Environmental flow assessments in estuaries related to preference of phytoplankton

摘要

An approach to assess estuarine environmental flow based onphytoplankton preference, including the complex relationships betweenhydrological modifications and ecosystem biomass, was developed in thisstudy. We initially established a relationship between biomass requirementsfor primary and higher nutritional level organisms based on the ecosystemnutritional energy flow principles. Subsequently, diagnostic pigments wereemployed to represent phytoplankton community biomass, which indicatedcompetition between two groups of phytoplankton in the biochemistry process.Considering empirical relationships between diagnostic pigments and criticalenvironmental factors, biomass responses to river discharge were establishedby simulating distributions of critical environmental factors under actionof river discharges and tide currents. Consequently, environmental flowswere recommended for different fish biomass requirements. We used the YellowRiver estuary as a case study; and May and June were identified as criticalmonths for maintaining environmental flow. Temporal variation in naturalriver flow dynamics, which was used as a proxy for environmental flow,should be carefully examined in artificial hydrological regulationstrategies, particularly during high-amplitude flood pulses, which mightresult in negative effects on phytoplankton groups, and subsequently higheraquatic species biomass.