New sites expanding the “Sardinian cold‐water coral province” extension: A new potential cold‐water coral network?

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Can we adjust a marine cyclopoid copepod to freshwater?—First step towards a ‘universal’ live feed product for fish and shrimp larvae

The copepod Apocyclops royi tolerates very low salinity while being highly capable of synthesizing n-3 fatty acids based on PUFA-poor diets. The feasibility of culturing A. royi in freshwater fed with baker's yeast was evaluated. The copepods were adjusted for 8 days by decreasing stepwise from salinity 20 to freshwater diluting with deionized water. Initially, the cultures exhibited adequate survival and reproduction. However, after 10 days in freshwater, they stopped reproducing presumably due to the lack of vital ions in the medium. Therefore, before continuing the freshwater cultures, we tested the survival of a batch of salinity 1 pre-acclimated adults and copepodites in various types of freshwater: deionized, bottled ‘mineral’ and tap water for 48 h. All copepods died in deionized water, but a significantly higher survival, 29% ± 11%, was found in mineral water versus 11% ± 8% in tap water. Hence, we continued culturing the copepods in freshwater using ‘Maglekilde spring’ water as diluter. The copepods regained and kept reproducing until day 71 where the experiment was terminated. After a 48 h freshwater versus salinity 20 exposure, nauplii survival was significantly less in freshwater 25 ± 12 versus 79 ± 20 (±STD) at salinity 20 but not different in mean body length. For the first time, we conducted NMR metabolomics revealing a large decrease in glycine betaine and a large increase in lactate in the copepods when challenged by freshwater versus salinity 20. There is obviously a ‘price to pay’ when culturing not only the copepods in freshwater, but also perspectives in developing a ‘universal’ A. royi live-feed product.     

The lake at Llandrindod Wells—a restoration comedy?

• 1. The lake at Llandrindod Wells, Wales, UK, is a typical urban shallow lake. Created in the 19th century for amenity, it has a long history of management for various, often conflicting, purposes. After the 1950s, the once clear water became turbid with phytoplankton, and aquatic plants became very scarce.
• 2. The most likely reason for this was introduction of common carp, for angling, into a fish community that contained no piscivores. Mobilization of phosphorus from the sediments by activities of the fish led to severe internal phosphorus loading, culminating ultimately in a requirement to close the lake, temporarily in summer, to water contact activities, because of a risk of toxic cyanophyte blooms.
• 3. The lake‐owners decided to restore the lake to greater amenity and conservation value by biomanipulation of the fish community and associated works. The restoration was successful in restoring clear water and plant communities, but because of the nature of the plants reintroduced, there were new problems of dense plant growth. Ownership of the lake then changed and, in a somewhat confused situation, the lake has been returned to a carp fishery.
• 4. Documents on the history of management of the lake, and available limnological data, are reviewed in relation to a general strategy for lake restoration and general lessons are drawn for future restoration projects.

Copyright © 2002 John Wiley & Sons, Ltd.     

Hole‐in‐the‐head disease in discus fish,Symphysodon (Heckel, 1840): Is it a consequence of a dietary Ca/P imbalance?

Hole‐in‐the‐head (HITH) disease‐affected fish develop characteristic lesions in the skin above sensory pores of the head and the trunk. This study investigated whether an unfavourable Ca/P ratio in the diet could provoke lesions consistent with HITH disease in discus fish Symphysodon (Heckel, 1840) as a comparable condition to secondary hyperparathyroidism of tetrapod species. Two groups of five fish were fed a plain beef heart diet (Ca/P of 0.03), whereas two other groups were kept on commercial discus feed (Ca/P of 2.73). Each feeding group was submitted to two different water hardness regimes (35.66–71.39 mg/L CaCO₃ and 124.94–196.33 mg/L CaCO₃, respectively). All fish were observed for the development of the characteristic lesions for 16 weeks. At the end of the study, histological, bacteriological and parasitological examinations were conducted and plasma Ca, P and Mg values were determined. Diplomonad flagellates were detected in two fish. Isolated bacteria of all groups mostly belonged to Aeromonadales and Pseudomonadales. No significant difference of plasma mineral values between the groups was observed. Compared to the results of other authors, Ca stayed mainly in the range and P exceeded the reference values. Histological examinations did not indicate HITH disease, and no fish developed signs of the disease during the study. Clinical trial registration number GZ 68.205/0135‐WF/V/36/2014.     

