黄河口及附近海域鱼卵和仔鱼种类组成及分布特征

根据2009年5月和8月2个航次对黄河口及附近海域18个站位的鱼卵和仔鱼调查资料,对该水域鱼卵仔鱼的种类组成和数量分布特征进行了分析和探讨.结果表明,鱼卵仔鱼的种类组成和数量分布呈现明显的季节变化特征;春季鱼卵仔鱼种类数高于夏季,平面分布范围大于夏季,主要优势种季节更替明显;与历史同期资料相比,鱼卵仔鱼种类和数量大幅下...     

Alongshore distribution and abundance of fish larvae off the coast of Kenya

Knowledge is limited on the fish larval assemblage in shallow lagoonal reefs along the Kenyan coast. Fish larvae from five lagoons, spanning 120 km on the Kenyan coast, were sampled in March 2007 and April 2008 to compare interannual spatial variations in species composition, abundance and diversity along the coast. In all, 2 644 fish larvae were sampled, comprising 26 families and 37 species in 2007 and 43 families and 73 species in 2008. The larval assemblage was dominated by Gobiidae, Blenniidae, Pomacentridae and Gerreidae during both years. Larvae hatched from non-pelagic mode of spawning constituting 92% of total numbers. Mean larval abundance (no. 100 m^?3 ± SE) along the coast ranged from 5.0 ± 1.0 to 414 ± 226, with highest densities occurring on the northern sites of Watamu (414 ± 226) and Malindi (31 ± 10). Interannual variation in larval abundance between 2007 (2.17 ± 0.3) and 2008 (2.16 ± 0.1) was not significant (p > 0.05). Shannon-Wiener species diversities between sites ranged from 1.2 ± 0.4 to 2.3 ± 0.3, with highest diversities occurring in Mombasa (2.2 ± 0.5) and Nyali (2.3 ± 0.3). In 2007, the occurrence of preflexion larvae increased northwards from Mombasa (18.2%) to Watamu (86.4%), whereas in 2008, the reverse was the case with the incidence of preflexion larvae reducing northwards from Mombasa Marine Park (76%) to Watamu Marine Park (2%). These trends indicate interannual variation in larval source sites for fish species. Correspondence analysis revealed distinct larval assemblages at sites along the coast, which varied between years.     

长江口及其邻近水域鱼卵、仔鱼的种项组成与分布特征

鱼卵、仔鱼作为海洋生物的被捕食者、捕食者,不仅种类多,而且数量大,常是研究海洋生态系统重要的组成部分.通过对鱼卵、仔鱼的调查研究,可了解和掌握鱼类产卵场和产卵期,确定中心渔场的位置和寻找产卵鱼群,鱼卵仔鱼尚决定着资源的补充,从而为资源量的估算提供理论基础.     

Occurrence patterns of mesopelagic fish larvae in Sagami Bay, central Japan

The species composition, seasonal abundance, and vertical distribution of mesopelagic fish larvae are described based on discrete depth sampling from the surface down to 1000 m depth during four cruises at a fixed sampling station in Sagami Bay. The abundances of total mesopelagic fish larvae in April, July, September, and December were 65.7, 13.6, 118.9, and 17.2 individuals per 10 m² sea surface, respectively. Twenty species or types of mesopelagic fish larvae belonging to 10 families were collected. Diaphus garmani, Lipolagus ochotensis, Diogenichthys atlanticus, Sigmops gracile, and Maurolicus japonicus were the five most abundant larvae and accounted for 43.1, 14.5, 7.4, 6.3, and 5.9% of the total mesopelagic fish larvae, respectively. These five species showed clear seasonal changes in abundance, i.e. L. ochotensis, D. atlanticus, and S. gracile larvae mainly occurred during winter— spring; D. garmani and M. japonicus were collected during summer—autumn. No obvious diel vertical migration was found in these larvae. The larvae of D. garmani and M. japonicus were concentrated in the 25–50 and 50–100 m depth layers, respectively. The transforming stage of L. ochotensis, S. gracile, and D. atlanticus occurred at 400–1000 m depth, while their larvae (<8 mm standard length) occurred in the upper 100 m layer, indicating that metamorphosis of these species takes place in the 400–1000 m layer. Based on the occurrence of mesopelagic fish larvae and oceanographic processes in Sagami Bay, with the exception of D. garmani and M. japonicus, most larvae are considered to originate from the Kuroshio region where their main spawning grounds are formed.     

