Low biomass of macrobenthic fauna at a tropical mudflat: An effect of latitude?   总被引：1，自引：1，他引：0  

Agus Purwoko  Wim J. Wolff   《Estuarine, Coastal and Shelf Science》2008,76(4):869-875

The macrobenthic animal biomass of the intertidal area of the Sembilang peninsula of South Sumatra, Indonesia, has been studied in 2004. Each month (March–August) 21 core samples were taken at each of six sampling stations. Macrobenthic fauna were identified at the lowest taxonomical level possible and counted. Biomass was measured as ash-free dry mass (afdm). The average biomass over all stations and months was 3.62 g afdm m⁻², the highest biomass (47.45 g afdm m⁻²) found at a station in one month was due to abundant occurrence of the bivalve Anadara granosa. Low biomass of macrobenthic fauna at Sembilang peninsula cannot easily be explained but is in line with low biomasses found elsewhere in the tropics. For that reason we analyzed a data set of 268 soft-bottom intertidal biomasses collected world-wide to look for a relationship with latitude. It was shown that average biomass of intertidal macrobenthic fauna in the tropics was significantly (p < 0.05) lower than that at non-tropical sites. A significant second-order relationship between biomass of macrobenthic fauna and latitude was established.  相似文献   

Growth and production of Pisidium amnicum in the freshwater tidal area of the River Minho estuary     

Ronaldo Sousa  Antnio J.A. Nogueira  Carlos Antunes  Lúcia Guilhermino 《Estuarine, Coastal and Shelf Science》2008,79(3):467-474

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新月形沙丘形态参数与移动速度的关系   总被引：1，自引：2，他引：1  

李爱敏  韩致文 《中国沙漠》2020,40(1):29-40

在塔克拉玛干沙漠腹地的新月形沙丘演变监测区，运用华测X90 GNSS接收机获取毫米级高时空分辨率三维坐标数据，利用ArcGIS 10.0和CASS 9.0提取新月形沙丘的15个形态参数和移动速度，利用SPSS 21.0对沙丘移动速度与15个形态参数间的数值相关性进行曲线估计分析。结果表明：以移动方向230°为界，沙丘移动速度与移动方向间存在明显的分段线性函数关系；当移动方向为210°~230°时，沙丘移动速度 > 1.5 m/月，移动较快且与主风向NE的下风向方向一致；当移动方向为230°~320°时，沙丘移动速度 ≤ 1.5 m/月，速度较低。沙丘移动速度与沙丘高度之间存在负线性函数关系，沙丘高度每增大1个单位，速度会相应减小2.263个单位，沙丘高度对移动速度的影响较大。移动速度和沙丘走向间存在正的增长函数关系，与沙丘左、右翼走向均呈正线性相关性。研究结果为明确新月形沙丘移动速度的具体影响因素和完善其计算公式提供支持，并对小尺度风沙地貌演变的精确分析有所裨益。  相似文献   

南海西北部陆架区住筒虫属的种类描述及其丰度分布     

李开枝  尹健强  黄良民  陈清潮  林强 《海洋学报(英文版)》2010,29(5):76-86

住筒虫是浮游被囊动物的一类,隶属于脊索动物门、尾索动物亚门、有尾纲、住筒虫科、住筒虫属,在海洋生物食物链中占重要位置。根据南海西北部陆架区2006年夏季、冬季和2007年春季3个航次各82个站的浮游动物拖网(网目孔径169 μm)调查资料,共鉴定到8种住筒虫:Fritillaria aberrens,F.abjornseni, F.formica, F.haplostoma, F.megachile, F.pacifica, F.pellucida, F.tenella,其中F.aberrens、F.abjornseni和F.pacifica为南海新纪录。对它们进行了形态描述,并结合环境因子探讨其丰度分布特征。夏季出现住筒虫8种,平均丰度为(2.62±4.68 )个/m³;冬季3种,春季4种,平均丰度分别为(0.23±0.52)和(1.72±5.43)个/m³。F.formica是丰度最高的一种,在夏季、冬季和春季分别占总丰度的43.88%,80.18%和84.29%;其次是F.pellucida和F.haplostoma;以上三种分布广,丰度较高。与环境因子分析表明,夏季琼东沿岸上升流和雷州半岛东部海域冷涡现象对种类向沿岸推移及其丰度增加有一定的助长作用。  相似文献   

Extinction cross-section of Norwegian spring-spawning herring   总被引：1，自引：1，他引：0  

Foote  K. G. 《ICES Journal of Marine Science》1999,56(5):606-612

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A modified multiple tension upward infiltration method to estimate the soil hydraulic properties          下载免费PDF全文