201型家鱼人工孵卵箱试制成功

法库县尚屯水库发扬自力更生、艰苦奋斗的革命精神,试制成功了201型家鱼人工孵卵箱。     

201型家焦人工孵卵箱试制成功

法库县尚屯水库发扬自力更生、艰苦奋斗的革命精神,试制成功了201型家鱼人工孵卵箱。 201型家鱼人工孵卵箱材料来源方便,结构简单,制作方便,使用效果好,受精卵孵化率达百分之九十五以上。现介绍如下:     

Diversification economies and efficiencies in a ‘blue-green revolution’ combination: a case study of prawn-carp-rice farming in the ‘<Emphasis Type="Italic">gher</Emphasis>’ system in Bangladesh

‘Gher’ farming is a unique system that incorporates the joint operation of three enterprises: freshwater prawn, fish and HYV rice and is expanding rapidly in the coastal regions of Bangladesh. In this paper we evaluate the performance of this unique system in terms of the existence of diversification economies (amongst the three integrated enterprises), scale economies and technical efficiency using a stochastic input distance function approach on a sample of gher farmers. The results reveal evidence of a diversification economy in the rice–carp combination. Economies of scale exist in the ‘gher’ farming system. The level of technical efficiency is estimated at 68% implying that a substantial 47% [(100−68)/68] of potential output can be recovered by removing inefficiency. Significant efficiency gains are made from diversification amongst these enterprises. Also, the education of farmers and the female labour input significantly improve efficiency whilst larger operation size reduces efficiency. The key policy implication is that the diversification of enterprises, particularly the rice–carp combination, is beneficial and should be promoted. Also investment in education and creation of a hired labour market for females would improve technical efficiency.     

Stable isotope analysis reveals ontogenetic migration and the importance of a large mangrove estuary as a feeding ground for juvenile John’s snapper <Emphasis Type="Italic">Lutjanus johnii</Emphasis>

Stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios were measured to investigate the migration of John’s snapper Lutjanus johnii and its dependence on the food resources provided within the large Matang Mangrove Forest Reserve (40,151 ha), Malaysia. John’s snapper, and its main prey food such as penaeids, Acetes shrimps and mysids, showed generally depleted δ¹³C values in the inner mangrove area but more enriched values in the river mouth and coastal area. Some juveniles migrated into the inner mangrove areas, although they were also distributed near the river mouth areas. Isotopic signatures of snapper fish and prey reveal the ontogenetic migration of the youngest juvenile fish (<5 cm in total length) from the coastal area into the mangrove area, shifting their dependence from the coastal food web to the inner mangrove food web with their growth. The study shows the importance of the complex interconnected mangrove waterways and associated prey animals present in the large mangrove system to juvenile John’s snapper.     

Spatial–temporal variations in the composition of two <Emphasis Type="Italic">Zostera</Emphasis> species in a seagrass bed: implications for population management of a commercially exploited grass shrimp

We examined spatial and temporal variations in the species composition of two seagrass species, Zostera marina and Z. caespitosa, in a lagoon facing the Sea of Okhotsk. We also considered how those variations affected habitat quality for motile epifauna, especially for a commercial shrimp. A long-interval comparison between 1996 and 2013 showed that seagrass species composition in the lagoon did not vary, while their relative abundances did. A survey in 2012 revealed that the abundance of Z. caespitosa was affected by the abundance of Z. marina, water depth, and location in the lagoon. Although these seagrass species have similar aboveground morphology, differences in their fine structures were detected. Diversities of motile animals inhabiting the seagrass species were the same. Differences in seagrass utilization were observed when we focused on a commercial shrimp, Pandalus latirostris. This shrimp always preferred higher densities of shoots irrespective of the species and seasonally changed their preference for the number of leaves per shoot. They were therefore more abundant in Z. caespitosa, which had those structural characteristics. The results suggest that the management of shrimp resources could be improved by flexibly changing protected areas in accordance with the dynamics of seagrass distribution in the lagoon.     

