长江口几种优势桡足类对微型浮游动物的摄食研究

利用现场海水培养实验,结合浮游动物网样数据,研究长江口邻近海域几种优势桡足类(中华哲水蚤、背针胸刺水蚤、太平洋纺锤水蚤和精致真刺水蚤)对微型浮游动物的摄食影响。结果表明,精致真刺水蚤虽然属于肉食性种类,但几乎不摄食微型浮游动物;其余三种杂食性桡足类中华哲水蚤、背针胸刺水蚤和太平洋纺锤水蚤对微型浮游动物(纤毛虫+异养甲藻)的摄食率分别为0.66、0.09和0.59μg C/(ind·d),分别占其日总摄食量的29%、24%和37%。其中,异养甲藻在初始生物量和对桡足类饵料贡献上分别占整个微型浮游动物的30%和28%,是微型浮游动物中一个重要的组成类群。中华哲水蚤对微型浮游动物的摄食率与初始食物浓度有显著的正相关关系,并且对体长20μm纤毛虫的清滤率要明显高于对体长20μm的纤毛虫(P0.01)的清滤率,表明其偏好摄食较大个体的食物。通过Chesson选择性指数显示,尽管微型浮游动物在生物量上远小于浮游植物,但桡足类能优先选择摄食微型浮游动物;进一步结合网采浮游动物数据,获得各站三种优势桡足类丰度平均占桡足类总丰度的77%,但它们对微型浮游动物现存生物量的摄食压力仅为0.8%,表明桡足类对微型浮游动物群落的下行控制作用并不明显,仍有大部分微型浮游动物生物量未通过摄食途径进入到桡足类群落中。     

海水营养盐现场自动分析技术

介绍了目前国内外对海水营养盐浓度测量仪器的研究现状，论述了吸光光度法测量营养盐浓度的基本原理，以及硅酸盐和氨氮现场测量分析工艺流程。     

Temporal Variations in the Dissolved Nutrient Stocks in the Surface Water of the Western North Atlantic Ocean

Changes in patterns of undetectability and molar ratios of dissolved nutrients in the euphotic zone of the oligotrophic western North Atlantic Ocean were investigated utilizing the Bermuda Atlantic Time-series Study (BATS) data set of the US Joint Global Ocean Flux Study (JGOFS). Our aim was to examine the temporal dynamics of nutrient stocks over a decade (1989∼1998) and to gain insight into the interactions between the different biotic and abiotic factors underlying BATS. Patterns of nutrient undetectability clearly revealed the depleted nature of the nutrients in surface water at the BATS location, particularly phosphorous. The N:P ratio was consistently far above the nominal Redfield ratio (mean, 38.5) but was significantly lower during the 1993∼1994 period (22.1). Over the same period the proportion of samples depleted in N only increased while the proportion of samples depleted in P only decreased. This indicates an overall reduction of N relative to P in the surface water at BATS during the 1993∼1994 period, the reasons for this anomaly, though, are not clear. The correlation analysis between the biotic and abiotic variables at BATS has indicated some interesting relationships that can help understand some of the parameters affecting nutrient stocks in the euphotic zone and their consequent impacts on marine biota. Although nutrient stocks in the oligotrophic environment are limited, they might be subject to interannual variation that may become anomalous in some cases. These variations might underlay significant feedback mechanisms by affecting marine productivity, the prime factor controlling the sequestration of atmospheric CO₂ by the oceans. This revised version was published online in July 2006 with corrections to the Cover Date.     

东山八尺门海堤西侧网箱养殖海域营养状态初探

本文根据1989年10月和1990年4月在福建东山县八尺门海堤西侧网箱养殖海域现场调查获得的海水化学、浮游植物、叶绿素a等资料,以有机污染指数和营养状态指数为指标,研究了该海域的营养状态,结果表明:1989年4月中旬,该海域有机污染严重,富营养化程度高。底层水呈低氧或无氧状态。推测10月9日夜间网养鱼大量死亡的主要原因是水体缺氧状态加剧所致。     

胶州湾营养盐限制浮游植物生长的初步模拟现场实验研究

于1998年8月至1999年2月，有胶州湾采用现场添加营养盐的实验方法初步研究了硝酸盐，磷酸盐，铁，硅酸盐对浮游植物生长的限制作用。分级叶绿素a的结果显示，在1998年夏季，氮（N）或单独，或与磷（P）同时限制浮游植物的生长；在1998的秋季则可能是N与P共同对浮游植物群落产生调控作用，而在1999年冬季，硅（Si)则是首要的限制浮游植物生长的营养元素。     

Simulation of upper-ocean biogeochemistry with a flexible-composition phytoplankton model: C, N and Si cycling in the western Sargasso Sea

