Variabilidad estacional de la productividad primaria y su relación con la estratificación vertical en la Bahía de la Paz, B.C.S.

Primary productivity (pp) during October of 1996, March, April, May, June, July, September, November of 1997 and January of 1998, was estimated via natural fluorescence in La Paz bay. Simultaneously to pp vertical temperatura profiles (CTD) were registered to determine the structure of the water column, which was calculated by using the stratification index (ɸ) from 0 to 100 m depth. The highest average values in pp (16 mg C m-3 h-1) were observed during the spring and the minimum values of ɸ (50 J m-3)  corresponded to a almost homogeneous water column. In contrast, to other seasons (summer and autumn), the pp fell to minimum values (2 to 5 mg C m-3 h-1), while ɸ increased significantly (249 and 347 J m-3). The results indicated a lineal dependence between pp and water column mixture (r2 = 0.62, p <0.05) during the summer months. Periods with high stratification seem to inhibit the fertilization on the surface layer, while the well mixed water column facilitate the fertilization process. Therefore, it is evident that the water column stratification in La Paz bay plays an important role mechanism that controls the pp and partially explains the seasonal variability.