Reef systems are of special interest to me, a geologist, because reefs accumulate in the tropics, in shallow-water systems where calcium carbonate, the fundamental mineral of reefs, is precipitated on the sea floor and in the skeletons of tropical reef inhabitants. Reefal organisms changed many times through geologic history, as they suffered losses from extinctions and mass extinctions, and as they recovered and established new ecosystems.
All underwater scientific research at Indiana University proceeds through the Center for Underwater Science, directed by Professor Charles Beeker.
Reefs, therefore, are an ecosystem in constant biotic flux. Darwin was the first to illuminate the succession of reef evolution from barrier to lagoon to atoll, and as such, reefs have held an intellectual fascination for geologists and biologists alike.
Our challenge is to present and test hypotheses of paleoenvironmental processes operating in the tropics, and in the northerly reaches of the subtropics, for warm periods in Earth’s history.
At present, I am working with my Ph.D. graduate student Katherine Nold on the paleoclimate record of the American tropics.
While observing modern and fossil collections at the Museo de Hombre Dominicano in Santo Domingo, Dominican Republic–the premier archaeological museum in Hispaniola-I noted innumerable brown paper bags of shell collections from the island. I developed the hypothesis that if we could analyze shells from the Taino midden collections, now housed in the museum, we would be able to extract dates from the shells, and thereby establish a timeline connecting the midden deposits from the northern Atlantic coast and the southern Caribbean coast of the Dominican Repubic in the tropics.
From that date, that tie point across the island, we would have the basis for analyzing the shallow water marine ecosystems from two distinct basins at or near the time of the arrival of Columbus in the New World.
My IUB archaeology colleagues Professor Beeker and Dr. Conrad had established a working relationship with the Director of the Museo del Hombre Dominicano in Santo Domingo, Dominican Republic over the past decades, and because I was invited to join that relationship, I was able to obtain obtain a long-term loan of thousands of shells from archaeological middens in the north and south coasts of the Dominican Republic.
The shells were from the sea, so not only could dates be obtained from the shells, but also the isotopes of carbon and oxygen could be analyzed, leading to interpretations of water temperatures off the north and south coasts for the time period of 1040 to 1490 AD.
Importantly, this research establishes the baseline conditions of the ocean waters in the Caribbean, and the biodiversity of the shallow coastal seas that the indigenous people were harvesting prior to the arrival of Columbus in the New World.
This work is in progress with my Ph.D. student K. Nold. We thus are asking questions of the taxonomic diversity of the shallow marine ecosystem prior to the merging of peoples of the Old and New Worlds.
This research underscores greatly the need for continued focus on museum curation of valuable specimens and field collections research.
Grants and Publications
Ms. Nold has the following manuscripts drafted for submission, and we have four abstracts presented on our work. This research was supported by grants:
From this latter grant came a National Geographic documentary of the same title in which we researchers from IUB are featured, including an interview with me for the geologic perspective of carbonate deposition.
These grants also served to support research that resulted in a paper on primate evolution in the tropics, published in the prestigious Journal of Human Evolution: Kay, R.F., Hunt, K.D., Beeker, C.D., Conrad, G.W., Johnson, C.C. and Keller, J. 2011. Preliminary notes on a newly discovered skull of the extinct monkey Antillothrix from Hispaniola and the origin of the Greater Antillean monkeys. Journal of Human Evolution 60(1):124-128.
Because radical changes in the reef ecosystem are occurring at an unprecedented rate across the globe, my research continues to expand with collaborations from my Informatics colleague. Our long-term goal is to contribute substantially to our global scientific knowledge of conservation and management of this ecosystem essential to our global oceans, even in the face of global warming and ocean acidification.
Our research discussions and grant proposals center on paleoclimate investigations to assess patterns and rates of climate change in the tropics. For the Caribbean, species, coral diseases, depth, and 62 million temperature records spanning 1974-2015 are used to test the hypothesis of temperature driving coral disease.
dr. claudia c. johnson
department of earth and atmospheric sciences
1001 e. 10th st. bloomington in 47405