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We examined 536 permit (Trachinotus falcatus, 65–916 mm FL) collected from the waters of Florida Keys and from the Tampa Bay area on Florida’s Gulf coast to describe their growth and reproduction.Among permit that we sexed, females ranged from 266 to 916 mm in length (mean=617) and males ranged from 274 to 855 mm (mean=601). Ages of 297 permit ranging from 102 to 900 mm FL were estimated from thin-sectioned otoliths (sagittae). The large proportion of otoliths with an annulus on the margin and an otolith from an OTC-injected fish suggested that a single annulus was formed each year during late spring or early summer.Permit reach a maximum age of at least 23 years.Permit grew rapidly until an age of about five years, and then growth slowed considerably. Male and female von Bertalanffy growth models were not significantly different, and the sexes-combined growth model was FL=753.1(1–e –0.348(Age+0.585)). Gonad development was seasonal, and spawning occurred during late spring and summer over artificial and natural reefs at depths of 10–30 m. Ovaries that contained oocytes in the final stages of oocyte maturation or postovulatory follicles were found during May–July. We estimated that 50% of the females in the population had reached sexual maturity by 547 mm and an age of 3.1 years and that 50% of the males in the population had reached sexual maturity by 486 mm and an age of 2.3 years. Because Florida regulations restrict the maximum size of permit caught in recreational and commercial fisheries to 20-inch (508-mm), most fish harvested are sexually immature. With the current size selectivity of the fishery, the spawning stock biomass of permit could decrease quickly in response to moderate levels of fishing mortality; thus, the regulations in place in Florida to restrict harvest levels appear to be justified.

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龙门河地区地处湖北省的西部,神农架的南坡,处于中亚热带向北亚热带过渡的地带。对其植物与植物群落的研究得到如下结果: 龙门河地区共有维管植物160科724属1737种,其中种了植物140科692属共1686种。其植物区系有显著的温带性,温带分布属共380属,占总属数的54.9%,这可能和该地区的地理位置,海拔及人为活动的影响有关,该地区的植物区系还具有古老性,特有属丰富特点,且有较多的珍稀濒危植物分布。 龙门河地区的植被共划分三个自然植被型共16个群系。在高海拔地区保存有较原始的落叶阔叶林,低海拔地区多为人为破坏后的次生类型。这些植被类型随环境条件的变化呈现较有规律的分布,依照其垂直分布的情况,可以将该地区植被划为三个带,即常绿阔叶林带低于海拔900(-1300)m;常绿落叶阔叶混交林位于海拔900(-1300)-600m之间;落叶阔叶林带在海拔1600(-1300)-2200m之间,无针叶林带在龙门河地区分布。应用TWINSPAN和DCA程序对各调查样地进行数量分类和排序结果说明,植物群落的分布与环境因子明显相关,但排序轴不能用海拔等单个的因子来解释。对各群落乔木层的Gleason丰富度指数,Shannon-Wiener指数及Pielou均匀度指数对比后发现,各种指数在不同的群落之间及不同海拔高度上没有明显的规律,这可能是由于人类活动混淆了群落成分及结构的结果。 锐齿槲栎林是神农架地区一种重要的落叶阔叶林,其分布广泛,保存较好。通过对锐齿槲栎种群大小结构的研究发现,中等大小的锐齿槲栎个体数量较多,幼苗与幼树的数量在不同样地间变化很大,其大小结构分布图中多有一定程度的缺失。锐齿槲栎种群多呈现聚集分布,不同的尺度下其聚集程序不同。在大多数尺度下,幼苗幼树的聚集程度比相同尺度下成体的聚集程序高。幼苗更新是锐齿槲栎更新的一种主要形式,其幼苗的出现与林窗的形成有密切的关系。在锐齿槲栎幼苗成长为幼树的过程中,同于种内与种间竞争的影响。导致了许多幼树的死亡。正是由于林窗形成等干扰因素的影响才使锐齿槲栎幼树得以进入群落上层。

