Outbreak Of Green Tide Research Articles

Distribution of Ulva macroalgae before and after the outbreak of the Yellow Sea green tide in aquaculture ponds and rivers nearshore Jiangsu, China

Green tide caused by the extensive proliferation of Ulva macroalgae in the Yellow Sea has been continuously occurring for 17 years. Previous studies indicate the Neopyropia aquaculture area in Jiangsu to be the main source of green tides in the Southern Yellow Sea. However, whether there are additional supplementary sources for the green tide in the Yellow Sea remains to be studied. This study conducted sampling of Ulva macroalgae in 14 aquaculture ponds and rivers nearshore Jiangsu in February and November in 2022. The molecular biology identification of samples through ITS and 5S indicates that the Ulva macroalgae in aquaculture ponds and rivers are composed of Ulva prolifera, Ulva linza, Ulva simplex, Ulva torta, Ulva flexuosa, and Ulva meridionalis. The results of micropropagules indicate that the abundance of micropropagules in aquaculture ponds is significantly higher than in rivers. In both February and November, the points with the highest abundance of micropropagules were located in aquaculture ponds, reaching 2090 inds L−1 and891 inds L−1, respectively. This study found that before and after the outbreak of green tide, the dominant species of green tide outbreak,5S-II U. prolifera,existed in aquaculture ponds and rivers nearshore Jiangsu. 5S-II U. prolifera in aquaculture ponds and rivers may have a potential impact on the outbreak of green tide in the Yellow Sea.

Bacteria associated with Ulva prolifera: a vital role in green tide formation and migration

Ulva prolifera green tide in the Yellow Sea of China is a typical cross-regional marine ecological disaster. We hypothesized that the complex interactions between U. prolifera and its associated bacterial communities possibly impact the formation and outbreak of green tide. To test this hypothesis, the U. prolifera-associated bacterial community changes in the entire migration area were investigated through field sampling and high-throughput sequencing. The results showed that (1) with the green tide migration, the richness and diversity increased for U. prolifera epiphytic bacterial communities, while they decreased for seawater bacterial communities in the phycosphere. (2) The richness, diversity, and community composition of U. prolifera-associated bacteria changed more dramatically in the 35.00°N sea area. (3) Potential interactions between bacteria and U. prolifera existed during the entire long-distance migration of green tide, and six bacterial functional groups (BFGs) were defined. Growth-regulating BFG I and antibacterial and stress-resistance BFG II were the dominant communities in the early stage of the green tide migration, which have the role of regulating algal growth and synergistic protection. Heterotrophic BFG III and algicidal BFG IV were the dominant communities in the late stage of the green tide migration, and they were able to compete with algae for nutrients and inhibit algal growth. Nutritive BFG V and algae-derived nutritional type BFG VI symbiotically lived with algal host. Our study highlights the spatial and temporal complexity of U. prolifera-associated bacterial communities and provides valuable insights into the potential contribution of U. prolifera-associated bacterial communities to green tide outbreaks.

Good news: we can identify Ulva species erupted in the Yellow Sea more easily and cheaply now

The green tide in the Yellow Sea which has been erupting continuously for 13 years, has brought a huge disaster to the ecosystem. There are four Ulva species from the early stage of green tide in the Yellow Sea usually: Ulva prolifera, Ulva compressa, Ulva flexuosa and Ulva linza. With the passage of time, the green tide floating to Qingdao mainly consists of Ulva prolifera. Molecular biological identification of species during the outbreak of green tide in the Yellow Sea has always been a focus of surveillance, but the ‘ITS-5S’ test system we have been using for a long time is not perfect. Through analyzing the mitochondrial genome of species published by our laboratory and combining with the other mitochondrial genome data, we find that the rps2-trnL gene spacer sequences can accurately distinguish the Ulva species of the green tide. After gene amplification and the construction of Maximum Likelihood phylogenetic tree, we find that the rps2-trnL gene spacer sequence is completely suitable for the barcode sequence of common Ulva species. This discovery could save researchers a lot of money and time, also, provide basic data for future green tide prevention and control.

