基于iSIGHT重于水的无人自治潜水器概念设计及优化方法

介绍一种新型重于水的无人自治潜水器的概念设计及主艇体优化方法,阐述了主艇体、机翼、尾翼等设计原理。以飞鱼Ⅱ设计过程为例,详细描述了重于水的无人自治潜水器概念设计流程,并通过iSIGHT优化设计软件对主艇体的设计参数进行优化。优化结果表明,优化后主艇体重量能够减小48%,阻力减小2.9%。     

Frigate tuna Auxis thazard in New Zealand waters (note)

Previous records of the frigate tuna Auxis thazard (Lacépède, 1802) were probably misidentifications of the slender tuna Allothunnus fallai. Frigate tuna were caught on the north‐east coast of New Zealand during 1975–76; the modal fork length of 176 specimens was 32–34 cm, and more detailed morpho‐metry and counts from 4 specimens are presented.     

Identification of larvae of snapper Chrysophrys auratus forster by electrophoretic separation of tissue enzymes (note)

A comparison was made between the electrophoretic patterns of isozymes of esterases and glucosephosphate isomerases of adult snapper Chryosophrys auratus, suspected snapper larvae, jack mackerel Trachurus novaezelandiae larvae, and blue mackerel Scomber australasicus larvae. The suspected snapper larvae revealed similar isozyme patterns to those of the adults, but differed from the other two larval species.     

Minimising errors in estimating fish population and biomass densities using the ‘acoustic volume backscattering strength’ method

The basic acoustical methods for estimating the volume backscattering strength and the absolute biomass density are commonly known. However, the detailed techniques for minimising errors in fitting the calibrated parameters of an echo sounding system in these computations are still not adequately examined and discussed. This paper describes and discusses the following computing techniques involved in the absolute biomass estimation: (i) the fitting of the calibrated time varied gain (TVG) curve, the selection of its operating interval, and the correction of its response; (ii) the compensation for the limitation of the signal bandwidth; (iii) the computation of the equivalent beam width of a transducer using its calibrated beam patterns; and (iv) the accuracy in the conversion from the volume backscattering to the absolute fish density using individual fish target strength measurements.     

Tools for gauging the capacity of salmon spawning substrates

We present a set of river management tools based on a recently developed method for estimating the amount of salmon spawning habitat in coarse‐bedded rivers. The method, which was developed from a mechanistic model of redd building by female salmon, combines empirical relationships between fish length, redd area, and the sizes of particles moved by fish during spawning. Model inputs are the grain‐size indices D₅₀ and D₈₄ and an estimate of female fish length, which is used to predict the size of the redd that they will build and the size of the largest particle that they can move on the bed. Outputs include predictions of the fraction of the bed that the fish can use for redd building and the number of redds that they can build within the useable area. We cast the model into easy‐to‐use look‐up tables, charts, an Excel worksheet, a JavaScript web applet, and a MATLAB user interface. We explain how these tools can be used in a new, mechanistic approach to assessing spawning substrates and optimizing gravel augmentation projects in coarse‐bedded rivers. © 2016 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.     

象山港大黄鱼Pseudosciaena crocea网箱养殖区沉积物-水界面营养盐通量研究

2013年5月、8月和11月调查了象山港大黄鱼网箱养殖区及附近沉积物中总有机氮(TON)、总有机碳(TOC)和总磷(TP)含量,并采用实验室模拟法研究了底泥耗氧率(SOCs)和沉积物-水界面营养盐(NH⁺₄、NO^-₂+NO^-₃和PO^3-₄)通量。结果表明:养殖区(YZ)沉积物中的TON和TP含量显著高于距离养殖区50 m(F1)和100 m(F2)的区域(P<0.05)。底泥释放NH⁺₄到上覆水中,但是从上覆水中吸收NO^-₂+NO^-₃和PO^3-₄。沉积物-水界面营养盐通量表现出明显的季节性变化,在8月,NH⁺₄及PO^3-₄的释放量达到最大值。上覆水中NH⁺₄、NO^-₂+NO^-₃和PO^3-₄的质量浓度随着沉积物-水界面营养盐通量的变化而变化。研究表明,象山港大黄鱼养殖活动对养殖区底泥造成了一定污染,且通过影响沉积物-水界面营养盐通量影响上覆水中营养盐分布,最终给整个养殖系统造成生态负担。     