Can water disinfection prevent the transmission of infectious koi herpesvirus to naïve carp? – a case report

Hygienic measures such as disinfection are important tools for the maintenance of fish health in aquaculture. While little information is available on the disinfection of water intended for fish containment, Huwa‐San^®, a disinfectant used in food and water industries, was used for daily treatment at concentrations of approximately 60 ppm over a total period of 3 months (experiment 1) with a 3‐week treatment‐free interval after 2 months (experiment 2). During this period, koi herpesvirus (KHV) was added to the water of two aquaria, one used as a normal contact control, the other one receiving daily water disinfectant treatments that prevented KHV infection of carp. In the second experiment, Huwa‐San^® treatment was interrupted and KHV infection was prevalent. However, when naïve fish were introduced to the same aquarium after re‐application of disinfectant, KHV could not be detected in those naïve fish. Whilst KHV could not be detected in samples where disinfectant had been applied, it was present in samples of naïve fish cohabiting with infection contact control animals which had undergone no disinfectant treatment over experiments 1 and 2. The results presented here show that water treatment with a disinfectant may prevent transmission of infectious KHV to naïve carp cohabited with infected carp.     

2017月10全国水产养殖病害预测预报

<正>今年10月,有我国农历的寒露和霜降两个节气,预示着全国天气已经转凉,全国平均温度为10℃~20℃,降水量也显著减少,全国平均降水量只有49mm。我国大部分地区的水产养殖进入后期管理阶段,养殖的鱼类进入越冬前的最后生长期,由于池塘载鱼量较大,残饵及代谢物沉积较多,易厌氧发酵产生氨氮、硫化氢等有害物质,同时昼夜温差逐渐增加,上下     

精&#183;新&#183;实&#183;易&#183;活——优化课堂教学初探

为了实现由应试教育向素质教育的转变 ,适应现代社会对高素质人才的需要 ,必须加强素质教育 ,而实现素质教育的核心问题是提高课堂教学质量 ,因此 ,创设最优化课堂教学、促进学生个性健康发展和素质的全面提高是极其必要的。本文拟就这一问题 ,举《淡水生物学》教学中之例 ,谈谈粗浅的“五字法”。一、精指授课“精”和板书“精”。1、授课“精”。教师讲课时照本宣科 ,会使学生无所适从 ,觉得枯燥乏味 ,甚至于“丢了西瓜 ,拣了芝麻”。因此 ,教师应深入钻研教材 ,挖掘课程体系 ,找出每章、每节课的难点和重点 ,分清轻重、强弱 ,强化重点和…     

中国渔政201船北太平洋渔政巡航顺利归来

按照中国渔政指挥中心关于加强北太鱿钓渔场管理的指示精神,2003年7月30日—8月30日,农业部东海区渔政渔港监督管理局所属的中国渔政201赴北太平洋执行了渔政巡航管理任务。此航次历时32天,航程6200海里,航时600小时,耗油130吨。主要在151°E、42°N至167°30′E、42°30′N为轴线的公海海域对在北太作业的我国鱿钓渔船进行了指导、管理和服务。由于北太渔场的天气状况很不稳定,低气压频繁。在一个月的巡航中少有晴天,经常大雾弥漫,能见度差,涌浪始终不断,受风浪影响,渔政船无法实施登临检查,只能以观察”记录”拍摄为主。据统计,共观察记…     

Cypermethrin and λ-cyhalothrin induced alterations in nucleic acids and protein contents in a freshwater fish, <Emphasis Type="Italic"> Channa punctatus</Emphasis>

