氰戊菊酯对斑马鱼和稀有鮈鲫不同生命阶段的毒性效应

为探明氰戊菊酯对鱼类不同生命阶段的毒性效应,以斑马鱼和稀有鮈鲫为测试生物,评价了氰戊菊酯对斑马鱼和稀有鮈鲫不同生命阶段的急性毒性差异。研究发现,氰戊菊酯对斑马鱼和稀有鮈鲫胚胎的96 h-LC50值分别为0.901(0.664~1.22)和0.636(0.233~1.74)mg·L~(-1)。氰戊菊酯对稀有鮈鲫胚胎孵化有明显的促进作用,染毒48 h后,0.188和0.375 mg·L~(-1)氰戊菊酯对稀有鮈鲫胚胎的孵化率分别为88.9%和100%。氰戊菊酯对斑马鱼仔鱼、幼鱼和成鱼的96 h-LC50值分别为0.00340、0.0183、0.00487 mg·L~(-1),氰戊菊酯对稀有鮈鲫仔鱼、幼鱼和成鱼的96 h-LC50值分别为0.0520、0.00277、0.00345 mg·L~(-1)。因此,氰戊菊酯对斑马鱼不同生命阶段的毒性从高到低顺序依次为:仔鱼成鱼幼鱼胚胎,氰戊菊酯对稀有鮈鲫胚胎、仔鱼、幼鱼和成鱼的毒性为幼鱼成鱼仔鱼胚胎。试验结果表明,斑马鱼仔鱼对氰戊菊酯的敏感性高于稀有鮈鲫相应的生命阶段,相对于斑马鱼,稀有鮈鲫胚胎、幼鱼以及成鱼对氰戊菊酯的毒性作用更为敏感,说明氰戊菊酯对斑马鱼和稀有鮈鲫不同生命阶段的毒性效应差异较大。     

三唑酮对斑马鱼和稀有鮈鲫不同生长阶段的急性毒性比较

为探明三唑酮对鱼类不同生长阶段的毒性效应,以斑马鱼和稀有鮈鲫为测试生物,检测了三唑酮对斑马鱼和稀有鮈鲫不同生长阶段的急性毒性差异。研究发现,三唑酮对斑马鱼和稀有鮈鲫胚胎为低毒,其96 h-LC50值分别为21.1(14.4~31.0)和14.2(9.65~20.9)mg·L~(-1);高浓度的三唑酮对斑马鱼和稀有鮈鲫胚胎的孵化有明显的抑制作用,染毒96 h后,23.7 mg·L~(-1)三唑酮组斑马鱼胚胎的孵化率为4.17%,22.5 mg·L~(-1)三唑酮组稀有鮈鲫胚胎的孵化率为33.3%。三唑酮对斑马鱼仔鱼、幼鱼和成鱼为低毒,其96 h-LC50值分别为24.8、21.3、13.1 mg·L~(-1),三唑酮对稀有鮈鲫仔鱼、幼鱼和成鱼为中毒,其96 h-LC50值分别为9.96、7.89、6.89 mg·L~(-1)。因此,三唑酮对斑马鱼和稀有鮈鲫不同生长阶段的毒性效应排序一致,毒性从高到低顺序依次为:成鱼幼鱼仔鱼。试验结果表明,相对于斑马鱼,稀有鮈鲫对三唑酮的毒性作用更为敏感,三唑酮对稀有鮈鲫不同生长阶段的毒性均高于斑马鱼相应生长阶段的毒性。     

不同实验条件下稀有鮈鲫胚胎的自然受精率和孵化率

以中国本土鱼种稀有鮈鲫(Gobiocypris rarus)胚胎为实验生物,研究稀有鮈鲫胚胎在正常光照条件下(温度(26±1)℃,自然光照)和光照周期颠倒条件下(温度(26±1)℃,光照周期为12 h(暗):12 h(光))的96 h自然受精率和孵化率,并在放大倍数为40倍的体视显微镜下观察稀有鮈鲫在胚胎发育过程中的形态发育时序及特征。结果表明,在光照周期颠倒和(26±1)℃条件下,9次重复试验的稀有鮈鲫胚胎自然受精率和孵化率平均值分别为92.2%和92.8%,变异系数(CV)分别为5.65%和6.21%,比正常光照和(26±1)℃条件下稀有鮈鲫胚胎的自然受精率和孵化率更高,为鱼类胚胎试验提供更高质量的胚胎。稀有鮈鲫胚胎的形态发育时序及特征满足胚胎试验观察的需求,可在特定的时间点观察特定表征。     

