Typical relationships between phytoplankton biomass and transport time in river‐dominated coastal aquatic systems
Qubin Qin, Jian Shen
Abstract
Abstract Both abiotic and biotic factors control phytoplankton dynamics. Among the multiple factors regulating the variability of phytoplankton production and biomass, physical transport that distributes both phytoplankton and other substances (e.g., nutrients, salts, and suspended solids) is one of the key factors in coastal aquatic systems. While the effect of transport processes is best understood by the relationship between phytoplankton biomass/production and transport time (e.g., flushing time, residence time, and age), diverse relationships have been broadly observed. No consensus on the existence of a general relationship has been reached. Using a simplified zero‐dimensional mathematical model, we show that diverse relationships between phytoplankton biomass/production and transport time under different conditions of light and nutrient limitations can be synthesized into four patterns in river‐dominated coastal aquatic systems. Three patterns show a non‐monotonic relationship and one pattern shows a positive relationship. The non‐monotonic relationship between biomass and flushing time is demonstrated well by two realistic examples. The revealed non‐monotonic relationship provides insight into the widely observed nonlinear responses of many biogeochemical processes to changes in transport processes.