In this study, a freshwater fish Channa punctatus was exposed to subacute concentrations of synthetic pyrethroid insecticides (cypermethrin and λ-cyhalothrin) for 96 h to evaluate their impact on the levels of nucleic acids and protein in its different organs. Significant enhancement in the level of DNA was recorded in all tissues of the fish at high concentration of cypermethrin, whereas RNA and protein contents increased in tissues at all concentrations of cypermethrin tested. In contrast, λ-cyhalothrin treatment caused an increase in the level of DNA only in liver and brain, whereas increase of RNA and protein varied to different levels in different tissues. Cypermethrin treatment induced RNA/DNA ratio in all fish organs tested, whereas λ-cyhalothrin caused a sharp decrease in the ratio. Protein/DNA ratios were found to be tissue specific in treatments with both of the insecticides. The results clearly indicated that both of these pyrethroids exerted their effects in a similar manner in fish liver but differed in other tissues. These insecticides acted as potential biomodulators in C. punctatus, though following different routes. The results may be an indicator of aquatic pollution affecting freshwater fauna and flora and thus signaling the need for strict regulation on the indiscriminate input of pyrethroids from agricultural sites.     

Studies on feminization,sex determination,and differentiation of the Southern catfish, <Emphasis Type="Italic">Silurus meridionalis</Emphasis>—a review

The sex ratio of the feral Southern catfish was reported to be about 1:1, while the fish obtained by artificial fertilization were always female. Hence, we examined the possible influence of the micro-environment during artificial insemination (pH of the ovarian fluid and concentration of the semen) and early development (feed, hatching temperature, and water) on the sex ratio of Southern catfish fry. In order to examine the possibility of the occurrence of gynogenesis during artificial propagation, cytological observations on the insemination processes and the artificial induction of gynogenesis were also performed. However, no male fish were obtained even in these experiments, excluding the possibilities of these micro-environmental changes on catfish sex ratio and the occurrence of gynogenesis during artificial propagation. Female-to-male sex reversal was achieved by treatment with fadrozole (an aromatase inhibitor) and tamoxifen (an estrogen receptor antagonist). Histological analyses on the gonadal development of both female and induced male fish were subsequently performed. Moreover, several genes involved in sex differentiation, such as dmrt1, foxl2, and cyp19, and three subunits of gonadotropin (gth), i.e., gthα, lhβ, and fshβ, were isolated. Their expression patterns were studied under normal gonadal development and sex reversal conditions. The results revealed that dmrt1, foxl2, and cyp19a were closely related to catfish sex differentiation, and the gth subunits were possibly related to ovarian differentiation and oocyte development. Taken together, we hypothesized that estrogen was highly responsible for the ovarian differentiation and feminization of catfish fry under artificial propagation, although the mechanism involved remains elusive.     

中国渔政201、118圆满完成北太巡航任务

(本刊讯继风报道)2004年8月12日上午9:30,中国渔政东海总队码头上空骄阳似火,一艘雪白色的渔政船鸣着气笛缓缓靠上码头.东海总队副总队长王浩急步走下弦梯,向正在迎候渔政201归来的中国渔政指挥中心、东海区局及有关单位的领导报告:"中国渔政201完成北太巡航任务,顺利返航归来."船舷一侧,35名执行本次巡航任务的渔政员站成两列同时向前来迎接的领导和同志们敬礼致意.一双双眼睛经过海水地洗礼显得格外清澈,一身身蓝色渔政制服在阳光地映衬下显得格外鲜艳.     

Cloning,expression, and induction by 17-β estradiol (E<Subscript>2</Subscript>) of a vitellogenin gene in the white cloud mountain minnow <Emphasis Type="Italic">Tanichthys albonubes</Emphasis>

Vitellogenins (Vtgs), the precursors for the yolk proteins, are very important for the embryonic development of teleosts, and have also been studied extensively as biomarkers for environmental estrogenic mimics. The cDNA for a Vtg was isolated from the liver of the female white cloud mountain minnow (Tanichthys albonubes) by 3′- and 5′-RACE methods. It is 4,171 bp in full length, and encodes a putative protein of 1,326 amino acids. This putative Vtg, designated as wcmmVtg, contains complete portions of LVI and PV, but lacks the C-terminal half of LVII and thus belongs to type I vitellogenin. In addition to the liver of the female fish, wcmmVtg was also shown to be expressed in the ovary. During ovarian development, the mRNA expression of wcmmVtg in both the liver and ovary was continuously increased from the previtellogenic to late vitellogenic stages, but then decreased significantly at post-spawning stage. In the male fish, expression of wcmmVtg mRNA was induced in the liver by treatment with E₂ (10 and 100 ng/l) for 14 days. These results suggest that the Vtg originated from the ovary of the white cloud mountain minnow may also contribute to the accumulation of yolk proteins during oocyte growth, and that the male white cloud mountain minnow is sensitive to the estrogenic treatment in terms of Vtg mRNA expression, which could also be applied to monitor the environmental estrogenic mimics.     

