A Limnological Investigation of the Microbiota of an Illinois Pond

Abstract

This study entailed an intensive one-year limnological investigation of the microbiota of a small Illinois pond with emphasis on physico-chemical interrelations and physico-chemical vs. organismal interactions. The numbers of organisms/liter belonging to a given taxon were determined, and these data were related to the physico-chemical data at a given time by means of multiple regression programs. Most phytoplankton populations were correlated with nitrate-nitrogen and water temperature. Less frequent negative correlations were observed with ammonia-nitrogen and nitrite-nitrogen, and positive or negative correlations occurred with total alkalinity. Diatoms were the first phytoplankters to produce a spring bloom. They were followed by desmids and other green algae. The presence of ciliate Protozoa usually was not correlated with any specific physico-chemical factor, lending credence to the supposition that their numbers and species composition are controlled by the presence and abundance of particulate food material. Several species belonging to the same genus, e.g., Euglena spp. and Vorticella spp., were present at the same time in samples collected from the pond. Intensive long-term sampling presented a panorama of the changes occurring in taxon composition and numbers of organisms within a period of several days and throughout the year. Sudden fluctuations in population size and taxon presence reemphasized the need for such intensive sampling during the studies of the interrelationships between taxa and the physico-chemica] factors producing changes in the population density of the affected taxa. INTRODUCTION The present study involved a one-year limnological investigation of the microbiota of a small artificial pond in Champaign, Illinois. Qualitative and quantitative interrelationships were investigated under field conditions. A statistical approach was desirable, not only because it had been employed infrequently in previous such studies, but also because of its potential significance in any sound approach to such a problem. The analysis of data represents, therefore, not only a presentation of the day-to-day and annual dynamics of the microbiota of a pond, but also it quantifies the interrelationships between taxa and the physico-chemical factors that affect their presence and abundance. I am indebted to Dr. Horace Norton, Department of Agronomy, University of Illinois, for advice on statistics, and to Michele S. Stern, Department of Biology, Tulane University, for aid in preparation of the manuscript. MATERIALS AND METHODS DESCRIPTION OF THE POND The survey was conducted on a small artificial pond on the grounds of the Vivarium at the University of Illinois. The irregularly shaped Current address: Department of Biology, Louisiana State University in New Orleans, Lakefront, New Orleans, Louisiana 70122.