Composition variations and spatiotemporal dynamics of dissolved organic matters during the occurrence of green tide (Ulva prolifera blooms) in the Southern Yellow Sea, China

Seawater samples were collected from April 6 to September 6, 2017 in the Southern Yellow Sea, China where green tides often occurred, and analyzed for nutrients, dissolved organic carbon (DOC), and fluorescent dissolved organic matter (FDOM). The DOC concentrations increased significantly in the green tide areas by approximately 1.2 times compared to those in the non-green tide areas. From the large-scale outbreak to the complete dissipation of the green tide, the fluorescence intensities of the four FDOM fluorescent components identified in the green tide areas were significantly higher than those in the non-green tide areas. During the extinction period, the fluorescence intensities of the three humus-like components and one protein-like component were approximately 1.8 and 1.3 times higher than those in the non-green tide areas, respectively. These findings suggested that the outbreak of green tide could release DOM into water and affect the biogeochemical cycle in green tide regions.

Phycoremediation of coastal waters contaminated with bisphenol A by green tidal algae Ulva prolifera

The phycoremediation of coastal water contaminated with bisphenol A (BPA) by Ulva prolifera (U. prolifera) during green tide blooming was investigated. The results demonstrated that BPA could be removed rapidly in the presence of U. prolifera. >94.3% of BPA was removed by live U. prolifera while <2.5% of BPA was removed by dead biomass. The accumulation of BPA in U. prolifera was confirmed by laser confocal scanning microscopy (LCSM). Uptake experiments under different conditions showed that the removal efficiency of BPA by U. prolifera had positive relationships with light, nutrient and temperature while the salinity had no effect. A linear relationship existed between the removal efficiency and the BPA initial concentration when the BPA initial concentration increased from 50 to1000 μg L−1, indicating the high tolerance of the green-tidal algae to the toxic effect of BPA. High BPA removal efficiency (>94%) was achieved at the environmental relevant concentrations of BPA. The field investigation indicated that the BPA concentration in the coastal water in the green tide blooming area was much lower than that in the adjacent coastal water without green tide. The contribution of the green-tidal algae in the removal of BPA in the coastal waters was remarkable due to the high BPA removal efficiency, and high biomass & huge covered area of the U. prolifera during the outbreak of green tide. These findings demonstrate a new important phycoremediation process for coastal water containing typical endocrine-disrupting chemicals (EDCs) during the green tide blooming.

Removal of phenanthrene from coastal waters by green tide algae Ulva prolifera

Ulva prolifera (U. prolifera) has been frequently involved in terrible algal proliferation in coastal areas. Although it is known to be associated with green tide, its contribution to the natural attenuation of the polycyclic aromatic hydrocarbons (PAHs) in seawater has not been evaluated. In this study, the removal of phenanthrene using U. prolifera collected from coastal water with green tide blooming was investigated. The results showed that phenanthrene could be removed efficiently in the presence of both the live and heat-killed U. prolifera. The phenanthrene concentrations of the live algae treatment decreased smoothly from 10.00 to 0.80μgL−1 through the whole process, while those of the heat-killed algae treatment decreased sharply from 10.0 to 2.71μgL−1 in one day and kept constantly after that. The in situ monitoring and visualizing using laser confocal scanning microscopy (LCSM) confirmed the accumulation of phenanthrene in U. prolifera. The increase in nutrient and temperature led to the increase of phenanthrene removal rate, while the salinity had less influence on the removal of phenanthrene. The removal efficiency by U. prolifera had a good linear relationship with phenanthrene initial concentration (r2=0.999) even at 100μgL−1 which was higher than its environmentally relevant concentrations. High removal efficiency (91.3%) was observed when the initial phenanthrene concentration was set at environmental relevant concentration (5μgL−1). Results of this study demonstrate a potential new natural attenuation process for typical PAHs in coastal water during the outbreak of green tide. These findings indicate that the outbreak of harmful green tide algae may bring positive environmental benefits in the terms of the removal of harmful organic pollutants from coastal waters.