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本文主要通过大量的植物群落学调查和植被、环境状况的数量分析,分别从植物区系、森林群落及其主要木本物种、干扰和物种多样性五个方面分析了三峡大老岭地区山地植被景观的空间格局及其与环境因子的关系,结果表明: 1) 植物区系:科的分布区类型以热带性质为主;属一级温带性质明显,北温带、东亚和泛热带诸分布类型突出;区系上属于华中植物区系地区的东部。 2) 在垂直梯度上:种子植物属热带分布诸类的比例自海拔400至800米(~1100米)之间呈上升趋势,然后下降;温带分布的第8、9、10、11类随海拔而上升;地中海-中亚中心分布的第12、13类只见于比较干热的河谷地带;东亚分布和中国特有属在海拔900~1100m和1600~1800m段取得小的峰值;世界分布属的比例随海拔而上升,蕨类植物属则相反。 分别用种子植物属的分布型比列构成,和全部521个属的种类数量,对15个海拔段作聚类分析:前者首先反应了海拔1100~1200m处的划分,与植被干扰状况的垂直分布差异一致;后者强调了海拔900/1000m和1800/1900m 处的分异,可能反映了地带性常绿阔叶林基带/常绿落叶阔叶混交林带,和常绿落叶阔叶林带/落叶阔叶林带的分异。 3) 对本地区森林植被的数量分类结果表明:基本上可以分为中低海拔次生落叶 针阔混交林和中高海拔山地常绿落叶阔混交林两大群。第一群主要包括栓皮栎林-杉木林-马尾松林组(低海拔段)和短柄抱栎林-锥栗林组(中低海拔段)。第二群包括中低海拔沟谷常绿阔叶林组、中海拔段常绿落叶阔叶混交林组和高海拔段米心水青冈林-茅栗林组。 DCCA排序区分了11个群落类型或群落组。采用的7个地貌因子变量中效果显著的可归纳为三组:①海拔,主要反映热量和降水梯度;②坡度和坡位,可能主要反映土壤厚度及其水分和养分状况;③坡向及坡位,反映光照条件。其中植被格局的海拔梯度效应最显著。沿海拔梯度分段分析上述诸因子对植被格局差异影响的垂直分布,表明海拔因子的局部效应在海拔600-800m和1500-1700m段最显著;坡向的效应在海拔1600m以上最突出;坡面、坡位、坡形、坡度等因子的作用在海拔中部最大。对植被格局影响因子的贡献进行定量分离,表明地形对对大老岭森林格局具有强烈的控制作用。 4) 对大老岭森林植被275个主要的木本种类进行TWINSPAN分类,得到16个种组;DCCA排序结果将上述16组合并为8群,两方面都主要反映了沿海拔和坡位+坡向的分化;海拔中部的局部地形差异导致物种组的分化比两端更细致和强烈。 根据物种生活型及其在植物群落中的地位,分6个种组进行排序和环境解释,表明:①尽管低海拔地段受到强烈人为干扰,常绿种类仍显示了数量和性质沿海拔梯度的变化;②珍稀物种在海拔梯度上形成两个相对集中的区段,大致对应于山地常绿落叶阔叶混交林带的上下边缘;③先锋树种在中低海拔的中上坡位富集;④在中、高海拔的中低坡位,落叶的乔木伴生种显示了极大的多样性;⑤为数不多的针叶树种在海拔和局部地形梯度上也有明确分异;⑥它们和落叶的栎(Quercus)、栗(Castanea)、水青冈(Fagus)、鹅耳枥(Carpinus)属物种在大老岭地区不同地形部位的植被中起着主要的建群作用。 具体统计海拔梯度上,常绿和落叶的乔、灌木4类物种分布的种数变化表明:海拔1100m以下人为活动干扰与木本物种多样性呈一致的负相关;海拔1100m以上常绿种减少与与落叶种的增加形成对照;1100~1700m之间是落叶乔木种最丰富的地段,海拔1700m以上四类物种数量急剧下降,与山顶脊附近生境多样性降低、植物群落类型趋同有关。另外,典型亚热带的棕榈和蕉只见于海拔1000m以下;针叶树种以海拔1150m左右为界分成两组。前述4类物种的分布边界在海拔850~1050m和海拔1650~1750m之间形成比较明显的峰值,基本对应着山地常绿落叶阔叶混交林带的上下边缘。 根据海拔分布范围,将样方中出现的558种木本植物按常绿乔/灌种和落叶乔/灌种分别分成5个热量生态类群。统计各自的面分比表明:a. 落叶灌木种的多样性分布重心在海拔梯度上的位置比落叶乔木种高,常绿种则相反,因此灌木和类的分布特征能更好的反映次生环境中的植被-气候关系;b. 在海拔850~1850m的木本物种形成巨大的多样性,仅出现于这一段的物种也很可观;亲缘物种的分化和替代突出,反映其对生物多样性发生和维持的意义重大;c. 亚热带中山地带对落叶种生物多样性的意义远大于常绿种。 5)统计全部群落样方内枯立木、倒伏木、断头木和伐桩四类受干扰木的大小、数量、物种以反映地形对干扰的影响:①枯立木以2~15cm径级个体为主,小径级的树种选择性不强,主要分布在山南坡口上坡位,海拔1800m以上尤多,在陡峭的坡地中部减少;其大径级个体的物种构成和分布格局反映了与生境干旱有关干扰的存在。②倒伏木主要分布在海拔1200~1800m之间坡面中部和顶脊两侧,发生频率与坡度成正比;坡地中部以中、小径级阳性树种为主,山坡顶脊两侧的倒伏木则多为大径级的群落优势种。③断头木主要分布在海拔1200~1700m,和海拔1900m以上。小径级的断头木分布格局接近于枯立木,较大径级的断头木则多与倒伏木的分布相关,断头木中少有典型的阳性树种,主要由林下荫耐种构成。④人为砍伐的伐桩主要为中大径级的植被建群种或优势种个体,在海拔1000m以下,1100-1200m和1600-1800m形成三个峰值,其分布主要与人口密度、生产方式、林木种类以及交通运输便捷程度有关,通常沟谷和山脊线上的伐桩密度较大。大老岭地区人为干扰主要反映在海拔1100m以下,自然干扰的格局在海拔1100m以上才得到反映。 6)在不同取样尺度上,对大老岭地区森林群落各层次α多样性和β多样性的空间格局分析表明:i. 