Environmental Factors Promoting and Regulating N2 Fixing Blue-Green Algal Blooms in the Chowan River, N.C.

摘要

Primary productivity, nitrogen fixation and the physical-chemical parameters regulating these processes, were examined in situ at a location in the lower Chowan River previously known to support blooms. During 1980 periods of weak thermal stratification, particularly during warming periods, coupled with phosphorus sufficiency, were crucial to nitrogen fixing blue-green algal bloom development. Phosphorus sufficiency could be established at relatively low ambient orthophosphate levels. Indirectly, nitrogen sufficiency was important as well. Spring diatom and green algal blooms relied heavily on nitrogenous nutrients for maximum development; the degree of spring bloom development was related to the potential for subsequent deoxygenation of river sediments and overlying waters during warm, weakly stratified summer periods. The chemical inhibition affected non blue-green algal growth more severely than blue-green algal growth.