Movements and behaviors of swordfish in the Atlantic and Pacific Oceans examined using pop‐up satellite archival tags     

HEIDI DEWAR  ERIC D. PRINCE  MICHAEL K. MUSYL  RICHARD W. BRILL  CHUGEY SEPULVEDA  JIANGANG LUO  DAVID FOLEY  ERIC S. ORBESEN  DERKE SNODGRASS  R. MICHAEL LAURS  JOHN P. HOOLIHAN  BARBARA A. BLOCK  LIANNE M. MCNAUGHTON 《Fisheries Oceanography》2011,20(3):219-241

Swordfish are highly specialized top‐level predators that have been challenging to study. In this paper, data from 31 pop‐up satellite archival tags attached to swordfish from (i) the eastern Pacific, (ii) central Pacific, and (iii) western North Atlantic‐Caribbean were analyzed. Common across locations was a pronounced diel vertical pattern with daytime hours spent primarily below the thermocline and nighttime hours spent in warmer waters, close to the surface. One exception to this pattern was periodic daytime basking events which were most common in cooler waters off California. Maximum daytime depths were significantly correlated with light penetration as measured by the diffuse attenuation coefficient at 490 nm. Temperature did not appear to influence daytime depths, and swordfish tolerated both extremely low temperatures (4°C) and rapid and dramatic temperature changes (>20°C). Temperature did appear to influence the nighttime depths in the Pacific where fish typically remained in the surface mixed layer. In contrast, in the warm tropical Atlantic this was not the case, and nighttime depths were much deeper. In all areas, nighttime depth increased around the full moon. Given the parallels between the vertical movement patterns of swordfish and those of the deep sound scattering layer we suggest that swordfish vertical distribution patterns, especially during daytime, are influenced largely by resource availability. At night, when swordfish are typically targeted by fisheries, both ambient light and temperature influence movements. Understanding vertical movement patterns of swordfish can help evaluate gear vulnerability, improve population assessments, and potentially reduce fisheries bycatch.  相似文献   

三角帆蚌新发现的贝壳基质蛋白基因hic9的分离、鉴定及其在珍珠早期形成过程中的作用     

刘晓军  郭炜  金参  白志毅  李家乐 《水产学报》2019,43(4):782-789

为进一步研究珍珠质形成的分子机理,使用RACE-PCR技术从三角帆蚌外套膜中克隆到一个新的贝壳基质蛋白基因hic9。RT-PCR和原位杂交技术结果显示,hic9主要在闭壳肌和外套膜中表达,且在外套膜外褶的外表皮各部分都有信号,在壳皮沟中同样有信号,这些结果表明,hic9是一个同时参与了贝壳角质层、棱柱层和珍珠层形成的多功能基质蛋白基因。hic9富含甘氨酸(14.81%)、脯氨酸(13.58%)和丙氨酸(12.35%),在序列中部形成"Gly-X-X"的结构(X为任意氨基酸),与近C末端连续重复丙氨酸结构(polyA)一起使hic9具有类似蛛丝蛋白的结构特征。hic9 C末端由一段疏水性序列"LAWMLFV"组成,推测这段序列形成β折叠结构,紧邻该序列89～91位是"Asp-Leu-Asp"序列,这是一个典型的Ca2+结合位点。此外,通过实时定量PCR检测了珍珠形成早期阶段hic9在初生珍珠囊中的表达情况,插片后3～15 d hic9在珍珠囊中的表达水平维持在大致相同的表达水平,在碳酸钙沉积物从无序向有序转变时期(18～25 d),表达水平较第15天有显著的升高,这表明hic9参与了这一过程,在珍珠层的形成过程中发挥了关键作用。  相似文献   

Japanese sardine (Sardinops melanostictus) mortality in relation to the winter mixed layer depth in the Kuroshio Extension region     

HARUKA NISHIKAWA  ICHIRO YASUDA 《Fisheries Oceanography》2008,17(5):411-420

A drastic population change in Japanese sardine (Sardinops melanostictus) has been noted as being related to winter sea surface temperature (SST) in the Kuroshio Extension region. The former studies suggest two possible explanations. One is that temperature itself affects sardine. The other is that SST represents the environmental change of the Kuroshio Extension region and other causes directly affecting sardine. In this study, we found that sardine mortality from post‐larva to age 1 negatively correlated with the winter mixed layer depth (MLD) in the Kuroshio Extension region from 1979 to 1993. During the period of a deep winter mixed layer (during the early 1980s), sardine mortality was low, whereas mortality was high when the winter mixed layer was shallow (during the late 1980s to early 1990s). By using a lower trophic‐level ecosystem model forced by the observed time series of MLD, SST, light intensity and nutrient data, we found that the estimated spring zooplankton density drastically varies from year to year and has a significant negative correlation with sardine mortality. The inter‐annual variation of spring zooplankton density is caused by the winter MLD variation. During the deep winter mixed layer years, a phytoplankton bloom occurs in spring, whereas during the shallow winter mixed layer years, the bloom occurs in winter. The results of our study suggest that the decline in the Japanese sardine population during the late 1980s to early 1990s was due to an insufficient spring food supply in the Kuroshio Extension region where sardine larvae and juvenile are transported.  相似文献   