乔木层α多样性在海拔1200-1800m之间取值较高,灌木、草本层α多样性的垂直梯度不显著,但在海拔1200-1800m之间的波动变化较为剧烈,南坡面有最丰富的灌木层多样性而西坡乔木层的物种最丰;从植被整体上,海拔1000m以下物种丰富度较低,1000-1700m之间变化剧烈,1700m以上丰富度水平较高。ii. 海拔1000-2000m之间94个样方中,乔、灌、草三层多种生物多样性指数变化影响因子的大小顺序是:坡位>海拔>坡向>坡面>坡度>坡形。乔、灌、草各层几种多样性指数在多维的地形因子梯度上形成各异的分布格局,反映了山地物种多样性格局控制因子的多样性和多尺度,及局部地形因子对景观尺度上生物多样性空间格局的强烈影响。iii.对海拔1050m和1670m处植被α多样性的变尺度分析表明:随取样尺度增大,低海拔乔木、灌木层α多样性增长速率比高海拔大;后者草本层的多样性增长比较快。海拔1050m处群落各层的α多样性在800m~2尺度上渐近稳定;海拔1670m处,400m~2尺度上各层α多样性指数已基本稳定。 南、北、西坡面β多样性沿海拔梯度大致减少,在海拔1600m以上更明显,在海拔梯度中部变化剧烈。反映不同坡面上群落间异质性水平是:西坡>北坡>南坡。 在对植被、环境上述各个方面的格局特征分析基础上,对三峡地区侵入岩山地类型建立了一个综合的植被景观格局模式。 文章最后就两个景观尺度植被-环境的综合性问题进行了讨论:1)气候、植物区系、植被和物种分布等对老岭以至于三峡地区和亚热带山地常绿落叶阔叶混交林带的位置、宽度的反映;和气候、地形、干扰等因子对这一生态过渡带格局和动态的影响;2)三峡地区生物多样性垂直分布的特征、维持和变化的现代机制,以及保护的重点和策略

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松嫩平原盐碱化草地是我国著名的天然草场,又是东北西部绿色生态屏障,具有较高的经济价值和重要的生态意义。但是由于各种自然因素和人为因素,致使草地出现退化、沙化和盐渍化,尤其是草地盐渍化加重,生态环境日趋恶化。当地地形条件和气候要素是导致草地原生盐碱化的主要原因。而人类对草地的过度使用,如过度放牧和割草等则是导致草地快速次生盐碱化的主要原因,不仅导致土壤的退化,而且引起草地群落发生次生演替过程。在典型的次生演替过程中,常常可以出现羊革(Aneurolepidium chinense)群落、羊草和一虎尾草(Aneurotepidium chinense&Chloris virgata)群落、虎尾草(Chloris virgata)群落、碱蓬(Suaeda glauca)群落等演替阶段。 本文试图建立一个过程模型,来模拟草地的生态学过程机理以及人类过度放牧对草地生态系统的影响。本模型包括5个部分:1)主要气候因子的模拟,2)土壤水分动态的模拟,3)土壤盐碱化动态的模拟,4)草地群落生长的模拟,5)不同放牧强度对草地生态系统的影响评价。以下将对各个部分分别描述a 在气候因子模拟子模型中,给出了影响草地生态系统主要气候园子的种类,并重点介绍了如何利用解析法计算太阳辐射,包括平地和坡地的理论可照时间,天文辐射日总量以及总辐射量。利用改进后的Penman式,模拟了全国的潜在蒸散量,与900多个气象站点的水面蒸发观测资料进行了验证,模拟结果很好。 利用面向对象技术,将土壤水分动力学模型与水分平衡模型相结合,建立了土壤水分动态的物理过程模型。模型以ld为步长,可以模拟多种土壤质地的水分动态。利用松嫩平原4中典型土壤(碳酸盐草甸黑钙土、栗钙土、碱化盐土、草甸碱土)1997年土壤湿度观测资料对模型进行了验证,效果根理想。 在水盐平衡模型和动力学模型基础上建立了物理过程模型,来模拟土壤盐碱化动态。模型以ld为步长,适合于模拟异质性强的多层土壤水盐动态。模拟了1997年羊草及碱蓬群落下的土壤盐分、碱化度、pH值动态,并与实验资料进行了比较,模拟结果可以反映土壤盐分和碱化的季节变化规律。 模型将气候要素、土壤湿度、土壤盐分浓度、碱化度和pH值作为影响草地群落生长最重要的环境因子,在土壤水分动态和盐碱化动态模型基础上,建立了过程模型来模拟以羊草(A.chinense)、虎尾草(C.virgata)、星星草(Puccinellialenuiflora)和碱蓬(S. glauca)为建群种的4种植物群落的地上生物量、地下生物量以及枯死生物量变化动态。利用吉林省长岭的气候资料和实验资料,模拟了1991年土壤湿度动态,1991年4种群落土壤盐分、碱化度和pH值变化动态,以及1991年4种群落生长动态,并分另fj利用实验资料进行了验证,模拟效果非常理想。 在此基础上,利用模型对不同放牧强度对土壤水分动态、盐碱化动态的影响进行了评价,并探讨了对群落演替和生长的可能影响。模型选择不放牧、轻牧、重牧、过牧、极牧5种放牧强度,利用模型每15天将地上生物量分别去除0%. 25%、50%、75%和90%,并且相应改变了土壤导水特性来模拟不同的放牧强度。模拟结果表明,重牧、过牧、极牧下土壤湿度显著降低,但在轻牧下土壤温度略有上升。在不放牧时,土壤以脱盐、脱碱过程为主,而轻牧下脱盐、脱碱过程则会变缓:重牧、过牧、极牧下则以盐碱化为主。.不放牧时羊草群落一直占优势,而轻牧下则被羊草一虎尾草群落替代:虎尾草可以忍受轻的盐碱,因此在重牧F取代羊草群落成为优势种;在过牧和极牧下,土壤盐碱化非常迅速,最终只有碱蓬可以忍受强度的盐碱,这时草地变为碱蓬群落或光碱斑。不放牧下草地群落生长良好,生物量最大;轻牧下,草地群落生物量保持在中等水平;而重牧、过牧、极牧下草地生物量迅速减少。通过将每年收割的生物量进行累加,可以发现轻牧下收获的生物量总量是最大的,随着放牧强度的增加,收获的生物量迅速减少,如果同时考虑到适口性的问题,则可以发现轻牧下可 以收获最多的生物量,而过牧和极牧下只能收获极少的适口性非常差的碱蓬。 模拟结果表明,过牧是导致松嫩草地次生盐碱化最重要的原因,它不仅造成草地土壤的退化,而且加速了草地群落的次生演替。适宜的放牧强度对于保护草地免受退化,保持较高的草地生产力水平至关重要。而过牧不仅降低了草地的生产力,而且严重破坏了草地环境,引起草地的迅速退化。

