The contribution of phytoplankton productivity in turbid freshwaters to their trophic status

Certain factors influencing phytoplankton productivity are accentuated in turbid waters. They include mixing, spectral quality shifts, scattering, light fluctuations, and overall light attenuation. Measurements of productivity is influenced by the presence of inorganic turbidity. Together with the above factors high turbidity causes difficulties to assess and model phytoplankton productivity. Estimations of ^B, P_m^B, I_k and _m only reflect on the physiological condition of the phytoplankton, which differs little between water types of temperate regions. Measurement of integral vertical productivity, efficiency and fractional absorption by the phytoplankton of light energy conversion, however, are greatly influenced by inorganic turbidity. Because of high ratios of mixing to euphotic depth, the critical mixing depth is one of the most important factors influencing overall productivity in turbid waters.