Splenic immunotoxicity in developing cane toads (Rhinella marina) from Bermuda

Area of Science:

• Environmental Toxicology
• Immunology
• Amphibian Ecology

Background:

• Contaminated sediments pose environmental risks to wildlife.
• Amphibians are sensitive indicators of ecosystem health.
• Bermuda's unique aquatic environments may harbor specific contaminants.

Purpose of the Study:

• To assess the impact of Bermuda pond sediment on cane toad immune function.
• To compare immune responses between Bermuda and North American cane toad populations.
• To investigate the effects of environmental exposure on amphibian immune system resilience.

Main Methods:

• Partial life-cycle experiment exposing tadpoles to pond sediment through metamorphosis.
• Immunological assessment including necropsy, spleen somatic index, and splenocyte analysis.
• Lymphocyte proliferation assay using Mycobacterium chelonae challenge.

Main Results:

• Bermuda cane toads exposed to pond sediment showed lower splenocyte density and lymphocyte proliferation.
• Increased spleen weight and lesions were observed in challenged Bermuda toads.
• Immune function was compromised in Bermuda toads compared to North American populations, exacerbated by sediment exposure.

Conclusions:

• Bermuda pond sediments negatively impact Rhinella marina immune function.
• Environmental contaminants in Bermuda pose a significant risk to amphibian health.
• Further research is needed to identify specific causative agents in Bermuda sediments.