大海马幼苗人工养殖条件的研究

研究了在人工养殖条件下,大海马幼苗在不同的温度、盐度、光照强度和放养密度下的生长状况及其成活率。实验在室内进行,分别对每一个环境因子设置不同的梯度,每15 d测量记录1次大海马幼苗的体长和成活率,共记录4次,并做了3次重复,最后进行统计分析。结果表明,大海马幼苗生长的最适温度为28℃,水体温度在24~32℃时,其生长速率没有明显的差异;大海马幼苗较喜欢高盐度且盐度较稳定的海水环境(20以上),至60d时,盐度为30的幼苗生长速率最快,成活率也最高;阴暗的环境较适宜幼苗生长,但光照强度过低会降低其成活率;最佳的放养密度为250ind/m3。     

Rearing the spotted seahorse Hippocampus kuda by feeding live and frozen copepods collected from shrimp ponds

This study evaluated the use of live and frozen copepods collected from shrimp ponds for rearing juveniles of the spotted seahorse Hippocampus kuda. Protein and HUFA contents in frozen copepods were all higher than in Artemia nauplii, the conventional live food for seahorse juveniles. The results of this study showed that copepods can be used as feed for rearing seahorse fry and juvenile. The spotted seahorse showed obvious preference for live copepods and rarely fed on dead copepods on the tank bottom. Furthermore, the combination of frozen copepods and live Artemia nauplii resulted in highest growth and highest survival of the experimental seahorses. Further research on possible effects of DHA:EPA ratio on survival and growth of young H. kuda is recommended.     

Biochemical composition of the wild and cultured seahorses, Hippocampus kuda Bleeker and Hippocampus trimaculatus Leach

The biochemical composition of wild and cultured seahorses Hippocampus kuda Bleeker and Hippocampus trimaculatus Leach was analysed in this study. The crude protein contents (% dry weight) of wild seahorses were high: 72.7±2.5% in H. kuda and 78.5±4.2% in H. trimaculatus . The crude lipid contents (% dry weight) of wild and cultured seahorses (1.1±0.1 vs. 1.4±0.2 for H. kuda and 1.2±0.1 vs. 1.2±0.2 for H. trimaculatus ) were low and did not differ significantly ( F _3, 12=1.461, P =0.12). The essential amino acids and flavour-enhancing amino acids in wild seahorses were higher than those in cultured seahorses, although the essential amino acid index in wild and cultured H. kuda and H. trimaculatus were generally low. The total amino acid content decreased with growth in cultured H. trimaculatus ( F _3, 12=14.927, P <0.05). The poly-unsaturated fatty acid (PUFA) contents in wild and cultured H. kuda and H. trimaculatus were 21.69%, 37.72%, 21.39% and 33.89% respectively. The fatty acid content in seahorses first decreased and then increased with growth both in wild and in cultured H. trimaculatus . The PUFA/saturated fatty acid ratio was 1.31 in cultured H. kuda and 0.87 in cultured H. trimaculatus . The trace metal concentrations in the wild seahorses were relatively low. The results presented in this study provide biochemical information necessary for understanding the medicinal value of H. kuda and H. trimaculatus and for elucidating the potential dietary requirements for their culture.     

Grow-out of juvenile seahorse Hippocampus kuda (Bleeker; Teleostei: Syngnathidae) in illuminated sea cages

This paper examines the feasibility of rearing 10–15-day- and 0.7–1.5-month-old seahorse Hippocampus kuda in illuminated sea cages to continue existing hatchery protocols to mass produce H. kuda for trade and enhance depleted wild stocks in their natural habitats. Thawed Acetes (a planktonic crustacean abundant in inshore seas) was fed to juvenile seahorses in lighted and unlighted sea cages while one group in lighted cages was not fed Acetes . After 10–12 weeks of rearing, both mean body weight and stretch height increased in all treatment groups, with lighted cage-reared seahorses fed Acetes being heavier (2 g) and longer (8 cm) than the other two treatment groups. Although instantaneous growth rates declined during the rearing period, these were generally higher among Acetes -fed seahorses in lighted cages (0.02–0.07) compared with those in the unlighted cages with Acetes and lighted cages without Acetes feeding. Mean survivorship in all groups ranged from 9% to 74% after the trials, but mean survivorship of juveniles in lighted cages with Acetes feeding (9–74%) was consistently lower than the two treatment groups as a likely result of crustacean and piscine predators being attracted by light and the odour of leftover Acetes in the lighted cages. These results demonstrate that light-attracted zooplankton prey supplemented by Acetes feeding may provide essential nutrients for the growth of H. kuda juveniles in illuminated sea cages. With further improvement in the grow-out protocol, it may provide a possible alternative livelihood to seahorse fishers and sufficient seed to re-populate depleted wild stocks of H. kuda .     

