Wei Song’s research while affiliated with First Institute of Oceanography and other places

Field observations were combined with a coupled hydrodynamic and water quality model to investigate the spatial and temporal variation in Chlorophyll-a (Chl-a) in Jinmeng Bay, China. The relatively high Chl-a values were distributed in the inshore waters, mainly due to the abundant nutrient inflow from the Tanghe River. The model’s results indicate that the Chl-a concentration was much higher in seaweed beds surrounded by artificial islands and reefs under the southeasterly wind, largely due to the fact that pollutants are prone to accumulate in coastal areas where flow is attenuated by the presence of natural and artificial marine structures. It was also found that the southwesterly winds suppress the inflow of nutrients from the Tanghe River to the coastal areas, and, therefore, lower the Chl-a levels. River input and wind forcing are the major factors that influence Chl-a concentrations in the anthropogenically influenced bay. This finding provides useful guidance for the prediction and mitigation of green tides in Jinmeng Bay in the future.

Since 2015, the coastal waters of Qinhuangdao in Hebei province, China have experienced green tide disasters for consecutive years. Resource utilization is an important measure for preventing and controlling green tides. To comprehensively utilize green tide algae, this study first identified theses green tide algae and then assessed their nutritional value. Based on analysis of the internal transcribed spacer (ITS), 5S spacer regions (5S) and the mitochondrial cytochrome C oxidase I (COI), the dominant species were Ulva prolifera, Bryopsis plumose, Ulva australis, and Gracilariopsis lemaneiformis. The basic nutritional components, i.e., chlorophyll, amino acids, mineral elements, and heavy metal contents, of these four algae were measured and analyzed, and the four dominant species were shown to be high-nutrient-value marine foods with complete and reasonable protein, amino acid, and mineral compositions. This indicates that there is value in further research and development towards their utilization as nutrient sources. This study provides a basis for the comprehensive development and utilization of green tide algae resources in the coastal waters of Qinhuangdao.

Blidingia sp. is a prominent fouling green macroalga and we previously found that extracts from Blidingia sp. alleviated intestinal inflammation in mice challenged with lipopolysaccharides. However, whether these extracts are effective in weanling piglets remains unknown. In the present study, Blidingia sp. extracts were supplemented in the diet and their effects on growth performance, incidence of diarrhoea and intestinal function in weanling piglets were explored. The results showed that diets supplemented with 0.1% or 0.5% Blidingia sp. extract significantly increased average daily body weight gain and feed intake in weanling piglets. Meanwhile, piglets supplemented with 0.5% Blidingia sp. extract showed decreased incidence of diarrhoea as well as reduced fecal water and Na+ content. Furthermore, the diet supplemented with 0.5% Blidingia sp. extracts improved intestinal morphology, as indicated by the results of hematoxylin and eosin staining. Diet supplemented with 0.5% Blidingia sp. extracts also improved tight junction function, as indicated by increased expression of Occludin, Claudin-1 and Zonula occludens-1, and alleviated the inflammatory response, as indicated by decreased tumor necrosis factor-α and interleukin-6 (IL6) contents and increased IL10 levels. Taken together, our results showed that Blidingia sp. extracts had beneficial effects in weanling piglets and we suggest that Blidingia sp. extracts could be potentially used as an additive for piglets.

Since 2015, a novel green tide began to bloom along the Qinhuangdao coastal area in the Bohai Sea, China. A year-round field survey was conducted in 2016 to reveal the development process of the green tides. The hydrodynamic comparison between 2004 and 2016 was carried out through model simulation. The results of field investigations indicated that the green tides lasted about five months from the early April to late September. The macroalgae in the green tides were mainly suspended to shallow waters, and the biomass peaked in July and August, after which they declined rapidly in September. The species composition of the macroalgae changed obviously during the blooming period. The model analysis showed that the construction of artificial islands affected the hydrodynamic force and weakened the water velocity. Therefore, based on the development process of the tides, we speculated that (1) the coastal eutrophication might be the major cause of the Qinhuangdao green tides, and (2) Slow flow was conducive to the growth of macroalgae, promote the formation of the green tide. (3) Seawater temperature might be one of the main factors controlling the succession of green tide species in Qinhuangdao.

Since 2015, green tides with Ulva prolifera as the dominant species in the Qinhuangdao coastal waters have continued to occur. In this study, the relationship between green tides in Qinhuangdao and the Yellow Sea (setting sites in Rudong and Qingdao) was evaluated by genetic analyses of U. prolifera. Single nucleotide polymorphism (SNP) markers were used to analyze genetic diversity and genetic relationships among groups. Genetic differentiation was lower among floating U. prolifera populations in Rudong and Qingdao than in Qinhuangdao. The floating U. prolifera population had higher genetic diversity and polymorphism levels in Qingdao and Rudong than in Qinhuangdao. Physiological experiments showed that the growth rate and net buoyancy of floating U. prolifera were highest in Qinhuangdao and Qingdao, respectively, under the same environmental conditions (temperature and light). Overall, these findings showed that U. prolifera populations in the Qinhuangdao and Yellow Sea green tides (Rudong and Qingdao) differ significantly at the molecular and physiological levels. Therefore, the Qinhuangdao green tide is not correlated with the Yellow Sea green tide and has a different origin and development mode. This study provides insight into the mechanism underlying green tide blooms in coastal waters of China.

