2011 Grant Recipients

Monica Arienzo ($3,000)
Ph. D. Student
Rosenstiel School of Marine and Atmospheric Science
University of Miami

Bahamas Stalagmites as Recorders of Millennial Scale Temperature Variability

Abstract - The impact of rapid climate change events, specifically Dansgaard/Oeschger cycles (D/O) and Heinrich events, in the subtropics is still not well understood. There are few high resolution studies from the subtropical Atlantic and this project provides a unique opportunity to ascertain whether and how these events are recorded in the subtropics and how they compare to other records. In the proposed project, geochemical tools will be utilized to analyze the chemical composition of the speleothems to better understand the change in temperature associated with these rapid climate events in the Bahamas.

The main goal of this project is to determine temperature through clumped isotope analysis and fluid inclusion analysis. Fluid inclusion analysis relies on the extraction of water from microscopic cavities within the speleothem calcite. The extracted water represents the paleoprecipitation which is analyzed to determine temperature. In contrast, clumped isotope analysis relies on the measurement of the heavy, ex 13C-18O bonds in the stalagmite calcite. Clumped isotope paleothermometry is a relatively new area of research for cave studies and utilizing both methods will aid in the calibration and utilization of the clumped isotope paleothermometer. These results will be compared to the timing and duration of these events in deep sea sediment records and ice core data from Greenland to understand the relationship between the subtropics and high latitudes. This project will aid in the crucial development of more accurate regional models for the subtropics during rapid climate change events.

Erika Crespo ($3,000)
Ph. D. Student
Department of Earth and Environmental Sciences
University of Texas at Arlington

The Mayan Culture-Climate Interactions Revealed through a Composite Speleothem Record

Abstract- The ancient climate for the pre-Columbian Maya of Mexico, Belize, and Guatemala is poorly understood. Although anthropological studies on the collapse of this civilization have revealed it to have been primarily climate-induced, there is significant variation in the timing and duration of the events. Previous researchers have attempted to use lake bottom sediments to reconstruct regional climate conditions, but cave deposits, in particular stalagmites, provide a more precise and detailed environmental record (Fleitmann et. al, 2008). The stable isotope signatures (δ13C and δ18O) and the trace metal geochemistry (e.g., Sr/Ca. Mg/Ca, Ba/Ca) of the calcite formations archive temperature, humidity, and precipitation conditions. Additionally, the analysis of cave drip waters serves as a calibration technique with current cave conditions. The use of this type of climate reconstruction can aid in our understanding of recent and future climate trends. This proposed study seeks to understand the linkages between cave formations, regional hydrology, and the climate system of the Yucatan Peninsula in southern Mexico

It will include a detailed analysis of multiple stalagmites, drip water samples, precipitation collections, and modern-forming calcite deposits using a variety of geochemical methods. An initial study was conducted at San Eduardo Cave near Tecoh, Yucatan Mexico. Additional caves in the region, as yet to be determined, will be investigated for study suitability. Such a task will ensure that this study provides a more regional context for climate changes. It will also offer a thorough view of the cave-climate system dynamics, which is presently lacking in the scientific literature.

Kendra L. Phelps ($1,500)
Ph.D. Student
Department of Biological Sciences
Texas Tech University

Prioritizing Karst Formations to Conserve Cave-Dependent Bats in the Phillipines

Abstract - In the Philippines, karst formations represent critical areas for biodiversity. Numerous bat species are dependent upon solution caves weathered into karsts to provide a stable environment suitable for roosting and rearing young as well as shelter from predators and adverse weather. Solution caves house some of the largest and most diverse aggregations of bat species in the world. Cave-dependent bats are considered keystone species because of the vital ecological and economic services they provide, specifically pollination, seed dispersal, and pest control in addition to providing the only nutrient input (guano) in caves. Unfortunately, cave-dependent bats are being threatened by human disturbances at multiple scales in karst landscapes, including widespread disturbances like quarrying and logging which result in the direct loss of roosting and foraging sites. Localized disturbances, such as unregulated hunting, cave tourism, and guano extraction, add additional pressures. Such human threats jeopardize the viability of cave bat populations in the Philippines. Thus, to determine the response of keystone bat species to increasingly human-dominated karst landscapes, my study aims to compare cave-dependent bat assemblages among karst formations experiencing differing levels of human disturbance on Bohol Island, an island centrally located in the Philippines. Specifically, I will document ecological characteristics (species diversity, composition) and general health parameters (body condition, ectoparasite loads) of cave-dependent bats across karst landscapes on Bohol Island that experience minimal, moderate, and high levels of disturbance. Results from my study will be used to identify priority karsts for protection to improve cave bat conservation in the Philippines.

Wendy Whitby ($2,240)
Ph.D. Student
School of Forensic and Investigative Sciences
University of Central Lancashire, UK

AMS Dating of Archaeological Basketry Samples from Cache Caves in South-Central California

Abstract -Distributed across the mountainous region situated just inland from Santa Barbara, in south central California, a number of dry caves have yielded more than 700 Native American artefacts. Xeric conditions in the caves have resulted in exceptional preservation of organic materials, and the cached objects include feather headdresses, wooden bullroarers, bone whistles, matting, bundles of plant materials, and large quantities of basketry. Indigenous material culture in California would have comprised a very high proportion of organic material but it is rare for archaeologists to have the opportunity to study objects such as these. The artefacts collected from these caves are now mostly housed in museums in the USA and their study enables consideration of indigenous subsistence, ritual, and ceremonial practices. Most of the region under study was occupied from prehistoric times by the Chumash people but the mountainous interior is relatively understudied compared to the coastal Chumash zone. Study of cache caves and their artefacts thus provides an opportunity to redress this balance.

My doctoral research is primarily combining archival research with museum-based study of cache cave artefacts. This should enable classification of artefacts and geographic based distribution studies. A further key objective is to construct a chronological framework for the use of cache caves and I propose to carry out a small programme of AMS dating on basketry specimens that are accessioned at Santa Barbara Museum of Natural History.