泉州市三个海湾浮性鱼卵和仔稚鱼的种类组成与数量分布特点

本文根据2007年3月至2008年2月期间在泉州地区3个海湾的调查资料,对其浮性鱼卵和仔稚鱼的种类组成与数量分布特点进行初步研究和探讨．结果表明,本调查海域共出现鱼卵和仔稚鱼51种（含未定种）,隶属于21科,主要是近岸底层鱼类、近海中上层鱼类和港湾河口型鱼类三个生态类型．各站鱼卵总平均丰度是81．2彬网,仔稚鱼总平均丰度31．0个／网．数量平面分布呈现优势种明显,占总量比例大,不同季节不同海湾差别较大,规律性不强等特点．整体数量上与往年比有下降趋势．     

基于DNA条形码技术的珠江口春季鱼卵和仔稚鱼种类组成和分布特征的研究

采用线粒体COⅠ和12S rRNA基因片段作为DNA条形码,分析珠江口春季鱼卵和仔稚鱼种类组成和分布特征,并探究两种条形码在鱼卵和仔稚鱼种类鉴定中的适用性。研究共扩增样本391个,成功鉴定的鱼卵和仔稚鱼共7目25科42属60种（2种未鉴定到种）。其中,以鲈形目（Perciformes）种类和数量最多,种类数占比为51.6%,数量占比为47.91%;其次为鲱形目（Clupeiformes）,种类数占比为25%,数量占比为34.56%。优势种10种,其中凤鲚（Coilia mystus）优势度最高,为0.071;棘头梅童鱼（Collichthys lucidus）最低,为0.014。COⅠ和12S rRNA基因片段扩增结果显示,鱼卵和仔稚鱼12S rRNA基因片段扩增成功率（95.60%）明显高于COⅠ基因（43.22%）。遗传距离和ABGD分析显示,COⅠ基因种内遗传距离为0～0.005（平均0.003）,种间遗传距离为0.061～0.376（平均0.253）,两者间存在明显的“条形码间隙”,ABGD划分结果与数据库比对结果一致;12S rRNA基因种内遗传距离为0～0.011（平均0.007）,种间遗传距离为0.007～0.487（平均0.283）,龟鰉（Chelon haematocheila）和前鳞龟鰉（Chelon affinis）种间遗传距离与种内遗传距离不形成“条形码间隙”,ABGD将其划分为同一种。系统发育分析显示,在种的分类阶元,所有物种均能聚为独立分支,得到有效区分。综上,线粒体COⅠ和12S rRNA条形码可有效鉴定珠江口大多数鱼卵和仔稚鱼,但是COⅠ基因扩增成功率较低,12S rRNA基因部分近缘物种存在区分困难的情况,两种基因结合使用更能提高鱼卵和仔稚鱼种类鉴定的成功率和准确性。     

春季珠江口水域鱼卵和仔稚鱼的分布及其与环境因子的关系

根据2004~2007年春季珠江口水域10个站位的鱼卵和仔稚鱼调查资料,着重就鱼卵和仔稚鱼的数量分布和年际变化及其与环境因子的相关关系进行研究.结果表明：其鱼卵和仔稚鱼隶属于9目33科58种（类）,以鲈形目种类数所占比例最高（为53.4%）,其次为鲱形目（为20.7%）.鱼卵和仔稚鱼大致分成半咸水性、近岸性和近海性3个生态类群.鱼卵和仔稚鱼优势种类共9种,其中鱼卵优势种为6种,仔稚鱼的也为6种.青洲附近水域是春季鱼卵和仔稚鱼的最主要分布区域之一.鱼卵和仔稚鱼数量的年际变化明显,鱼卵和仔稚鱼个体数量的最大值均出现在2006年.水温、pH值和溶解氧含量是影响鱼卵个体数量的较显著因子,盐度和溶解氧含量为影响仔稚鱼个体数量的较显著因子.盐度、pH值及溶解氧、悬浮物、叶绿素a含量对鱼卵和仔稚鱼种类数均有不同程度的影响.     

