诏安湾浮游植物的生态特征研究

根据2001年5月、8月和11月对诏安湾网采浮游植物样品的分析鉴定结果,对浮游植物的种类组成和细胞数量等的平面分布和季节变化进行了分析研究,结果表明:诏安湾浮游植物种类丰富,共鉴定浮游植物5门58属172种,浮游植物的生态类群以广布种为主;浮游植物细胞数量的季节变动范围在2.03×106cell/m3～4.01×107cell/m3,数量高峰出现在11月,这与海水中无机氮和活性磷酸盐含量的明显上升有关.海水中活性磷酸盐为影响诏安湾浮游植物生长繁殖的限制因子之一.     

桑沟湾浮游植物种类组成、数量分布及其季节变化

根据2006年4、7、11月和2007年1月4个航次的调查数据,分析了桑沟湾水域浮游植物种类组成、数量分布及其季节变化特征。调查期间共采集浮游植物28属92种(含变种和型),主要由硅藻类(74种)和甲藻类(11种)组成。优势度指数分析显示,硅藻是绝对优势种。物种多样性Shan-non-Wiener指数全湾平均变化范围在1.91～2.74之间(春季夏季秋季冬季)。桑沟湾浮游植物的细胞密度及其水平分布格局的季节变化较大,细胞密度冬季最高(平均为188.4×104cells/m3),春季(平均为63.0×104cells/m3)和秋季(平均为11.7×104cells/m3)次之,夏季最低(平均为9.2×104cells/m3),冬、夏季数量中心在湾内近岸浅水区,春、秋季在位于海湾中部的贝藻养殖区。与历史资料对比显示,经过20多年的养殖活动,桑沟湾浮游植物种类数量下降、优势种发生演变,湾内海水养殖品种、数量以及养殖模式是影响浮游植物数量及其季节变化的主要因素。     

2009年春夏季浙江中北部近岸海域浮游植物群落特征

分析了2009年春季(4月)和夏季(8月)在浙江中北部海域(121°30′~123°30′E、28°30′~30°45′N)进行调查所采集的浮游植物样品,对调查海域浮游植物群落的物种组成、细胞丰度的平面分布、优势种分布和群落的多样性指数等群落特征进行分析研究。初步鉴定浮游植物6门62属169种,硅藻占绝对优势。春季主要优势种为中肋骨条藻、蛇目圆筛藻、星脐圆筛藻和辐射圆筛藻。夏季主要优势种为尖刺拟菱形藻、窄隙角毛藻、中肋骨条藻和远距角毛藻。不同季节优势种既有交叉又有演替;春季浮游植物细胞丰度介于0.01×104~40.67×104cells/m3之间,平均为3.80×104cells/m3;夏季介于0.28×104~6 546.22×104cells/m3之间,平均为467.59×104cells/m3。细胞数量季节变化显著,浮游植物平面分布特征呈明显的斑块状分布,优势种明显。春季的香农-维纳指数和Pielou均匀度指数都好于夏季,而细胞丰度却低于夏季。     

桑沟湾浮游植物生态特征

根据2003年8月～2005年5月桑沟湾4个航次调查结果，对该海区浮游植物的种类组成、数量分布和群落结构进行分析。结果表明，调查海域共检出浮游植物32属72种。其中，硅藻29属60种，占83.3%。甲藻3属12种，占16.7%。浮游植物数量的变动范围为5.0×10^4～3416.0×10^4cell/m^3，浮游植物数量均值的最高值出现在2003年8月，最低值出现在2005年5月。经多样性指数、丰富度指数、均匀度指数和单纯度指数分析，调查海域浮游植物的群落结构随季节变化明显，秋季的种类数、多样性明显高于春季。综合评价表明，桑沟湾海域浮游植物种类个体数量分布不均匀，生物多样性一般。     

渤海近岸浮游植物种类组成及其数量变动的研究

1998年5、8和10月渤海近岸浮游植物调查结果显示,已鉴定的浮游植物有2门23属53种,其中硅藻门占绝对优势,计有19属45种,其次是甲藻门有4属8种,且浮游植物种类组成及其优势种类的季节变化比较明显。浮游植物的月平均数量为56.73×10~4 cells/m3,其中,硅藻门的平均数量为55.21×10~4 cells/m3,占浮游植物总量的97.3％,甲藻门的平均数量为1.52×10~4 cells/m3,占浮游植物总量的2.7％。渤海近岸浮游植物数量分布具有明显的季节变化,数量高峰出现在春季(5月)和秋季(10月)。与历史同期调查资料相比,渤海近岸浮游植物数量的年间变化亦较明显。     

