Feeding repellence in Antarctic bryozoans

Area of Science:

• Marine Biology
• Chemical Ecology
• Zoology

Background:

• Antarctic benthic communities feature key predators like the sea star Odontaster validus and amphipod Cheirimedon femoratus.
• Bryozoans, prey for these predators, are expected to evolve defensive strategies, including chemical mechanisms.
• The chemical ecology of Antarctic bryozoans remains largely unexplored.

Purpose of the Study:

• To investigate the presence and nature of anti-predatory defenses in Antarctic bryozoans.
• To assess the efficacy of bryozoan extracts against key Antarctic predators, O. validus and C. femoratus.

Main Methods:

• Extraction of 16 bryozoan species using ether (EE) and butanol (BE).
• Feeding assays conducted with Antarctic sea stars (O. validus) and amphipods (C. femoratus).
• Analysis of extract bioactivity, including repellence and lipophilicity/hydrophilicity.

Main Results:

• Nine bryozoan species exhibited activity against the sea star, with repellence primarily associated with lipophilic compounds (12 EE, 1 BE).
• All tested bryozoan species showed repellence against the amphipod, with defenses involving both lipophilic and hydrophilic compounds (10 EE, 12 BE).
• Variability in bioactivity suggested potential environmental, symbiotic, or genetic influences.

Conclusions:

• Repellent compounds are significant anti-predatory defenses in Antarctic bryozoans.
• Defenses against sea stars are predominantly lipophilic, while those against amphipods involve both lipophilic and hydrophilic compounds.
• Chemical defenses are crucial for bryozoan survival in Antarctic ecosystems, complementing other protective strategies.