大海马在人工养殖条件下的生长速率

报道了在人工养殖条件下,大海马(Hippocampus kuda Bleeker)的体长与体重的相对生长率、生长比率及生长速度与饵料、水温等环境因子的关系。结果表明，大海马生长高峰期为5～11月，群体体长月平均增长率为12.20％，体长特定增长率为15.92％；体重月平均增重率为15.87％，体重特定增重率为27.70％，群体增重倍数为13.8。大海马体长呈逻辑斯蒂曲线增长，关系式为L＝192.3460／(1＋e     

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。     

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。     

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.     

Biochemical composition of wild and cultured seahorses (Hippocampus kuda Bleeker)

The seahorse has been used for thousands of years as an important traditional Chinese medicine (TCM) in China. Many species of wild seahorse have become endangered, but demand for them continues to grow rapidly. Therefore, it is urgent to cultivate seahorses to relieve the strain on natural populations and meet the market demand for this TCM. In this study, medicinal components of wild and cultured yellow seahorses (Hippocampus kuda Bleeker) were analysed and compared. Different parts of the body (cortex and bone), male and female specimens, and seahorses of different ages were analysed. Crude protein, crude fat, trace elements, calcium, amino acid, fatty acid, steroid and cholesterol content were measured. The results showed that moisture content accounted for 70% of wet weight and ash content increased with growth. Crude protein and fat contents were higher in cultured seahorses than in wild specimens, and the content of Zn in cultured seahorses (93.26 ± 10.44%) was significantly higher than that of same‐aged wild seahorses (74.20 ± 3.83%). Amino acid and fatty acid contents of cultured seahorses also were higher than those of wild seahorses. These findings show that cultured seahorses can also be used in TCMs and that 1‐year‐old cultured seahorses have the best properties.     

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.     

环境因子对胭脂鱼精子活力影响的研究

通过观察精子的快速运动时间和寿命,研究了6种环境因子对胭脂鱼(Myxocyprinus asiaticus Bleeker)精子活力的影响。结果表明:胭脂鱼精子对酸碱的耐受能力较强,在pH值为4~10时,精子均可以快速运动,且在pH值为8时精子的活力最强。不同浓度的NaCl、KCl、葡萄糖、CaCl2、MaCl2溶液对胭脂鱼精子运动的诱导效果不同。5种溶液最适于胭脂鱼精子运动的浓度分别为:NaCl 102 mmol/L;KCl 75 mmol/L;葡萄糖100 mmol/L;CaCl275.6 mmol/L;MgCl275.6 mmol/L。且在5种溶液低浓度时精子活力较强,超过一定浓度精子的运动开始被抑制。     

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.