The Application of Hydrogen Peroxide as a Treatment for the Ectoparasite Amyloodinium ocellatum (Brown 1931) on the Pacific Threadfin Polydactylus sexfilis

Ectoparasite infections can cause death or a decline in the general health of farm-raised finfish. This paper reports the findings from two studies conducted to evaluate the efficacy of hydrogen peroxide as a therapeu-tant for the control of infections of Amyloodinium sp. on cultured Pacific threadfin Polydactylus sexfilis (locally called "moi"). Threadfin with amyloodiniasis collected from a commercial farm were used in both trials. Prior to the trials, and following hydrogen peroxide treatment, the extent of infection was determined by a gill biopsy procedure. An initial trial was conducted in the laboratory to assess the response of juvenile threadfin and Amyloodinium sp. trophonts to hydrogen peroxide exposure at four dosages: 0, 75, 150, or 300 mg/L for 30 min. In a trial on a commercial farm, a hydrogen peroxide treatment at 75 mg/L for 30 min was applied to juvenile threadfin in a grow-out tank. In both trials, hydrogen peroxide was immediately flushed from the culture system with sea-water after the 30 min exposure period. In the laboratory trial, treatment with 300 mg/L hydrogen peroxide resulted in 100% mortality of the exposed group of fish. However, single treatments with hydrogen peroxide at concentrations of 75 or 150 mg/L eliminated Amyloodinium sp. trophonts without causing loss of fish. In the field trial, a single treatment with 75 mg/L hydrogen peroxide greatly reduced levels of Amyloodinium infestation, and a second treatment 6 d later reduced Amyloodinium trophonts to a nondetectable level. These findings suggest that hydrogen peroxide is a suitable chemical for the treatment of amyloodiniasis of cultured, juvenile Pacific threadfin.     

Description of the water quality conditions in a semi-intensively cultured marine fish pond in Eilat,Israel

Monthly sampling showed typically a large diurnal trend in dissolved oxygen and temperature with a slight trend also in dissolved inorganic nitrogen but not in phosphate or silica. There is a high uptake of all these nutrients in the pond as shown by the difference between the input water and pond water. Temperature in the pond decreased to a minimum of 15°C in February and then increased to 33°C in July. In the autumn there was relatively high primary productivity (PP) supported mainly by nutrients in the inflow. PP decreased to a minimum in winter, probably due to decreasing temperature and light, then increased to a summer maximum together with planktonic biomass, and diurnal oxygen variation. The increase was due mainly to increased temperature and nutrient supply from food input. These data were used to explain the incidence of fish mortalities mainly in mid-summer. The importance of frequency of sampling in such a dynamic system is discussed.     

Effects of depth and eutrophication on the zooxanthella clades of Stylophora pistillata from the Gulf of Eilat (Red Sea)

• 1. The symbiotic association between corals and zooxanthellae has been a major contributing factor in the success of reef‐building corals.
• 2. The diversity of zooxanthellae harboured in the hermatypic coral Stylophora pistillata in the Gulf of Eilat (Aqaba), northern Red Sea, was investigated on the basis of the length and sequence variation of the 18S small subunit ribosomal DNA. Of several clades found worldwide, only clades A and C were found to be associated with this coral species in the Gulf.
• 3. No correlation between the pink and brown colour morphs of the coral S. pistillata and the zooxanthella clade was found. Shallow‐water colonies (5 m) harbour clade A while deeper‐water colonies (17 m) harbour either clade A or C. This coral is a brooding species that associates with different zooxanthellae at different depths.
• 4. Eutrophication from fish farms did not affect clade identity associated with Stylophora.

Copyright © 2008 John Wiley & Sons, Ltd.     

