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Extremely acidic environment: Biogeochemical effects on algal biofilms
Ana Teresa Luís1, Manuela Teixeira2, Nuno Durães1
1GeoBioTec - GeoBioSciences, GeoTechnologies and GeoEngineering Research Unit - Department of Geosciences, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
Ecotoxicology and Environmental Safety
|April 14, 2019
Summary
Acid mine drainage (AMD) severely impacts aquatic life, reducing biofilm biomass and biodiversity. However, biofilms exhibit stress responses, with lead (Pb) in site AS increasing toxicity and driving adaptation.
Area of Science:
- Environmental Toxicology
- Ecology
- Biochemistry
Background:
- Acid mine drainage (AMD) creates extremely acidic aquatic environments, posing significant toxicological challenges.
- Understanding biological responses to AMD is crucial for assessing water quality and organism survival mechanisms.
Purpose of the Study:
- To evaluate the effects of acidic pH and heavy metals on biofilms from AMD-affected sites.
- To compare the toxicity and adaptive responses of biofilms from a permanent acid pond (AP) and a temporary acid stream (AS) against a neutral control (C).
Main Methods:
- Biofilm samples were collected from two AMD-contaminated sites (AP, AS) and one control site (C).
- Physico-chemical parameters (pH, metal concentrations) and biological indicators (biomass, biodiversity, photosynthetic pigments, proteins, antioxidant enzymes, lipid peroxidation) were analyzed.
Main Results:
- AMD sites exhibited low pH (<3) and high metal concentrations (Al, Cu, Fe, Mn, Pb, Zn), drastically reducing biofilm biomass and biodiversity.
- Acidobiontic species dominated, with low photosynthetic pigments and protein content, indicating stress.
- Increased antioxidant enzyme activity (CAT, SOD, GSTs) and membrane damage (peroxidized lipids) were observed in stressed biofilms.
- Site AS showed higher toxicity than AP, attributed to elevated lead (Pb2+) concentrations, which are readily available in acidic conditions.
Conclusions:
- Extreme acidity and heavy metals from AMD significantly impair biofilm communities.
- Biofilms demonstrate stress responses and adaptive mechanisms, with heavy metal composition influencing toxicity levels.
- Lead (Pb2+) emerges as a key toxicant in AMD environments, driving differential biological impacts and adaptation strategies.
Keywords:
Acid tolerant diatomsBiofilmsEnzymatic activityExtremely acid pHHeavy metalsNon-enzymatic protection mechanismsMore Related Videos
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