Investigation of the Use of Pulse Amplitude Modulated (PAM) Fluorometry as an Indicator of Submerged Aquatic Vegetation (SAV) Health in Mobile Bay
Timothy D. Sherman
Department of Biological Sciences, University of South Alabama, Mobile AL 36688
The proposed study will concentrate on response of SAV photosynthesis to environmental conditions. This physiological parameter is tightly coupled not only to light conditions, but also to nutrient availability (i.e. DIC and nitrogen availability), stress (temperature, UV-B, etc.), and toxins. This study will utilize a recently developed technique known as pulse amplitude modulated (PAM) fluorometry and will demonstrate the utility of PAM methodology in SAV research. It also will produce baseline data on SAV photosynthetic parameters.

This pilot project will allow the determination of the utility of PAM fluorescence for use under field conditions to ascertain the physiological state of a native SAV (Vallisneria) and two introduced species (Eurasian milfoil and Hydrilla).


1. PAM measurements will be compared with those generated by polarigraphic measurement (using an analytical Clark-type oxygen electrode) under field conditions.

2. Measurements taken in the field will be compared to those taken on similar tissues transported back to the laboratory using conditions that have been utilized in previous reports

3. PAM and oxygen electrode data from different tissues of the same plants (i.e. young vs. old leaves, young vs. old parts of the same leaf, and similar tissues during the course of the day and of the growing season will be compared.

4. The effects of a variety of treatments (i.e. salinity, light attenuation, UV-B attenuation, and dissolved nutrient concentrations) will be determined.

From these data, an understanding will be generated of which parameters and tissues will yield reliable data for subsequent studies. Additionally, if laboratory-based measurements are indeed reflective of the physiological condition of field-measured materials, much less costly ($500 to $1000) non-submersible teaching-grade PAM fluorometers could be tested for useful in this type of work.