Fungal community dynamics during a marine dinoflagellate (Noctiluca scintillans) bloom.

Contamination and eutrophication have caused serious ecological events (such as algal bloom) in coastal area. During this ecological process, microbial community structure is critical for algal bloom succession. The diversity and composition of bacteria and archaea communities in algal blooms have been widely investigated; however, those of fungi are poorly understood. To fill this gap, we used pyrosequencing and correlation approaches to assess fungal patterns and associations during a dinoflagellate (Noctiluca scintillans) bloom. Phylum level fungal types were predominated by Ascomycota, Chytridiomycota, Mucoromycotina, and Basidiomycota. At the genus level drastic changes were observed with Hysteropatella, Malassezia and Saitoella dominating during the initial bloom stage, while Malassezia was most abundant (>50%) during onset and peak-bloom stages. Saitoella and Lipomyces gradually became more abundant and, in the decline stage, contributed almost 70% of sequences. In the terminal stage of the bloom, Rozella increased rapidly to a maximum of 50-60%. Fungal population structure was significantly influenced by temperature and substrate (N and P) availability (P < 0.05). Inter-specific network analyses demonstrated that Rozella and Saitoella fungi strongly impacted the ecological trajectory of N. scintillans. The functional prediction show that symbiotrophic fungi was dominated in the onset stage; saprotroph type was the primary member present during the exponential growth period; whereas pathogentroph type fungi enriched in decline phase. Overall, fungal communities and functions correlated significantly with N. scintillans processes, suggesting that they may regulate dinoflagellate bloom fates. Our results will facilitate deeper understanding of the ecological importance of marine fungi and their roles in algal bloom formation and collapse.

[Distribution of suspended matter concentration in the Changjiang Estuary and adjacent area after the first-stage storage of the Three Gorges Project].

The first-stage storage of the Three Gorges Project started on the 1st June, 2003 and ended on the 10th June, 2003. In order to investigate the influences of the Three Gorges Project on the Changjiang Estuary and adjacent area environment, a cruise was carried out from the 15th June, 2003 to the 25th June, 2003 to synthetically study the environment. Suspended matter concentrations (SMC) in different water layers at different sites were calculated and distributions of SMC were discussed combining with salinity and temperature of water based on recovered data. In results, SMC increase from surface to bottom in Changjiang Estuary and adjacent area. Suspended matters are enriched in the water over the river mouth bar and alongshore area which are located at the west of 123 degrees E. Compared to that before the storage, SMC are reduced obviously in the Changjiang course and south branch after the storage. For example, at the Xuliujing, SMC are reduced from 400 - 500 mg/L to 60.2 mg/L, and in the south branch, from 445 mg/L to 148 mg/L. In other areas, SMC do not show a significant change that they are both less than 10 mg/L in the surface player and 100 mg/L in bottom player. Generally, the distributed patterns of SMC in the investigation area after the storage are still similar to that before the storage.