Chironomids as Environmental
Indicators:Heavy Metals
and Deformities
Chaleen Shephard
May 6, 1999
Pollutants
• Often manmade materials
• Excesses occur naturally
Bioaccumulation
• Build-up of toxic materials in
tissues
• Magnify in food chain
Heavy Metals
• Chromium
• Copper
• Manganese
• Nickel
Chironomids
• Non-biting Midges
• Aquatic Insect
Larvae
• 1/2 Inch
• Two Small Prolegs
• Found In Sediment
• Detritivores
Chironomids
g
f
a
b
e
d
c
Indicator Species
• Large distribution area
• Variety of habitats
• Primary food source for
many organisms
Morphological Testing
• Deformities in mouthparts,
antennae, mandibles
• Effect of chemical contaminants
Sampling
• Flow Line Division, New Castle,
Pennsylvania
• Five sites, Five Subsamples at Each
Site
• Sediment Sample: AA, ICP
spectrometry
• Chironomid Samples
• Sampled on 10/28/98 and 1/30/99
Microwave Digester
AA
ICP
Mounting
• Head Capsule
• CMCP-9/ CMCP-9AF
Medium
Classification
Normal
Classification
Class I
Classification
Class II
Classification
Class III
Statistical Analysis
• At each site the five subsamples
were combined to produce a
sufficient sample size
Percent Deformity
= chironomids at each site with
deformed mouthparts divided
by the total number of
chironomids at that site
Toxic Score
[No. Class I+2(No. Class II)+3(No. Class III)] X 100
Total Number Of Larvae
Concentration of Metals
• Kruskal-Wallis test
(nonparametric alternative to
Analysis of Variance)
• Followed by a distributionfree Multiple Comparisons
Test
Results
p= 0.010
Average Concentration
(ppm)
Chromium
4000
3500
3000
2500
2000
1500
1000
500
0
1
Above
pipe
2
3
Site
4
5
Results
p= 0.012
Average Concentration
(ppm)
Copper
2500
2000
1500
1000
500
0
1
Above pipe
2
3
Site
4
5
Results
p= 0.013
Average
Concentration (ppm)
Manganese
2500
2000
1500
1000
500
0
1
Above
pipe
2
3
Site
4
5
Results
p= 0.008
Average Concentration
(ppm)
Nickel
3500
3000
2500
2000
1500
1000
500
0
1
Above
pipe
2
3
Site
4
5
Results
Correlation
Metal
Cr
Cu
Mn
Ni
P-Value
P-Value
Conc. & % Deformity Conc. & Toxic Score
0.107
0.331
0.181
0.431
0.164
0.418
0.179
0.43
Conclusions
• High concentrations of metals,
especially at the outflow pipe
• No correlation between deformities
and concentrations of heavy metals
• Low numbers of chironomids
• Lethal concentrations of heavy
metals
Future Studies
•
•
•
•
Tissue Analysis
Laboratory tests
Identification of species
More samples, more chironomids,
quantitative sampling
• Similar locations