How sediment granulometry affects feeding behaviour in sea cucumbers: a case study on Holothuria sanctori

Area of Science:

• Marine Biology
• Ecology
• Benthic Ecology

Background:

• The sea cucumber Holothuria sanctori is an Atlanto-Mediterranean deposit feeder with a significant role in coastal sediment processing.
• Its feeding ecology and sediment processing capacity under controlled conditions are not well understood.

Purpose of the Study:

• To investigate the impact of sediment granulometry on the feeding behavior of Holothuria sanctori.
• To assess organic matter (OM) selectivity and sediment ingestion capabilities.
• To evaluate the species' sediment processing capacity across various particle sizes.

Main Methods:

• Experimental trials with Holothuria sanctori using sediments ranging from 0 to 1000 μm particle sizes.
• Standardized organic matter availability across treatments.
• Measurement of defecation rate and fecal OM content to determine sediment processing capacity.

Main Results:

• Holothuria sanctori optimally selects organic matter and processes sediment in fine particle treatments (< 250 μm).
• The species exhibits a broad sediment processing capacity, handling particles up to 1000 μm.
• Sea cucumbers increase sediment ingestion to compensate for reduced organic matter availability, maintaining constant organic matter intake.

Conclusions:

• Sediment granulometry may not be the primary factor limiting Holothuria sanctori's microhabitat preference due to its wide processing capacity.
• Findings contribute to understanding Holothuria sanctori feeding ecology.
• The species shows potential for applications in Integrated Multi-Trophic Aquaculture.