高生产力区LISST-100和OBS对悬浮颗粒物测量的比较研究

LISST-100通过激光前向散射测量32个粒径的悬浮颗粒物体积分数,OBS通过接受后向散射光强测量浊度,浊度反映水体浑浊程度,可用其变化代表悬浮颗粒物浓度变化。利用LISST-100和OBS于浙江外海高生产力区对悬浮颗粒物进行周日变化的同步观测,结果表明,浮游生物高生物量水体中,LISST-100能够测量出悬浮颗粒物体积分数的变化,由于颗粒物体积与其粒径成立方关系,其对于大颗粒物质变化比较敏感;OBS只能反映部分浓度变化,OBS接收的后向散射量强度取决于颗粒物后向散射截面的影响,因此对于小颗粒悬浮物质更为敏感,对大颗粒物质变化不敏感。无机小颗粒占优水体中LISST-100和OBS对于悬浮颗粒物的测量均较为理想。在悬浮颗粒物组分复杂的水体中,采用LISST-100有其优势,它可以获得不同粒径组分的体积分数,而OBS则适用于更小粒径范围的水体,主要是因为其对大粒径的浮游生物不敏感。     

基于ADCP回声的黑潮-亲潮混合区浮游动物昼夜垂直迁移研究

利用深海潜标所搭载的声学多普勒流速剖面仪(acoustic doppler current profiler,ADCP)得到的后向散射强度Sv,研究了黑潮-亲潮混合区浮游动物的垂向分布、其昼夜垂直迁移(diel vertical migration;DVM)的基本特征、多时间尺度变化及对反气旋式中尺度暖涡的响应.结果表...     

天文大潮对南海北部浮游动物生物量的影响

基于2020年8月至11月在南海北部获取的声学多普勒流速剖面仪观测数据,利用后向散射强度数据估算得到相对体积散射强度并用其表征浮游动物生物量的相对大小,对相对体积散射强度的半月变化与具有半月周期的潮流动能进行相关性分析,进而分析天文大潮对声学估算的浮游动物生物量的影响。结果表明：半月周期的相对体积散射强度与潮流动能之间呈负相关关系,即天文大潮时,潮流动能较强,水体相对体积散射强度较低,浮游动物生物量则较小,天文小潮时则情况相反。初步推测其原因为：天文大潮时,强潮流一方面导致浮游动物生存环境恶化,使其生物量下降,另一方面也改变了浮游动物垂直迁移特性,浮游动物迁移到近海底处使其难以被观测。     

收稿日期:2011-10-28

为研究南黄海浮游动物垂直迁移的季节变化,分析了2006年至2007年4个季节布放潜标中声学测流仪的观测数据.结果是:声学测流仪测量的后向散射强度呈现显著的日变化特征,这是由浮游动物垂直迁移造成的;在4个季节中都出现这一凌晨向下、黄昏向上的垂直迁移,但是垂直迁移发生的时间有季节变化.利用南黄海辐射通量的直接观测数据,讨论了垂直迁移发生时间与光照的关系,结果表明垂直迁移的季节变化主要受光照的影响.这对于研究浮游动物垂直迁移机制有一定意义.     

基于声学方法的南黄海浮游动物垂直迁移季节变化研究

为研究南黄海浮游动物垂直迁移的季节变化, 分析了2006 年至2007 年4 个季节布放潜标中声学测流仪的观测数据。结果是: 声学测流仪测量的后向散射强度呈现显著的日变化特征, 这是由浮游动物垂直迁移造成的; 在4 个季节中都出现这一凌晨向下、黄昏向上的垂直迁移, 但是垂直迁移发生的时间有季节变化。利用南黄海辐射通量的直接观测数据, 讨论了垂直迁移发生时间与光照的关系,结果表明垂直迁移的季节变化主要受光照的影响。这对于研究浮游动物垂直迁移机制有一定意义。     