Nitrate leaching in a silage maize field under different irrigation and nitrogen fertilizer rates   总被引：4，自引：0，他引：4  

Mahdi Gheysari  Seyed Majid Mirlatifi  Mehdi Homaee  Gerrit Hoogenboom 《Agricultural Water Management》2009,96(6):946-954

Quantification of the interactive effects of nitrogen (N) and water on nitrate (NO₃) loss provides an important insight for more effective N and water management. The goal of this study was to evaluate the effect of different irrigation and nitrogen fertilizer levels on nitrate-nitrogen (NO₃-N) leaching in a silage maize field. The experiment included four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil moisture depletion, SMD) and three N fertilization levels (0, 142, and 189 kg N ha⁻¹), with three replications. Ceramic suction cups were used to extract soil solution at 30 and 60 cm soil depths for all 36 experimental plots. Soil NO₃-N content of 0-30 and 30-60-cm layers were evaluated at planting and harvest maturity. Total N uptake (NU) by the crop was also determined. Maximum NO₃-N leaching out of the 60-cm soil layer was 8.43 kg N ha⁻¹, for the 142 kg N ha⁻¹ and over irrigation (1.13 SMD) treatment. The minimum and maximum seasonal average NO₃ concentration at the 60 cm depth was 46 and 138 mg l⁻¹, respectively. Based on our findings, it is possible to control NO₃ leaching out of the root zone during the growing season with a proper combination of irrigation and fertilizer management.  相似文献   

蛋鸡J亚群禽白血病病毒gp85基因遗传进化分析     

林甦  陈珍  朱春华  江斌  刘斌琼  蔡国彰  胡奇林  黄瑜 《福建农业学报》2015,(2):113-116

为了解福建省蛋鸡J亚型禽白血病病毒(ALV-J)的遗传进化关系,对来自福建省蛋鸡场发病蛋鸡中分离鉴定的3株ALV-J的gp85基因进行克隆与测序,并与国内外18株ALV-J参考株的基因序列进行分析。结果表明:3株蛋鸡分离株的gp85基因与亚群2的国内蛋鸡分离株(CL09DP02、GL09DP01和HuB09JY03)以及原型株HPRS-103的亲缘关系较近,达97.8%~99.6%,表明福建省蛋鸡ALV-J株很可能与国内部分蛋鸡ALV-J分离株有着共同的来源。  相似文献   

大兴安岭天然林不同林分溶解有机碳变化特征   总被引：1，自引：0，他引：1  

杜浩  张成福  程宇琪  王雨晴  潘思涵  杨宇娜 《水土保持研究》2019,26(6):46-52

为确定不同林分和季节变化对森林碳库影响。在内蒙古大兴安岭根河林业局境内选取具有代表性的林分,即白桦林、白桦落叶松混交林以及落叶松林为研究对象。收集并测定了树干径流、有机质层和0-30 cm土层中DOC浓度,并分析了DOC变化特征以及不同月份对DOC的影响。结果表明:不同林分中树干径流中DOC平均浓度分别为60.12,172.77,205.02 mg/L;有机质层中DOC平均浓度分别为35.32,39.64,34.45 mg/L;0-30 cm土层中DOC平均浓度分别为26.23,37.08,26.53 mg/L。结果表明:不同林分中DOC浓度表现为树干径流 > 有机质层 > 0-30 cm土层,落叶松林树干径流DOC浓度明显高于白桦林（p<0.05）,且落叶松树干比白桦树干淋溶DOC强;不同林分中有机质层和0-30 cm土层表现为白桦落叶松混交林>白桦林、落叶松林,但无明显的差异（p>0.05）,而且有机质层和土层对DOC有吸附固定作用;不同林分6-9月份树干径流中DOC浓度呈现先升高后降低的趋势,7月份达到最大,机质层和0-30 cm土层中DOC浓度6月份最高,7月、8月最低,而9月份又升高。不同林分和月份的变化,影响了天然林中DOC浓度分布。  相似文献   