Experimental infection of <Emphasis Type="Italic">Betanodavirus</Emphasis> in freshwater fish <Emphasis Type="Italic">Gambusia affinis</Emphasis> (Baird and Girard, 1853)—a potential infection model for viral encephalopathy and retinopathy

Betanodaviruses are the causative agents of the disease known as viral nervous necrosis (VNN) or viral encephalopathy and retinopathy (VER) in a variety of marine and freshwater fish species. The aim of this study was to demonstrate experimental infection of an isolate of betanodavirus (RGNNV genotype) in freshwater fish, Gambusia affinis, for elucidation of transmission mechanism and potential use as a laboratory model. Morbidity and mortality rate was significantly higher by injection route of infection as compared to immersion by bath and resembled the natural infection of juvenile marine fish. The fish in disease affected group showed severe neurological disorders accompanied by extensive vacuolar degeneration and mild to moderate neuronal necrosis of the brain in comparison to control. Amplification of ~?427 bp product in the variable region of the coat protein gene of betanodavirus was achieved by RT-PCR with 100% sequence homology to RGNNV genotype.     

Microbiological aspects of common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis>) and its processing—relevance for final product quality: a review

The aquaculture production of common carp (Cyprinus carpio) is one of the biggest on a global scale, although European production represents a minor part. Thus, common carp is a little-exploited, low-cost, and highly nutritious food source. For development of new quality products that have customers’ appeal and are safe, a combination of traditional and novel technologies can be used. However, good quality raw material is of basic importance for further processing and final product quality. Fish microbiota have a major role in fish spoilage and as potential human pathogens. To diminish the negative impact of the microbiota on fish, different methods and technologies can be used. The important steps before the final product processing in the production of common carp products include purging, transport, pre-slaughter storage, slaughter method, bleeding, cleaning, desliming, descaling, and gutting. The most important factor in fish spoilage prevention is chilling, although to assure longer freshness and shelf-life, the concept of hurdle technology should be used. Many preservation and packaging techniques have been developed for fish products, but not all have been researched for common carp products. This review aims to identify the gaps in research, knowledge, and practice for the microbiological aspects that impact upon the production of high-quality common carp food products.     

Effects of fish species composition on Diphyllobothrium spp. infections in brown trout – is three‐spined stickleback a key species?

Subarctic populations of brown trout (Salmo trutta) are often heavily infected with cestodes of the genus Diphyllobothrium, assumedly because of their piscivorous behaviour. This study explores possible associations between availability of fish prey and Diphyllobothrium spp. infections in lacustrine trout populations. Trout in (i) allopatry (group T); (ii) sympatry with Arctic charr (Salvelinus alpinus) (group TC); and (iii) sympatry with charr and three‐spined stickleback (Gasterosteus aculeatus) (group TCS) were contrasted. Mean abundance and intensity of Diphyllobothrium spp. were higher in group TCS compared to groups TC and T. Prevalence, however, was similarly higher in groups TCS and TC compared to group T. Zero‐altered negative binomial modelling identified the lowest probability of infection in group T and similar probabilities of infection in groups TC and TCS, whereas the highest intensity was predicted in group TCS. The most infected trout were from the group co‐occurring with stickleback (TCS), possibly due to a higher availability of fish prey. In conclusion, our study demonstrates elevated Diphyllobothrium spp. infections in lacustrine trout populations where fish prey are available and suggests that highly available and easily caught stickleback prey may play a key role in the transmission of Diphyllobothrium spp. parasite larvae.