Effects of marine fish farming on nutrient composition and plankton communities in the Eastern Aegean Sea (Turkey)

The hypothesis that the presence of fish farming zones affects the water quality and plankton communities was investigated in an Aegean Sea fish farm during February, June, September and January 2000–2001. In the spatial coverage, a total of 12 stations were sampled; three of them were reference stations. A variance analysis was applied to the measurements made at the stations near the fish farms and at the control stations. While no significant differences in concentrations of nutrients, chlorophyll a, particulate organic carbon and particulate organic nitrogen were detected between the stations and the control sites within one season, significant differences were detected between the parameter values measured except for total dissolved phosphorus and dissolved organic phosphorus at different seasons. The seasonal differences were also significant with regard to the biodiversity. Together with these temporal differences in general, there was a higher diversity of species at the control site as compared with the other stations in September, which was the key season to detection of significant changes. The most important consideration is that it is not sufficient to take the instantaneous values for the physico‐chemical variables; rather, it is necessary to monitor the biological parameters in order to define the differences in the ecosystem.     

寄生海水养殖鱼类的拟格拉夫涡虫的流行、危害与防治

葡萄糖激酶（GK；E．-C．2．7．1．1）是己糖激酶家族成员，葡萄糖激酶在控制葡萄糖利用率保持葡萄糖平衡方面起着重要的作用。但是，鱼类对糖的利用率却较低，目前对此较公认的解释是由于鱼类肝脏缺乏可诱导的GK活力而不能有效地使细胞内的葡萄糖转化为6-磷酸葡萄糖，可这一解释和现有有关鱼类存在有功能的GK样酶活力以及饲料中碳水化合物对GK表达的诱导作用明显有矛盾。本文报导了从翘嘴红鲐肝脏中分离到的GKcDNA全序列，对其序列进行了比较和分析，为进一步研究翘嘴红鲐GK酶在不同营养条件下的表达奠定基础。     

寄生海水养殖鱼类的拟格拉夫涡虫的流行、危害与防治

自2000年10月中旬,在罗源湾发现一种罕见的能够寄生鱼类的涡虫,对其流行病学、形态学以及进化地位进行了大量的研究,结果表明：这种涡虫是一种未被报道过的新种,在福建省的各海水养殖区广泛流行,能够寄生于眼斑拟石首鱼（Sciaenops ocellatus）、大黄鱼（Pseudosciaena crocea）、鮸鱼（Miichthys miiuy）、牙鲆（Paralichthys olivaceus）、黑鲷（Sparus macrocephalus）和横纹东方鲍（Takifugu oblongus）等海水养殖鱼类的鳃、鳍及体表,造成寄生部位的严重损伤,鱼因呼吸困难或细菌的继发性感染而造成大量死亡,死亡率可达20％-60％;流行季节主要为秋季（8-11月）;水温22-26℃,盐度25-30。此外,提出了使用地下水,降低盐度、温度,合理用药等切实可行的防治本涡虫病的建议。     

福建省夏季网箱养殖鱼类主要病害情况及对策

研究了6种中草药水提取物对刺激隐核虫(Crytocaryon irritans)的体外杀灭效果,发现用7.14 mg·mL^–1的乌梅(Fructus mume)、槟榔(Areca catechu)、贯众(Dryopteris setosa)和石榴皮(Punica granatum)的水提取物分别处理幼虫5 min,幼虫死亡率达100%,用28.57 mg·mL^–1处理包囊4 h,包囊死亡率达84.1%以上。为评估喂服乌梅水提物对珍珠石斑鱼(Epinephelus lanceolatus♀×E.fuscoguttatus♂)预防刺激隐核虫病的效果,投喂第14天后对石斑鱼的增重、溶菌酶活性、补体旁路途径溶血活性和鱼体滋养体数量及死亡率进行测试和评估。结果显示,药物组石斑鱼的增重和旁路补体溶血活性与对照组没有显著性差异(P>0.05),溶菌酶活性均显著高于对照组(P<0.05),感染刺激隐核虫后滋养体数量均显著低于对照组(P<0.05);致死剂量攻毒后,药物组(11.4 g·kg^–1、6.84 g·kg^–1、3.42 g·kg^–1)和对照组鱼的成活率分别为40%、20%、46.67%和0%。结果表明乌梅对预防刺激隐核虫病具有一定的开发前景。     