稀有鮈鲫作为鱼类胚胎急性毒性试验受试鱼种的敏感性研究

通过验证稀有鮈鲫在鱼类胚胎急性毒性试验中的敏感性,评价其在鱼类替代试验中的应用潜力,为相关化学品测试国家标准的制定提供依据.选取3,4-二氯苯胺(3,4-DCA)、五水硫酸铜(CSP)、2,3,6-三甲基苯酚(2,3,6-TMP)、二甲基亚砜(DMSO)、七水硫酸锌(ZSH)、三甘醇(TEG)、氯化钠(SC)、十二烷基硫酸钠(SDS)、重铬酸钾(PD)、甲基异噻唑啉酮(MIT)、二苯甲酮(BP)、二氯苯氧氯酚(TCS)、1,2-苯并异噻唑啉-3-酮(BIT)、三唑酮(T)、多菌灵(C)和N-(4-氯苯基)-N'-(3,4-二氯苯基)脲(三氯卡班,TCC)16种化学品,按照《OECD化学品测试准则No.236鱼类胚胎急性毒性试验》,分别进行稀有鮈鲫胚胎急性毒性试验,将结果与稀有鮈鲫成鱼急性毒性试验结果比较,评价稀有觞鲫在不同生命周期对同一化学品的敏感性差异;同时与已有的或试验所得的斑马鱼胚胎急性毒性试验结果比较,评估稀有绚鲫胚胎与国际标准试验鱼种胚胎间的敏感性差异.稀有鮈鲫胚胎急性毒性试验96 h半数致死浓度(96 h-LC50)值与其成鱼及斑马鱼相比,敏感性类似,毒性值差异均未超过一个数量级.稀有鮈鲫作为一种中国本土的标准试验鱼种,其胚胎生物学特征与斑马鱼类似,其胚胎敏感性不亚于成鱼和其他国际标准鱼种,适宜进行鱼类胚胎急性毒性试验的应用.     

摄食水平和氨氮对梭鱼幼鱼食物消化及生长的影响

以鮻鱼(Liza haematocheila)为研究对象,采用半静态实验法探讨了摄食水平和氨氮联合作用对鮻鱼幼鱼摄食、食物转化率、生长、肠胃蛋白酶等方面的影响。结果表明:氨氮对鮻鱼幼鱼的摄食具有抑制作用,高浓度氨氮(3.32mg·L-1)对幼鱼摄食的抑制率达28.78%。鮻鱼幼鱼对食物的转化率(FCE)随氨氮浓度升高而减小,随着摄食水平的增加而增加,FCE最大值出现在饱食未添加氨氮组(BS5),为19.83%;最小值出现在低摄食水平的高浓度氨氮组(HS1),为-22.19%。鮻鱼幼鱼特定生长率(SGR)的增长水平受摄食水平和氨氮的影响与幼鱼的FCE变化一致。氨氮对实验幼鱼肠胃蛋白酶活性的影响因摄食水平而不同,本实验中,仅饱食条件下高浓度氨氮对幼鱼的肠胃蛋白酶有显著抑制效应,这可能与氨氮胁迫情况下幼鱼摄食量较小有关;氨氮浓度相同时,对照组和低氨氮浓度组鮻鱼幼鱼肠胃蛋白酶活性受摄食水平影响显著,而高氨氮浓度条件下,由于饱食组幼鱼肠胃蛋白酶活性受抑制,导致摄食水平对肠胃蛋白酶活性影响不显著。研究证实,摄食水平是影响鮻鱼生长及肠胃蛋白酶活性的主要因素,氨氮会抑制鮻鱼摄食,进而影响蛋白酶活性。     

城市污水处理厂进出水中类雌激素暴露影响评价

以稀有鮈鲫（Gobiocypris rarus）为模型动物,利用卵黄蛋白原（VTG）和生长发育指标作为类雌激素污染的生物标志物,评价了沙湖污水处理厂进出水中类雌激素暴露对稀有鮈鲫仔鱼的影响.结果表明：暴露21d后,未稀释进水和一级处理出水对稀有鮈鲫仔鱼VTG有显著诱导,各级处理水对稀有鮈鲫的生长发育也造成了一定的影响,在进水和一级处理出水暴露组中有死亡现象发生.以17β-雌二醇（E2）为阳性对照,对稀有鮈鲫VTG的诱导作标准曲线,计算进水以及各级出水的类雌激素E2的活性当量,发现污水处理厂一级和二级处理工艺对污水的类雌激素活性的去除率分别为47%和95%以上.表明在现有污水处理工艺中,二级处理工艺可去除大部分的类雌激素,而一级处理工艺却不能有效去除类雌激素.     