2013 年夏秋季黄、渤海悬浮颗粒物粒径分布特征

悬浮颗粒物及粒径是水质重要参数,研究其分布特征有助于加深对海洋生态环境的了解。利用2013年6月和2013年11月LISST-100观测数据,研究了黄、渤海区域悬浮物粒径和浓度的分布情况,浓度分布整体上近岸高远岸低,粒径分布呈现近岸细远岸粗的特征,季节分布特征明显。通过典型断面分析发现,悬浮物粒径和浓度随着水深变化明显,连续站数据分析结果表明,大风对底层颗粒物的再悬浮作用显著,潮流对悬浮物的时空分布有着重要影响;水体衰减系数随着体积浓度变化明显。此外,还研究了悬浮颗粒物粒径Junge分布在黄、渤海区域的适用性。     

利用ADCP和LISST-100仪观测悬浮物浓度的研究

利用黄河口海床基声学多普勒流速剖面仪(ADCP)的周日观测资料对悬浮物浓度进行了反演,反演过程中综合考虑了球面扩散、声学近场的非球面扩散、海水和悬浮颗粒的吸收衰减以及其他因素对回声信号的影响,结果表明在粒径保持相对稳定的情况下,利用ADCP仪回声强度反演悬浮物浓度具有较高的精度.结合现场激光粒度仪(LISST-100)测得的粒径分布信息在反演过程中考虑了粒径修正,重点讨论了观测区域粒径变化对结果的影响,结果表明粒径的剧烈变化会降低体积后向散射强度与悬浮物浓度之间的相关性.大颗粒物质的存在使计算得到的悬浮物浓度偏高,粒径修正虽然在一定程度上消除了这种影响,但线性拟合的相关性并未提高.     

《海洋与湖沼》2011年第4期论文导读

黄、东海悬浮细颗粒物浓度和粒径分布变化研究 分析了2006年6月和2007年1月用LISST-100对黄、东海悬浮物的观测数据,研究了黄、东海的悬浮物粒径和体积浓度分布情况,并从动力学角度对其进行解释。     

2013年夏秋季黄、渤海悬浮颗粒物及粒径分布特征研究

悬浮颗粒物及粒径是水质重要参数,其分布特征研究有助于加深对海洋生态环境的了解。利用2013年6月和2013年11月LISST-100观测数据,研究了黄、渤海区域悬浮物粒径和浓度的分布情况,浓度分布整体上呈现近岸高远岸低的状况,粒径分布呈现近岸细远岸粗的特征,季节分布特征明显;通过典型断面分析,悬浮物粒径和浓度随着水深变化明显,连续站数据分析结果表明大风对底层颗粒物的再悬浮作用显著,潮流对悬浮物的时空分布有着重要影响;水体衰减系数随着体积浓度变化明显;此外,还研究了悬浮颗粒物粒径Junge分布在黄、渤海区域的适用性。     

南海深海声学散射层垂直分布和昼夜变化初步研究

2013-09利用船载Simrad EK60科学鱼探仪(38kHz)对南海深海声学散射层进行了连续监测,并结合变水层拖网采样分析了其垂直分布和昼夜变化。结果表明,南海深海存在2个明显的声学散射层,特征深度分别为0~100m和350~700m,并且2个散射层间存在较为明显的昼夜垂直移动现象。其随时间变化情况为:16∶00-19∶00,350~700m散射层中的部分生物逐渐向上移动到0~100m散射层;04∶00-07∶00,这部分上升的生物又逐渐移回至350~700m散射层。变水层拖网采样结果发现,白天0~100m散射层内渔获物数量较少,夜间0~100m散射层内渔获物较多,验证了声学映像所检测到的2个散射层间确实存在昼夜移动的现象。     

Diurnal Cycle of Sound Scatterers and Measurements of Turbidity Using ADCP in Beppu Bay