The pathology of Haplorchis pumilio (Looss, 1896) infections in cultured tilapias

Abstract. Haplorchis pumilio (Looss, 1896) is a common digenean parasite of many species of fish of economic importance and has been found to infect cultured Sarotherodon spp. Fry of S. spilurus (Günther), S. mossambicus (Peters) and S. galilaea (L.) were experimentally infected with cercariae of H. pumilio from natural infections of Melanoides tuberculata (Müller) from an East African fish farm. Large numbers of cercariae were lethal to the fry within a few hours. Histopathological examination showed that the most significant pathological effect was focal haemorrhages in skeletal muscles in heavily infected fish. Migration of cercariae was through connective tissue and the final location of the metacercariae was connective tissue associated with skeletal structures. Clusters of cysts occurred at the bases of fins and in the loose connective tissue of the head, but the reaction to encysted metacercariae was insignificant. The overall effect on growth performance and thus economic importance of H. pumilio infection was assessed. Growth studies showed no significant differences between specific growth rate, food conversion ratios and condition of infected and uninfected fish.     

Studies on cryptocaryoniasis in marine fish: effect of temperature and salinity on the reproductive cycle of Cryptocaryon irritans Brown, 1951

Abstract. Trophonts of Cryptocaryon irritans Brown from infected three-spot damselfish, Dascyllus trimaculatus Ruppell, were kept at temperatures ranging from 7 to 37°C to observe encystment and development of the tomites. At 30, 25 and 20°C, the percentage of trophonts that had encysted in 16 h were 70, 77 and 64% respectively; at 37°C, 44% encysted and at 7°C only 10% had encysted.
The optimum temperature for excystment was 30°C; 50% excysted in 5 days and 100% in 7 days. At 25°C, 60% of the tomites started to excyst on the eighth day, and 70% on the ninth day. At 20°C, 10% started to excyst on the ninth day, reaching 40% on the tenth day. No excystment occurred at 37 and 7°C.
Newly encysted tomonts were placed in various dilutions of sea water (31 %₀) and kept at temperatures ranging from 7 to 37°C. Low salinities, i.e. 16%₀ and lower caused tomonts to rupture. At 37, 20 and 7°C, 35% of the tomonts started to rupture immediately in 50% sea water, while at 30 and 25 C, 30% of the tomonts ruptured in 25% seawater. However, none of the cysts developed normally at these dilutions. The percentage rupturing increased with decreasing salinity.     

清江河多鳞白甲鱼胚胎发育观察

为了提高尖翅燕鱼 (Platax teira) 的卵孵化率和苗种成活率,并为人工催产和苗种繁育提供理论依据,观察分析了尖翅燕鱼受精卵胚胎发育和仔稚鱼发育的时序特征,对其形态学指标进行测量,推算出仔稚鱼阶段生长特性的回归方程。结果显示,尖翅燕鱼受精卵为浮性卵,直径 (1.29±0.09) mm,卵壳较坚韧,呈黄色透明的球状,单个油球,无黏性。在孵化温度 (26±0.3) ℃、盐度34~36和pH 7.8±0.5条件下,整个胚胎发育经历7个阶段共27个时期,耗时27 h 45 min。初孵仔鱼全长 (3.120±0.349) mm,呈透明状,体表散布着大量分枝叶黄素,先后经历仔鱼期 (0~17 d) 和稚鱼期 (17~25 d),25 d后进入幼鱼期。此时幼鱼鳍棘和鳍条已发育完全,其典型特征为头部、躯干部和尾部各有3条黑色条带,身体呈银白色。统计模型显示,尖翅燕鱼早期阶段生长速度较缓,7日龄后生长加速;8日龄仔鱼出现残食和攻击行为。     

