Environmental Parameters Influencing the Growth of Enteromorpha clathrata (Roth) J. Ag. in the Intertidal Zone on Guam

Abstract

Laboratory studies were conducted to determine the light intensity, salinity, temperature and nutrient levels that would provide optimum growth for E. clathrata. The criteria for determining growth were the ratio of net productivity to respiration and mass volume change over a defined incubation period. Environmental conditions providing optimum growth were found to be a light intensity of 2600 ft-c or higher; 30.permill.; 25.degree. C; and 150 .mu.g-atoms/l of N, where the N:P ratio was maintained at 4:1. Seasonality, zonation and the influence of substratum were examined in the field. E. clathrata at Tumon Bay occurred year-round, and seasonal variations were correlated to wave height. Additional factors influencing the presence of this alga were wind-generated surge and grazing by herbivorous fish. The zone of E. clathrata growth in Tumon Bay occurred between mean tide level and mean lower low water. Adequate-sized substratum which varied with the degree of water movement, was necessary to maintain a population of Enteromorpha.