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

a

bcd

e

f

g

Chironomids

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

Microwave Digester

AA ICP

Mounting• Head Capsule • CMCP-9/ CMCP-9AF

Medium

ClassificationNormal

ClassificationClass I

ClassificationClass II

ClassificationClass 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 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