心土培肥犁改良瘠薄土壤的效果   总被引：2，自引：2，他引：2  

王秋菊  刘峰  高中超  姚春雨  张劲松  常本超  高盼  张春峰  贾会彬  焦峰  姜辉 《农业工程学报》2016,32(6):27-33

研究根据心土培肥的改土技术要求研制出心土培肥犁,并分别在瘠薄黑土和碳酸盐草甸黑钙土上开展大面积机械改土试验,明确自主研发的心土培肥犁改土后对土壤理化性质影响及对作物产量的效果,为其广泛应用到低产土壤改良提供机械及技术支持。试验设深松、心土培肥和常规对照耕作,采用大田对比方法。研究结果表明:心土培肥和深松在不同类型土壤上对土壤理、化性质,对作物产量及产量性状影响后效不完全一致;心土培肥降低土壤抗剪强度后效明显,碳酸盐草甸黑钙土10~30 cm土层土壤抗剪强度比对照降低6.65~12.16 k Pa,黑土比对照降低8.20~11.31 k Pa,碳酸盐草甸黑钙土改土后效果明显,黑土改土后效长,心土培肥改土效果优于深松;土壤容质量和硬度趋势同上;心土培肥提高土壤透气系数为2.78~14.28倍,饱和导水率为2.38~11.62倍;深松和心土培肥可提高下层土水分消耗比例,30~60 cm土层耗水量为心土培肥区深松区对照区,心土培肥耗水量比照高10%;心土培肥处理可提高土壤磷含量和供磷强度,20~30 cm和30~40 cm土层土壤供磷强度比对照分别提高4.19~5.17倍和4.96~17倍,碳酸盐草甸黑钙土高于黑土;心土培肥可提高玉米产量,碳酸盐草甸黑钙土上心土培肥增产幅度为6.82%~18.01%,黑土增产幅度为6.45%~11.18%,平均增产效果碳酸盐草甸黑钙土薄层黑土,但黑土持续增产效果好。  相似文献   

典型干旱荒漠绿洲区耕层土壤养分空间变异   总被引：7，自引：0，他引：7  

王雪梅  柴仲平  武红旗 《水土保持通报》2016,36(1):51-56

[目的]对干旱荒漠绿洲区耕层土壤养分空间特征进行研究,为绿洲土地资源的合理开发利用,以及土壤施肥方案的科学制定提供理论依据。[方法]基于GIS与地统计学方法对新疆维吾尔自治区精河县耕层土壤养分空间变异特征及影响因素进行分析。[结果](1)研究区内有效磷的空间变异性较强(变异系数Cv为67.45%),速效钾的空间变异性最弱(Cv为40.76%)。(2)有机质、碱解氮和有效磷存在较强的空间自相关性,其空间变异主要由地形、土壤质地和土壤类型等结构性因素所引起;速效钾为中等程度的空间自相关性,其空间变异不仅受结构性因素的影响,还与随机因素(即施肥和种植结构)有关。(3)各土壤养分元素在绿洲内部具有较高含量的片状和斑块状分布,而在绿洲外缘,其含量相对较低,且呈大面积的片状分布。[结论]精河县耕层土壤养分总体呈现出有机肥含量缺乏,磷钾肥相对丰富的特点。  相似文献   

基于生态化学计量学的秦岭林地养分特征初探     

刘帅  王紫泉  田海霞  李丹丹  耿增超  和文祥 《水土保持学报》2016,(4):194-198,248

以秦岭典型林地土壤为对象,分析了夏、秋两季锐齿栎、油松、华山松、云杉4种典型林分下林地不同土层土壤的生态化学计量学特征。结果表明:5个林地腐殖质层(O层)、表层(A层)土壤有机碳含量分别在76.23~260.70,26.60~44.81g/kg之间;全氮含量在4.19~8.76,1.46~3.29g/kg之间;全磷含量分别在0.38~0.61,0.33~0.63g/kg之间。5个林地O层、A层C/N范围分别为16.48~29.76,12.31~19.39;C/P范围分别为144.93~465.52,44.63~107.42;N/P范围分别为7.97~18.37,2.58~6.23。土壤有机碳和全氮及C/N,C/P,N/P均表现为O层大于A层,且O层碳氮含量动态变化较大。阔叶林地土层间差异小于针叶林地。华山松林地土壤碳氮磷含量及C/N、C/P均高于其他林地。土壤C/P和N/P的空间变异性较大,C/N相对稳定。土壤碳氮磷含量及化学计量比值大多表现为夏季高于秋季。  相似文献   

气力式1JH-2型秸秆深埋还田机设计与试验     

田阳  林静  李宝筏  张桐嘉  齐林  王佳琦 《农业工程学报》2018,34(14):10-18

针对东北黑土区合理耕层构建秸秆深埋还田的技术要求,实现虚实并存合理耕层结构,研制了气力式1JH-2型秸秆深埋还田机,能够一次完成破茬、秸秆捡拾粉碎、开沟碎土、行间深松、秸秆深埋、覆土镇压等功能。机具主要由传动系统、破茬装置、捡拾粉碎装置、气力输送装置、开沟装置、覆土装置、镇压装置等组成。其关键部件是气力输送装置,应用离散元气固耦合数值模拟法对秸秆在气力气力输送装置中不同转速下的运动过程进行了数值模拟研究,得到了秸秆和气流输送气固耦合的运动规律。正交试验结果表明,机具运行最优参数组合为开沟装置转速215 r/min,风机转速1 850 r/min,机具作业速度3.0 km/h。田间试验表明,在最优参数组合条件下,秸秆深埋率为94%,秸秆粉碎合格率为94.2%,碎土率为95.4%,满足了东北黑土区秸秆深埋还田技术指标要求,为秸秆深埋还田机的改制和评价提供参考。  相似文献