Abstract
Phytoplankton photosynthetic parameters (maximum light utilization coefficient, alpha*; maximum photosynthetic rate, P*m; maximum quantum yield, phi-max) off Baja California were estimated from samples collected at the 50% light level during winter, spring, summer, and autumn 1999. Chlorophyll concentration was also determined, and in situ experiments were conducted using the 14C method to determine primary production (PP) in the euphotic zone. The highest alpha* and phi-max values were found during the spring survey, mainly at the coastal areas, associated with diatom and dinoflagellate abundances and high chlorophyll concentrations. However, high P*m values were measured during autumn in both inshore and offshore areas due to the presence of smaller phytoplankton cells. The average profiles of the photosynthetic parameters (alpha*(z) and P*m(z)) in the water column were estimated for 2 regions. These parameters were used to estimate PP with semi-analytical models. Modeled PP was contrasted with in situ PP to validate our calculated photosynthetic parameters in the euphotic zone. In general, modeled PP values were similar to in situ values (94 mg C·m–2·h–1), with a high correlation coefficient (r = 0.85). Modeled PP for coastal waters in the northern and central regions was 1.5-fold greater than in situ estimates during spring. In conclusion, when used with remotely sensed phytoplankton pigment and surface irradiance data, the average profiles of alpha* and P*m(z) could be a useful tool to calculate PP in our study area.
Highlights
Primary production (PP) determination based on data derived from remote sensors, requires regional and temporal estimations of phytoplankton photosynthetic parameters such as maximum light utilization coefficient ( *) and maximum photosynthetic rate ( Pm*) (Platt and Sathyendranath 1988, Platt et al 1991, Sathyendranath et al 1996)
One way to solve this issue is to divide the ocean into regions with similar oceanographic characteristics (Longhurst et al 1995, Sathyendranath et al 1995), where photosynthetic parameters derived from the photosynthesis–irradiance (P–E) curves remain almost constant accross a region, over a season, or in time
The Chla integrada (Cint) estimates for the coastal zone were higher during spring and autumn than during winter and summer but lower than the estimates for the 2000–2002 period reported by Gaxiola-Castro et al (2010)
Summary
Primary production (PP) determination based on data derived from remote sensors, requires regional and temporal estimations of phytoplankton photosynthetic parameters such as maximum light utilization coefficient ( *) and maximum photosynthetic rate ( Pm*) (Platt and Sathyendranath 1988, Platt et al 1991, Sathyendranath et al 1996). One of the main issues with PP estimation based on remote sensing data is the extrapolation of local determinations of spatial and temporal photosynthetic parameters and bio-optical properties to large regions and long periods of time. This constitutes one of the most important tasks in biological oceanography (Longhurst et al 1995, Sathyendranath et al 1995). One way to solve this issue is to divide the ocean into regions with similar oceanographic characteristics (Longhurst et al 1995, Sathyendranath et al 1995), where photosynthetic parameters derived from the photosynthesis–irradiance (P–E) curves remain almost constant accross a region, over a season, or in time
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