三氯酚暴露致稀有鮈鲫肝脏损伤的比较蛋白质组研究(Proteomic Analysis of Hepatic Protein Profiles in Rare Minnow （Gobiocypris rarus） Exposed to Trichlorophenol （TCP）)

为探讨2,4,6-三氯酚（2,4,6-TCP）暴露致鱼类肝脏损伤的毒性效应,以稀有鮈鲫（Gobiocypris rarus）为模式生物,TCP暴露浓度为1、10、100μg·L-1,进行流水暴露实验（28d）,利用二维凝胶电泳方法（2-DE）,结合质谱分析技术（MALDI-TOF-MS）,对TCP致稀有鮈鲫肝脏损伤的蛋白表达谱进行了研究. 结果显示,共发现35个差异蛋白点,其中11个蛋白被成功鉴定（C.I.>95%）. 对鉴定的蛋白根据GO Terms 进行功能分类,发现它们主要参与脂类代谢与转运、氧化应激以及蛋白修复和氧化磷酸化等生物学过程。以上结果表明,TCP对稀有鮈鲫具有明显的肝脏毒性效应.     

三氯酚暴露致稀有鮈鲫肝脏损伤的比较蛋白质组研究

为探讨2,4,6-三氯酚(2,4,6-TCP)暴露致鱼类肝脏损伤的毒性效应,以稀有鮈鲫(Gobiocypris rarus)为模式生物,TCP暴露浓度为1、10、100μg·L-1,进行流水暴露实验(28d),利用二维凝胶电泳方法(2-DE),结合质谱分析技术(MALDI-TOF-MS),对TCP致稀有鮈鲫肝脏损伤的蛋白表达谱进行了研究.结果显示,共发现35个差异蛋白点,其中11个蛋白被成功鉴定(C.I.>95%).对鉴定的蛋白根据GOTerms进行功能分类,发现它们主要参与脂类代谢与转运、氧化应激以及蛋白修复和氧化磷酸化等生物学过程。以上结果表明,TCP对稀有鮈鲫具有明显的肝脏毒性效应.     

稀有鮈鲫细胞凋亡相关基因的克隆及序列分析

细胞凋亡是调控机体发育和维护内环境稳定的重要机制。在克隆了稀有鮈鲫(Gobiocypris rarus)肝脏组织中凋亡相关的bcl-2、apaf-1、caspase-3和caspase-9基因的部分cDNA片段之后,进行了序列分析。结果表明,caspase-3和caspase-9基因片段与唐鱼(Tanichthys albonubes)相对应的核苷酸序列同源性最高,而bcl-2、apaf-1基因片段则分别与鮈鱼(Gobio gobio)和鲤鱼(Cyprinus carpio)相对应的核苷酸序列同源性最高,为99%和89%。基于稀有鮈鲫和已知物种的caspase-3基因核苷酸序列构建了系统发育树,发现稀有鮈鲫与唐鱼、斑马鱼(Danio rerio)的亲缘关系最近,而与金头鲷(Sparus aurata)、红鳍东方鲀(Takifugu rubripes)的亲缘关系较远。本研究为深入理解外源性化学物质对鱼类的毒理学机制及其生态健康风险评价提供科学数据,同时也为稀有鮈鲫在鲤科鱼类的分类及进化地位的研究提供分子水平的重要参考。     

