裸项栉鰕虎鱼消化系统组织形态学观察

目的 研究裸项栉缎虎鱼消化系统的组织形态学.方法 对裸项栉鰕虎鱼进行解剖,并测量和计算肠道系数、食道长度等数据;制作组织切片,采用光镜技术对消化系统的组织器官进行观察分析.结果 裸项栉鰕虎鱼的消化系统由消化管和消化腺组成,其中消化管包括口咽、食道、胃、小肠和大肠等,消化腺包括肝脏和胰腺.咽部上皮和食道上皮为复层扁平上皮,内有较多的杯状细胞和黏液腺,食道肌层为横纹肌.胃上皮为单层柱状上皮,胃底腺主要位于胃体部的固有层中.肠黏膜向肠腔突起形成许多皱襞,肠上皮为单层柱状上皮,上皮中有数量不等的杯状细胞.肠道系数(IC)约为0.30.胃和肠的肌层都为平滑肌.肝细胞中含有丰富的脂滴,在HE染色标本中因脂滴被溶解而呈大小不等的空泡.胰腺包括外分泌部和内分泌部,外分泌部是浆液腺,内分泌部又称胰岛,主要由内分泌细胞组成.结论 裸项栉鰕虎鱼的消化系统组织形态学与其杂食性相适应,本研究可为裸项栉鰕虎鱼的实验动物化提供支持.     

盐度对裸项栉鰕虎鱼繁殖和生长的影响

目的探索裸项栉鰕虎鱼繁殖和育苗的适宜盐度。方法比较不同盐度梯度条件下裸项栉鰕虎鱼的产卵率、孵化率和生长存活情况。结果裸项栉鰕虎鱼性腺成熟、产卵和孵化的适宜盐度为10‰-20‰,过低或过高盐度该鱼产卵量少,孵化率极低;适宜的盐度有利于裸项栉鰕虎鱼的生长。结论裸项栉鰕虎鱼适盐范围广,适宜的繁殖、生长盐度较低。     

Cu^2＋和十二烷基硫酸钠对裸项栉鰕虎鱼仔鱼急性毒性影响

目的研究Cu^2＋和SDS对裸项栉鰕虎鱼仔鱼存活率的影响,了解裸项栉鰕虎鱼的毒性敏感性。方法实验选取了五个不同日龄的仔鱼,设置了8个不同Cu^2＋浓度水平和7个SDS浓度水平,实验时间为96 h。结果日龄、Cu^2＋浓度和SDS浓度均对裸项栉鰕虎鱼仔鱼的存活率产生影响,随日龄的增加,各处理组仔鱼存活率均升高。结论实验结果表明裸项栉鰕虎鱼用于生物毒性检测,具有比同类生物更宽的适用范围、更适宜的毒性敏感性。     

裸项栉鰕虎鱼的全人工繁殖及其胚胎发育

目的研究裸项栉鰕虎鱼全人工繁殖及胚胎发育,为该鱼的实验动物化研究奠定基础。方法对胚胎和仔稚幼鱼各个发育期的连续取样,系统地观察了裸项栉鰕虎鱼各发育期的形态变化及生长特征。结果水温25．8℃～26．5℃,裸项栉鰕虎鱼受精后约82h仔鱼开始出膜,初孵仔鱼全长1．42～1．73mm,1d开口摄食,3d卵黄囊消失,23d第一背鳍形成,鳞片出现;33d全身被鳞;初孵仔鱼经97d发育成熟,繁殖周期约为36d;雌鱼性腺成熟系数可达40％,个体相对生殖力达每克8193．5粒。结论裸项栉鰕虎鱼具有个体小、性成熟早、生殖季节长、繁殖周期短、繁殖力强等特点,可进行室内规模化人工繁殖和培育。     

盐度和pH突变对不同日龄裸项栉鰕虎鱼仔鱼存活的影响

目的研究盐度和pH突变对裸项栉鰕虎鱼仔鱼存活率的影响。方法实验选取了五个不同日龄（2d、4d．6d、8d和10d）的仔鱼,设置了7个不同盐度突变水平（O、10、20、30、40、50和60）和6个pH突变水平（5、6、7、8、9和10）。结果96h的实验结果表明,日龄、盐度和pH均对裸项栉鰕虎鱼仔鱼的存活率产生影响,随日龄的增大,各处理组仔鱼存活率升高;0和60的盐度以及pH为10的各组裸项栉鰕虎鱼仔鱼死亡。结论裸项栉鰕虎鱼仔鱼对于一定范围内盐度（10—50）和pH（5—9）的突变具有很好的适应性。     