Study on an integrated eco‐aquaculture system for rearing the yellow seahorse,Hippocampus kuda Bleeker

Seahorse aquaculture is challenged by insufficient feeding supply and lack of biological and nutritional knowledge, resulting in low survival rate and poor economical profitability. We report here an integrated eco‐aquaculture system in which the yellow seahorse and its natural prey were co‐cultured with fertilized water and seaweed in cement ponds. In the first stage, urea (10 g m^?3) and chicken manure (50 g m^?3) were used to fertilize the cultured water, 5–7 days later, rotifer and micro‐crustaceans were flourishing. Then, seahorse juveniles were stocked at 200 ind m^?3. After 2 weeks, seaweed Gracilaria lichevoides was transplanted into the ponds to regulate water quality, light and to provide holdfast attachment for seahorses. The optimal density of G. lichevoides was controlled between 0.5 and 2 kg m^?3. The introduction of seaweed provides the habitat for natural food of seahorse. Within the cluster of the seaweed, small crustacean density was over 450 individuals per 100 g of fresh weight. Initial size of seahorse juvenile was 1.03 ± 0.091 cm, After the 146‐day rearing period, seahorse survival rates were 70.8%, 57.7% and 42.5%, and body standard lengths were 11.33 cm, 10.84 cm and 10.04 cm in the integrated eco‐aquaculture system (GFA) and in monoculture systems of FA (fertilized + feeding) and BA (only feeding) respectively. This system incorporated traditional Chinese aquaculture technique in which feedings nature food organisms were cultivated by fertilization and ecological regulation. Results from these preliminary experiments suggest that the integrated system could be technically feasible, suitable and exemplary.     

A study on bacteria associated with the intestinal tract of farmed yellow seahorse,Hippocampus kuda (Bleeker, 1852): characterization and extracellular enzymes

The microenvironment of bacteria associated with the gastrointestinal tract of an animal influences the host in many ways, including the metabolism of several nutrients. Isolation, molecular characterization and enzymatic activities of culturable bacteria associated with the gastrointestinal tract of hatchery‐reared oceanic yellow seahorse, Hippocampus kuda, were investigated in the present study. 16S rRNA sequencing of bacterial isolates yielded 10 different bacterial genera belonging to two major groups: proteobacteria (62.9%) and firmicutes (37.03%). The predominant microbial flora belonged to the genera Vibrio spp., Enterovibrio sp. and Bacillus spp. Burkholderia cenocepacia, hitherto unreported from the gastrointestinal tract of marine fish, was retrieved from the seahorse gut, albeit in small numbers. Enzymatic studies indicated that the bacterial isolates possess the ability to degrade lipids, cellulose, xylan, starch and proteins. Lipase activity was exhibited by a majority of the isolates (70.4%), indicating that the bacterial flora associated with the intestinal tract of seahorses is capable of digesting foods rich in lipids. The possible implications for the role of these bacteria in the digestion and physiological processes are discussed. To our knowledge, this is the first time that the characterization and enzymatic activities of bacteria associated with the intestinal tract of farmed seahorses have been reported.     