磷酸三(2,3-二氯丙基)酯阻燃剂对稀有鮈鲫的毒性效应

为研究新型阻燃剂磷酸三(2,3-二氯丙基)酯(TDCPP)的毒性效应,以稀有鮈鲫(Gobiocypris rarus)为实验生物,采用半静态实验方法,分别进行96 h和28 d的染毒,研究TDCPP对稀有鮈鲫的急性毒性和慢性毒性效应,并通过对稀有鮈鲫脑组织中与神经纤维的生长、发育、轴突再生等相关基因mRNA表达量的检测,初步探讨了TDCPP的神经毒性作用。结果表明：TDCPP对稀有鮈鲫的96 h-LC₅₀为2.99(2.20～3.38) mg·L^-1,根据化学物质对鱼类毒性分级标准TDCPP属于剧毒性。经0.9、1.5、2.1和2.7 mg·L^-1 TDCPP染毒28 d,与对照组相比,暴露组稀有鮈鲫肝脏及脑组织中SOD和GSH-Px的活性均受到抑制,且随着TDCPP的暴露浓度增加,其抑制作用显著增强;暴露组稀有鮈鲫脑组织中与神经纤维的生长、发育相关的微管蛋白α/β、神经丝NF-M以及关键蛋白GAP-43等基因的mRNA表达量,与对照相比均发生显著下调。可知,TDCPP暴露可以诱发稀有鮈鲫神经毒性作用。     

稀有鮈鲫Ras信号通路相关基因的克隆、序列分析及其组织分布

Ras基因是一类在生物进化过程中较为保守的原癌基因,在多种细胞生命活动中起到细胞增殖、分化和细胞骨架构建等重要作用。本文克隆了稀有鮈鲫Ras信号通路相关的k-ras、n-ras、pik3cd、pin1和raf1基因的部分c DNA片段,并分析了其序列。序列分析结果表明,k-ras的氨基酸序列与鲤鱼相对应的氨基酸序列同源性最高,为99%;n-ras、pik3cd、pin1和raf1的氨基酸序列均与斑马鱼相对应的氨基酸序列同源性最高,分别为99%、87%、96%和97%,结果表明稀有鮈鲫与鲤鱼、斑马鱼的亲缘关系较近。组织表达分析表明,k-ras、n-ras、pik3cd、pin1和raf1基因在肝脏、鳃、肾脏、脑和性腺等组织中具有表达差异性。本文为研究环境污染物对鱼类致癌作用机制和安全性评估提供分子生物学基础和科学依据。     

Pups crying bass: vocal adaptation for avoidance of age-dependent predation risk in ground squirrels?

In most mammals, larger adult body size correlates with lower fundamental frequency and more closely spaced formants in vocalizations relative to juveniles. In alarm whistles of two free-living rodents, the speckled ground squirrel Spermophilus suslicus and yellow ground squirrel S. fulvus, these cues to body size were absent despite prominent differences in body weight and skull and larynx sizes between juveniles and adults. No significant correlations were found between the individual maximum fundamental frequency and body weight, both within age classes and for pooled samples of all animals within species. Furthermore, the mean alarm whistle maximum fundamental frequencies did not differ significantly between age classes (juvenile versus adult) in the speckled squirrel and were even significantly lower in juvenile yellow squirrels. We discuss the hypothesis that the obfuscation of vocal differences between juvenile and adult squirrels may represent a special adaptation of pup vocal behaviour—a form of “vocal mimicry,” resulting in imitation of adult vocal pattern to avoid infanticide and age-dependent predation risk.     

全氟辛烷磺酸盐(PFOS)替代品对4种本土水生生物的生态毒性

本文选择了紫背浮萍、四尾栅藻、蚤状溞和稀有鮈鲫4种本土水生生物,开展了阳离子表面活性剂、织物三防整理剂、C4三防整理剂和C6三防整理剂4种全氟辛烷磺酸盐(PFOS)替代品的安全性评估,为筛选理想PFOS化学替代品提供科学依据。急性毒性结果发现阳离子表面活性剂对4种水生生物均未显示出急性毒性;织物三防整理剂、C4三防整理剂和C6三防整理剂对蚤状溞的LC50值分别为17.97、64.61和85.58 mg·L-1,显示出低的急性毒性。另外,织物三防整理剂对四尾栅藻的半数抑制浓度(EC50)值为88.32 mg·L-1,而对稀有鮈鲫半致死浓度(LC50)值为14.79 mg·L-1,均存在急性毒性。短期生长抑制试验结果发现阳离子表面活性剂、织物三防整理剂、C4三防整理剂和C6三防整理剂对稀有鮈鲫生长抑制最低可见效应浓度(LOEC)值分别为20、1.5、100和50 mg·L-1,表明4种PFOS替代品均显示低慢性毒性。急慢性综合分析可知C4和C6三防整理剂相对较安全,可能成为理想的PFOS替代品。     

