Land-Use and Climate Influences on Lake Tanganyika Floor Sediments and Ecosystems

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

The goal of this project is to determine the degree to which agricultural and urban development activities on the shores of Lake Tanganyika affect the bottom-dwelling and -nesting organisms. Lake Tanganyika is widely considered a "natural laboratory" for the study of evolutionary and ecological processes, because many of the organisms have evolved and diversified within the lake itself. This ecological treasure is under threat. Numerous studies have focused either on open-water fisheries or on watershed (sedimentation and pollution) issues as these affect the health and wealth of the four riparian countries. However, the vast shell beds within the shallow (10-30 m) regions of Lake Tanganyika have received much less attention, even though these accumulations of dead shells are a unique habitat to Lake Tanganyika and host a diverse, endemic fauna, including numerous Cichlid fish. These accumulations of dead snail shells are pervasive, but appear to contain no living snails in the same habitat. If living snails are absent, then it implies either natural environmental change or acute anthropogenic impacts. Thus, these shell beds, if measured correctly, may provide a means of assessing natural and human-induced environmental change. The researchers will use the results of this work in courses and within a summer science camp for middle school students taught at the University of Oklahoma. The chief investigator also leads study abroad courses in which the topics of conservation and resources of African lakes are featured. The team will publish the results of the research in both scientific and popular press venues, and will carry out public outreach through posting to related web sites (e.g. Cichlid fish hobbyists) and through blogging of the field experience to make it accessible to both American and African science students. The research team will compare and contrast three sites within shallow regions of Lake Tanganyika that are floored by shell beds, but that vary in terms of their land-use (highly disturbed, moderately disturbed, and a control site). Data to be collected will include: the nature of the lake bottom at each site, including the age and character of the shells as well as the texture and composition of the intermixed sediment; the diversity and abundance of certain bottom-dwelling organisms among the sites; changes in sedimentation over time inferred from data from core collected at each site; and changes in sedimentation patterns over time as inferred by geophysical (seismic) data from each site. Comparison of the data among the sites will allow the investigators to determine whether the accumulation of the shells record lake-wide or regional changes and whether the distribution of modern organisms using the shell beds as a habitat vary as a result of land-use changes. These results would impact researchers interested in the biodiversity, conservation and evolutionary history of Lake Tanganyika and other modern and ancient tropical lakes. The proposed activity will train one PhD student and six undergraduates within an integrated research program. This research would involve the University of Oklahoma, the University of Arizona, and the National Museum, London. Work with the United States Geological Survey and Northern Arizona University would also enhance exposure and interdisciplinary research. The team's collaboration with Tanzanian Fisheries Research Institute would provide their scientists with increased experience in studying benthic ecology, and the results would vest governments and other stakeholders, such as conservation groups, with knowledge to manage these critical ecosystems.