裸项栉鰕虎鱼感染创伤弧菌初报

目的分离及鉴定感染实验用鰕虎鱼的病原菌。方法将病料分离培养,纯化培养后,用16s rRNA及生理生化方法鉴定病原菌。结果分离到了革兰阴性弧菌,命名为:GDLAMI-1210株,显微镜下观察为逗点样形态,电镜下可看到菌的一端钝圆,一端长杆弯曲的鞭毛,生理生化鉴定结果与弧菌一致,16s rRNA测序结果与创伤弧菌标准菌株(ATCC27562T)等聚为一类菌,回归实验证实该菌对裸项栉鰕虎鱼有一定的致病性。结论裸项栉鰕虎鱼感染创伤弧菌初报。     

非离子氨和亚硝酸氮对虾虎鱼仔鱼的急性毒性及安全浓度评价

目的检测非离子氨和亚硝酸氮对鱼类的生态毒性效应。方法在水温（25±1）℃、溶氧（6.07～6.77）mg/L、盐度30～31、pH8.0～8.2的条件下,采用半静水式生物毒性试验方法研究了非离子氨和亚硝酸氮对裸项栉虾虎鱼（Ctenogobius gymnauchen）仔鱼的急性毒性效应（非离子氨浓度梯度设置为0、0.413、0.735、1.309、2.329、4.147 mg/L,亚硝酸氮浓度梯度设置为0、3.0、4.14、5.713、7.884、10.88 g/L）。结果非离子氨和亚硝酸氮暴露后仔鱼出现呆滞、侧游、呼吸困难、体色变白、身体弯曲等中毒症状,且随着暴露浓度的升高与暴露时间的延长,死亡率逐渐增加,存在明显的剂量效应关系和时间效应关系;非离子氨和亚硝酸氮对裸项栉虾虎鱼仔鱼96 hLC50分别为9.1 mg/L和12.405 g/L,其安全浓度分别为0.91 mg/L和1.2405 g/L。结论裸项栉虾虎鱼对非离子氨和亚硝酸氮具有较强的耐受力,非离子氨对裸项栉虾虎鱼仔鱼的毒性显著大于亚硝酸氮。     

基于碳、氮稳定同位素研究胶州湾普氏栉虾虎鱼的摄食习性

普氏栉虾虎鱼属于小型暖温性底层鱼类,是胶州湾鱼类群落中的优势种之一,在胶州湾食物网和生态系统中发挥着重要作用.本文应用碳、氮稳定同位素技术,基于胶州湾渔业资源底拖网调查采集的样品,对普氏栉虾虎鱼的摄食习性进行了研究.结果表明: 胶州湾普氏栉虾虎鱼的δ¹⁵N值范围为11.24‰～13.99‰,平均值为(12.70±0.70)‰,δ¹³C值范围为-20.67‰～-18.46‰,平均值为(-19.08±0.36)‰;各体长组的营养级范围为3.49～3.76,平均营养级为(3.62±0.21),其δ¹⁵N值和营养级与体长呈显著负相关,δ¹³C值与体长无显著相关性.普氏栉虾虎鱼摄食的主要饵料生物类群为多毛类、虾类和软体动物,浮游动物和颗粒有机物(POM)的饵料贡献率较小.聚类分析结果表明,普氏栉虾虎鱼各体长组食物组成的相似性均在92%以上,相似性较高,说明其摄食习性随体长变化无明显差异.普氏栉虾虎鱼在胶州湾生态系统中属于中级消费者,其摄食各饵料生物类群比例的变化可能是其营养级与体长呈负相关关系的主要原因.     