Gastrointestinal pH and development of the acid digestion in larvae and early juveniles of<Emphasis Type="Italic"> Sparus aurata</Emphasis> (Pisces: Teleostei)

Changes in digestive pH and protease activity have been determined throughout the transition from larvae to the juvenile stage in Sparus aurata in rearing conditions (from 0.04 to 100 g wet weight). Measurements of pH have been taken in the stomach and different segments along the length of the intestine using a pH microelectrode. In starved fish, the gastric pH ranged between 6.0 and 8.0 approximately, except in juveniles of intermediate size (between 1.0 and 7.0 g wet weight), which exhibited a wider pH range of 2.0–8.0. Fed fish with digestive content showed, in general, lower pH values in the stomach. A progressive decrease was observed from a pH range of 5.5–8.0 in the youngest animals (0.04 g) to a pH range of 2.0–6.2 when juveniles were approaching 1.0 g wet weight. Above this weight, the gastric pH remained constant (between 2.0 and 6.0 approximately). The pH values in the intestine ranged between 6.7 and 8.4. They were similar in the different segments and weight classes examined, and there were no significant differences between fed and starved animals. Specific acid protease activity (units per milligram soluble protein) in fed animals increased from small (0.04–1.0 g) to intermediate juveniles (1.0 and 7.0 g), but then remained similar in larger juveniles. On the contrary, specific alkaline protease activity in fed animals decreased from small to intermediate juveniles, and then remained at a similar level in larger juveniles. The results reflect a progressive transition during several months from alkaline digestion in larvae with undeveloped stomachs to the acid digestion in juveniles with fully developed stomachs. Full gastric capacity is developed in seabream juveniles of 1 g wet weight, which represents approximately 100 days post-hatching in cultured populations. Nevertheless, in the following 2.5 months, during which the intestine reaches the appropriate length, juveniles still show a transitional period in the regulatory mechanism of digestion, probably linked to the adaptation to a different feeding habit.Communicated by S.A. Poulet, RoscoffThis revised version was published in December 2003 with corrections to the legend of Fig. 3.     

饵料加标研究二甲苯麝香在鱼体内的蓄积和清除能力

二甲苯麝香(musk xylene,MX)是一种人造麝香,具有强烈的麝香气,可用作化妆品香精和皂用香精等的定香剂。由于其持续不断地输入环境,它们在水、土壤、大气中的浓度逐渐升高,并且在动物和人体组织中产生了蓄积,其蓄积效应相当于有机氯农药(organochlorine pesticides,OCPs)等持久性有机污染物,因而研究MX在鱼体内的蓄积特征是十分必要的。本文用含浓度为50 mg·kg-1和100 mg·kg-1的MX的饵料投喂斑马鱼(Danio rerio)和稀有鮈鲫(Gobiocypris rarus)14 d,继而进入为期28 d的清除实验。通过快速溶剂萃取(accelerated solvent extraction,ASE)、凝胶渗透色谱(gel permeation chromatography,GPC)、气相色谱-质谱联用法(gas chromatography-mass spectrometry,GC-MS)测定斑马鱼和稀有鮈鲫体内MX的浓度,继而评估鱼对MX的清除能力。结果表明,饵料中MX浓度越高,鱼体内MX的蓄积水平越高,100 mg·kg-1浓度组的蓄积水平为50 mg·kg-1浓度组的蓄积水平的2~3倍。在整个试验阶段的不同时间点分析鱼的体重和脂肪与鱼体内MX浓度的关系,数据显示,MX在鱼体内的蓄积水平与鱼的体重存在正线性关系,而与鱼体内脂肪含量的关系还有待进一步研究。经28 d的清除,鱼体内的MX残留量接近于零,说明斑马鱼和稀有鮈鲫对MX的清除能力较强。     

Towards a global model of in situ weight-specific growth in marine planktonic copepods

