Increase in developmental instability in a field-collected Chironomus population maintained under laboratory...

Area of Science:

• Environmental toxicology
• Developmental biology
• Ecotoxicology

Background:

• Morphological defects in aquatic invertebrates can indicate exposure to teratogenic stressors.
• Understanding transgenerational inheritance of these defects is crucial for accurate biomonitoring.

Purpose of the Study:

• To investigate whether morphological defects in parent Chironomids (midges) from a contaminated river are passed to their offspring.
• To analyze mentum defects, including deformities, fluctuating asymmetry, and mean shape change, across generations.

Main Methods:

• Comparison of morphological variations between parental Chironomids and their progeny.
• Progeny were reared in uncontaminated sediment under laboratory conditions.
• Geometric morphometrics were used to measure mentum defects.

Main Results:

• No significant difference in the rate of mentum deformities between parental and offspring generations.
• A significant increase in fluctuating asymmetry was observed in the offspring.
• A significant decrease in mentum centroid size was found in the offspring.

Conclusions:

• Mentum shape defects in Chironomids are not solely caused by direct exposure to teratogenic contaminants.
• Potential explanations include contaminants in egg clutches, mutagenic effects, costs of tolerance, or genetic impoverishment.