Diseases of captive yellow seahorse Hippocampus kuda Bleeker,pot‐bellied seahorse Hippocampus abdominalis Lesson and weedy seadragon Phyllopteryx taeniolatus (Lacépède)

Seahorses, pipefish and seadragons are fish of the Family Syngnathidae. From 1998 to 2010, 172 syngnathid cases from the Toronto Zoo were submitted for post‐mortem diagnostics and retrospectively examined. Among the submitted species were yellow seahorses Hippocampus kuda Bleeker (n = 133), pot‐bellied seahorses Hippocampus abdominalis Lesson (n = 35) and weedy seadragons Phyllopteryx taeniolatus (Lacépède; n = 4). The three most common causes of morbidity and mortality in this population were bacterial dermatitis, bilaterally symmetrical myopathy and mycobacteriosis, accounting for 24%, 17% and 15% of cases, respectively. Inflammatory processes were the most common diagnoses, present in 117 cases. Seven neoplasms were diagnosed, environmental aetiologies were identified in 46 cases, and two congenital defects were identified.     

Identification and characterization of the pathogen associated with skin ulcer syndrome in lined seahorse,Hippocampus erectus

The lined seahorse, Hippocampus erectus, is an Atlantic species, which mainly inhabits shallow sea beds or coral reefs. Seahorse has become very popular in China due to its wide use in traditional Chinese medicine (TCM). However, the aquaculture of the lined seahorse has been threatened by a variety of diseases, especially bacterial infections. Skin ulcer syndrome becomes more and more common in the culture of seahorses, leading to skin ulcer, liver erosion and minority tail rotting. These diseased seahorses die in only 72 hr, causing huge economic losses in aquaculture. Pathogen HMT‐1 was isolated from the lined seahorses with skin ulcer syndrome, which was identified as Vibrio harveyi. The median lethal dose (LD₅₀) of HMT‐1 was 2.88 × 10⁸ cfu/ml. The pathogenic mechanism of HMT‐1 was preliminarily studied, and the pathological changes of the diseased lined seahorses were also investigated. Moreover, the activities of ACP, complement 3, SOD and LZM at different time post injection were measured by commercial kits. Our findings can provide reliable reference for diagnosis and treatment in the future.     

Effect of starvation on survival and biochemical profile of newborn juvenile lined seahorses,Hippocampus erectus (Perry, 1810)

This study assessed the effect of starvation on survival and nutritional status of newborn juveniles H. erectus (<10 days) to optimize rearing protocols, thereby helping to reduce wildlife exploitation. Maximum starvation time (MST) was estimated through the survival of juveniles continuously starved from birth. Resistance to starvation and the effect of food re‐introduction after 1, 2, 4 and 6 days of starvation on survival and metabolite concentrations (total proteins, total lipids, acylglycerides, cholesterol, glucose) were also determined. Survival amongst continuously starved animals decreased from 6.6 ± 0.5 to 0% from days 9 to 10 of starvation. Seahorses under different starvation–refeeding treatments all had 100% survival up to day 5 of experiments. After 10 days, however, a 4‐day starvation period followed by refeeding showed negative effects with <50% survival. During continuous starvation, lipids were the first energy reserve used to maintain basal metabolism, followed by proteins. Except for cholesterol, all metabolite concentrations differed between continuous starvations and feeding. Despite high seahorse survival after 5 days in the absence of food, the recovery of the metabolic status is possible after a starvation period of no more than 2 days, since irreversible physiological changes compromising the ultimate survival of the organisms take place after this time.     

Feeding selectivity of the seahorse,Hippocampus kuda (Bleeker), juveniles under laboratory conditions

This study examined the feeding selectivity of Hippocampus kuda juveniles under captive conditions and evaluates different food organisms that could be used to improve hatchery‐rearing of this species. Newly born H. kuda were reared for 10 days in 60‐L capacity tanks and fed rotifers (Brachionus rotundiformis), zooplankton (mostly Pseudodiaptomus annandalei and Acartia tsuensis) alone or both food sources. The size and amount of food ingested increased as seahorses grew. Selective feeding of seahorses appeared to change as they develop, preferring copepod adults over nauplii and rotifers. A. tsuensis was highly selected by juveniles over P. annandalei. Specific growth rate in terms of body weight (SGR‐BW, 15% day^–1) was the highest and mortality rate (9% at day 10) the lowest in seahorses fed a mixed food sources. Slowest growth rate (0.3% day^–1) and highest mortality rate (60% at day 7) were observed in seahorses fed rotifers alone. These results indicate that copepods are suitable food for seahorse juveniles, but a mixture of food organisms in the rearing tank environment enhances survivorship and growth of H. kuda, thus potentially providing a source of cultured rather than wild specimens for characterizing the life history of this threatened species.     

