The linearity of the BZI (biomass, photic depth and irradiance) regression model for the estimate of depth-integrated primary productivity in the water column is evaluated. It is shown that the linear model can be derived from traditional production-irradiance (P-I) curves by assuming a linear production-irradiance relationship. A correction tem is obtained for water depth shallower than the photic depth. The analysis revealed that the slope of the linear BZI model is determined by the slope of the P-I curve. Following similar steps and assumptions, some of the well-known nonlinear light functions such as Steele's function, Smith's function and the Monod function were analytically integrated yielding nonlinear BZI models which go through the origin naturally allowing zero productivity at zero light. The nonlinear model integrated from Steele's function was successfully applied to three subtropical estuaries in Florida: the St. Lucie Estuary on the east coast, the Caloosahatchee River and Estuary and the Escambia Bay on the west coast. Despite being more faithful to theory (zero intercept), the non-linear version yielded only slightly better results than the linear model.

评估了 BZI（生物量、光深度和辐照度）回归模型的线性，用于估计水体中深度整合的初级生产力。结果表明，通过假设线性生产-辐照度关系，可以从传统的生产-辐照度 (PI) 曲线导出线性模型。获得比光深度浅的水深的校正项。分析表明，线性 BZI 模型的斜率由 PI 曲线的斜率决定。遵循类似的步骤和假设，一些著名的非线性光函数，如斯蒂尔函数、史密斯函数和莫诺函数，经过分析整合，产生非线性 BZI 模型，这些模型自然地通过原点，允许零光下的零生产率。由斯蒂尔函数集成的非线性模型成功应用于佛罗里达州的三个亚热带河口：东海岸的圣露西河口、西海岸的卡卢萨哈奇河河口和埃斯坎比亚湾。尽管更忠实于理论（零截距），但非线性版本的结果仅比线性模型略好。