Report on the Health of Hodges Creek:

Follow-up research on the fish kill that occurred July 2010 in Boone, NC

Erin Abernethy

Environmental Toxicology BIO3542-101/5542-101

April 27, 2011

In Collaboration with Anthony Marino, Matthew Cox, and Donna Lisenby

I have not violated the Appalachian State University Academic Integrity Code.

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ABSTRACT

Following the contamination of Hodges Creek with coal-tar based asphalt sealant, a fish kill

occurred in July of 2010 in Boone, NC. It is believed that all life was killed within the stream from the

PAHs released during the contamination event. We sampled sediments for PAHs and surveyed fish and

invertebrates in March of 2011 to assess the current ecological status of Hodges Creek. Although fish and

invertebrates have recolonized the stream in reduced numbers, it is believed that the high levels of PAHs

detected in the sediment samples will continue to negatively impact the wildlife of Hodges Creek by

causing low abundances and poor health. Monitoring should be continued to more fully map the extent of

contamination and determine the level of PAHs in the sediments in following years.

INTRODUCTION

On July 17, 2010, a fish kill occurred on Hodges Creek in Watauga County, Boone, NC. It was

believed that all life within the 1.5 mile section of Hodges Creek between the BB&T bank along Highway

105 and the Boone Mall was killed. A total of 97 dead fish, mostly trout, were collected. The cause of the

fish kill was a coal-tar based asphalt sealant that had been applied to the BB&T parking lot earlier that

day in the rain (Lisenby 2010). The rain caused this pollutant to wash off the parking lot and into Hodges

Creek. The asphalt sealant contained a chemical called benzo[a]pyrene, a polycyclic aromatic

hydrocarbon (PAH), that is listed by the EPA as a suspected carcinogen and a highly persistent toxin

(EPA 2010). Considering the potential negative health effects of this asphalt sealant on wildlife and

humans, the Town of Boone banned this product. Although the ban is not a full ban, the opportunities to

apply the sealant are so minimal that from now on other products will most likely be chosen in its stead

(Oakes 2011).

PAHs are released naturally into the environment from processes such as volcanic eruptions and

forest fires, but humans have drastically increased the amount of PAHs that are present through extensive

fossil fuel combustion (Menzie et al. 1992). While PAHs can be detected in the air, water, and soil, within

aquatic environments PAHs tend to accumulate in the sediments (Den Besten et al. 2003). Depending on

the substrate size composing contaminated sediments, PAHs are bioavailable at varying rates and

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durations to different species of aquatic organisms (Landrum & Scavia 1983; Eadie et al. 1984; Landrum

et al. 1984). Certain species have the ability to metabolize PAHs at significantly different rates (Lu et al

1977; Southworth 1979; Dobroski & Epifanio 1980; Neff 1982; Maccubbin et al. 1985). Although PAHs

do not appear to biomagnify as they move up trophic levels, they do accumulate in the tissues of lower

trophic level aquatic invertebrates, possibly causing adverse health effects (Neff 1979; Varanasi et al.

1980; Baumann et al. 1982; Stegeman et al. 1982; Couch & Harshbarger 1985; McCarthy & Jimenez

1985; McCarthy et al. 1985). It is suggested that within aquatic systems PAHs have the potential to

biominimize when moving up trophic levels, but they can still have prolonged negative effects on the

health, abundance, and diversity of aquatic invertebrates (Eisler 1987).

We are interested as to whether PAHs from the BB&T spill in the summer of 2010 are still at

detectable levels within the sediments of Hodges Creek. We also want to know if fish and invertebrates

have recolonized the stream and if so in what abundance and diversity. We predict that PAH levels are

still high within sediments and that fish and invertebrates will have not recolonized the stream due to this

contamination.

METHODS

Six sites on Hodges Creek were sampled for PAHs. Two reference sites above the BB&T parking

lot were sampled and four sites downstream before the confluence with Boone Creek (Figure 1). To

collect the sediment samples for PAH analysis, we used a stainless steel pot and spoon to scoop sediment

from Hodges Creek into an amber colored wide mouth jar with a teflon lid. Before going into the field

and between each collection materials were washed with 1% Alconox solution and rinsed with acetone.