The dependency of in situ weight-specific fecundity of adult females (as egg production) and growth of juveniles (as somatic production) upon individual body weight in marine planktonic copepods was examined. A compilation was made of results where wild-caught individuals were incubated in natural seawater (often pre-screened to remove large organisms), at near in situ temperatures, over short periods of the order of 24 h. The results demonstrate that for the adult broadcast-spawning group weight-specific fecundity rates are dependent upon body weight, but independent of temperature. We postulate this may be the result of global patterns in available phytoplankton. Weight-specific growth rates are dependent upon individual temperature and body weight in juvenile broadcast-spawners, with rates declining as body weight increases. Sac-spawners have growth/fecundity rates that are independent of body weight in adults, juveniles, and both combined, but which are temperature-dependent. Globally applicable equations are derived which may be used to predict growth and production of marine copepods using easily quantifiable parameters, namely size-distributed biomass and temperature. Some of the variability in growth which remained unaccounted for is the result of variations in food quantity and quality in the natural environment. Comparisons of the rates compiled here over the temperature range 10 to 20 °C with previously compiled food-saturated rates over the same temperature interval, revealed that in situ rates are typically sub-optimal. Adults appear to be more food-limited than juveniles, adult rates in situ being 32 and 40% of those under food saturation in broadcasters and sac-spawners, respectively, while juvenile in situ rates are on average ∼70% of those at food saturation in both broadcasters and sac-spawners. Received: 18 September 1997 / Accepted: 13 May 1998     

Responses to conspecific scent marks and the ontogeny of territorial marking in immature terrestrial salamanders

We investigated the ontogeny of responses to scent marks in immature terrestrial salamanders (Salamandra lanzai) that inhabit the southwest Alps. In this species, sexual maturity is usually reached at about 8 years, and adults exhibit territoriality. One should expect territoriality to take place largely before the acquisition of sexual maturity if sexual competition is not the main force driving territoriality. However, both the difficulties for inexperienced animals to find a suitable territory and size-related competition may delay the acquisition of territoriality in juveniles. We performed choice tests with juveniles belonging to two age groups (1±1 years old versus 4±1 years old). Each focal animal was offered, in random order, the choice between two shelters, one without scent and the other containing one of the following scents: own, same-aged animal, a juvenile belonging to the other age group, or adult female. We also performed choice tests with adult females for which the scents of two juveniles belonging to a different age group were successively offered in a random order. Older juveniles were strongly attracted toward their own shelter and mostly avoided the shelters that contained the scent of juveniles of about the same age and of adult females. Adult females avoided the scents of older juveniles but not younger juveniles. These results therefore suggest that older juveniles use territorial marking. Conversely, young juveniles behaved randomly with respect to their own scents and to those of a same-aged juvenile, and they were significantly attracted towards the odor of an older animal, especially adult females. Both older juveniles and adult females displayed a random behavior toward the scents of young juveniles. Our results suggest that young juveniles do not defend territories but use spaces occupied by older individuals.Communicated by A. Mathis     

稀有鮈鲫作为水生模式生物的研究及探讨

我国本土水生生物稀有鮈鲫(Gobiocypris rarus Ye et Fu,1983年)是一种优良的试验用鱼,具备成为模式生物必要条件。本文总结了稀有鮈鲫生物生态学研究情况,分析了稀有鮈鲫在多个应用领域与模式生物斑马鱼、青鳉存在的不足和差距,同时借鉴发达国家推动模式生物的实践经验,提出了针对性建议。     

Some notes on the population dynamics of the monogenean gill parasite Gastrocotyle indica

The fish Caranx kalla of different size groups (2 to 18 cm body length) is present during various calender months of the year off the Madras coast (S. India). C. kalla displays a definite progressive shift in growth during successive months; the fish grows from 2 cm (September) to about 18 cm (August) over a period of 12 months. The highest (47%) or lowest (11%) incidence of a monogenean gill parasite Gastrocotyle indica has been observed in the C. kalla size groups 2.0 to 3.9 cm or 16.0 to 17.9 cm; however, the maximum specific density of 10.9 parasite/infested fish was observed in the size group 14.0 to 15.9 cm. Small fish (2.0 to 3.9 cm) carry only larvae (58/100 fish); larger hosts (4.0 to 5.9 cm) larvae (45/100 fish) and juveniles (8/100 fish); individuals of the 6.0 to 15.9 cm size group harbour larval, juvenile and adult stages of G. indica. Fishes of more than 16 cm carry only adult parasites. The level of parasitization is higher on the male hosts (30% incidence; 5 parasites/infested male) than on the females (25% incidence; 4 parasites/infested female). The highest incidences of larval, juvenile and adult G. indica occur in September, February, and May, respectively; the parasite seems to live for 1 year. The host requires a period of about 8 months to acquire immunity against infestation by G. indica or copepod parasites.