2015年春、秋季瓯江口鱼卵和仔稚鱼生态分布

为了解瓯江口海域鱼卵和仔稚鱼的生态分布现状,分别于2015年4月和10月在该海域开展生态调查。春、秋两季共采集到鱼卵42粒,仔稚鱼295尾;共鉴定出鱼卵和仔稚鱼16种,分别隶属于8目14科15属,其中鲈形目种类最多。春季鱼卵、仔稚鱼物种数和丰度均远高于秋季。春季鱼卵优势种为斑鰶Konosirus punctatus,秋季为舌鳎属未定种Cynoglossus sp.;春季仔稚鱼优势种为鮻Liza haematocheila、花鲈Lateolabrax japonicus和矛尾鰕虎鱼Chaeturichthys stigmatias,秋季为侧带小公鱼属未定种Stolephorus sp.。瓯江口海域春季鱼卵和仔稚鱼的丰度高值区均位于大门岛周围,该海域应在海洋生态红线划定时予以考虑,秋季则相对分散在较外侧海域。春季仔稚鱼数量分布与盐度和营养盐有极显著相关性。与20世纪90年代初相比,该海域的鱼卵、仔稚鱼物种及数量均在发生变化,数量略呈下降趋势。与浙江近岸其他海域相比,瓯江口海域的鱼卵、仔稚鱼数量偏低。     

韩国的乡村林木与农业生物多样性(英文)

韩国的乡村林木处于偏远村庄附近,单独的树木或一片树林,往往构成风水因素。乡村林木也有野生动物生境的功能,有益于农业生物多样性。本文中,乡村林木分为4种类型(天然林、半天然林、半人工林、人工林)23个主要树种(优势种或次优势种)。赤松(Pinus densiflora)在50个地点是优势种,光叶榉(Zelkova serrata)在45个地点为优势种。乡村林木立地植物共分125科、519属、1081种。尽管乡村林木占地面积极小,占100 000 km2韩国国土面积的0.00278%,但这种生态系统具有重要的生物多样性和生境保护功能。乡村林木不仅是保育生物多样性的一个基础,还能为韩国提供生态系统服务。     

Fish assemblages in subtropical rivers: low-flow hydrology dominates hydro-ecological relationships

Abstract

Effective environmental flow management depends on identification of ecologically-relevant flow attributes to maintain or restore flows in the context of other natural and human influences on stream ecosystems. This study in subtropical eastern Australia identified associations of fish with climatic and flow gradients, catchment topography, reach geology, habitat structure and land use across 20 catchments. Land-use patterns and associated stressors accounted for very little variation in fish assemblage structure. Of the 35 fish species analysed, 24 were strongly associated with gradients in mean daily flows and their variability, baseflow, number of zero-flow days and high-flow pulses, magnitude of the 1-year annual return interval flood and the constancy and predictability of monthly flows. The finding that 22 species (benthic and pelagic) were associated with gradients of antecedent low-flow hydrology indicates that these species (or functional trait groups) should be the focus of further analysis to explore hydro-ecological relationships in systems with regulated flow regimes.

Editor Z.W. Kundzewicz; Guest editor M. Acreman     

科尔沁沙地沙丘固定过程中植物生物量及土壤特性

为了解沙丘固定不同阶段植物群落的生物量特点及土壤理化特性的变化规律,研究比较了科尔沁沙地流动沙丘、半固定沙丘、固定沙丘、沙质草地4种生境的地上、地下生物量,并分4层土壤深度分析了土壤理化特性的演变特征及相关关系.结果表明:(1)植物地上生物量与地下生物量显著正相关,0~10 cm土层地下生物量最大,随着沙丘的固定,地下10～20、20～40、40～60 cm深度土层的生物量显著增加,植物地上生物量依次增大,分别为2.20、98.10、131.41、190.38 g·m^-2,地下地上生物量比依次为10.44、1.67、0.81、1.18;(2)随着沙丘的固定,表层土壤容重由1.62 g·cm³下降到1.33 g·cm³,各土层的粉沙和极细沙的占比依次增加,中沙比例依次减小,土壤碳氮含量、碳氮比、pH值、电导率均逐渐增加;(3)地上、地下生物量均与表层土壤碳氮含量、pH值、电导率显著正相关,土壤碳、氮含量均与pH值、电导率、土壤水分含量显著正相关,与土壤容重显著负相关(p<0.05).综上所述,沙丘恢复过程中植物生物量的增加与表层土壤颗粒细化、营养物质增多、水分增加密切相关,土壤-植被系统构成了有机的综合体.