What's in the Sand? Caribbean Reef Sediment as an Analog of the Living Community
Open Access
- Author:
- Siomades, Sunday
- Area of Honors:
- Geosciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Brian Kelley, Thesis Supervisor
Peter J Heaney, Thesis Honors Advisor - Keywords:
- biodiversity
reef sediment
urchin populations
echinoid populations
shifting baselines
taphonomy
taphonomic bias
preservation bias
St. John reefs
Caribbean reefs
community structure
coral reefs
reef ecology
echinoids
urchins - Abstract:
- Reef sediment provides a potential archive of reef health and ecosystem evolution across expanded timescales, but the relationship between living reef communities and the sediment they produce is poorly constrained. Previous studies evaluating modern reef diversity and health are limited by shifting ecological baselines, and studies that employ fossilized reefs to evaluate community diversity in deep time are influenced by taphonomic bias. To examine reef biology over a time period less influenced by these constraints, this study compared the composition of modern reef sediment to a biological census of the living reef community to assess the potential for reef sediment to record living reef communities. Two types of data were collected from nearshore reefs on St. John, USVI: echinoid subfossils in surficial reef sediments, and transect images of the reef bodies (in which an average number of visible echinoids per photo was calculated). A Spearman correlation was used to determine the strength of the relationship between the abundance of echinoid subfossils and the abundance of live echinoids across three different near-shore reefs; calculated r values ranged from 1 to 0.5 (strong to moderate correlation). These results suggest that live measures of population density may correlate to the abundance of subfossil fragments apparent in reef sediment, and that the sediment record is sensitive to even geologically recent population changes.