Research Interests
Research in my laboratory focuses on molecular biology and microbiology of the aquatic environment: freshwater, estuarine, and marine microbial ecosystems. Our studies include marine biotechnology, i.e., increased productivity of the world oceans and alleviating human health problems by reducing cholera epidemics in developing countries through understanding of marine microbial ecosystems. Our research has also included studies of the effect of pollutants on the oceans, e. g., effects of waste dumping on marine and estuarine microbial ecosystems. This work includes effects of heavy metals, petroleum, domestic, and industrial wastes deposited in the New York Bight, Puerto Rico Trench, and the Gulf of Mexico. Work on Chesapeake Bay viruses and bacteria provides an understanding of the annual cycle of these important microorganisms, the effect of climate and other environmental factors on their abundance, and their interactions with plankton and animals in the Bay. In effect, our work is focused on marine and estuarine molecular ecology and biocomplexity in the environment.

Cholera is a disease caused by drinking water contaminated with Vibrio cholerae and offers a model for our research work. The symptoms of the disease are severe diarrhea and dehydration, leading to death, if not properly treated. Once the source of major epidemics in European and American cities, cholera remains a serious problem in developing countries lacking a clean water source. Our studies showed that the bacterium is associated with the surface and gut of zooplankton, notably copepods. A simple and inexpensive solution to reduce the presence of cholera bacteria in drinking water for developing countries came out of our work on V. cholerae, namely to filter water through cloth, trapping zooplankton and particulates to which the majority of the cholera bacteria are attached. The cloth used is that employing in making the sari, a traditional dress in developing countries, including India and Bangladesh, where severe cholera epidemics are common and treated water supplies are not available to a significant portion of the population of those countries. Filtering water through four or more layers of sari cloth removes zooplankton and other particulate matter and, from our epidemiological studies now in progress, reduces the number of cholera bacteria in the water used as the drinking water source. As a result of the practice of cloth filtration, the incidence of cholera has been reduced significantly in the villages of Bangladesh included in our studies.

Evidence from our near-shore and deep-ocean microbiology and molecular microbial ecology studies show that bacteria and viruses present in seawater, even though not readily culturable in the laboratory, are viable and metabolically active. This phenomenon, the viable but not culturable state that is demonstrated by Gram-negative, nonsporulating bacteria, has been a focus of research in our laboratory and has been found to be an important strategy for survival of microorganisms in the environment.

In other studies, we are examining the distribution and interrelationships of viruses, bacteria, and plankton in the Chesapeake Bay and in the estuarine and marine environment, in general. The majority of bacteria and, apparently, viruses are beneficial, and play important roles in the marine ecosystem. Our studies indicate that bacteria and viruses are widespread throughout the Chesapeake Bay, and their populations peak in late summer and early fall.