尖吻鲈仔鱼骨骼发育观察

掌握尖翅燕鱼 (Platax teira) 仔稚鱼脊柱及附肢骨骼系统的发育时序特征,可为其苗种繁育、环境适应及分类鉴定提供理论依据。采用软骨-硬骨双染色法对尖翅燕鱼仔稚鱼 [0~30日龄 (dah)] 脊柱、胸鳍、腹鳍、背鳍、臀鳍以及尾鳍进行染色观察与分析。结果表明,尖翅燕鱼有24枚脊椎骨,尾部骨骼由5枚尾下骨和2枚尾上骨构成,附肢支鳍骨的发育顺序为胸鳍、腹鳍、尾鳍、臀鳍和背鳍。尖翅燕鱼在初孵仔鱼已具备胸鳍支鳍骨原基和脊索,4 dah仔鱼胸鳍和腹鳍最先发育;7 dah仔鱼髓弓、脉弓开始出现;13 dah仔鱼骨骼形态和数量基本稳定;26 dah左右稚鱼开始骨化,脊柱和脊椎最先完成骨化;30 dah进入幼鱼阶段,其外表形态已经固定,与成鱼无异,典型特征为头部、躯干部和尾部各有3条黑色条带,身体呈雪白银色,受到外界刺激时体色瞬间变为黑色。尖翅燕鱼脊柱及附肢骨的发育顺序与其他海水鱼基本一致,但骨骼发育时间节点和数量有所不同。     

The occurrence of proliferative kidney disease (PKD) in cultured and wild fish: further investigations

Abstract. In an investigation of the occurrence of proliferative kidney disease (PKD) in freshwater fish other than rainbow trout, 18 species of wild fish and seven species of fish raised in cultivation wore sampled from waters where the disease occurred annually in rainbow trout, Oncorhynchus mykiss (Richardson). Results revealed that certain wild stocks of brown trout. Salmo trutta L., grayling, Thymallus thymallus L., and pike, Esox lucius L., were infected with PKD, as were cultivated Atlantic salmon, Salmo salar L., parr, brown trout and char, Salvelinus alpinus (L.). Microscopical examination revealed the presence of the PKX cell in these species and also intraluminal protozoa possibly related to the PKX cell, which were not found in the rainbow trout. Other species of freshwater fish had myxosporidan infections but, unlike PKD infection, there was little host/parasite tissue response. The PKX cell as a myxosporidan stage is discussed and the presence of the disease in wild fish is reported.     

Studies on the epizootiology of Myxobolus insidiosus Wyatt and Pratt, 1963 (Protozoa: Myxosporida)

Abstract. Myxobolus insidiosus from the striated musculature of chinook salmon, Oncorhynchus tshawytscha (Walbaum), was studied in disease free and naturally contaminated waters. Infection could not be induced in susceptible fish in a disease free water supply by any means triad. Experiments in naturally contaminated waters provided data on minimum and other exposure times. Studies were also carried out on the effect of water temperature, different substrates and flow rates, time of year and size of fish on infection. The rainbow trout, Salmo gairdneri Richardson, was also checked for infection and not found with this disease in naturally contaminated waters. Transovarian infection was ruled out.     

Gill pathology caused by infestations of adult and preadult Dissonus manteri Kabata (Copepoda: Dissonidae) on coral trout, Plectropomus leopardus (Lacépède), (Serranidae)

