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Mortality, preference, avoidance, and activity of a predatory LeechExposed to cadmium
D Wicklum1, Smith DEC, R W Davies
1Division of Ecology, Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada.
Archives of Environmental Contamination and Toxicology
|February 1, 1997
Summary
Cadmium significantly impacts freshwater leech Nephelopsis obscura hatching success and survivorship. Larger leeches show increased resistance to cadmium toxicity and altered habitat preferences.
Area of Science:
- Ecotoxicology
- Aquatic invertebrate biology
- Environmental toxicology
Background:
- Freshwater ecosystems are vulnerable to heavy metal contamination.
- Cadmium (Cd) is a toxic heavy metal posing risks to aquatic life.
- Nephelopsis obscura, a freshwater predatory leech, serves as an important indicator species.
Purpose of the Study:
- To investigate the effects of cadmium exposure on Nephelopsis obscura.
- To assess impacts on hatching success, hatchling survivorship, and adult leech responses.
Main Methods:
- Exposure of leech cocoons to various cadmium concentrations.
- Measurement of hatching success and post-hatchling survivorship.
- Determination of 96-hour lethal concentration (LC50) and effective concentration (EC50).
- Preference-avoidance tests and activity level monitoring of leeches.
Main Results:
- The 96-hour EC50 for leech cocoons was 832.6 microg Cd/L.
- Cadmium exposure significantly reduced post-hatchling survivorship at higher concentrations (1,000-4,000 microg Cd/L).
- Resistance to acute cadmium toxicity (LC50) increased with leech biomass.
- Both large and small leeches exhibited altered preference-avoidance behaviors and reduced activity at specific cadmium concentrations.
Conclusions:
- Cadmium poses a significant threat to the reproductive success and survival of Nephelopsis obscura.
- Leech biomass influences cadmium resistance and behavioral responses.
- Findings highlight the ecotoxicological risks of cadmium in freshwater environments.