Brevetoxin abundance and composition during ECOHAB-Florida field monitoring cruises in the Gulf of Mexico

This project was undertaken to provide information about the composition and fate of brevetoxins in concert with the multidisciplinary study, ECOHAB-FL, of Karenia brevis blooms in the Gulf of Mexico. Brevetoxin composition was provided for water samples collected during and in the absence of K. brevis blooms from November 1998, through September 2002. The identity and concentration of the most abundant brevetoxins were determined using high performance liquid chromatography with ultraviolet diode array detection (HPLC-DAD). The analytical methods changed in 2002 to the use of a mass spectrometer for brevetoxin identification and quantitation. The most abundant brevetoxins observed during blooms were PbTx-1, -2 and -3. PbTx-2 was the most abundant toxin observed in viable bloom situations with an abundance of K. brevis cells. Starting with the 2000 cruises, a distinction was made between intra-cellular toxins (inside viable K. brevis cells) and extra-cellular brevetoxins (dissolved brevetoxins outside of the cell). An important observation was the change in composition of the major brevetoxins from intra-cellular to extra-cellular toxins. The most abundant intra-cellular toxin was PbTx-2, whereas the most abundant brevetoxin recovered from the extra-cellular (dissolved) fraction in the water was PbTx-3. The abundance of PbTx-3 relative to PbTx-2 generally increased as a bloom aged, indicating the conversion of PbTx-2 to -3 as cells lysed, and the persistence of PbTx-3 in the water after cell death.     

海洋生态预报的研究进展与发展应用

从介绍海洋生态预报的概念和作用开始,根据赤潮、绿潮、水母暴发、珊瑚白化等海洋生态灾害的致灾种类和涉及的富营养化、低氧和致病菌等灾害指标,阐述了国内外近年来海洋生态预报的研究进展,进而探讨了河口区、陆架海以及全球大洋等不同海域差异所涉及的海洋生态预报的发展应用,论述了经验预报、统计预报和数值预报等海洋生态预报的国内外研究进展与实际应用,最后展望提出海洋生态预报在未来发展中面临的挑战和亟需解决的关键科学问题。     

Why did some larger benthic foraminifera become so large and flat?

Biostromes and low-relief bioherms, some of which are characterized by exceptionally large, flat specimens of larger benthic foraminifera, are common in Palaeogene and Miocene carbonates, most notably those deposited along the Neotethys Seaway and tropical Pacific islands. By incorporating insights from palaeoceanographic research and the biology of living larger benthic foraminifera, a scenario is proposed that can account for palaeontological and sedimentological features while augmenting previous interpretations. Sexual reproduction by gamete broadcasting is common in foraminiferal taxa, including extant Nummulitidae and Amphisteginidae. Resultant zygotes can develop into tiny, resistant, easily dispersed propagules that recruit in suitable benthic-environmental conditions. The role of algal symbiosis in the biology of larger benthic foraminifera is well-documented. Palaeoceanographically, such taxa proliferated during times of reduced thermal stratification of the oceans. In regions with exceptionally clear, nutrient-depleted waters, ‘twilight-zone’ light penetration was sufficient, at least intermittently, to support some photosynthesis. On outer-shelf or promontory sites at depths of ca 100 to 200 m, the tiny propagules of larger benthic foraminiferal species, incorporating algal symbionts with the lowest light requirements, could have settled and recruited, growing very slowly, nourished by feeding on bacteria and the limited photosynthate produced by their algal symbionts. Under such conditions, thin microspheric individuals of one or two larger benthic foraminiferal taxa could have survived and grown slowly over several years to very large shell diameters, seldom reproducing asexually. Resulting carbonate accumulation rates would have been very slow, such that even rare disturbances by currents, major storms or internal waves could have produced evidence of winnowing and sedimentary structures. The fossil evidence of such habitats should include biostromes or possibly low-relief bioherms of low diversity assemblages characterized by abundant, exceptionally large, flat, microspheric larger benthic foraminifera.     

The decline process and major pathways of Microcystis bloom in Taihu Lake, China

Eutrophication has become a serious concern in many lakes, resulting in cyanobacterial blooms. However, the mechanism and pathways of cyanobacteria decline are less understood. To identify and define the growth and decline of Microcystis blooms in Taihu Lake of China, and to illuminate the destination of surface floating blooms, we investigated the biomass distribution and variations in colony size, morphology, and floating velocity from October 2008 to September 2009. The results showed that the Microcystis bloom declined in response to biomass decrease, colony disaggregation, buoyancy reduction, and increased phytoplankton biodiversity, and these indicative parameters could be applied for recognition of the development phases of the bloom. Three major decline pathways were proposed to describe the bloom decline process, colony disaggregation (Pathway Ⅰ), colony settlement (Pathway Ⅱ), and cell lysis in colonies (Pathway Ⅲ). We proposed a strategy to define the occurrence and decline of Microcystis blooms, to evaluate the survival state under different stress conditions, and to indicate the efficiency of controlling countermeasures against algal blooms.     

