Reconstructing reef fish communities using fish otoliths in coral reef sediments.

Area of Science:

• Paleontology
• Marine Biology
• Ecology

Background:

• Long-term changes in coral reef fish communities remain poorly understood.
• Existing methods for reconstructing past fish communities are limited.

Purpose of the Study:

• To introduce a new technique using fish otoliths from reef sediments to reconstruct coral reef fish communities.
• To assess the abundance and taxonomic resolution of otoliths in reef sediments.
• To compare fossil otolith assemblages with modern fish communities.

Main Methods:

• Collected and analyzed over 5,400 otoliths from modern and mid-Holocene reef sediments in the Caribbean.
• Utilized a specialized reference collection for otolith identification to the genus and family level.
• Compared sediment otolith assemblages with fish communities sampled using ichthyocide.
• Employed radiocarbon dating to assess sediment mixing.

Main Results:

• Otoliths are abundant in Caribbean reef sediments, with over 4,400 identified to various taxonomic levels.
• Otolith assemblages from modern reefs showed slightly higher richness than mid-Holocene assemblages.
• Sediment otolith assemblages accurately reflect the general composition of living fish communities.
• Otolith assemblages are dominated by small, fast-turnover fish, suggesting intense predation as a key accumulation process.

Conclusions:

• Fish otoliths in reef sediments provide a powerful new tool for reconstructing past coral reef fish communities.
• This method allows for the exploration of ecological changes in reef fish populations over ecological and geological timescales.
• Understanding these long-term dynamics is crucial for effective coral reef conservation and management.