The collagen from jellyfish has many beneficial effects, including antioxidant, anti-inflammatory and immune-modulatory activities. However, whether jellyfish collagen hydrolysate (JCH) has any effects on high-fat diet-induced obesity remains unknown. Consequently, we in the present study orally administrated JCH in high-fat diet-fed mice to explore its effects on body weight gain, inflammatory and oxidative status, and cecum microbe composition. The results showed that oral administration of JCH prevented the body weight gain in high-fat diet-treated mice. Meanwhile, glucose, triglycerides, and total cholesterol level in serum were maintained by JCH administration. Furthermore, JCH administration alleviated oxidative stress by increasing the GSH content and decreasing the level reactive oxygen species in the liver and improved inflammatory response by decreasing the expression of TNF-α, IL-1β, and IL-8 gene in the liver and ileum. Importantly, JCH administration helps recover the alteration of microbiota composition induced by high-fat diet, and the genus Romboutsia may critically involve in the beneficial effects of JCH administration. In conclusion, our results indicated that JCH could be potentially used for the prevention and treatment of diet-induced obesity.

Since 2015, the coastal waters of Qinhuangdao have been experiencing bloomed of green tides from April to September, with Jinmenghaiwan bath being the main affected area. Previous studies have shown that micro-propagules play an important role in the formation of green tides. In this study, we aimed to assess the temporal and spatial distribution of green algae micro-propagules in the coastal waters of Qinhuangdao after the green tides bloom in 2020. We found that the number of green algae micro-propagules in Jinmenghaiwan bath was significantly higher than that of the other surveyed areas. In addition, these micro-propagules of green algae presented a distribution trend of “high near the shore and low away from the shore” pattern. Compared to the period from October 2016 to April 2017, both the number of green algae micro-propagules and the proportion of Ulva prolifera micro-propagules in the coastal waters of Jinmenghaiwan bath decreased considerably in the period from October 2020 to April 2021. This may also be the reason why the green tides scale in 2021 was significantly lower than that in 2017. The results of this study will provide a theoretical basis for early warning and control of green tides in Qinhuangdao.

Manganese (Mn) deficiency exacerbates colitis symptoms, whereas diet supplemented with inorganic Mn merely maintains colon length in experimental colitis. In the present study, a new form of Mn, Ulva prolifera polysaccharide cheated-Mn (PMn) was used and its treatment effects on dextran sulfate sodium (DSS)-induced colitis were investigated. Male C57BL/6 mice were orally administrated with 3.5% DSS to induce colitis. Then, the colitis mice were treated with PBS or PMn for 7 days. The results showed that PMn administration help retrieve the body weight loss and intestinal morphology damage, and alleviate apoptosis and inflammatory responses in colitis mice. Moreover, PMn administration decreased intestinal infiltration as indicated by decreased concentration of myeloperoxidase and eosinophil peroxidase. Importantly, PMn retrieved the increased abundance of Firmicutes and the decreased abundance of Bacteroidetes caused by DSS, suggested its beneficial roles in regulating microbiota composition in mice with colon inflammation. Gut microbiota composition at the genus level in the mice administrated with PMn was similar to those in control mice, whereas they were clearly distinct from DSS-treated mice. These results support the potential therapeutic role of PMn in the treatment of intestinal colitis and microbes may play critical roles in mediating its effects.

Green tides have increasingly become a nuisance worldwide in recent years, and especially in China. Since 2015, green tides have started recurring in Jinmeng Bay, Qinhuangdao, western Bohai Sea of China, and have severely deteriorated the tourism environment there. In order to investigate the migration process of the green tides in Jinmeng Bay, a hydrodynamic model and a particle-tracking model were applied based on the latest green tide event in August 2021. The hydrodynamic model was applied with triple-level 2DH meshes with different refinements and scales, which provided the hydrodynamics to drive the green macroalgae into the particle-tracking model. From the model results, the semi-enclosed waters surrounded by multiple artificial structures are a low-energy hydrodynamic environment, which is not helpful for water exchange and thus the dispersal of nutrients. The green macroalgae are distributed substantially within the semi-enclosed waters, and few are transported out with low biomass. The effects of wind and artificial structures both increase the coverage of the green macroalgae trajectories; the effect of wind plays a more important role. A sensitivity analysis of the effect of wind showed that 6 m/s wind in ENE led to the maximum coverage of the green macroalgae trajectories in the cases of different magnitudes and directions of winds. This study can provide references for the pre-warning and mitigation of green tides in Jinmeng Bay and other similar places.