(full paper is archived in the Miller Library)
Title: Circadian and circatidal patterns of ammonia excretion in the high intertidal gastropod Littorina planaxis
Student Author(s): Baum, Linda G.
Faculty Advisor(s): Phillips, John H.
Location: Final Papers Biology 175H
Date: June 1978
Keywords: biological rhythms in marine and maritime organisms
Abstract: 1. Moisture appears to be a stimulus for ammonia excretion; since this nitrogenous waste product is water-soluble, ambient moisture would facilitate diffusion. 2. L. planaxis displays peaks of excretory activity which coincide with times of greatest moisture, i.e., night and high tide, thus maximizing opportunities for excretion. 3. Light and dark seem to be the strongest factors influencing this change in excretory activity; the tidal correlations become more apparent when normal light and dark cues are removed. 4. If deprived of moisture, L. planaxis excretes smaller amounts of ammonia; since this compound is toxic, ammonic synthesis could be harmful if no means were available for excretion. 5. Rates of ammonia synthesis appear to be greater at night than during the day.