table 2),
although this observation could not be tested statistically because the
composite sample methodology utilized did not allow for an estimate of
sample variance. Lee and Marianna (1977) observed that measures of sediment
chemical concentrations were not good indicators of sediment toxicity as
indicated by tests using shrimp (Palaemonetes pugio). DiToro (1989)
believed that the chemical concentration in pore water was a better indicator
of toxicity, as it was more associated with bioavailability. Texasgulf
discharged about 1 million pounds of fluoride each year in 1989-1990 (Cunningham
et al. 1992) but is moving towards a recycling program which is expected
to reduce fluoride discharges by 75 percent.
Tissue
We sampled rangia clam, gizzard shad and longnose gar tissues to determine
if fluoride present in the sediments was also evident in biota, and to
complement the area database for tissue concentrations of other contaminants
(Riggs et al. 1989, North Carolina Division of Environmental Management
1991, Benkert 1992, Gemperlirie et al. 1992, Weinstein et al. 1992). These
samples constitute the first assessment of fluorides in tissue for this
area and subsequently should provide a reference for future comparisons.
Rangia clams collected from the Pamlico River at Texasgulf had a fluoride
concentration approximately seven times as high as that observed at Bath
Creek which was the only other site at which fluoride occurred above the
lower limit of quantification. The rangia clam composite samples utilized
from 17 to 50 clams per sample so that the observed concentration represented
an average for several organisms. Rangia clams are non--selective filter
feeders that transform plant detritus and phytoplankton into clam biomass.
They move very little compared to fish and crabs and are suitable indicators
of site quality.
Rangia clams are eaten by fish, crustacea, and waterfowl (La Salle and
de la Cruz 1985). Fish that eat rangia include important commercial species
such as spot (Leiostomus xanthurus), Atlantic croaker (Micropogon
undulatus), and southern flounder (Paralichthys lethostigma).
Ring-necked duck (Avthya collaris), greater scaup (Avthya
marila), lesser scaup (Avthya affinis), black
duck (Anas rubripes), mallard (Anas platyrhynchos),
and ruddy duck (Oxyura jamaicensis) eat rangia. However, a review
of the literature does not indicate that the levels of fluoride found in
tissues of rangia clam should present any threat to waterfowl that consume
them (Jim Fleming, National Biological Survey, Raleigh, NC, personal communication).
Crustacea that consume rangia clams include blue crab (Callinectes sapidus)
and white shrimp (Peneaus setiferus). Blue crab consumption
of rangia clams and other benthic food organisms with body burdens of fluorides
and other contaminantes may be associated with the frequency of shell lesions
(approximately 10% and regionally up to 90%, Weinstein et al. 1992) in
blue crabs taken from the Pamlico River.
Gemperline et al. (1992) analyzed trace and minor element concentrations
in blue crab gills, muscle, and hepatopancreas tissues using principle
component analysis. They concluded that diseased and non-diseased crabs
had distinctly different concentrations of minor and trace elements. The
authors speculated that since many of the elements observed in the tissue
samples are normally not soluble, fluoride or phosphate concentrations
in the Pamlico River may be causing enhanced solubility of these elements.
Weinstein et al. (1992) stated that toxic concentrations of metals or trace
elements could potentially cause shell disease through physical degradation
of the hypodermis which secretes the shell or through interference of wound
repair. Another more subtle mechanism that could cause shell disease would
involve disruption of copper regulation which would result in stress from
reduced oxygen transport to the tissues (Engel 1987, Engel and Brouwer
1984, Depledge and Bjerregaard 1989). Noga et al. (1990) observed that
Pamlico River blue crabs had reduced hemocyanin levels. Hemocyanin is the
respiratory pigment which contains 50-60 % of the copper in blue crabs.
Pamlico River blue crabs were described as unhealthy in terms of behavior,
survival, hemocyte levels, and wound repair capability (Weinstein 1991).
Healthy blue crabs in tanks develop lesions when exposed to Pamlico River
water (Noga et al. 1990).
The North Carolina Division of Environmental Management (DEM) conducted
surveys in the Pamlico River at sites that have contaminated sediments.
Samples of midge (Chironomus sp.) larvae which inhabit the sediment
and the midges were examined for the presence of tooth deformities. Larva
midge tooth deformity is being evaluated by DEM as a potential biological
indicator of contaminant loading in North Carolina (Lenat 1993). Tooth
deformities in midge larvae are associated with contaminated sediments
(Hamilton and Saether 1971, Warwick 1985, 1988, 1990, Warwick and Tisdale
1988). Midge tooth deformities were observed at levels above background
in Kennedy Creek, but midges were not present in the sandy sediment around
Texasgulf which precluded this technique from being used there. These findings
are especially interesting because blue crabs and midge are both arthropods,
both undergo growth molts, and both midge teeth and blue crab shells are
composed of chitin. It can be assumed that midge larvae developed on the
sites at which they were collected in contrast to
blue crabs, which are less sedentary.
Gizzard shad are planktivorous and longnose gar are piscivorous. Both
are considered freshwater fish although they frequent brackish sites, such
as those we sampled, along with some of the more typical estuarine species.
They were selected for sampling because they represented a diversity of
trophic levels and because they could be easily collected at all sites.
Although both gizzard shad and longnose gar sampled at Texasgulf had the
highest fluoride concentrations of any of the sites sampled, the difference
in concentrations between Texasgulf and the other sites appeared too small
to be meaningful. Fluoride accumulates in calcium rich tissues, such as
bone. Therefore differences in fluoride concentrations in whole fish may
have disguised the potentially major differences in fluoride exposure among
sites that was indicated by sediment and rangia clam samples.
4. SUMMARY
Samples of sediment, rangia clams, gizzard shad, and longnose gar were
collected from five sites in the lower Pamlico River and analyzed for elemental
contaminants, organochlorines, aliphatic hydrocarbon, and polynuclear aromatic
hydrocarbons. In general sample concentrations were either beneath the
detection limit or too low to be associated with biological impacts. However,
sediment concentrations of cadmium and fluoride were elevated for the Texasgulf
site when compared to the other sites sampled, and were observed at levels
that could be associated with biological impacts. Concentrations of fluoride
in fish and clam tissue in this report are the first available for this
area and subsequently should provide a reference for future comparisons.
LITERATURE CITED:
Benkert, K.A. 1992. Contaminant assessment of biota and sediments
in the Albemarle-Pamlico region. U.S. Fish and Wildlife Service, Raleigh,
N.C.
Cunningham, P.A., R.E. Williams, R.L. Chessin, J.M. McCarthy, R.J. Curry,
K.W. Gold, R.W. Pratt and S.J. Stichter. 1992. Watershed planning in
the Albemarle-Pamlico Estuarine System: toxics analysis. Report No.
92-04. AlbemarlePamlico Estuary Study. Raleigh, N.C.
Depledge, M.H. and P. B)erregaard. 1989. Haemolymph protein composition
and copper levels in decapod crustaceans.
Heloglander Meersuntersuchungen 43:207-223.
DiToro, D.M. 1989. A review of the data supporting the equilibrium
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Keywords={same keywords listed above - used for search tools}