From September 20 to 22 in 1994, the vertical profiles of echo intensity and three-component velocities were measured with a bottom-mounted 300 kHz broadband acoustic Doppler current profiler (ADCP) in Beppu Bay in the Seto Inland Sea of Japan. A very strong thermocline was observed from 50 to 60 m. A pronounced diurnal cycle of backscatter strength (BS) was found above the thermocline. However, it was not found under the thermocline where there was a lack of dissolved oxygen. We suggest that the diurnal cycle of BS is caused by the vertical migration of zooplankton. The downward and upward migration occurred in early morning and late afternoon, respectively. The migration speeds estimated from BS isopleth displacements were about 1 cm s^–1. Further, the contribution of turbidity (Tur) to BS was examined by separating out the effect of migrating zooplankton. There was a significant correlation between BS and turbidity under the thermocline. The maximum contributions of the Tur, migrating zooplankton and non-migrating plankton on BS were estimated at 3, 12, 25 dB, respectively. These data suggest that when using an ADCP to estimate Tur, it is very important to consider carefully the backscatter signal from zooplankton.     

Vertical Migration of Sound Scatterers in the Southern Yellow Sea in Summer

Acoustic volume backscattering strength data were collected and Conductivity Temperature Depth (CTD) measur e m e n t s were conducted in the southern Yellow Sea in summer 2005 and 2006. The high temporal and vertical resolution acoustic data measured with a 307 kHz Acoustic Doppler Current Profiler (ADCP) and a 250 kHz acoustic Doppler profile (ADP) had dominant diel variation, which resulted from vertical migration of sound scatterers. Some scatterers congregating in the bottom layer in the daytime migrated upward at dusk, and migrated downward into the bottom layer at dawn. The migration speeds were estimated. More than 33 days data show that the diel migration varies with time. The feature of migration measured with ADCP and ADP is consistent to some extent with what is described in the study on vertical migration of zooplankton in the southern Yellow Sea with conventional net samples.     

后向散射强度与温跃层关系研究

2003年8月12-13日，用300kHz的坐底式声学多普勒海流剖面仪(ADCP)在台湾海峡北部海区进行了观测。根据回声强度计算得到的后向散射强度具有明显的日变化，这是浮游动物的垂直迁移造成的。此外，后向散射强度还与叶绿素、浊度和温度梯度有关，其中叶绿素、浊度和温度梯度对后向散射强度的贡献分别是1．41，7．73和3．54dB。温度梯度最大值的深度与后向散射强度第一个峰值的深度一致，故根据后向散射强度能推断出温跃层的位置。     

Diel variations of marine snow concentration in surface waters and implications for particle flux in the sea

Successive measurements of the size distribution and abundance of marine snow in the upper 100 m of the Santa Barbara Channel, California, with an in situ still camera system following 11 tagged water masses revealed a consistent pattern of nighttime decreases in the abundance of large particles. A net nocturnal reduction in particulate flux from the upper 100 m as calculated from camera profiles occurred in 75% of the day–night comparisons, and nighttime aggregate carbon losses resulted in a 38% average reduction in camera-derived aggregate flux. Intensive investigation of three stations for 24–48 h each indicated that nighttime decreases in aggregate concentrations and derived aggregate flux could be registered throughout the observed water column. Nocturnal decreases in marine snow concentration are unlikely to result from diel variations in the production of marine snow either as feeding webs of zooplankton or through variations in aggregation rates of smaller particles. Moreover, measured diel variations in the intensity of surface mixing and convective overturn during one of the 24 h deployments were not intense enough to produce aggregate fragmentation and reduced aggregate flux. Nighttime increases in large crustacean zooplankton (i.e., euphausiids and the large copepod Calanus pacificus) could explain some or all of the reduction in aggregate abundance at most stations. Fragmentation and consumption of marine snow by migrating macrozooplankton could produce our observed synchronous diel cycles in marine snow concentration. This is the first empirical evidence of a diel pattern in the concentration and calculated particulate flux of large sinking particles in near-surface waters. The data presented here are consistent with the only other existing diel study, which also reported decreases in marine snow abundance at night at 270 m depths in the oceanic north Atlantic. Diel variations in the sizes and concentrations of marine snow may impact water column processes dependent upon particle availability and size, such as grazing and remineralization, and may generate a diel cycle of food availability to the benthos.     

