chironomids as environmental indicators:heavy metals and deformities chaleen shephard may 6, 1999
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Chironomids• Non-biting Midges
• Aquatic Insect Larvae
• 1/2 Inch
• Two Small Prolegs
• Found In Sediment
• Detritivores
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
• 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
Sampling
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
Concentration of Metals
• Kruskal-Wallis test (nonparametric alternative to Analysis of Variance)
• Followed by a distribution-free Multiple Comparisons Test
ResultsChromium
0500
1000150020002500300035004000
1 Abovepipe
2 3 4 5
Site
Av
era
ge
Co
nce
ntr
atio
n
(pp
m)
p= 0.010
ResultsCopper
0
500
1000
1500
2000
2500
1 Above pipe 2 3 4 5
Site
Ave
rage
Con
cent
rati
on
(ppm
)
p= 0.012
ResultsManganese
0
500
1000
1500
2000
2500
1 Abovepipe
2 3 4 5
Site
Ave
rag
e
Co
nce
ntr
ati
on
(p
pm
)p= 0.013
ResultsNickel
0500
100015002000250030003500
1 Abovepipe
2 3 4 5
Site
Ave
rage
Con
cent
rati
on
(ppm
)p= 0.008
Results
P-Value P-ValueMetal Conc. & % Deformity Conc. & Toxic Score
Cr 0.107 0.331Cu 0.181 0.431Mn 0.164 0.418Ni 0.179 0.43
Correlation
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
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