2013年夏季昌黎生态监控区浮游植物群落结构特征分析

根据2013年8月昌黎生态监控区海域浮游植物及环境因子的监测资料,利用地理信息系统技术和统计分析工具,对夏季浮游植物的种类组成、优势种、丰度及其空间分布和多样性等进行了分析。结果表明,浮游植物有3门35种,硅藻门种类最多,共29种,占总种类数的83.86%,其次是甲藻和金藻(5种和1种),分别占浮游植物总数的14.29%和2.86%。浮游植物可划分为广温类群、暖水类群和暖温类群,以广温类群为主;主要优势种为中肋骨条藻、缢缩角毛藻、发状角毛藻,其中中肋骨条藻占有绝对优势。浮游植物平均细胞数量为17.96×105个/m3,细胞数量空间分布自大蒲河口向外海逐渐降低。相关性分析表明,温度和盐度是浮游植物细胞数量的主要限制因子。此外,浮游植物群落的多样性随细胞丰度值的增加而降低。     

黄海秋、冬季浮游植物的调查研究

20 0 1年 11月和 2 0 0 2年 1月分别对黄海中、南部进行生物资源调查 ,共获得和分析浮游植物样品 94站次。结果显示 ,在两个航次调查中共鉴定浮游植物 2 9属 72种 ,主要以沿岸性广温、广盐性种类为主 ,还有一定数量的外洋性种类和底栖附着性种类。其中硅藻门有 2 6属 6 5种 ,甲藻门 3属7种 ,种类组成具有明显的季节差异。两个航次黄海浮游植物的平均数量为 15 0 5× 10 4 个 /m3,其中硅藻门的平均数量为 14 6 9× 10 4 个 /m3,甲藻门的平均数量为 0 36× 10 4 个 /m3,数量的分布呈南高北低的格局。秋季浮游植物及其主要种类的数量均明显高于冬季。与历史同期调查相比 ,黄海中南部浮游植物的平均数量显著低于 1985年 (平均降低 77 7% )而明显高于 1999～ 2 0 0 0年 (平均升高2 84 5 % )。     

三道河水库浮游植物群落结构特征及其渔产潜力分析

2007年8月-2008年4月调查并分析三道河水库浮游植物的群落结构及时空分布特征,并探讨水库的浮游植物多样性及渔产潜力.结果显示,该水库浮游植物有8门49属79种,主要由绿藻、硅藻和蓝藻组成;各采样点浮游植物种类数为43 ～56,但种类组成相似;不同季节浮游植物种类组成有很大差异,秋季种类数最多,冬季最少.浮游植物年平均细胞数量为20.33×104个/L,年平均生物量为0.21 mg/L.Shannon-Wiener多样性指数年均值为2.10,Pielou均匀度指数为0.85,且冬季最高,秋季最低.根据浮游植物水质评价标准,三道河水库为中营养型.据估算,三道河水库浮游植物渔产潜力9 072.45 kg,单产为22.68 kg/hm2.     

筼筜湖浮游植物的分布与生态评价

根据2001～2002年对筼笃湖所采集样品的分析,对浮游植物的种类组成、优势种组成和细胞数量等的空间分布和季节变化进行分析研究.结果表明,筼筜湖浮游植物共出现91种,优势种为中肋骨条藻(Skeletonema costatum)和裸藻(Euglena),浮游植物具有种类数少,细胞数量高,丰富度、多样性指数和均匀度都较低,优势度高的特点,表明筼筜湖水体受污染的程度较为严重.     

春季南日岛人工鱼礁海域浮游植物的群落特征

根据2011年4月、2014年5月在南日岛人工鱼礁区及邻近海域进行的2次生态环境调查资料,研究投礁前后南日岛海域浮游植物的群落特征。结果表明:两次调查共鉴定浮游植物3门40属82种。2011年共鉴定3门32属52种,拟建礁区中心及四周和对照区种类组成相似,平均种类数分别为26种/站和27种/站,细胞数量分别为3.34×104个/dm~3和5.68×10~4个/dm~3。投礁前浮游植物丰富度平均值为1.750,物种多样性指数平均值为2.206,均匀度平均值为0.464,优势度平均值为0.753。2014年共鉴定3门34属60种,礁区中心及四周和对照区种类组成相似,平均种类数分别为35种/站和32种/站,细胞数量分别为1.07×10~4个/dm~3和1.05×10~4个/dm~3。投礁后浮游植物丰富度平均值为2.504,物种多样性指数平均值为3.424,均匀度平均值为0.672,优势度平均值为0.551。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