Jars were filled to the top with superfine mud-like sediment. Once labeled the jars were placed in sealable

plastic bags and stored in a cooler with ice. The samples were given to Dr. John Weinstein from the

Citadel for analysis.

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Figure 1. Map of sampling sites on Hodges and Winklers Creeks in Boone, NC. The location of sampling

sites and BB&T are shown by the pushpin icons. Site 1 & 2 are the upstream reference sites for PAH soil

sampling along Poplar Grove Rd. The site labeled Upstream Reference is where fish and invertebrates

were sampled upstream of BB&T. Sites 3, 4, 5, & 6 were where soil, invertebrate, and fish sampling was

done. Fish were also sampled on Winklers Creek at the site marked by the appropriately labeled pushpin.

In Dr. Weinstein’s lab the samples will be subjected to ultrasonication in acetonitrile three times

for 10 minutes each time. After being centrifuged, the supernatant will be filtered through a 0.5 micron

filter and run through a high-performance liquid chromatography (HPLC). The HPLC will detect the

presence and concentrations of the 16 EPA priority PAHs. QA/QC will be run with standards from NIST.

Fish surveys were performed on Hodges Creek by electro-shocking. Five sites were sampled, one

upstream of the BB&T parking lot and four downstream (Figure 1). Winklers Creek was also sampled as

a separate reference site. Shocking was carried out for approximately 150 seconds throughout all habitat

types available, riffles, runs, and pools. Fish were captured in hand nets and seines. The species, lengths,

and weights of each fish were recorded. Condition, diversity, and abundance indexes were calculated for

each site from this data. For the condition index, Fulton’s Condition Factor (K) was calculated (Carlander

1950).

K = (W/L3) x 100,000

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W represents the weight in grams. Length (L) was measured in millimeters. 100,000 is a constant value

that brings the condition value close to a single digit that was then rounded to one decimal place. The

condition indexes for each individual fish were averaged to calculate a final condition index for each site.

The Shannon-Wiener Diversity Index (H) was calculated using the standard equation.

H = -∑Pi(lnPi)

Pi is the proportion of each species within the sample collected at each site. The abundance value for each

site was calculated by dividing the total number of fish captured by the number of seconds spent

searching. Crayfish and salamander species and numbers were recorded. The presence of snails, Elimia,

was also noted.

Invertebrate surveys were performed in the same reaches as the fish surveys the following day. A

fine mesh seine was set up downstream, and two scientists kicked over rocks upstream while walking

towards the scientist holding the seine for approximately 30 seconds. This technique was performed five

times at each site, and invertebrates were preserved in 70% ethanol for identification in the lab. The

Shannon-Wiener Diversity Index and abundance was calculated from this data using the same methods as

with the fish data. A biotic index (BI) was calculated using tolerance values from the North Carolina

Department of Environment and Natural Resources Standard Operating Procedures (2006) and the Digital

Key to Aquatic Insects of North Dakota from Valley City State University Macro-Invertebrate Lab.

BI = ∑(TVi)(ni) / N

TVi represents the ith taxa’s tolerance value. ni represents the ith taxa’s abundance value of 1, 3, or 10,

where 1 is rare, 3 is common, and 10 is abundant. N is the sum of all abundance values. Based on the

biotic index each site was rated on a scale of excellent to poor.

RESULTS

The PAH results from Dr. Weinstein are preliminary due to machine failure and time constraints.

Qualitative results were obtained from the two reference sites upstream of BB&T and two sites

downstream of BB&T. The reference sites showed very low levels of PAH content. The sites downstream

of BB&T showed some of the highest levels of PAH that Dr. Weinstein had seen in his work, which is

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mainly with stormwater pond sediments. Dr. Weinstein will be re-running these samples in May 2011 and

will be able to give us more specific results.