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本文主要通过样线法和样方法相结合,进行了大量的群落学调查和分析,分别从植物区系、物种多样性的垂直分布格局和森林群落类型三个方面分析了神农架植被的基本特征及其物种多样性,结果表明: 1.神农架地区具有很高的物种丰富度,有高等植物3,479种,隶属于1,010属,202科。 其中,蕨类植物305种,80属,32科;种子植物3,174种,930属,170科,其中裸子植物32种,19属,6科,被子植物3,142种,911属,164科;单子叶植物501种,175属,21科,双子叶植物2,641种,736属,143科。植物区系属的分布区类型中北温带分布型最多,其次为东亚分布、泛热带分布、东亚北美间断分布、旧世界温带分布以及热带亚洲分布。中国特有成分占5.65%,较全国的8.12%低。温热比(温带分布型(8-11)属数与热带分布型(2-7)属数的比值)为1.200,比全国(0.385)高。 调查样方中共出现高等植物784种,隶属于454属,144科,其中蕨类植物41种,32属,16科;种子植物743种,422属,128科,其中裸子植物20种,14属,5科,被子植物723种,408属,123科;单子叶植物86种,58属,11科,双子叶植物637种,350属,112科。属的分布区类型中北温带分布型最多,其次为东亚分布、泛热带分布、东亚北美间断分布、旧世界温带分布以及热带亚洲分布。温热比为1.52,草本层>乔木层>灌木层分别为2.18、1.76和1.14。 2.神农架植被类型多样,具有常绿阔叶林、常绿落叶阔叶混交林、落叶阔叶林、针阔混交林、亚高山针叶林、硬叶常绿阔叶林和亚高山灌丛草甸等自然植被类型。本文,依据乔木物种的重要值将神农架地区的森林植被划分出了69个类型。用Twinspan将调查的森林群落划分为32组,能基本上反映群落间相似的关系。 3.神农架地区具有完整的植被垂直带谱:海拔900 (1300) m以下为常绿阔叶林带;海拔900 (1300) m~1500 (1800)ⅡI为常绿落叶阔叶混交林带;海拔1500 (1800) m-2000 (2200)m为落叶阔叶林带;海拔2000 (2200) m~2400 (2600)m为针阔混交林带:海拔2400 (2600)m以上为亚高山针叶林带。神农架地区植被的垂直带的分化从总体上比较显著,但由于小生境的异质性和人为干扰,垂直带谱又具有一定的模糊性和次生性。南北坡具有一定的差异,但不十分明显,也说明神农架植被的过渡性。 4.神农架物种多样性的垂直分布格局。神农架的物种多样性与海拔的关系,类似于“中间膨胀”规律(mid-altitude bulge),在中低海拔处生物多样性最高。通过二次多项式回归拟合,得到如下拟合曲线: 1)海拔与总体物种数:y= _14.445x2+ 34.74lx+42.07,Xd=1.203km; 2)海拔与乔木层物种数:y=-6.9707x2+ 21.334x+0.2004,Xdrl.530km; 3)海拔与灌木层物种数:y=-6.1599x2+ 9.9747x+30.991,Xd=0.8 lOkm: 4)海拔与草本层物种数:y= _3.9907x2+ 10.455x+15.35,Xd-1.308km; 5)海拔与乔木层Shannon-Wiener指数:y=_0.3337x2+ 0.9877x+0.2537,Xd' 1.480km; 6)海拔与灌木层Shannon-Wiener指数:y=-0.1938xz+ 0.422lx+1.2103,Xd=1.089km: 7)海拔与草本层Shannon-Wiener指数:y=_0.1072x2+ 0.294lx+0.9954,Xd=1.372km; x为海拔( km),y为各物种多样性指标,Xd为物种多样性的最大时的海拔。 从这些拟合曲线中可以看出:总体物种多样性在海拔1200m左右的常绿落叶阔叶混交林带最高:乔木层物种多样性在海拔1500m左右的常绿落叶阔叶混交林带与落叶阔叶林的过渡带最高;灌木层物种多样性在海拔800-llOOm左右的常绿阔叶林与常绿落叶阔叶混交林带的过渡带最高;草本层物种多样性在海拔1300-1400m左右的常绿落叶阔叶混交林带最高。 但物种多样性随海拔变化有许多的起伏和波动。这些波动有些反映了群落的垂直带谱随海拔梯度变化的特点,在垂直带谱的过渡区物种多样性往往较高;有些波动反映了一些特殊的生境,有些反映了人为活动的影响,造成了神农架植被的次生性。因此,影响神农架物种多样性垂直分布的因素有:植被本身的性质和特点、过渡带的特点、生境的异质性和人为活动。 5.神农架植被水平地带性的过渡性。海拔1300m以下的植物属的分布区类型的温热比南坡总是比北坡小,而且相差十分显著,反映了神农架作为植被分界线的价值。神农架南坡的基带植被是常绿阔叶林,因此南坡属于中亚热带。北坡的基带植被,虽然也有常绿树种的零星分布,甚至有小块的常绿阔叶林,完全由于小生境所至,分布的主要类型是常绿落叶阔叶混交林,应属于北亚热带。因此,神农架是中、北亚热带重要的过渡地带。神农架地区中北亚热带的具体分界线宜按照分长江干流和汉水的水岭来划界,即猴子石、大窝坑、神农架、神农顶、老君山一线,南坡属于中亚热带,北坡属于北亚热带。 总之,神农架处于我国中、北亚热带的过渡带,具有过渡带的性质,具有很高的物种多样性,拥有完整的植被垂直带谱,具有多种多样的植物群落及其组成的生态系统。而且,具有我国许多特有植物和珍稀濒危保护植物和许多资源植物。因此,神农架植被在我国植被体系中具有重要的地位,是我国生物多样性最丰富的地区之一,是生物多样性保护的关键地区,也应是生物多样性研究的热点地区。 另外,调查分析了黄山和万朝山植被及其物种多样性与垂直分布格局,结果表明: 6.黄山样方中共出现高等植物259种,隶属于263属,110科,其中蕨类植物14种,II属,8科,种子植物345种,152属,105科,其中裸子植物9种,8属,6科,被子植物336种,144属,99科,其中单子叶植物37种,27属,6科,双子叶植物299种,117属,90科。属的分布区类型中北温带分布最多,其次为东亚分布和泛热带分布,再次为东亚北美间断分布、热带亚洲分布以及旧世界温带分布,与神农架和万朝山也较相似,但热带分布的属更多一些。