Impact of climate and hydrodynamics on sole larval immigration towards the Tagus estuary, Portugal

Spawning grounds of the soles, Solea solea and Solea senegalensis, are distant from the estuarine nurseries where juveniles concentrate. Recruitment of these species is highly dependent on the success of the larval migration towards the inshore nursery grounds. Unfavourable climate and hydrodynamic circulation may lead to high mortality rates at this stage. The relation between river drainage, NAO index and the North-South wind component intensity over the three months prior to the end of the estuarine colonization and the densities of S. solea and S. senegalensis in the nursery grounds were investigated for both species based on a discontinuous historical dataset (from 1988 to 2006) for the Tagus estuary. Multiple linear regression models were developed for sole density and environmental data (separately for each species). Results showed that river drainage is positively correlated with juveniles’ densities of both species, possibly due to the existence of chemical cues used by larvae for movement orientation. NAO index and the North-South wind component intensity relations with soles densities were non-significant. It was concluded that the high complexity of the Portuguese upwelling system makes it hard to detect causal relations of the environmental variables tested. The importance of river flow for coastal ecosystems was stressed. Since climate change scenarios predict a strong decrease in rain fall over the Portuguese river basins, as well as a concentrated period of heavy rain in winter, it was hypothesised that future river drainage decrease over much of the year may lead to lower recruitment success for soles, especially for S. senegalensis.     

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...     

Abundance and composition of decapod larvae at Saint Paul's Rocks (equatorial Atlantic)

We investigated the effect of interannual variation on the biodiversity and distribution of decapod larvae at Saint Paul's Rocks, an isolated small group of equatorial islands linked to the Atlantic Mid‐Ocean ridge. Zooplankton samples were collected between 2003 and 2005 from a range of different environments off the archipelago. Horizontal surface hauls were conducted in the inlet and at three increasing distances from the archipelago, both in the morning and at night, using a 200‐μm mesh net. Decapod larvae collected included 11 species and 37 individual taxa. Seven of them have not previously been recorded in the area. Samples taken at the shortest distance from the archipelago exhibited a significantly greater abundance than samples taken further away. No significant differences were detected between months in terms of decapod larvae abundance in the inlet. However, in the open ocean at night, the mean abundance was much higher in May and July. Decapod larvae abundance was much higher at night for both the open ocean and the inlet. Brachyuran and caridean larvae exhibited the greatest abundance and frequency in the inlet, mainly represented by the first‐stage larvae of: Grapsus grapsus, Plagusia depressa, Platypodiella spectabilis and Alpheidae. In contrast, Sergestidae holopelagic shrimps were the most abundant and the most frequent larvae in the surface waters of the open ocean. The composition, abundance and distribution of decapod larvae were very similar during the 2 years sampled. Species accumulation curves indicate that even greater diversity exists, demonstrating that long‐term research is important for acquiring accurate knowledge about the biodiversity of dynamic ecosystems such as those at Saint Paul's Rocks.     

皱肋文蛤胚胎、幼虫及稚贝的发育

在水温28.5～30℃、盐度23.6～25.4 条件下, 观察了皱肋文蛤(Meretrix lyrata)胚胎、幼虫和稚贝的发育过程。结果表明, 皱肋文蛤的胚胎经历桑椹期、囊胚期、原肠胚期等阶段, 形成担轮幼虫。根据行为方式和形态特征, 其幼虫阶段可分为D 形幼虫、壳顶初期幼虫、壳顶中期幼虫、壳顶后期幼虫、变态期幼虫、附着期幼虫。稚贝发育可分为无管期稚贝、单管期稚贝和双管期稚贝。皱肋文蛤幼虫在不同阶段的生活习性逐渐改变, 从担轮幼虫至壳顶后期幼虫营浮游生活, 变态期和附着期幼虫分别营匍匐生活和附着生活。壳顶初期幼虫出现足原基, 壳顶中期和壳顶后期幼虫分别形成平衡囊和鳃丝。稚贝阶段开始从附着生活向埋栖生活过渡。稚贝出现明显的次生壳, 无管期稚贝和单管期稚贝的次生壳为红褐色, 而双管期稚贝的次生壳为白色。皱肋文蛤从D 形幼虫发育到附着期幼虫, 后者的壳长和壳高分别增至前者的1.77 倍和2.10 倍; 稚贝阶段从无管期发育到双管期, 后者的壳长和壳高分别增至前者的3.13 倍和3.28 倍, 显示皱肋文蛤幼虫阶段缓慢生长, 稚贝阶段快速生长的特征。     

饵料密度对花鲈仔鱼生长和存活的影响

于2001年12月，在集美大学水产试验场，测定了不同的轮虫密度培育的花鲈(Lateolabrax japonicus)仔鱼的摄食量、生长、存活率和耐饥饿能力。结果表明。饵料密度对花鲈仔鱼的摄食、生长和存活均有较大的影响。在轮虫密度为10个/mL的条件下,仔鱼的摄食量较大、生长最快、存活率最高、耐饥饿能力较强。当轮虫密度为20个／mL时,花鲈仔鱼的存活率降低、耐饥饿能力下降。当轮虫密度低于5个／mL,随着轮虫密度的降低。仔鱼摄食量下降、生长变慢、存活率降低、耐饥饿能力下降。     

温度对凡纳滨对虾幼体生长、变态和存活率的影响

通过不同水温的比较实验,研究了凡纳滨对虾人工育苗的适宜水温,旨在了解33℃及其以上水温对凡纳滨对虾幼体生长、变态和存活率可能造成的不良影响.实验结果表明,在29、31、33、35℃这4种温度实验组中,33℃组幼体的生长最快.Z1—P15期幼体的存活率以31℃组的最高（为29.8%）,其次是33℃组（为20.9%）,35℃组的最低（为4.7%）.实验过程中31℃组幼体的活力状态最佳、最稳定.因此,31℃左右是凡纳滨对虾幼体生长、发育的适宜水温.考虑到33℃组幼体的总存活率虽然低于31℃组,但其具有生长较快的优势,因此可认为目前凡纳滨对虾人工育苗普遍采用的31～32℃水温是合适的.     