Nutrient Input and the Summer Nanoplankton Bloom in the Northern Adriatic Sea

Abstract. A four-year oceanographic data set from the Northern Adriatic Sea identified the factors favoring development of the nanoplankton or microplankton components of the phytoplankton crop. Latitudinally atypical summer nanoplankton blooms, perhaps of recent origin, develop under vertically stratified conditions in the presence of high nutrient concentrations (including silicates). Including the summer blooms, the nanoplankton were responsible for more than half the total phytoplankton production about 90% of the time. No single mechanism governed phytoplankton cell size or size succession, but rather a number of mechanisms which were not mutually exclusive.     

巢湖蓝藻水华时空分布(2000-2015年)

巢湖是我国五大淡水湖之一,近年来水体富营养化严重,蓝藻水华频繁暴发.通过收集2000-2015年晴好天气下2478景MODIS Terra和Aqua影像,利用浮游藻类指数,提取巢湖蓝藻水华时空分布数据.结果显示,巢湖蓝藻水华覆盖面积、暴发频率以及持续时间都在增加,每年最初暴发时间提前.从分布上来看,西巢湖依然严重,中巢湖、东巢湖水华暴发面积较以往大大增加;过去16年内巢湖蓝藻水华暴发频率持续增长,其中2007年最为严重,2008-2010年暴发频率出现缓和,此后又出现增长趋势.这些研究结果有助于掌握蓝藻水华的情况,为巢湖科学治理提供了数据支持.     

Phytoplankton in the Beaufort and Chukchi Seas: Distribution, dynamics, and environmental forcing

Time-series of remotely sensed distributions of phytoplankton, sea ice, surface temperature, albedo, and clouds were examined to evaluate the variability of environmental conditions and physical forcing affecting phytoplankton in the Beaufort and Chukchi Seas. Large-scale distributions of these parameters were studied for the first time using weekly and monthly composites from April 1998 to September 2002. The basic data set used in this study are phytoplankton pigment concentrations derived from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), ice concentrations obtained from the Special Sensor Microwave Imager (SSM/I) and surface temperature, cloud cover, and albedo derived from the Advanced Very High Resolution Radiometer (AVHRR). Seasonal variation of ice cover was observed to be the dominant environmental factor as the ice-edge blooms followed the retreating marginal ice zones northward. Blooms were most prominent in the southwestern Chukchi Sea, and were especially persistent immediately north of the Bering Strait in nutrient-rich Anadyr Water and in some fronts. Chlorophyll concentrations are shown to increase from a nominal value during the onset of melt in April to a maximum value in mid-spring or summer depending on location. Large interannual variability of ice cover and phytoplankton distributions was observed with the year 1998 being uniquely associated with an early season occurrence of a massive bloom. This is postulated to be caused in part by a rapid response of phytoplankton to an early retreat of the sea-ice cover in the Beaufort Sea region. Correlation analyses showed relatively high negative correlation between chlorophyll and ice concentration with the correlation being highest in May, the correlation coefficient being −0.45. 1998 was also the warmest in the 5 years globally and the sea-ice cover was least extensive in the Beaufort/Chukchi Sea region, partly because of the 1997–1998 El Niño. Strong correlations were noted between ice extent and surface temperature, the correlation coefficient being highest at −0.79 in April, during the onset of the bloom period.     

富营养化湖库天空地一体化监控平台系统设计与实践

湖泊和水库是我国的主要饮用水源地,但大都处于富营养化状态,蓝藻水华频发,已成为影响社会稳定、制约区域社会经济可持续发展的重大问题.蓝藻水华的整体应对策略,已经从被动应急转变为主动防御;但要做到主动防御,必须有现代化全方位的蓝藻灾害监测监控手段和体系,及时掌握蓝藻水华及其衍生灾害现状和动向,在未发生或者刚发生时及时觉察.本文针对富营养化湖库富营养化引起的蓝藻水华应急监控问题,按照"整个湖体、重点区域、关键位置"3个监测层次,利用中高分辨率卫星、无人机、岸基/平台视频、自动浮标、人工巡测等技术或手段,围绕"现状掌握、异常报警、原因追溯"的建设目标,提出了天-空-地一体化监控系统建设框架,明确了不同手段的协同方式和业务流程,并正在巢湖进行应用实践.相信本文提出的系统架构不仅在巢湖,在更多的富营养化湖库都具有重要的应用和推广价值.