温热比为1.1875,灌木层>草本层>乔木层,分别为1.3818、1.2609和1.2143。 黄山的森林植被类型有针叶林、常绿阔叶林、常绿落叶阔叶混交林、针阔混交林、落叶阔叶林和竹林。Twinspan将调查的森林群落划分为22组,反映群落间相似的关系,比较清楚和适用。依据乔木物种的重要值将森林植被划分出了34个类型。黄山物种多样性的与海拔的关系不十分明显。黄山植被的垂直带谱不是十分明显,将其垂直带谱划分为:海拔1300m(1500m)以下为常绿阔叶林带;海拔1300m(1500m)-1500m(1600m)常绿落叶阔叶混交林 带;1500m(1600m)以上为落叶阔叶林、黄山松林、山地灌木草丛带。垂直带谱在不同坡向上有差别,东、南、西坡的相似性较大,而北坡与其差别较大。 7.万朝山样方中共出现高等植物490种,隶属于339属,124科,其中蕨类植物21种,18属,11科,种子植物469种,321属,113科,其中裸子植物9种,7属,4科,被子植物460种,314属,109科,其中单子叶植物47种,37属,11科,双子叶植物413种,277属,98科。植物属的分布区类型中,北温带分布所占最多,其次为泛热带分布、东亚分布、东亚北美间断分布、旧世界温带分布以及热带亚洲分布,。温热比为1.3366,草本层>乔木层>灌木层,分别为1.5429、1.4063和1.0645。 万朝山的植被类型包括针叶林、落叶阔叶林、针阔混交林和常绿落时阔叶混交林,但没有典型的常绿阔叶林。依据乔木物种的重要值将森林植被划分出了20个类型。万朝山物种多样性与海拔的关系则不十分明显。万朝山的人为干扰比较强,植被的次生性很大,南、北坡物种多样性随海拔升高的起伏较大。

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Visakhapatnam is on the eastern sea board of India (17 degree 40' N and 83 degree 15' E) having a continental shelf of 45 km width which is provided with a polychaete rich, silty clay sea floor to a distance of 15 km and beyond, from the shore. Repeated trawling by a large number of trawlers over an area of 900 sq.km (30 x 30) resulted in the hardening of the substratum to the extent of making it uninhabitable to the polychaetes and polychaete feeding fish. The shoaling and strictly demersal marine catfish, Arius tenuispinis, which is a prolific polychaete feeder on the fishing grounds off Visakhapatnam, has been on the decline since 1979. The catch rate of fish dropped from 9.7 kg/boat per day in 1979 to 2.6 kg by 1985-86. In the bottomset gillnets, the catch per net dwindled from 4.4 kg in 1973 to 0.04 kg by 1985-86. The species has virtually disappeared from the fishing grounds off Visakhapatnam and further north, as a results of the cumulative effect of overfishing with trawlnets and bottomset gillnets. It is further aggravated by the hardening of the sea floor on these grounds due to repeated trawling over a narrow zone.

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A Catch Assessment Surveys (CAS) with the overall objective of generating information on the fish production and commercial value of the fisheries of Lake Albert and Albert Nile system was implemented by the National Fisheries Resources Research Institute (NAFIRRI) in collaboration with the Department of Fisheries Resources (DFR), Local Government staff (FOs) and BMU members at selected landing sites on Lake Albert (12 landing sites) and Albert Nile (26 landing sites) in July 2012. A total 622 and 313 boat days on Lake Albert and Albert Nile respectively were sampled for a period of 9 days. Results indicate an