光照对真鲷仔、稚、幼鱼摄食的影响

光照对真鲷（Pagrosomusmojor）仔、稚、幼鱼的摄食有重要影响。摄食的适宜光照度范围为100～102lx，最适光照度范围为101～102lx。103lx强光对仔鱼摄食的影响大于稚、幼鱼；100lx弱光对9d以前的仔鱼和稚、幼鱼的摄食影响较小，对9d以后的仔鱼影响较大。此结果和鱼的感觉器官发育及鱼所摄食的饵料种类有关。     

冠瘤海鞘幼体附着和变态的离子控制

研究了人工海水中三种金属离子K+,Mg2+和Ca2+分别在不同浓度下对冠瘤海鞘(Styelaca nopusSavigny)幼体附着和变态的影响,同时采用K+通道阻滞剂TEA检验其可兴奋细胞膜上的K+通道特性,对冠瘤海鞘幼体附着和变态的离子控制机制进行初步探讨,结果表明:K+的浓度为20~40mmol/dm3时诱导幼体附着和变态的效果最佳,低于45 mmol/dm3和高于80mmol/dm3的K+浓度都表现出抑制效果;Mg2+浓度在0~32 mmol/dm3时显著促进幼体附着和变态,达88mmol/dm3时起抑制作用;在人工海水中无论添加或减少Ca2+,均有效抑制幼体变态.TEA不能阻抑增加K+的诱导作用,这表明冠瘤海鞘幼体可兴奋细胞膜上的K+通道对外部TEA不敏感.另外,人工海水中缺乏K+或Ca2+或K+浓度达80mmol/dm3都会对冠瘤海鞘幼体产生毒害作用.     

臭氧对西施舌胚胎孵化率和幼虫摄食生长与成活的影响

研究了臭氧处理后的海水对西施舌(Coelomactra antiquata)胚胎孵化率、幼虫摄食率、生长率和成活率的影响。结果表明,臭氧处理后的海水的化学耗氧量(COD)及NH 4-N的浓度明显下降。西施舌胚胎在通入臭氧(4.17mg/L)10min的海水中,孵化率最高,为97%,在充入臭氧25min的海水中孵化率最低,为72.7%;西施舌幼虫在充入臭氧10～15min的海水中和未经处理的海水中生长较快;幼虫在充入臭氧5min和10min的海水中成活率有所提高。将幼虫放在多次充入臭氧的海水中培养,再放回未经臭氧处理的海水进行17h和30h恢复,30h后其死亡率达85%,而在充入臭氧时间短的的海水中死亡率较低,为33.3%,表明西施舌幼虫的生理机能受到了臭氧的不可恢复破坏。     

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．     

Comparative descriptions of some oyster larvae from New Zealand and Chile,and a description of a new genus of oyster,Tiostrea

Detailed comparisons of the larvae of four species of New Zealand oyster (Saccostrea glomer‐ata, Crassostrea gigas, Ostrea lutaria, and a new species of Ostrea) and one Chilean oyster (Ostrea chilensis) showed that larvae of species other than O. lutaria and O. chilensis share certain features. One conspicuous feature is a distinct tract, termed here the posterior dorsal sulcus, which runs from the posterior margin of prodissoconch I to the valve margin of prodissoconch II; other characteristic features are an umbonate, inequivalve shell and a provinculum bearing distinct teeth. The larvae of O. lutaria and O. chilensis, in contrast, lack the posterior dorsal sulcus, are nonumbonate, and have nearly equal valves with an edentulous provinculum. These distinctive features, together with other adult features, suggest that the two species are more appropriately included in a separate genus. The name Tiostrea is proposed for the new genus. Certain supraspecific groupings within the Ostreinae need to be re‐examined in the light of breeding experiments.     

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.     

酸碱度、盐度对方斑东风螺卵囊孵化率和不同饵料对幼虫生长发育、存活的影响

分别用pH6．32～9．76和盐度16．7～40．9共8个梯度的海水进行方斑东风螺(Babyloniaare Lamarck)卵囊的孵化试验。结果表明,卵囊孵化最适pH范围在8．23～9．35之间,孵化率均在80％以上,pH8．81时高达93．7％;卵囊孵化适宜盐度范围为30．3～37．0,盐度40．9时仍有67．0％的孵化率,表现出耐高盐的特性,盐度低于27．6,孵化率明显下降。幼虫在15d的培育过程中,通过投喂不同的饵料,结果显示投喂单胞藻比投喂人工配合饵料、酵母效果好,单独投喂扁藻(Platymonas subcondiformis (Wille)Hazen)幼虫生长发育最快,体长增长倍数达1．90倍;投喂扁藻、小球藻(Chdorella spp．)、扁藻 金藻(Isochrysis galbana Palbana)、扁藻 小球藻幼虫的成活率相差不明显,分别为58．5％、54．3％、63．3％和50．3％,而投喂人工配合饵料虾片、螺旋藻粉幼虫成活率则较低,只有3．6％和12．8％,投喂酵母第9天全部死亡。     

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.