Diel variation in the vertical distribution of particulate matter (>0.15 mm) in the NW Mediterranean Sea investigated with the Underwater Video Profiler

Day/night variations in the size distribution of the particulate matter >0.15 mm (PM) were studied in May 1995 during the DYNAPROC time-series cruise in the northwestern Mediterranean Sea. Data on vertical distributions of PM (>0.15 mm) and zooplankton were collected with the Underwater Video Profiler (UVP). The comparisons of the UVP data with plankton net data and POC data from water bottles indicated that more than 97% of the particles detected by the UVP were non-living particles (0.15 mm) and that the PM contributed 4–34% of the total dry weight measured on GF/F filters. Comparison of seven pairs of day and night vertical profiles performed during the cruise showed that in the upper 800 m, the mean size and the volume of particles was higher at night than during the day. During the night, the integrated volume of the PM increased on average by 32±20%. This increase corresponded to a shift of smaller size classes (<0.5 mm) towards the larger ones (>0.5 mm). During the day, the pattern was reversed, and the quantity of PM >0.5 mm decreased. During the study period, the standing stock of PM (60–800 m) decreased from 7.5 to less than 2 g m⁻² but the diel variations persisted, except for two short periods in the superficial layer following a wind event. The cyclic feeding activity induced by the diel vertical migration of zooplankton could be the best candidate to explain the observed diel fluctuations in the size classes of PM in the water column. However, our results also suggest that in the upper layer additional driving forces such as the increase of the level of turbulence after a wind event or the modification of the zoo- and phytoplankton community can influence the PM temporal evolution.     

Dirunal variability and its quantification of subsurface sound scatterers in the western equatorial Pacific

A downwardf-looking acoustic Doppler current profiler (ADCP), suspended by a series of surface and subsurface floats and connecte to an anchroed ship, proided a quite stable platform to measure the, vertical profiles of backscatter strenght *BS) and three components of the velocith from 12 to 22 November 1992 at 1°30S and 156°15E, in the Intensive Flux Array (IFA) of TOGA/COARE. While the variability of the horizontal velocity was controlled by the semi-diurnal tide, BS and vertifal velocity were dominated by diurnal variability probably caused by the diel migration of zooplakton. The downward migration occurred early in the moring (0500–0700 in local time) and the upward one late in the afternoon (1700–1900). The average values of about 4 cm s^–1 for the sinking and rising speed were estimated from Doppler shift and BS isopleth displacement. The subsurface chlorophyll maximum (SCM) coincident with the top of the thermocline at 80–100 m was also detectable in the BS data during daytime when almost no migrating zooplankton remained in the upper 300 m. Backscatter signals from the SCM and thermocline were separated by corrlating the BS data with the chlorophylla and temperature data. The maximum contribution of the migrating zooplanktion, passively drifting phytoplankton and temperature gradient on BS was estimated to be 14.8, 7.0, 5.1 dB, respectively.     

The vertical distribution of zooplankton in the western Irish Sea

Zooplankton diel vertical migration is evident on the mixed isothermal side of the western Irish Sea frontal system but is often influenced by large tides and persistent geostrophic currents. On the stratified side of the front, temperature acts as a controlling factor with most of the zooplankton occurring above the thermocline and carrying out pronounced vertical migration when chlorophyll a levels are low and diffuse. At higher chlorophyll levels, when discrete chlorophyll a maxima form, zooplankton vertical movement may be greatly modified with a large number of species and stages concentrating within these maxima at all times of the diel light cycle.     

