Phytoplankton community dynamics as a metrics of shrimp healthy farming under intensive cultivation

Abstract

In this study, the composition and temporal dynamics of phytoplankton communities were tracked in shrimp ponds of two crops with different health status (healthy or diseased) to explore the potential relationship between phytoplankton community dynamics and/or stability and shrimp health status. Differences in phytoplankton community structures and succession patterns between the two crops were detected by non-metric multidimensional scaling and time-lag regression analysis. Although no significant difference was observed in the α-diversity between the two crops, their community dynamics differed. The turnover and mean shifts in species rank abundance and composition changes of phytoplankton community in the second crop were higher than those in the first crop. Moreover, the stability values of the first crop were significantly higher than those of the second crop. Redundancy analysis revealed that total nitrogen and nitrogen to phosphorus ratio (N/P) were correlated with the phytoplankton community composition in the first crop. In the second crop, the phytoplankton community was regulated by water temperature and dissolved oxygen (DO) in addition to nutrients. Based on linear regression, the phytoplankton community dynamic was correlated with the changes of N/P in the first crop. The DO and the sum of nitrate and nitrite (NOx) and orthophosphate (PO4-P) were the major influencing factors of phytoplankton community dynamics in the second crop. In summary, our findings indicate that the phytoplankton community dynamics may affect the shrimp health, and maintaining a stable phytoplankton community will be helpful to the healthy farming of shrimp. This study provides evidence that the phytoplankton community dynamics can serve as the metrics to evaluate the quality of rearing environment in intensive shrimp pond.