鲻(鱼段)虎鱼属在四川省首次发现(鲈形目:(鱼段)虎鱼科)

鲻鰕虎鱼属(Mugilogobius Smitt)是鰕虎鱼亚科Gobiinae中一个较小的属。我国珠江口、郁江、长江中下游和闽江等水系有分布。1987年8月在嘉陵江采集鱼类标本时,采到一批鰕虎鱼标本,经鉴定为鲻鰕虎鱼属和栉鰕虎鱼属Ctenogobius,前者为四川省新纪录,记述如下。     

基于碳、氮稳定同位素技术研究象山港虾虎鱼类营养生态位

以象山港水域9种虾虎鱼为研究对象,利用稳定同位素技术分析虾虎鱼类的营养生态位和种间竞争关系。结果表明:所测样品δ13C值和δ15N值的变化范围分别为-20.4‰~-12.7‰和6.7‰~14.5‰,不同种类样品的δ15N值和δ13C值均存在显著差异;象山港虾虎鱼类营养层次整体较低,多数种类在该生态系统中起到次级消费者的作用;舌虾虎鱼(Glossogobius giuris)、矛尾虾虎鱼(Chaeturichthys stigmatias)和六丝钝尾虾虎鱼(Amblychaeturichthys hexanema)的营养生态位宽幅相对较大,而小头栉孔虾虎鱼(Ctenotrypauchen microcephalus)、绿斑缰虾虎鱼(Amoya chlorostigmatoides)和纹缟虾虎鱼(Tridentiger trigonocephalus)等营养生态位宽幅相对较小;象山港虾虎鱼类营养生态位重叠严重,小头栉孔虾虎鱼-孔虾虎鱼(Trypauchen vagina)、髭缟虾虎鱼(Tridentiger barbatus)-纹缟虾虎鱼等之间存在激烈的营养生态位竞争。     

Female preference for nest size in the stream goby Rhinogobius sp DA

Females of the stream goby Rhinogobius sp. DA with paternal care favor males courting in fast water currents, whereby they mate males of high parental ability. Here we examined female choice of male nest size of this goby in laboratory. The dichotomous choice experiment clearly indicated that females prefer large nests. Spawning at large nests seems to improve egg survival rates in natural habitats in this goby. We discuss the possibility of multiple criteria in mate choice of this goby.     

Why Be a Both-ways Sex Changer?

Sex change is a rather common phenomenon among aquatic animals, but only a few have been reported to change sex in both directions. In laboratory experiments we demonstrated that the coral goby, Paragobiodon echinocephalus, changed sex in both directions with the same likelihood. When the goby lost its mate in the field, it preferred changing sex in either direction over moving a long distance in search of a heterosexual mate. Change in social rank, which is likely to occur in many other hermaphroditic fish, corresponded exactly with the direction of sex change. This constitutes a new condition for the evolution of both-ways sex change among plants and animals.     

Secretion of prolactin-synergizing activity (synlactin) by the liver of ectothermic vertebrates in vitro

Recent work in our laboratory indicated that the liver of rats and pigeons secretes a prolactin synergist (synlactin) in vitro. We have investigated the secretion of this activity by the liver of nine species of ectothermic vertebrates. Liver from three teleosts (goby, salmon, and tilapia), four amphibians (Ambystoma, Necturus, bullfrog, and grass frog) and two reptiles (turtle and anole) was diced, washed, and incubated for 3 hr in isotonic medium. After dialysis, the liver incubation media (LIM) were tested with and without prolactin (PRL) in the local pigeon crop-sac bioassay. The LIM for turtle, larval bullfrog, freshwater salmon, and 5% seawater-adapted goby significantly augmented the local crop-sac response to PRL, but the LIM from anole, adult bullfrog, grass frog, fasted larval Ambystoma, Necturus, 100% seawater-adapted goby, and tilapia did not contain synergizing activity. We conclude that synlactin is secreted by the liver of several species representing three of the major ectothermic classes of vertebrates. It is significant that in two cases, larval bullfrog and 5% seawater-adapted goby, the presence of synlactin occurs in physiological states in which PRL is active. In the opposite cases (adult frog and 100% seawater-adapted goby) the activity was not detectable. We also found that the liver of larval and adult bullfrogs and tilapia released a factor in vitro that had proliferative activity in the crop-sac. This activity appears to be distinct from synlactin.     

The reproductive behavior of <Emphasis Type="Italic">Economidichthys pygmaeus</Emphasis>: secondary loss of sound production within the sand goby group?