Adult and preadult Dissonus manteri attached to the gills of Plectropomus leopardus cause significant pathology in the form of large hyperplastic nodules on the afferent (leading) edges of gill filaments. Nodules result from the dual actions of parasite attachment and feeding. The host response is characterized by severe epithelial hyperplasia, supplemented by fibroplasia and inflammation. Parasites attach close to the gill arch near the base of filaments. They have little effect on gill vasculature as the maxillipeds penetrate the filament superficial to the efferent filament artery and do not interfere with the blood vessels of the secondary lamellae. Tissue proliferation is limited to the wide portion of filament 'edge' epithelium in the proximal third and also does not extend to the secondary lamellae. Nodules are most numerous towards the ends of hemibranchs and are generally absent from the central regions. Leading hemibranchs bear significantly more nodules than their trailing counterparts. Of the total number of nodules, 20.5% are located on the pseudobranchs. Distribution patterns are considered to be primarily the result of D. manteri avoiding strong water currents, although this cannot explain the difference between numbers on leading and trailing hemibranchs.     

Environmental effects of a marine fish farm of gilthead seabream (Sparus aurata) in the NW Mediterranean Sea on water column and sediment

This study examined the effects of organic enrichment on water column, sediments and macrofauna caused by a fish farm in the Mediterranean Sea. Samples were collected on four sampling campaigns over a one‐year cycle. Significant differences were found in the water column in dissolved oxygen, dissolved inorganic nitrogen, phosphate and total phosphorus concentrations between the fish farm and the control. The increase in the dissolved inorganic nitrogen and phosphate concentrations at the fish farm modified the stoichiometric ratios between nutrients, with silicate acting as limiting nutrient at the fish farm 11% more than at the control. Nevertheless, chlorophyll a concentration in the water column was higher at the control station, probably due to the fouling of the underwater fish farm structures. Significant differences were found in sediment concentrations of organic matter, total phosphorus and redox potential between the fish farm and the control. The Canonical Correlation Analysis indicated that organic matter, total phosphorus, redox potential and% of gravels accounted for 68.9% of the total variance in the species data. Changes were observed in macrofauna, with a decrease in number of species and up to a nine‐fold increase in abundance with respect to the control.     

Mapping of benthic habitats in northern Safaga Bay (Red Sea,Egypt): a tool for proactive management

1. The spatial distribution of the most important subtidal habitats (coral reefs, coral carpets, seagrass meadows, sand with corals, macroids, mud, hardgrounds) and mangroves was mapped in northern Safaga Bay, Red Sea, Egypt. Coral communities were analysed separately for their ecological and spatial patterns. This, coupled with information about major current patterns in the bay, provides a framework on which to base impact predictions for planned developments or for those already underway. 2. Because the entire shoreline of northern Safaga Bay is earmarked for tourism development, the following impacts have already been observed and can be expected to worsen: dredging, coastal infilling, marina construction, alteration of inshore current patterns as a result of breakwater construction and eutrophication. 3. The maps of habitats could be used by management authorities to either license or forbid these activities in specific areas, thus avoiding damage to sensitive environments. Properly used, resource mapping is a powerful proactive management tool that allows resource managers to anticipate and avoid impacts at an early stage in the process. Copyright © 2000 John Wiley & Sons, Ltd.     

东海稀有鱼类——冠丝鳍鱼的形态与分布

1999～2011年东海渔业资源监测调查共采集到273 ind冠丝鳍鱼(Zu cristatus)样本。这是我国首次报道在东海海域采集到该种稀有鱼类。冠丝鳍鱼的主要形态特征为:背鳍6+129;胸鳍11;腹鳍Ⅰ,5;尾鳍9+3;侧线鳞112;鳃耙2+9。体极侧扁,前部高大,肛门后急剧变细,侧线完全。背鳍前部1～6鳍条和腹鳍延长成细丝状。调查结果显示,冠丝鳍鱼仅在夏季出现于东海海域,从南到北均有分布,分布范围为27°00'～32°30'N、122°00'～127°00'E,集中出现于台湾暖流与黑潮暖流之间以及黄海暖流和黑潮暖流的交界水域。冠丝鳍鱼作为暖水性鱼种,主要栖息于热带水域,在东海海域出现主要是受黑潮暖流势力的影响。