annual landing of 151,600 and 5,900 tonnes (t) of fish with an estimated beach value of 122.5 and 14 Billion (UShs) from Lake Albert and Albert Nile respectively. Over 80% of the catch from Lake Albert comprised the small pelagic species; Neobola bredoi (Muziri) and Brycinus nurse (Ragoogi) followed by Nile perch (6%). However, due to low market value of the small fishes and the high prices attached to Nile perch for industrial processing and export market, the contribution of the latter to beach value rose to 34% of the total. The contribution of the light fishery based on small pelagic species (B. nurse and N. bredoi) are insignificant on Albert Nile. Even if the small pelagic species may be present in the river system, a light fishery based on these two is yet to be developed. Proportionally, Albert Nile still remain a multispecies fishery with over 20 fish species harvested commercially. Interestingly, the Albert Nile fishery still remains primitive with simple crafts and gears (mainly dugout canoes, traps, and gillnets). This could suggest that the more developed the system becomes the higher the level of transformation in its fisheries leading to simplification, characterized by reduction in multispecies nature and dominance of few species. Illegal gears especially undersized gillnet of mesh size less than 4 inches were the most dominant in the Lake Albert and Albert Nile fisheries. They captured large quantities of immature fish particularly when used to target Nile perch, Bagrus, Nile tilapia, and large Barbus spp. Their impact when used to target the smaller species (Ragoogi, Angara & Ngasia) is yet to be evaluated. A specific study to analyze selectivity and impacts of these nets is a recommended. However, the dominance of 1.5” mesh sizes especially on Albert Nile to target Angara, Ngassia and Barbus, is definitely destructive to their fisheries and should be checked forthwith. In addition, there is an emerging fishing method locally referred to as “Salsio or Luzira” whereby fishers stay on the lake from 3 days up to 2 weeks without returning to the landing site. They carry with them food and salt for processing the catches on the lake, and in the case of Albert Nile on make shift shelters on islands and in the game park. They normally use gillnets of 3-3½ inch mesh size and caught mainly Nile perch & Bagrus (Pethi & Munama). On return they land several tons of fish. Most of these Catches are not captured in the estimates presented in our analyses since we target daily fishing boats. The possible impacts of this fishing method should be studied and appropriate action recommended.