D. Moret‐Fernández  B. Latorre  C. Peña‐Sancho  T.A. Ghezzehei 《水文研究》2016,30(17):2991-3003

Determination of saturated hydraulic conductivity, K_s, and the shape parameters α and n of the water retention curve, θ(h), is of paramount importance to characterize the water flow in the vadose zone. This work presents a modified upward infiltration method to estimate K_s, α and n from numerical inverse analysis of the measured cumulative upward infiltration (CUI) at multiple constant tension lower boundary conditions. Using the HYDRUS‐2D software, a theoretical analysis on a synthetic loam soil under different soil tensions (0, 0–10, 0–50 and 0–100 cm), with and without an overpressure step of 10 cm high from the top boundary condition at the end of the upward infiltration process, was performed to check the uniqueness and the accuracy of the solutions. Using a tension sorptivimeter device, the method was validated in a laboratory experiment on five different soils: a coarse and a fine sand, and a 1‐mm sieved loam, clay loam and silt‐gypseous soils. The estimated α and n parameters were compared to the corresponding values measured with the TDR‐pressure cell method. The theoretical analysis demonstrates that K_s and θ(h) can be simultaneously estimated from measured upward cumulative infiltration when high (>50 cm) soil tensions are initially applied at the lower boundary. Alternatively, satisfactory results can be also obtained when medium tensions (<50 cm) and the K_s calculated from the overpressure step at the end of the experiment are considered. A consistent relationship was found between the α (R² = 0.86, p < 0.02) and n (R² = 0.97, p < 0.001) values measured with the TDR‐pressure cell and the corresponding values estimated with the tension sorptivimeter. The error between the α (in logarithm scale) and n values estimated with the inverse analysis and the corresponding values measured with pressure chamber were 3.1 and 6.1%, respectively. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

福清湾及附近海域浮游动物的数量和分布   总被引：3，自引：0，他引：3  

林君卓 《台湾海峡》2008,27(1):58-63

本文分析了2005年10月和2006年5月在福清湾及其附近海域采集的浮游动物样品,结果表明,福清湾已鉴定的浮游动物有64种,10类浮游幼体.分为4个生态类群,包括河口低盐类群,近岸暖温类群,近岸暖水类群和广布外海类群.浮游动物物种多样性指数春季高于秋季.春季浮游动物总个体数均值为(161ind/m3)高于秋季的(83ind/m3),春季生物量均值为(67.7mg/m3)低于秋季的(87.7mg/m3);浮游动物总个体数的平面分布,春季湾内西部水域最高,海坛海峡最少;秋季福清湾东部水域最高,湾内西部水域最少.浮游动物生物量和总个体数的平面分布趋势基本一致.另外还对浮游动物的分布与环境因子的关系进行了分析.  相似文献   

Evidence of the top-down role of predators in structuring sublittoral rocky-reef communities in a Marine Protected Area and nearby areas of the Canary Islands     

Clemente  Sabrina; Hernandez  Jose Carlos; Brito  Alberto 《ICES Journal of Marine Science》2009,66(1):64-71

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Development of a new index for integrating landscape patterns with ecological processes at watershed scale   总被引：12，自引：3，他引：9  

Liding Chen  Huiying Tian  Bojie Fu  Xinfeng Zhao 《中国地理科学(英文版)》2009,19(1):37-45

Understanding the relationship between landscape patterns and ecological processes has been a central yet challenging research theme in landscape ecology. Over the past decades, many landscape metrics have been proposed but few directly incorporated ecological processes. In this paper, we developed a landscape index, namely, location-weighted landscape index (LWLI) to highlight the role of landscape type in ecological processes, such as nutrient losses and soil erosion. Within the framework of the Lorenz curve theory, we develop this index by integrating landscape pattern and point-based measurements at a watershed scale. The index can be used to characterize the contribution of landscape pattern to ecological processes (e.g. nutrient losses) with respect to a specific monitoring point in a watershed. Through a case study on nutrient losses in an agricultural area in northeastern China, we found that nutrient losses tended to be higher for a watershed with a higher LWLI value, and vice versa. It implied that LWLI can be used to evaluate the potential risk of nutrient losses or soil erosion by comparing their values across watersheds. In addition, this index can be extended to characterize ecological processes, such as the effect of landscape pattern on wildlife inhabitation and urban heat island effect. Finally, we discuss several problems that should be paid attention to when applying this index to a heterogeneous landscape site.  相似文献   

CASSIO4800计算器测量放样程序的应用及优化     

栗超 《北京测绘》2009,(1)

详细介绍了在公路开挖放样中,CASSIO4800计算器的测量放样程序的应用,并结合实际工作经验对圆曲线放样程序进行了优化。  相似文献