Temporal and spatial variations of benthic diatom communities at three estuaries in the Bohai Sea

Benthic diatoms are important primary producers in estuarine mudflat system, and the spatial and temporal changes in the communities can significantly impact the productivity of benthic fauna in the estuary. In this study, the ecological parameters in the estuaries of Daliao River, Hangu River and Huanghe River along the Bohai Sea coastline were surveyed and the related environmental factors were discussed, aiming to understand the seasonal variations and spatial differences of benthic diatom communities. The results showed that the species diversity index and absolute abundance of benthic diatoms were the highest in autumn, and the dominant species displayed obviously seasonal succession. The diatom absolute abundance in the estuaries of Daliao River and Hangu River were significantly higher than that of Huanghe River Estuary. The coarser sediments and significant phosphorus limitation in the Huanghe River Estuary are main reasons for the low diatom abundance. The correlation analysis between the benthic diatom communities and environmental factors indicated that the changes of temperature and nutrient concentration have significant effects on the seasonal pattern of the benthic diatom communities, while the sediment size, tidal range and runoff of the three estuaries are more important to explain spatial differences.