黄河口及邻近海域鱼卵、仔稚鱼群落结构及多样性的年间变化

为了解黄河口及邻近海域鱼卵、仔稚鱼的群落结构动态,分别于2014年、2015年、2017年和2018年的6月利用大型浮游生物网对黄河口及邻近海域进行4个航次的表层水平拖网调查。根据鱼卵、仔稚鱼的种类组成、数量分布等群落结构特征,运用生物多样性指数、聚类分析和皮尔逊相关性矩阵分析等方法对该海域鱼卵、仔稚鱼的资源分布进行了综合研究。结果表明,4年调查共采获鱼卵3 829粒,仔稚鱼234尾,隶属于7目14科15属。鱼卵的主要优势种为鳀（Engraulis japonicus）和短吻红舌鳎（Cynoglossus joyeri）,仔稚鱼的主要优势种为斑鰶（Konosirus punctatus）和虾虎鱼科未定种Gobiidae sp.。生物多样性各指数均以2015年最高,2018年最低。利用R语言对鱼卵、仔稚鱼年间种类组成相似性进行聚类,将4个调查年份划分为3组,各分组之间主要的分歧种均为鳀。生物多样性各指数与环境因子之间皮尔逊相关性分析表明,盐度与鱼卵、仔稚鱼生物多样性的关系较为密切。分析认为,黄河口及邻近海域鱼卵、仔稚鱼群落分布和多样性的年间变化特征体现了鱼类对环境变异的响应。     

福建省主要海湾浮性鱼卵和仔稚鱼的种类组成与丰度分布

根据2007年8月至2009年10月期间在福建省主要海湾的调查资料,对其浮性鱼卵和仔稚鱼的种类组成与数量分布特点进行初步研究和探讨.结果表明,本调查海域共出现鱼卵和仔稚鱼68种,隶属于29科,主要是近海中上层鱼类、浅海底层鱼类和港湾河口型鱼类3个生态类型.各站鱼卵总平均丰度是497.5粒/网,仔稚鱼总平均丰度50.8个/网.优势种明显,占总量比例大;不同季节和不同海湾的种类数相差不大;数量平面分布呈现不同季节不同海湾差别较大,规律性不强,偶然性大等特点.     

On vertical velocity fluctuations and internal tides in an upwelling region off the west coast of India

Hourly fluctuations of vertical velocity in relation to components of flow and wind and temperature oscillations at a morring site in the shelf waters off the west coast of India are discussed. The vertical velocities were computed from a time series of vertical temperature profiles assuming that horizontal advection of temperature is negligible. The computed values at a depth of 40 m during the 72-h period of observation were of the order of 10⁻¹ to 10⁻²cm s⁻¹, with a mean value of −2·77 × 10⁻² cm s⁻¹ indicating a net upward movement of water. The computed vertical velocity showed fluctuations of about 2–3 h, in addition to weaker signals of about 12 h. Based on the spectral estimates, we speculate that these fluctuations of 2–3 h in the vertical velocity may be caused by the fluctuations in the along-shore wind. The oscillations of isotherms found in the temperaturedepth time series and the spectral estimates of temperature and cross-shore flow component showed a periodicity of about 12 h, which indicated the presence of semi-diurnal internal waves. The fact that these internal wave troughs were associated with the measured onshore flow suggested that the waves were propagating offshore. The computed stability parameters showed little evidence of instability or mixing. It was found that the isotherm troughs in the temperaturedepth time series at about 12-h period coincided with high vertical shear in the cross-shore direction and low values of Brunt Vaisälä frequency.     

Statistical analysis of the distribution of fish eggs and larvae on the southeastern U.S. continental shelf with comments on oceanographic processes that may affect larval survival

Data collected in 1953 and 1954 by the U.S. Fish and Wildlife Service were statistically analyzed to ascertain where and when fish eggs and larvae are most abundant on the southeastern U.S. continental shelf. The results are related to some oceanographic processes that might affect the survival of larval fish. Along-shelf differences in numbers of eggs and larvae are minimal compared with differences that occur across the shelf. Highest numbers of fish larvae are found on the outer shelf during fall, winter and spring, but larvae are evenly distributed across the shelf in summer.Upwelling strongly influences the dynamics of plankton production on the outer shelf, and thus during most seasons of the year upwelling may be the most important process controlling the amount of food available to larval fish. During winter and spring, mean winds do not favor shoreward transport of larval fish from the outer shelf if the larvae are located in near-surface waters. Thus, during these seasons variability of winds on the ‘event’ time scale may be more important to onshore and offshore transport of larval fish than the mean strength and direction of monthly or seasonally averaged winds.     