The fish survey on Hodges Creek yielded 7 species of fish for a total of 31 individuals caught in

818 seconds of electroshocking. Winklers Creek yielded 27 individuals of 6 species within 150 seconds

of shocking. The abundance of fish on Hodges Creek was found to be 0.0379, compared to 0.1800 at

Winklers Creek, a value 4.7 times higher. The abundance per site on Hodges Creek was lowest at the

Upstream Reference, 0.0054, and highest at Site 6, 0.0859. The abundance was higher directly

downstream of BB&T at Site 3 than at Sites 4 or 5 (Table 1 and Figure 2). The number of species caught

and the Shannon-Wiener Diversity Index increase as you move downstream within Hodges Creek (Table

1 and Figure 3). The same number of species was caught at Winklers Creek as Site 6, but the diversity

index is lower for Winklers Creek. The average condition index is similar across sites, ranging from 1.0 to

1.2 on Hodges Creek and 1.1 at Winklers Creek (Table 1 and Figure 3).

Table 1. Fish survey data collected and calculated for Hodges and Winklers Creeks.

Site Number of

Species

Shannon-

Wiener

Diversity Index

Number of

Individuals

Abundance Average

Condition

Upstream Reference 1 0 1 0.0054 1.0

Site 3 1 0 4 0.0370 1.1

Site 4 3 1.01 6 0.0313 1.1

Site 5 4 1.33 6 0.0353 1.2

Site 6 6 1.73 14 0.0859 1.1

Winklers Creek 6 1.55 27 0.1800 1.1

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Figure 2. Fish abundance in Hodges and Winklers Creeks. Abundances for each site sampled are shown.

The y-axis represents abundance values calculated by dividing the number of individuals caught by the

amount of time spent electroshocking.

Figure 3. Fish survey data for Hodges and Winklers Creeks. Fish survey results showing how many

species were caught along with the diversity index and average condition index that was calculated for

each site on Hodges and Winklers Creeks.

The invertebrate survey yielded 6 Orders and 16 Families with a total of 508 individuals collected

in 12.5 minutes of search time within Hodges Creek. The greatest numbers of taxon groups were collected

at Site 4 and the Upstream Reference, and Site 3 had more invertebrates than Site 5 or 6 (Table 2 and

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

Upstream

Reference

Site 3 Site 4 Site 5 Site 6 Winklers Creek

Fish Abundance in Hodges and Winklers Creeks

0

1

2

3

4

5

6

7

Upstream

Reference

Site 3 Site 4 Site 5 Site 6 Winklers

Creek

Fish Survey Data for Hodges and Winklers Creeks

Number of Species

Shannon-Wiener

Diversity Index

Average Condition

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Figure 4). The Shannon-Wiener Diversity Index was greatest at Site 4 and the Upstream Reference and

slightly higher at Site 5 compared to Site 3. Site 6 had the lowest diversity. The abundance was highest at

the Upstream Reference and lowest at Site 3. The Biotic Index was best at Site 3 and worst at Site 6.

Table 2. Invertebrate survey data collected and calculated for Hodges Creek.

Figure 4. Invertebrate survey data for Hodges Creek. Invertebrate survey results showing the number of

families collected and the calculated diversity index, abundance, and biotic index for each site along

Hodges Creek.

Elimia were present at all sites (Table 3). Two taxon of salamanders were collected,

Desmognathus and Eurycea wilderae. The highest number of salamanders, 6, were collected at Site 3.

Two species of crayfish were collected Cambarus bartonii and Cambarus chasmodactylus. The greatest

number of crayfish, 30, were found at Site 4. No crayfish or salamanders were collected from Sites 5 or 6.

0

2

4

6

8

10

12

14

Upstream

Reference

Site 3 Site 4 Site 5 Site 6

Invertebrate Survey Data for Hodges Creek

Number of Taxa

Shannon-Wiener

Diversity Index

Abundance

Biotic Index

Site Number

of Taxa

Shannon-Wiener

Diversity Index

Number of

Individuals

Abundance Biotic Index

Upstream

Reference

10 1.81 164 1.09 4.22 – good

Site 3 7 1.41 44 0.29 3.77 – excellent

Site 4 12 1.83 120 0.80 5.02 – good/fair

Site 5 6 1.57 50 0.33 5.87 – fair

Site 6 3 0.52 130 0.87 7.24 – poor

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Table 3. Snail, Salamander, and Crayfish data collected for Hodges and Winklers Creeks.

