Cultivation of the brown alga Sargassum horneri: sexual reproduction and seedling production in tank culture under reduced solar irradiance in ambient temperature

As a large conspicuous intertidal brown alga, individuals of Sargassum horneri can reach a length of more than 7 m with a fresh weight of 3 kg along the coasts of the Eastern China Sea. The biomass of this alga as a vital component in coastal water ecology has been well documented. In recent years, a steady disappearance of the algal biomass along the once densely populated coastal areas of the Eastern China Sea has drawn attention in China. Efforts have been made to reconstruct the subtidal algal flora or even to grow the alga by use of long-lines. As part of the efforts to establish an efficient technique for producing seedlings of S. horneri, in this investigation a series of culture experiments were carried out in indoor raceway and rectangular tanks under reduced solar irradiance at ambient temperature in 2007-2008. The investigation demonstrated that: (1) sexual reproduction of S. horneri could be accelerated in elevated temperature and light climates, at least 3 months earlier than in the wild; (2) eggs of S. horneri had the potential to be fertilized up to 48 h, much longer than that of known related species; (3) suspension and fixed culture methods were both effective in growing the seedlings to the long-line cultivation stage; and (4) the life cycle of S. horneri in culture could be shortened to 4.5 months, thus establishing this alga as an appropriate model for investigating sexual reproduction in dieocious species of this genus.

Vast laminated diatom mat deposits from the west low-latitude Pacific Ocean in the last glacial period

Diatoms are one of the predominant contributors to global carbon fixation by accounting for over 40% of total oceanic primary production and dominate export production. They play a significant role in marine biogeochemistry cycle. The diatom mat deposits are results of vast diatoms bloom. By analysis of diatom mats in 136 degrees 00'-140 degrees 00'E, 15 degrees 00'-21 degrees 00'N, Eastern Philippines Sea, we identified the species of the diatoms as giant Ethmodiscus rex (Wallich) Hendey. AMS C-14 dating shows that the sediments rich in diatom mats occurred during 16000-28600 a B.P., which means the bloom mainly occurred during the last glacial period, while there are no diatom mat deposits in other layers. Preliminary analysis indicates that Antarctic Intermediate Water (AAIW) expanded northward and brought silicate-rich water into the area, namely, silicon leakage processes caused the bloom of diatoms. In addition, the increase of iron input is one of the main reasons for the diatom bloom.

Tectonic and geodynamic pattern of marginal seas on the West Pacific inferred from multi-satellite altewetry geoid

With the rapid development of satellite observations, we can use the altimetry geoid to study submarine tectonics and geodynamics. On the basis of the 4' x 4' geoid undulation calculated from altimeter data of Geosat, ERS-1/2 and Topex/Poseidon on the West Pacific, located between 0degreesN similar to 45degreesN, 100degreesC similar to 150degreesE, Bouguer, Glenni and isostatic geoid undulation are obtained from correction of gravitational potential of the global topography and isostacy. Moho discontinuity depth is inversed by the Glenni geoid undulation, and the stress field from small-scale mantle convection is reasonably calculated from the isostatic geoid undulation. The results show that within the Philippine Sea and the South China Sea, short-wavelength lineations of the geoid undulation are parallel or cross to magnetic lineations and rifting ridges. The Moho depth of marginal sea basins becomes shallow southward, and its values are similar to that of the Philippine Sea. These facts show that strength of tectonic activities are almost the same on the both sides of the Ryukyu-Taiwan-Philippine are. Various kinds of tectonic features with different driving mechanisms of small-middle and large-scale of mantle convection, however, display a special pattern of tectonics and geodynamics of the continental marginal seas distinguished from oceans and continents.

Carbonate cycle and its control factors in Kuroshio source region during the last 190ka BP

Two deep sea cores (Ph05-5, 16.05 degrees N, 124.34 degrees E, water depth 3382m and WP3: 22.15 degrees N, 122.95 degrees E, water depth 2700m) retrieved from the Kuroshio source region of the western Philippine Sea were selected to carry out the CaCO3 and calcareous nannofossil faunas study. Based on AMS(14)C data and comparing tire oxygen isotope curve with SPECMAP delta O-18 (Martinson et al., 1987) a stratigraphy was established. And, combining the changes of primary productivity and dissolution index of carbonate, the carbonate cycle and its control factors were analyzed in this region during the last 190ka BP. The carbonate contents showed higher values in the glacial periods and lower values during the interglacial and Holocene periods, which characteristics was similar to the tendency of "Pacific Type" carbonate cycle. However, there were high carbonate contents in the warm period and low values during the cold interval, which displayed the same tendency with the "Atlantic Type" carbonate cycle during the last glacial period (MIS4-2) in the east of Phillipines. The variations of primary productivity and carbonate dissolution index indicated that the carbonate dissolution was a major factor controlling the carbonate content in tire cast of Philippines, and the variations in carbonate contents were mainly affected by the productivity of calcareous organism in the Southeast of Taiwan. The "Atlantic Type" carbonate cycle in the cast of Phillipines during the last glacial period (MIS4-2) was an effect of the process of dissolution combined with the change of primary productivity.

东菲律宾海铁锰结壳（核）成因与古海洋环境响应

本文以东菲律宾海沉积物表层新型深水铁锰结壳、铁锰结核及结壳下伏沉积物为研究对象，通过对其显微结构构造、矿物组成、元素组分的分析、元素赋存状态的系统研究、铀系和10Be同位素年代学测试，结合结壳（核）成矿背景和控矿要素分析，研究和恢复了研究区深水铁锰结壳（核）的成因与古海洋环境响应。这一结果填补了深海沉积物表层新型深水铁锰结壳系统研究的空白，深化了对铁锰结壳（核）分布规律、成因和形成过程及其古海洋环境记录作用的认识，充实了海底金属成矿理论，为铁锰结壳（核）的勘探与开采提供了理论基础和支持，同时也为研究区晚中新世以来一直不甚明了的构造演化提供了新的研究载体和资料。 通过研究，得出如下结论：（1）研究区铁锰结壳（核）的成矿背景主要受控于南极底流强弱及物源供给的变化；（2）证实铁锰结壳（核）主要为水成成因，同时其物质组成也受一定程度的火山和陆源物质的影响；结壳（核）自形成以来没有遭受到明显的磷酸盐化等成岩后期改造和元素再迁移，具有重要的古海洋学意义；（3）通过新型铁锰结壳及下伏沉积物元素赋存状态的研究，认为生物作用对研究区结壳的形成并没有很大的直接影响，其物质成分主要来自于结壳中铁锰氧化物（氢氧化物）的吸附作用；（4）在控矿要素的研究中，归纳出了地质与海洋两大类结壳（核）控矿要素；（5）根据结壳成分长周期变化趋势，结合铀系和10Be测年结果，将研究区结壳的形成过程划分为三个主要阶段（5.6~2.8 Ma，2.8~2.7 Ma和2.7 Ma以来），并确定了晚中新世以来研究区南极底流的活动情况、火山和大陆来源（风尘）物质输入量的变化。