Predator density and timing of arrival affect reef fish community assembly

Area of Science:

• Marine Ecology
• Predator-Prey Dynamics
• Coral Reef Ecology

Background:

• Empirical predation studies often use constant predator densities, potentially misrepresenting natural temporal variations.
• The independent effects of predator density, temporal variability, and arrival timing on prey are not well understood.
• Hawkfish (Paracirrhites arcatus) exhibit natural variability in density and arrival timing on reefs.

Purpose of the Study:

• To investigate the relative contributions of predator density and arrival timing on prey abundance, diversity, and composition.
• To understand how different predator regimes influence coral reef communities.
• To assess the impact of hawkfish on prey dynamics.

Main Methods:

• Field experiments manipulating hawkfish density and arrival timing.
• Quantifying prey abundance, within-patch diversity (species richness), and between-patch diversity (beta diversity).
• Analyzing shifts in species composition based on species incidence.

Main Results:

• Hawkfish presence reduced prey abundance by 50%.
• Increased hawkfish density further reduced prey abundance by 33%.
• Later hawkfish arrival reduced prey abundance by 34% and increased beta diversity by 22%, altering species composition.

Conclusions:

• Predator arrival timing is as crucial as predator density in shaping prey abundance and community structure.
• Temporal dynamics of predators play a significant role in ecological interactions.
• Findings highlight the importance of considering dynamic predator regimes in ecological research.