2010-2011年长江河口及邻近水域春夏季仔稚鱼群落结构及其多样性的研究

根据2010—2011年春夏季对长江河口及邻近水域进行了仔稚鱼生态调查,应用单元和多元统计方法分析了春夏季长江河口及邻近水域仔稚鱼群落结构。4个航次调查共获得27个种类的仔稚鱼,隶属5目14科。优势种类主要包括鳀Engraulis japonicus、凤鲚Coilia mystus、康氏小公鱼Stolephorus commersonii、鮻Liza haematocheila、黄姑鱼Nibea albiflora、黄鳍刺虎鱼Acanthogobius flavimanus和寡鳞飘鱼Pseudolaubuca engraulis等。Shannon-Weaver指数(H′)在调查周期内的波动幅度较大,且2011年明显低于2010年。仔稚鱼群落结构和多样性指数春季年间较夏季年间差异性显著。调查区夏季群落结构年间相似性不高,春季群落结构格局年际变化则较明显。聚类分析表明,春夏季长江河口近岸水域仔稚鱼群落可划分为2个站位组,分别对应于长江河口淡水水域和长江口咸水水域。淡水水域组群落和咸水水域组群落总丰度与盐度相关性较高。表明盐度可能是造成长江河口仔稚鱼群落结构时空差异性的主要原因。     

Vertical distribution of barnacle larvae at a fixed nearshore station in southern California: Stage-specific and diel patterns

Patterns of vertical distribution in marine invertebrate larvae interact with coastal hydrodynamics to determine cross-shore distributions, dispersal ranges, and scales of connectivity among populations. We present observations on the vertical distribution of barnacle larvae from southern California, collected from 3 depth intervals every 2 h and over a 48-h period at a fixed nearshore station. Larvae were identified to species and stage of development, and their vertical distributions were tested for day/night and between-stage differences within each species, as well as for correlations with environmental variability. Stage-specific patterns of vertical distribution were distinct and consistent across species. Nauplii were most abundant near the surface at all times, and were numerically dominated by Chthamalus spp. (78% of N_n = 1835). Cyprids were substantially less abundant than nauplii in our samples (N_c = 146) and corresponded mostly to the subtidal barnacle Balanus nubilus (84%). Despite the lower counts and different species composition, our data suggest that cyprids remain within the mid-depth and bottom layers, and that changes in their mean depth of distribution (MDD) may track changes in pycnocline depth. Temporal changes in nauplii MDD were not correlated with water-column variability, wind forcing, or tidal height. The apparent vertical segregation of nauplii and cyprids may be related to previously documented differences in the cross-shore distribution of these stages.     

Spatial and diurnal distribution of invertebrate and fish fauna of a Zostera marina bed and nearby unvegetated sediments in Damariscotta River, Maine (USA)

Fish, epibenthos and macroinfauna were collected in a Zostera marina bed and nearby unvegetated sediments in the estuary of the Damariscotta River, on the mid-coast of Maine. Samples of epibenthic fauna and fish were collected at low tides both during day and night, and samples of infauna at low tides during the day. The mean density of Zostera shoots in the study area was 335 m⁻². Abundance and species number of fish were greater at night than during the day and greater in eelgrass beds (Z. marina) than in unvegetated habitats. Daytime fish collections were dominated by Atlantic silversides (Medinia medinia), while juvenile winter flounder (Pseudopleuronectes americanus) dominated night collections. Also Zostera-associated epifaunal abundances and number of species were significantly higher at night than during the day. Mysis stenolepis, Idotea balthica and Littorina obtusata were dominant species in the epifauna samples. Of the total of 37 invertebrate species encountered, only five occurred both in the infaunal and epifaunal samples. Nineteen different taxa were collected from the benthic core samples. The most abundant invertebrate infaunal taxa were sipunculids, the polychaete Nereis virens, and oligochaetes. Infaunal invertebrate abundances and species diversity were significantly higher in eelgrass beds than in unvegetated sediments. The abundance and number of species of benthic invertebrates were also positively correlated to seagrass biomass. Community diversity values (H′) were relatively low but fit well in the general pattern of decreasing diversity towards northern latitudes.