Water chemistry data was collected for all sites (Table 4). pH ranged from 7.2 to 7.68. Percent

dissolved oxygen ranged from 82.4 to 86.9, and dissolved oxygen measured in miligrams per liter ranged

from 9 to 10.06. Both measures of DO were highest at Winklers Creek. Salinity was 0.1 for the Hodges

Creek sites and zero for Winklers Creek. Conductivity ranged from 221.2 to 252.8 on Hodges Creek but

was only 33.2 on Winklers Creek. The temperature ranged from 9.1 to 10.4 on Hodges Creek, being

highest at Site 4, and was 9°C on Winklers Creek.

Table 4. Water chemistry and temperature is shown for Hodges and Winklers Creeks.

Site pH DO% DO (mg/L) Salinity Conductivity Temperature (°C)

Upstream

Reference

7.43 82.4 9.49 0.1 221.2 9.1

Site 3 7.54 84.8 9.67 0.1 234.2 9.9

Site 4 7.68 85.6 9.59 0.1 233.9 10.4

Site 5 7.3 84 9.63 - 230.8 9.5

Site 6 7.2 83.1 9 0.1 252.8 9.8

Winklers Creek 7.54 86.9 10.06 0 33.2 9

DISCUSSION

Based on the preliminary PAH analyses from Dr. Weinstein, concentrations of PAHs are still at

extremely high levels within the sediments of Hodges Creek. We suggest that this could have a negative

effect on the health of the aquatic invertebrates and possibly the fishes within Hodges Creek. Although

recolonization has taken place, the health of the invertebrate organisms for cancer or other potential health

problems was not examined. The fish that were found appeared to have a similar condition index as fish

Site Elimia

Present

Salamanders

Number of Taxa

Salamanders

Number of Individuals

Crayfish

Number of

Species

Crayfish

Number of

Individuals

Upstream

Reference

Yes 1 3 1 1

3 Yes 1 6 1 10

4 Yes 2 4 1 30

5 Yes 0 0 0 0

6 Yes 0 0 0 0

Winklers Creek Yes 1 1 1 9

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collected from the reference stream, Winklers Creek. The abundances of fish within Hodges Creek are

drastically lower than that of Winklers Creek, but the diversity does not appear to differ. We suggest that

the differences seen in abundance and diversity for fishes and invertebrates within Hodges Creek is more

a result of stream habitat. The stream is highly urbanized and subject to significant runoff and

sedimentation from roads, parking lots, and construction sites along its banks. Once the results come back

from Dr. Weinstein, we will be able to tell if the concentrations of PAHs in the sediments decreased as

distance increased from the spill site. If concentrations are reasonably constant, then this will confirm our

hypothesis that the fluctuations in abundance and diversity are a function of habitat and not a result of the

spill.

We believe that over time the invertebrates in Hodges Creek will suffer long term health effects,

and fish will continue to show reduced abundances due to diminished food resources, such as

invertebrates, due to the PAH contamination from the coal-tar based asphalt sealant that washed off the

BB&T parking lot in July 2010. Monitoring should take place every 6 months to determine whether

PAHs are still present in the sediments. Bioremediation techniques could be explored to purify the

sediments within Hodges Creek, but due to the lack of evidence supporting the effectiveness of these

tactics, residents may simply have to demand that testing be done every couple months in order to

determine when the PAHs have desorbed from the sediments. More testing should occur downstream and

within the New River to determine the extent of PAH contamination within this system.

With respect to human health, there are high levels of possible carcinogens within the sediments

of Hodges Creek, but due to the lack of long term exposure to humans playing in the creek, PAHs may

pose little risk compared to our regular daily intake. It is estimated that the average daily exposure to

carcinogenic PAHs is between 3 and 15 µg for adult American males. The majority of this exposure

comes from food and air (Menzie et al. 1992). Although dermal exposure to PAHs from the sediments is

not a very effective route of uptake, it might be prudent to not allow barefoot children to play in the creek

for the foreseeable future, and the consumption of any organisms from Hodges Creek is not advised

(Weinstein, personal communication).

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While invertebrates and fish have recolonized Hodges Creek, PAHs and poor stream management

practices have condemned this ecosystem to be highly impacted for a significant period of time. More

research is needed to show the extent, with respect to stream distance and time, that this stream will be

impacted by PAH contamination.

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