Is parasitic infection a buffer against metal pollution?

Area of Science:

• Environmental Toxicology
• Aquatic Ecology
• Parasitology

Background:

• Metal pollution poses a significant threat to aquatic ecosystems.
• Pollution can influence host-parasite interactions.
• The role of parasites in host tolerance to environmental stressors is not fully understood.

Purpose of the Study:

• To investigate the buffering effect of the larval trematode *Himasthla* sp. on the survival of the marine snail *Echinolittorina peruviana* under copper exposure.
• To assess the impact of copper (Cu) concentrations on snail survival.
• To determine if parasitism influences host resilience to metal pollution.

Main Methods:

• Collection of parasitized and unparasitized *Echinolittorina peruviana* snails from Coloso, northern Chile.
• Experimental exposure of snails to two copper (Cu) concentrations (3 and 6 mg/L).
• Survival analysis using Kaplan-Meier curves and nested ANOVA to assess rediae abundance.

Main Results:

• Snail survival was negatively affected by copper concentrations, with greater impact at 6 mg/L.
• Parasitized snails exhibited higher survival rates than unparasitized snails across both copper concentrations.
• At 240 hours, all unparasitized snails died, while 15% of parasitized snails survived, irrespective of copper levels.

Conclusions:

• Parasitism by *Himasthla* sp. confers a survival advantage to *Echinolittorina peruviana* in copper-polluted environments.
• This suggests a potential trade-off where parasitism enhances host tolerance to metal toxicity.
• Parasites may play a crucial role in the resilience of aquatic snail populations facing pollution.