Seasonal and spatial characterization of the Gulf of California phytoplankton photosynthetic parameters

Photosynthesis-irradiance and phytoplankton absorption data from waters of the central Gulf of California as well as data in the literature, were anal yzed in order to propose working averages of the physiological parameters o f phytoplankton to estimate primary productivity at large time and space sc ales. Since there is substantial variability within data sets, we conclude that it is not possible at this time to predict fine time- and space-scale variation in photosynthetic parameters. We recommend the following working averages for the whole Gulf of California and for "winter" conditions (surf ace T degrees C <22 degrees C): a surface P*(max) = 9.6 +/- 2.4 mgC mgChl(- 1) h(-1) (assimilation number), with a linear variation between this and 3. 7 +/- 0.3 at the middle of the euphotic zone let), and then a constant valu e for deeper waters; a single value of alpha*(inc) = 0.029 +/- 0.004 mgC mg Chl(-1) h(-1) (mu mol quanta m(-2) s(-1))(-1) (incubator's initial slope); and phi(max) = 0.06 +/- 0.01 molC (mol quanta)(-1) (quantum yield of photos ynthesis). For "summer" conditions we recommend: a surface P*(max) = 3.7 +/ - 0.3, with a linear variation between this and 1.5 +/- 0.2 at the middle o f the ez, and another linear variation between the latter and 0.4 +/- 0.1 a t the bottom of the ez; a surface alpha*(inc) = 0.013 +/- 0.001, with a lin ear variation between this and 0.001 at the bottom of the ez; and a single value phi(max) = 0.014 +/- 0.002. A procedure is given to correct alpha*(in c) for the in situ spectral distribution of light to obtain alpha*(in situ) .