The administration of Lactobacillus plantarum directly to food: An effective way to improve the survival and growth of juvenile lined seahorses (Hippocampus erectus)

Previously, we found Lactobacillus plantarum had probiotic effects on lined seahorse (Hippocampus erectus) juveniles by the addition Lactobacillus directly into rearing seawater containing juveniles and their food (i.e. copepods). However, how the juveniles consumed Lactobacillus, directly from water or from copepods in whose guts Lactobacillus may have accumulated by ingestion, is still unclear. To clarify this, three experiments were successively carried out in this study. In the first experiment, the manner by which juveniles consumed Lactobacillus, namely, directly from food, was discovered via a 2 × 2 factorial design with two factors of water and food, and two levels with and without L. plantarum. In the second experiment, a 5 × 4 factorial design with five levels of L. plantarum doses (D: 5, 10, 20, 40 and 80 × 10⁸ cfu/L) and four levels of enrichment time (T: 0.5, 1.0, 1.5 and 2.0 hr) was conducted to analyse lactic acid bacteria (LAB) contents in the enriched copepods under different treatments. In the third experiment, six kinds of Lactobacillus‐enriched copepods chosen from the second experiment that carried significantly different LAB contents were fed to juveniles, and it was found that the copepods containing LAB greater than 5 log₁₀colonies/g had the most improved effects for survival and growth. In conclusion, the effective manner of L. plantarum administration in seahorses is by the addition to their food. Additionally, D40 * T1.0, whose LAB content was more than 5 log₁₀colonies/g, is generally the most economic copepod treatment for improving survival and growth in H. erectus rearing.     

Effect of chemical and physical treatments on the inactivation of Macrobrachium rosenbergii nodavirus and extra small virus

White tail disease (WTD) is found to cause immense economic losses in hatcheries, with mortalities often reaching 100% within 4 or 5 days. The pathogenic agents have been identified as Macrobrachium rosenbergii nodavirus (MrNV) associated with extra small virus (XSV), which are 27 and 15 nm in diameter respectively. The effects of some chemical disinfectants hydrogen ions (pH), heat and ultraviolet (UV) irradiation on the inactivation of MrNV and XSV were investigated. The viral inoculum exposed to UV irradiation for a period of 5 min and more was totally inactivated and failed to cause mortality in postlarvae of prawn. The viruses were totally inactivated by this high pH (8.5, 9 and 10). The viral suspension treated with sodium hypochloride, formalin, Benzalkonium chloride and Benzethonium chloride at the concentration of 200 ppm caused 100% mortality in postlarvae of prawn. Iodine was found to be effective to inactivate MrNV and XSV at the concentration of 100 ppm or more, whereas the viral suspension treated with iodine at the concentration of 50 ppm or less caused mortality in postlarvae. The infected postlarvae in treated and positive control groups showed positive by RT‐PCR for these viruses.     

White spot syndrome virus epizootic in cultured Pacific white shrimp Litopenaeus vannamei (Boone) in Taiwan

White spot syndrome virus (WSSV) has caused significant losses in shrimp farms worldwide. Between 2004 and 2006, Pacific white shrimp Litopenaeus vannamei (Boone) were collected from 220 farms in Taiwan to determine the prevalence and impact of WSSV infection on the shrimp farm industry. Polymerase chain reaction (PCR) analysis detected WSSV in shrimp from 26% of farms. Juvenile shrimp farms had the highest infection levels (38%; 19/50 farms) and brooder shrimp farms had the lowest (5%; one of 20 farms). The average extent of infection at each farm was as follows for WSSV‐positive farms: post‐larvae farms, 71%; juvenile farms, 61%; subadult farms, 62%; adult farms, 49%; and brooder farms, 40%. Characteristic white spots, hypertrophied nuclei and basophilic viral inclusion bodies were found in the epithelia of gills and tail fans, appendages, cephalothorax and hepatopancreas, and virions of WSSV were observed. Of shrimp that had WSSV lesions, 100% had lesions on the cephalothorax, 96% in gills and tail fans, 91% on appendages and 17% in the hepatopancreas. WSSV was also detected in copepoda and crustaceans from the shrimp farms. Sequence comparison using the pms146 gene fragment of WSSV showed that isolates from the farms had 99.7–100% nucleotide sequence identity with four strains in the GenBank database – China ( AF332093 ), Taiwan ( AF440570 and U50923 ) and Thailand ( AF369029 ). This is the first broad study of WSSV infection in L. vannamei in Taiwan.     

