Reconstructing Parrotfish Tooth Size Distributions Over Millennia and Across Ocean Basins

Parrotfish are directly tied to coral reef health, as they consume the algae that compete with coral for space and nutrients. Understanding the size and abundance of parrotfish would therefore be useful in conservation and decoding parrotfishes’ roles on reefs. However, survey data only dates back to the early 20th century, long after human activity altered these ecosystems. Analyzing fossils emblematic of times before human activity would yield a fuller picture of the original parrotfish population structure in coral reefs. In this study, two questions were explored: how is tooth size different (1) across time periods and (2) ocean basins? To this end, sediment samples were collected from modern reefs in Palmyra and modern and fossil reefs in the Dominican Republic. Fish teeth were extracted, identified, and measured. When the teeth of these herbivorous fish were compared between sites, we found that parrotfish teeth were larger in the modern reef than in the fossil reef. There was no significant difference between the sizes of parrotfish teeth across ocean basins. This pilot study serves as the beginning in building a prehistoric baseline of the reef’s full potential. Knowing that coral reefs might have supported populations different than those in modern reefs can guide environmental management, as the prehistoric baseline can provide a more accurate target for ecosystem restoration.