We report the first application of a biogeochemical model in which the major elemental composition of the phytoplankton is flexible, and responds to changing light and nutrient conditions. The model includes two phytoplankton groups: diatoms and non-siliceous picoplankton. Both fix C in accordance with photosynthesis-irradiance relationships used in other models and take up NO₃⁻ and NH₄⁺ (and Si(OH)₄ for diatoms) following Michaelis-Menten kinetics. The model allows for light dependence of photosynthesis and NO₃⁻ uptake, and for the observed near-total light independence of NH₄⁺ uptake and Si(OH)₄ uptake. It tracks the resulting C/N ratios of both phytoplankton groups and Si/N ratio of diatoms, and permits uptake of C, N and Si to proceed independently of one another when those ratios are close to those of nutrient-replete phytoplankton. When the C/N or Si/N ratio of either phytoplankton group indicates that its growth is limited by N, Si or light, uptake of non-limiting elements is controlled by the content of the limiting element in accordance with the cell-quota formulation of Droop (J. Mar. Biol. Ass. U.K 54 (1974) 825).We applied this model to the Bermuda Atlantic Time-series Study (BATS) site in the western Sargasso Sea. The model was tuned to produce vertical profiles and time courses of [NO₃⁻], [NH₄⁺] and [Si(OH)₄] that are consistent with the data, by adjusting the kinetic parameters for N and Si uptake and the rate of nitrification. The model then reproduces the observed time courses of chlorophyll-a, particulate organic carbon and nitrogen, biogenic silica, primary productivity, biogenic silica production and POC export with no further tuning. Simulated C/N and Si/N ratios of the phytoplankton indicate that N is the main growth-limiting nutrient throughout the thermally stratified period and that [Si(OH)₄], although always limiting to the rate of Si uptake by diatoms, seldom limits their growth rate. The model requires significant nitrification in the upper 200 m to yield realistic time courses and vertical profiles of [NH₄⁺] and [NO₃⁻], suggesting that NO₃⁻ is not supplied to the upper water column entirely by physical processes. A nitrification-corrected f-ratio (f_NC), calculated for the upper 200 m as: (NO₃⁻ uptake—nitrification)/(NO₃⁻ uptake+NH₄⁺ uptake) has annual values ranging from only 0.05–0.09, implying that 90–95% of the N taken up annually by phytoplankton is supplied by biological regeneration (including nitrification) in the upper 200 m. Reported discrepancies between estimates of organic C export based on seasonal chemical changes and POC export measured at the BATS site can be almost completely resolved if there is significant regeneration of NO₃⁻ via organic-matter decomposition in the upper 200 m.     

三江平原湿地植物群落P、K的积累、动态及其生物循环

在三江平原湿地植物生长季节里,选择该区分布最广、面积最大且最具有代表性的毛果苔草(Carexlasioncarpa)-狭叶甜茅(Glyceria spiculosa)群落和小叶章(Deyeuxia angustifo-lia)群落为研究对象,逐月测定两类湿地群落生物量,并对植物样品分别用钼锑抗比色法和原子吸收法测定其P、K含量。在此基础上,探讨了两类湿地群落的P、K积累量及其生物循环特征。结果表明,三江平原不同的植物群落以及同一群落的不同器官,其P、K元素积累量不同,而且都有明显的季节变化。根是群落中P、K元素的最大贮存器官,其P、K积累量占总量的80%左右。湿地群落中K的吸收量、归还量、存留量、现存量和表土贮量都大于P的对应值,同时K的利用系数和循环系数均大于P,毛果苔草-狭叶甜茅群落K的吸收系数大于P,而小叶章群落K的吸收系数小于P。     

生态因子对萱藻(Scytosiphon lomentaria)孢子体生长发育的影响

采用实验生态学方法,研究了温度、光照、营养盐(N、P)对萱藻孢子体生长发育的影响.结果表明,在5-23℃范围内,温度越高,越有利于萱藻孢子体的生长.9-17℃是比较利于孢子囊产生的温度范围,其中13 ℃,L:D=10:14,20μmol/(m<'2>·s)条件下最有利于孢子囊的形成与孢子的放散.光强6-30μmol/(...     

九龙江河口区营养盐分布特征及其影响因素分析

根据2009、2010年"丰水期"和"枯水期"四航次九龙江河口混合区的调查资料,且结合历史资料对营养盐含量及分布特征、周日变化特征进行了统计和相关分析,研究了九龙江流域营养盐输入海洋的变化过程,探讨九龙江河口营养盐伴随潮汐变化,以及河口混合过程中的生物地球化学行为。调查期间溶解无机氮、硅和磷含量的平面分布呈现出由径流冲淡水高值向河口外海端递减的变化趋势;在涨潮时,河口区感潮段高溶解无机氮、硅、磷营养盐的陆源冲淡水与低溶解无机氮、硅、磷营养盐外海水相遇,随着外海水的侵入,外海水的作用逐渐加强,在稀释混合过程中呈现出无机营养盐逐步降低的变化趋势,退潮时则相反;营养盐在这复杂的河口过程中往往表现出在水动力的作用下稀释混合是主要过程,无机氮和活性硅酸盐在河口稀释混合过程中呈现保守性特征,活性磷酸盐在河口转移(补充)过程的行为复杂化,呈现缓冲作用为主。     

南黄海营养盐的平面分布及横向输运

黄海对我国是颇为重要的陆架海区,也是世界上最典型的半封闭性陆架浅海之一。它和所有陆架海区一样,是人类活动、经济开发最为集中的地带,也是陆地、海洋、大气各种过程相互作用较为激烈的地带。