美人鱼发光杆菌对凡纳滨对虾非特异性 免疫功能及抗病力的影响

在基础饲料中分别添加0.1%和1%美人鱼发光杆菌灭活菌、0.1%美人鱼发光杆菌活菌配制成3种免疫实验饲料,以基础饲料为空白对照组饲料,每组设3个平行样。对个体质量为(4.83±0.36)g的凡纳滨对虾进行为期20 d的饲养实验,分别在0、5、10、15和20d进行取样,以血清中的酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)和溶菌酶(UL)活性为免疫指标,探讨了美人鱼发光杆菌作为免疫制剂对凡纳滨对虾非特异性免疫效应的影响;在投喂免疫饲料后的第22天,按0.004 2 kg/kg体重的剂量,直接投喂对虾白斑综合征病毒(WSSV)病料,并记录累积死亡率。结果表明,美人鱼发光杆菌免疫实验组对凡纳滨对虾血清中PO、ACP、AKP、UL和SOD活性影响明显高于对照组,并且在饲料中添加美人鱼发光杆菌后,明显提高了对虾抵御WSSV感染的能力。其中0.1%美人鱼发光杆菌活菌实验组的抗病毒感染能力最强,WSSV感染14d内累计死亡率为63.3%±5.8%;而对照组为96.7%±3.3%。研究表明,美人鱼发光杆菌添加在对虾饲料中能提高凡纳滨对虾非特异性免疫水平,增强抵抗疾病的能力,将其作为对虾免疫增强剂具有良好的应用前景。     

Effects of Spirulina platensis as a feed additive on growth and coloration of blue dolphin cichlids (Cyrtocara moorii Boulunger, 1902)

This study was carried out to investigate the effects of replacing fish meal with dietary Spirulina as a feed supplement on the growth performance and coloration of blue dolphin cichlids (Cyrtocara moorii). Five isonitrogenous (47% crude protein) and isocaloric (17.36 kJ/g digestible energy) diets were for formulated to replace FM with 0, 5, 10, 15 and 20% Spirulina (designated as Control, SP5, SP10, SP15 and SP20 respectively) and fed to the fish (initial body weight, 3.15 ± 0.01 g). Fish were randomly distributed into fifteen 120 L aquariums (26.5 ± 1.00°C), 15 fish per aquarium. The diets were tested in triplicate for 12 weeks. Experimental groups were fed twice daily (09:00 and 17:00) by hand to satiation. At the end of the feeding trial, significantly (p < 0.05) higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and lower feed conversion ratio (FCR) were observed in fish fed the SP10 diet when compared to the SP20 diet. There was no significant difference in these parameters between the other groups. The skin coloration of blue dolphin cichlid fed a diet containing Spirulina meal was enhanced. The best coloration was observed in the SP15 group. These impressions were objectively validated by chemical determinations of carotenoids extracted from fish skins and passed statistical tests of significance. The study findings show that Spirulina meal does not diminish growth rates except at very high levels.     

Dietary thiamin and pyridoxine requirements of fingerling Indian major carp,Cirrhinus mrigala (Hamilton)

Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg^?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg^?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg^?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg^?1 diet (0.096–0.179 μg thiamin kJ^?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg^?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg^?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg^?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg^?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.     

Sea bream culture in Egypt; status, constraints and potential

Marine fish farming in Egypt began in 1976 with the culture of gilthead sea bream, (Sparus aurata) as this fish was notably adaptable to brackish and marine pond conditions. Today, marine fish and shrimp farms amount to about 19,000 ha, out of which 42% is already in production while the rest, i.e., 58% is still under construction. In 1997, cultured gilthead sea bream production of 2,250 tons made up 3% of the 75,000 tons total aquaculture catch. In polyculture, usually with the grey mullet and sea bass, gilthead sea bream contributed 440 kg ha^–1 to the total yield of 1,700 kg ha^–1 (26%) over a period of 16 months. For the same period, the yield of monoculture ponds averaged 100 kg ha^–1, while in marine cages, yields ranged from 4–10 kg m³. In 1996–1997, fry of 0.25–1 g and fingerlings 1–10 g with a total of 3 million, were collected from the wild and 1 million fry were produced in the three marine hatcheries out of the four existing ones. The development of sea bream culture in Egypt is now severely inhibited by the shortage of seeds and adequate feeds. Exports of both sea bream and sea bass, during 1994–1996 averaged 1,300 tons per year.     

A Minchinia mercenariae‐like parasite infects cockles Cerastoderma edule in Galicia (NW Spain)

The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni‐ and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae‐like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae‐like parasites infecting molluscs outside the United States is confirmed.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.