In this study, the reproductive behavior of Economidichthys pygmaeus was investigated under laboratory conditions with simultaneous video and acoustic recordings. Males of the freshwater goby E. pygmaeus do not produce sounds either during the courtship/spawning phase or during aggressive interactions. A detailed analysis of the behavioral sequences revealed the absence of any digging and nest-building activities, whereas the other behavioral components of courtship and spawning are similar to those described for other goby species, showing also a similar function. Results were discussed in terms of secondary loss of sound production within the sand gobies, a group of highly soniferous fishes in the family Gobiidae.     

Ontogenetic variability in the external morphology of monkey goby, Neogobius fluviatilis (Pallas, 1814) and its relevance to invasion potential

In the previous decade, four species of non-native gobies have invaded the middle section of the river Danube and its tributaries. An effective tool for understanding biological invasions is the evaluation of various biological traits (morphological, life history, ontogenetic) within an epigenetic context. The present study examines the external morphology of monkey goby Neogobius fluviatilis (Pallas, 1814) from the mouth of the River Hron, the morphological differences among three goby species (monkey, bighead and round) and the relevance of these differences for invasive potential. Monkey goby reach their definite phenotype very early in their ontogeny and thus represent a strongly precocial (specialized) species with direct development. The morphological differences between monkey and two other goby species also reflect its strong specialization for sandy substrata and smaller prey types. Thus, monkey goby are not expected to spread to new areas as fast as the round and bighead gobies, and their distribution is likely to be limited to sandy and/or sandy-gravel substrata. If this assumption is correct, then the potential adverse impact of monkey goby on native fauna or even ecosystem is likely to be less than that of the bighead and round gobies. Handling editor: K. Martens     

Sperm adaptation in relation to salinity in three goby species

In externally fertilizing species, the gametes of both males and females are exposed to the influences of the environment into which they are released. Sperm are sensitive to abiotic factors such as salinity, but they are also affected by biotic factors such as sperm competition. In this study, the authors compared the performance of sperm of three goby species, the painted goby, Pomatoschistus pictus, the two-spotted goby, Pomatoschistus flavescens, and the sand goby, Pomatoschistus minutus. These species differ in their distributions, with painted goby having the narrowest salinity range and sand goby the widest. Moreover, data from paternity show that the two-spotted goby experiences the least sperm competition, whereas in the sand goby sperm competition is ubiquitous. The authors took sperm samples from dissected males and exposed them to high salinity water (31 PSU) representing the North Sea and low salinity water (6 PSU) representing the brackish Baltic Sea Proper. They then used computer-assisted sperm analysis to measure the proportion of motile sperm and sperm swimming speed 10 min and 20 h after sperm activation. The authors found that sperm performance depended on salinity, but there seemed to be no relationship to the species' geographical distribution in relation to salinity range. The species differed in the proportion of motile sperm, but there was no significant decrease in sperm motility during 20 h. The sand goby was the only species with motile sperm after 72 h.     

Predation on invasive zebra mussel, Dreissena polymorpha, by pumpkinseed sunfish, rusty crayfish, and round goby

The enemy release hypothesis states that invasive species are successful in their new environment because native species are not adapted to utilize the invasive. If true for predators, native predators should have lower feeding rates on the invasive species than a predator from the native range of the invasive species. We tested this hypothesis for zebra mussel (Dreissena polymorpha) by comparing handling time and predation rate on zebra mussels in the laboratory by two North American species (pumpkinseed, Lepomis gibbosus, and rusty crayfish, Orconectes rusticus) and one predator with a long evolutionary history with zebra mussels (round goby, Neogobius melanostomus). Handling time per mussel (7 mm shell length) ranged from 25 to >70 s for the three predator species. Feeding rates on attached zebra mussels were higher for round goby than the two native predators. Medium and large gobies consumed 50–67 zebra mussels attached to stones in 24 h, whereas pumpkinseed and rusty crayfish consumed <11. This supports the hypothesis that the rapid spread of zebra mussels in North America was facilitated by low predation rates from the existing native predators. At these predation rates and realistic goby abundance estimates, round goby could affect zebra mussel abundance in some lakes.