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There has been a growing interest in hydrogenated silicon carbide films (SiC:H) prepared using the electron cyclotron resonance-chemical vapour deposition (ECR-CVD) technique. Using the ECR-CVD technique, SiC:H films have been prepared from a mixture of methane, silane and hydrogen, with phosphine as the doping gas. The effects of changes in the microwave power (from 150 to 900 W) on the film properties were investigated in a series of phosphorus-doped SiC:H films. In particular, the changes in the deposition rate, optical bandgap, activation energy and conductivity were investigated in conjunction with results from Raman scattering and Fourier transform infra-red (FTIR) analysis. It was found that increase in the microwave power has the effect of enhancing the formation of the silicon microcrystalline phase in the amorphous matrix of the SiC:H films. This occurs in correspondence to a rapid increase in the conductivity and a reduction in the activation energy, both of which exhibit small variations in samples deposited at microwave powers exceeding 500 W. Analysis of IR absorption results suggests that hydrogen is bonded to silicon in the Si-H stretching mode and to carbon in the sp3 CHn rocking/wagging and bending mode in films deposited at higher microwave powers.

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An alternative method for seeding catalyst nanoparticles for carbon nanotubes and nanowires growth is presented. Ni nanoparticles are formed inside a 450 nm SiO2 film on (100) Si wafers through the implantation of Ni ions at fluences of 7.5×1015 and 1.7×1016 ions.cm-2 and post-annealing treatments at 700, 900 and 1100°C. After exposed to the surface by HF dip etching, the Ni nanoparticles are used as catalyst for the growth of vertically aligned carbon nanotubes by direct current plasma enhanced chemical vapor deposition. © 2007 Materials Research Society.

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Two experiments were conducted to formulate and evaluate test diets using locally available ingredients to find out suitable diets for mono and polyculture of Macrobrachium rosenbergii in ponds. The first experiment was conducted from 1 July 2003 to 29 September 2003 in 12 experimental ponds each measuring 30 square meters behind the Fisheries Faculty Building, BAU campus, Mymensingh. Three experimental diets containing 30% protein were formulated using fish meal, meat and bone meal, mustard oilcake, sesame meal and rice bran and assigned to treatments 1, 2 and 3, respectively. A special shrimp feed (Starter-II) from Saudi-Bangla Fish Feed Ltd. was assigned to treatment 4 (Control). Each treatment had three replications. Juveniles of M. rosenbergii (2.90±0.81g) were stocked at the rate of 4/square meter. Prawns were fed three times daily at the rate of 15% of their body weight at the beginning, which was gradually reduced to 10% and 5% for the last two months. There was no significant (P>0.05) difference between the weight gains of prawns fed diets 1 and 4 (control), but they were significantly (P<0.05) higher than those of diets 2 and 3. The FCR values of diets ranged between 2.61 to 3.36 with diets 1 and 4 showing significantly (P<0.05) lower FCR values. The survival rate of prawns ranged between 68 to 78% with prawns fed diets 1 and 4 showing significantly higher survival rate. The production of prawn ranged from 921 to 1,428 kg/ha/90 days and diet 1 gave the highest production. Treatment 1 gave the highest net profit ofTk. 161,980/ha/90 days. The second experiment was conducted from December, 2003 to April, 2004 to see the growth of over wintered M. rosenbergii juveniles in polyculture with indigenous major carps (catla and rohu) in ponds using formulated diets. Three isoenergetic experimental diets formulated using fish meal, meat and bone meal, mustard oil cake, rice bran, wheat bran and molasses, and a shrimp feed 'Golda special feed' from Saudi-Bangla Fish Feed Ltd. were assigned to treatments 1, 2, 3 and 4 (control), respectively, each treatment had two replications. Eight experimental ponds each measuring 80 square meters in the Field Laboratory Complex of the Faculty of Fisheries, BAU campus, Mymensingh were used. The mean initial weights of M. rosenbergii, catla and rohu were 1.60±0.01, 30.0±0.09 and 25.0±0.08 g, respectively. A total of 160 fish and prawn (20,000/ha) were stocked in each pond at the ratio of 2:1:1 (prawn: catla: rohu). Fish were fed at the rate of 3-5% of their body weight. Prawns fed diet 1, 2 and 4 showed higher weight gains compared to diet 3. The weight gain of catla was significantly higher in T1 while in case of rohu was higher in T1 and T4, respectively. There were no significant differences (P>0.05) in the survival rate of fish as obtained from different treatments. The overall total fish production ranged from 2196 to 2679 kg/ha/5 months. The highest production and the highest profit (Tk. 56,531/ha/5 months) was obtained from T1 and the lowest (Tk. 24,932/ha/5 months) from T4.

