Composition and distribution characteristics of the eukaryotic community in seawater and saline-alkali water ponds and their correlation with the nutritional components of Scylla Paramamosain

We examined the correlations between the nutritional components of Mud crab Scylla paramamosain and the variation of eukaryotic communities in two types of aquaculture ponds in north China. The data covered the eukaryotic communities in the water and the sediment of two different types of ponds in two seasons. The dominant phyla of eukaryotic organisms in the seawater pond and the saline-alkali water pond included Ochrophyta, Bacillariophyta, Arthropoda, Alveolata, and Bicosoecida. Based on PCoA and NMDS analyses, the eukaryotic community structure of sediment samples from seawater ponds and saline-alkaline ponds showed minimal spatiotemporal differences. In contrast, water samples from these two types of ponds exhibited significant spatiotemporal variability. For both ponds, RDA analysis indicated that salinity, dissolved oxygen, and ammonia nitrogen significantly influenced the eukaryotic community in the water, whereas salinity, pH, and dissolved oxygen significantly influenced the eukaryotic community in the sediment. For the seawater pond, the eukaryotic communities in the sediment had higher diversity indexes (Chao1 index, Pielou_e index, Shannon index, and Simpson index) than those in the water, and for the saline-alkali water pond, the diversity indexes were significantly higher in September than in June. The indicate eukaryotic species, identified by the IndVal method, had significant correlations with the nutritional quality of S. paramamosain . The results are expected to facilitate the aquaculture of S. paramamosain in north China. • Seawater and saline-alkali water ponds of S. paramamosain had significantly different eukaryotic communities. • Eukaryotic communities were influenced by the seasonal and spatial variations of physicochemical factors. • Seawater pond had less diversity on water eukaryotic and sediment eukaryotic communities. • Most sensitive eukaryotes are positively correlated with the nutritional quality of S. paramamosain .