温度对大海马摄食行为及生长速率的影响

选取体质良好、活力强的大海马(Hippocampus kuda Bleeker),体重(3.075 g±0.16 g)、体全长(11.55 cm±0.31cm)。设置18℃、23℃、28 3℃个实验组和1个对照组(CT组:自然变温),每组3个重复,实验周期28 d。结果显示,大海马在23℃时生长速率最快,摄食活跃;28℃大海马反应最迅速(5.8 s±0.74 s),摄食量最大(153.92 g±10.33 g),活动频繁,泳速大;而18℃和自然变温条件下对食物的反应不敏感,多缠绕在附着物上,摄食时呈聚集式分布;23℃和28℃时,相对活跃,会主动游向饵料摄食,摄食效率较高。综上所述,温度的改变对大海马的生长速率及摄食行为均有一定影响;在适宜温度下,大海马的活力大,摄食量多,生长速率相对较快。本研究旨在为大海马饵料开发和养殖环境优化提供科学数据。     

Potential virulence factors of bacteria associated with tail fan necrosis in the spiny lobster,Jasus edwardsii

Tail fan necrosis (TFN) is a common condition found in commercially exploited spiny lobsters that greatly diminishes their commercial value. Bacteria possessing proteolytic, chitinolytic and lipolytic capabilities were associated with TFN in spiny lobsters, Jasus edwardsii. In this study, 69 bacterial isolates exhibiting all the three enzymatic capabilities from the haemolymph and tail fans of J. edwardsii with and without TFN were further characterized and compared, including morphology, biofilm formation, antimicrobial activity, antimicrobial resistance, and production of siderophores, melanin and ammonia. The genomic patterns of the most common Vibrio crassostreae isolates were also compared between TFN‐affected and unaffected lobsters. Biofilm formation was stronger in bacterial isolates from both haemolymph and tail fans of TFN‐affected lobsters compared to those from the unaffected lobsters, while melanin production and siderophore production were stronger in the isolates from tail fans of lobsters with TFN. By contrast, the other characteristics of isolates were similar in lobsters with and without TFN. The Vib. crassostreae isolates from the affected lobsters had similar genomic patterns. Overall, the results indicate that in addition to proteolytic, chitinolytic and lipolytic activities, the bacteria associated with TFN commonly have enhanced activity of important virulence factors, including biofilm formation, melanin production and siderophore production.     

Analysis of the diet of the long‐snouted seahorse Hippocampus guttulatus by 18SrDNA amplification of prey in faeces

Breeding in captivity for research or exhibition (e.g. in aquaria) can replace the capture of wild specimens of endangered species and allow controlled reinforcement of wild populations. With this aim, diet analysis and establishing the adequate prey are determinant factors for breeding success. However, non‐invasive approaches such as faecal DNA analysis are advisable for analysing the diet of these species. Therefore, the aim of the present study was to demonstrate the usefulness of faecal DNA analysis by specific PCR amplification of prey DNA for assessing the diet of the seahorse Hippocampus guttulatus. In a comparison of the suitability of different genes (COI, 18SrRNA and 28SrRNA), 18SrRNA was found to be the most suitable for designing specific primers for the prey types fed to seahorses (Artemia, Palaemonetes and Mysidae). The technique was assessed in feeding experiments in which prey ingestion was recorded daily, and faeces were collected for DNA extraction and presence/absence PCR analysis. Amplification of the prey DNA in faeces was consistent with the sequence of prey supplied (prey eaten the day before was always detected). Differences in the time between feeding and detection in faeces suggested prey‐specific gut passage times, which were shorter for Palaemonetes than for Mysidae. This fact highlights the importance of feeding trials to avoid overestimating the consumption of prey with long gut retention when PCR‐based methods are used. This molecular technique is thus applicable for studying the feeding behaviour of captive seahorses and could be adapted for use in other marine species.