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A socio-economic investigation was carried out in two fishermen cooperative societies namely Purba Helatala Fishermen Co-operative Society (E-1), Barhal Fishermen Co-operative Society (E-2), under Maldah district, West Bengal to which the beels (flood plains) under study belong. A total of 132 member fishermen, which constituted the sample, were personally interviewed. The age group of the fishermen of the sample in E-1 varied between 20 and 66 years whereas in E-2 it was 22 and 61 years. All the members of the sample belonged to Scheduled Caste (SC) community. The primary occupation of all the respondents of both the beels was observed to be fishing (100%). Maximum number of illiterate respondents was observed to 56% in E-2 and 35% in E-1. It has been observed that as many as 38.3% of fishermen were having fishing experience which ranging from 16 to 20 years in E-1 whereas it was 6 - 10 years (36.1%) in E-2. Maximum number of fishermen lived in thatched houses (41.66%) in E-1 whereas in E-2 most of them lived in houses made of corrugated tin/tile shed (41.66%). As many as 41.55% of E-1 and 30.55% of E-2 used dug-out canoes for their fishing. Maximum number of fishermen used cast net with individualistic approach (100%) followed by Gill net (E-1:41.56% and E-2:55.55%). Most of the fishermen of the sample participated in fishing activities for 241 to 270 days (41.66%) in E-2 whereas it was 211 to 240 days (33.33 %) in E-1 in a year. During fishing season as many as 40.0% of the respondents of E-1 earned on an average Rs. 801.00 to Rs. 900.00 per month whereas it was Rs. 901.00 to Rs.1,000.00 (43.05%) in case of E-2. A section of fishermen of the sample borrowed money often (51.6%) E-1 whereas it was most often (27.27%) of E-2. The respondents of E-2 made regular repayment of the loan to the maximum extent (79.48%) whereas it was 57.44% in E-1. Higher fish production vis-a-vis higher income for the fishermen was observed in the beel (E2) having close characteristic.

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Kalyani lake (P sub(1)), a weed infested recreational water body and a weed chocked derelict water body (P sub(2)) in the heart of Kalyani city of West Bengal were studied for a period of one year for their primary productivity and other physicochemical parameters. Very low primary productivity (GPP=360-1237mg C m super(-2) d super(-1); NPP=157-787 mg C m super(-2) d super(-1)) was recorded in P sub(2) in spite of having a high concentration of nutrients (PO sub(4)–P=0.052-0.260mg l super(- 1); NO sub(3)-N=0.110-0.412mg l super(-1)). On the other hand, moderate primary productivity (GPP=1687-3195mg C m super(-2) d super(-1); NPP=900-2700mg C m super(-2) d super(-1)) was found in P sub(1) with comparatively low range of nutrients (P0 sub(4)-P =0.010-0.058mg l super(-1); NO sub(3)-N=0.032-0.118mg l super(-1)). After studying the other physicochemical parameters (temperature, transparency, dissolved oxygen, free carbon dioxide, pH, alkalinity and macrophytic biomass), it was found that the overall hydro-biological conditions of the weed-chocked derelict water body (P sub(2)) is not congenial for biological production as compared to Kalyani Lake (P sub(1)). Kalyani Lake may be used for fish culture with proper management practices.

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This paper demonstrates a catalyst-free synthesis of ZnO nanostructures using platinum microheaters under ambient environmental conditions. Different morphologies of ZnO nanostructures are synthesized from the oxidization of Zn thin film by local heating. The synthesized ZnO structures are characterized by the SEM, EDX and Raman spectra. The characterization of two shapes of Pt microheaters is investigated and the relationship between the applied heating power and ZnO nanostructures synthesis is investigated under ambient conditions. We observe that the density and morphology of ZnO nanostructures can be controlled through applied heating voltages. Furthermore, a connected composite structural (Zn-ZnO-Zn) layer is synthesized using combinative microheaters. © 2011 IEEE.

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This study was made as an attempt to investigate the optimum packing density and the ice quantity suitable for the transport of Penaeus monodon juveniles. The results revealed that prawns of 40 mg size can be packed to as much as 3,000 per bag. While packing densities above 3,000 per bag containing 8 L seawater and 16 L oxygen can be used only for short transport periods. On the other hand in the ice-quantity experiment, mortality rate was less than 1% in all the bags containing 300 g, 600 g, 900 g and 1200 g of ice. A packing temperature of 20~’C must be maintained hence, 50 g of ice per hour should be allowed per box, counting from the moment the box is sealed to the time it is estimated to be opened.

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The combined effect of radiation and refrigeration on the shelf life of hilsa, Tanualosa ilisha was studied by monitoring the microbiological, chemical and sensory changes of unirradiated and irradiated fish samples using low dose irradiation, doses of 300 krad, 600 krad and 900 krad. Irradiation (900 krad) dramatically reduced population of bacteria, namely total viable counts 48.850cfu per gm for unirradiated, 31.850cfu per gm and 19.600cfu per gm of 300 krad and 600 krad, respectively. The effect was more pronounced at the higher dose (900 krad), total viable count were 14.100cfu per gm. Another microbial indicator total mould counts (TMC) was 8.750cfu per gm, 6.350cfu per gm, and 19.600cfu per gm for 300 krad and 600 krad, respectively. The effect was more pronounced at the higher dose (900 krad) where total viable counts were 14,100cfu per gm. Total volatile nitrogen values increased slowly attaining a value of 101.02mgN per 100gm for unirradiated T. ilisha during refrigerated storage, whereas for irradiated fish, lower values of 71.13, 59.33 and 47.03mgN per 100gm muscle were recorded. Sensory evaluation showed a good correlation with bacterial populations on the basis of overall acceptability scores.