Can the source-sink hypothesis explain macrofaunal abundance patterns in the abyss? A modelling test

Area of Science:

• Marine Biology
• Deep-Sea Ecology
• Oceanography

Background:

• Low food availability structures deep-sea benthic communities, leading to low organism densities.
• The Allee effect may inhibit reproduction in low-density populations, suggesting reliance on larval dispersal.
• The slope-abyss source-sink (SASS) hypothesis proposes abyssal populations are maintained by larval influx from productive continental slopes.

Purpose of the Study:

• To evaluate the SASS hypothesis regarding deep-sea macrofaunal population dynamics.
• To test predictions of larval transport, export, and abundance patterns from slopes to the abyss.

Main Methods:

• The study evaluated three key predictions derived from the SASS hypothesis.
• Assessed larval transport feasibility, projected larval export, and macrofaunal abundance gradients.

Main Results:

• Abyssal macrofaunal populations are unlikely to be sustained solely by slope-derived larvae.
• Local reproduction appears to sustain populations in higher-productivity abyssal zones.
• These productive abyssal areas may also serve as larval sources for food-poor regions.

Conclusions:

• The SASS hypothesis, as originally proposed, may not fully explain deep-sea macrofaunal sustainability.
• Local reproduction and self-seeding are significant factors in abyssal community structure.
• Productive abyssal regions play a dual role as both sinks and sources for macrofaunal populations.