北太平洋亚热带环流区与西太平洋暖池区浮游动物群落垂直分布的差异及其对碳通量的意义

The mesozooplankton in both epipelagic and mesopelagic zones is essentially important for the study of ecosystem and biological carbon pump. Previous studies showed that the diel vertical migration(DVM) pattern of mesozooplankton varied among ecosystems. However, that pattern was largely unknown in the Western Pacific Warm Pool(WPWP). The vertical distribution, DVM and community structure of mesozooplankton from the surface to 1 000 m were compared at Stas JL7K(WPWP) and MA(North Pacific Subtropical Gyre, NPSG). Two sites showed similarly low biomass in both epipelagic and mesopelagic zones, which were in accordance with oligotrophic conditions of these two ecosystems. Stronger DVM(night/day ratio) was found at JL7K(1.31) than that at MA(1.09) on surface 0–100 m, and an obvious night increase of mesopelagic biomass was observed at JL7K, which was probably due to migrators from bathypelagic zone. Active carbon flux by DVM of zooplankton was estimated to be 0.23 mmol/(m2·d) at JL7K and 0.16 mmol/(m~2·d) at MA. The community structure analysis showed that calanoid copepods, cnidarians and appendicularians were the main contributors to DVM of mesozooplankton at both sites. We also compared the present result with previous studies of the two ecosystems,and suggested that the DVM of mesozooplankton was more homogeneous within the WPWP and more variable within the NPSG, though both ecosystems showed typically extremely oligotrophic conditions. The different diel vertical migration strength of mesozooplankton between NPSG and WPWP implied different efficiency of carbon pump in these two ecosystems.     

南沙群岛海区毛颚动物的昼夜垂直移动

对1997年11月和1999年4月、7月在南沙群岛海区3个昼夜连续测站采集的毛颚动物样品进行了研究。结果表明，这些水域的毛颚动物的昼夜垂直移动可以划分为3个类型：种类作显著移动，不作显著移动和仅在夜晚移动。作为昼夜垂直移动显著的种类，又可以把它们划分为：（1）种类在整个水柱移动；（2）种类在上层（0－60m）移动；（3）种类在中层（60－100m）移动。作为昼夜垂直移动不明显的种类，又可以把它们分为：（1）种类分布在于上层（0－60m）。（2）种类分布于底层（100－200m）。种类在白天下降或附着在海底物体上，仅在夜晚移动。光照，水温，食物和种类特征是影响本水域毛颚动物昼夜垂直移动的重要因素。     

Changes in the composition of planktonic ostracod populations across a range of latitudes in the North-east Atlantic

A large database representing the bathymetric distribution of 117 species of halocyprid ostracods has been compiled from seven stations forming a transect from the equator to 60°N along 20°W, plus an additional station at 32°N, 65°W. This data base is analysed to examine the latitudinal and bathymetric changes in species composition and diversity of assemblages of this important, yet neglected, holoplanktonic group. At each station stratified sampling of the complete water column from the surface down mostly to 2000 m was carried out both day and night. Each sample resulted from the filtration of at least 2500 m³ of water and was analysed using a consistent protocol. The differences between the day and night profiles are attributable to diel vertical migrations, to local-scale heterogeneity, and possibly to a degree of net avoidance. There is a gradient of increasing species richness and diversity from high to low latitudes. By day, halocyprids are either infrequent or absent from the upper 50 m of the water column, but at night after diel vertical migration they become quite abundant in the epipelagic zone, particularly at low latitudes. Bathymetric profiles show ostracod abundances increase rapidly below the thermocline, reaching maxima at 200-400 m and then declining by at least an order of magnitude at 2000 m. Diversity (both species richness, H′ and evenness, J) also increases below the thermocline and thereafter is either maintained or declines only slightly to 2000 m. There are no relationships among diversity, abundance and productivity, but analysis of the whole database shows that the changes in community structure are consistent with Longhurst’s [Longhurst, A.R., 1998. Ecological Geography of the Sea. Academic Press, San Diego, pp. xiv, 398.] biogeochemical provinces.