Breeding and larval rearing of threatened, endemic fish stonesucker, Garra ceylonensis (Bleeker)

This study was aimed to develop captive breeding and nurture the young of stonesucker (Garra ceylonensis, Bleeker), a small threatened freshwater fish species endemic to Sri Lanka. Breeding of stonesucker was possible under indoor conditions without hormonal stimulation. They were single spawners having a fecundity of 562±176 eggs per fish (total length of 7.9±0.6 cm) with an egg size of 770–1877 μm. Duration of development stages were, egg to hatchling 36–48 h, hatchling to postlarva stage 3–4 days, postlarva to juvenile stage 5–64 days and adult stage in 300–365 days at 26–28°C. Juveniles exhibited bottom dwelling habit in 70–75 days. Postlarva fed with formulated feed exhibited the highest growth (P<0.05) compared with live diets, Artemia and microworm (Anguillula sp.). Although the juveniles revealed a significantly high growth performance (P<0.05) with swine liver diet up to day 45 compared with formulated feed and combination of detritus and plankton, formulated feed exhibited an increase in growth from day 50. Therefore, formulated feed could be used for rearing of postlarva and juvenile stages without any live feeds.     

光周期对卤虫摄食、生长和存活的影响

在不同光周期（０Ｌ：２４Ｄ、６Ｌ：１８Ｄ、１２Ｌ：１２Ｄ、１８Ｌ：６Ｄ和２４Ｌ：０Ｄ）下培养河北大清河盐场的卤虫,结果表明：卤虫的摄食率有随着光周期缩短而下降的趋势。大清河盐场的卤虫在不同光周期下的生长速度无显著差异,但成活率差异显著,６Ｌ：１８Ｄ组的成活率最高。建议在短光周期下培养卤虫。     

A comparison of retinol, retinal and retinyl ester concentrations in larvae of Atlantic halibut (Hippoglossus hippoglossus L.) fed Artemia or zooplankton

Atlantic halibut (Hippoglossus hippoglossus L.) larvae were fed enriched Artemia or zooplankton in duplicate tanks from 0 to 60 days after first‐feeding. Both diets and the larvae were analysed for vitamin A (VA) in order to confirm earlier findings, in which Artemia fed larvae had lower levels of VA compared with larvae fed zooplankton. Furthermore, we wanted to investigate the composition of the retinoids in the larvae. The results showed that Artemia and zooplankton contains low levels of VA, probably too low to sustain the assumed requirement. Nevertheless, larvae fed Artemia had the same level of retinal and retinol as larvae fed zooplankton. We found a significant lower level of retinyl esters in larvae fed Artemia. The total VA level was lower in larvae fed Artemia only at the end of the feeding trial after the onset of metamorphosis. Our conclusion is that feeding Artemia to Atlantic halibut larvae is not likely to cause VA deficiency.     

Daily food intakes and optimal food concentrations for red king crab (Paralithodes camtschaticus) larvae fed Artemia nauplii under laboratory conditions

Daily food intakes, optimal feeding regimes and food concentrations for laboratory reared Paralithodes camtschaticus (Tilesius, 1815) larvae were investigated. Artemia nauplii hatched at standard conditions were used as food. Daily food intakes of zoeae I–IV at 7–8 °C comprised 11.3, 22.4, 33.2, and 41.8 nauplii individuals (ind)^?1 day^?1, respectively, taking into account that wet weight of Artemia nauplii used for the experiments constituted 0.026 mg, dry weight 0.0042 mg. Optimal initial Artemia nauplii concentrations for feeding zoeae I–IV was determined as 400–600, 600–800, 800–1000 and 1000–1200 nauplii L^?1 respectively. Recommendations on using Artemia nauplii as food for red king crab larvae were outlined on the basis of experimental results. Growth, development and survival rates of zoeae I–IV reared in recycling water system at 7–8 °C and fed Artemia nauplii according to these recommendations were described.     

营养强化的轮虫、卤虫对牙鲆仔鱼的成活、生长及体脂肪酸组成的影响

用3种营养强化剂强化的轮虫和卤虫无节幼体投喂牙鲆仔鱼,研究牙鲆仔鱼的生长、成活、体脂肪酸的组成。结果表明:用强化的轮虫和卤虫无节幼体投喂牙鲆仔鱼,成活率、增重均显著高于对照组(p<0 01),其中V号强化剂的效果最好,成活率为29 34%,比对照组提高100%;增重倍数为217 90,比对照组提高68 61%;这是由于V号强化剂强化的卤虫无节幼体体内含有较多的AA的缘故,饵料中AA含量的提高,可以提高牙鲆仔鱼的成活率、促进其生长。牙鲆摄食强化过的轮虫、卤虫无节幼体后,其EPA、DHA、n-3HUFA、PUFA的含量随着饵料中含量的升高而升高,这也是牙鲆仔鱼生长速度和成活率提高的重要因素之一。     

Feeding juvenile Artemia enriched with ascorbic acid improves larval survival in the spiny lobster Jasus edwardsii

Newly hatched Jasus edwardsii phyllosoma were fed unenriched Artemia [endogenous ascorbic acid (AA) concentration of 166 μg g^?1 dry weight (dw)], Artemia supplemented with algae (AA concentration 594 μg g^?1 dw) or with ascorbyl‐2‐polyphosphate (A2P) (AA concentration 11 737 μg g^?1 dw) to examine possible benefits of AA enhancement on culture. Plain or algal‐enriched Artemia were fed continuously for 28 days in two treatments during the study. Four other treatments received A2P‐enriched Artemia on a progressive basis starting from the commencement of the trial (D‐0), the third (D‐3), sixth (D‐6) or ninth day (D‐9) of Stage I (14 days) and similarly during Stage II (14 days). Prior to the commencement of A2P supplementation, plain Artemia were supplied to these animals. By Stage III (28 days feeding), algal, D‐0 and D‐3 phyllosoma had attained the largest size. The uptake and retention of AA by Stage III phyllosoma appeared to be dose‐dependent with the highest concentration of AA incorporation evident in D‐0 phyllosoma (1816 μg g^?1 dw), while algal and plain phyllosoma contained the lowest concentrations (600 and 300 μg g^?1 dw, respectively). Survival at Stage III was highest in D‐0 phyllosoma (89%) and lowest in plain phyllosoma (51%). There was a positive relationship between phyllosoma AA concentration and larval survival (R² = 0.8328, P < 0.0001). D‐0 phyllosoma had the lowest stress index when subjected to an osmotic/temperature activity test, indicative of better survival in culture compared to plain, algal and D‐9 phyllosoma, which had consistently higher indices. A negative relationship existed between phyllosoma AA concentration and stress indices at Stage III (R² = 0.9263, P < 0.0001), suggesting that AA from the Artemia diet conferred stress resistance.     

一种新型杀虫生物活性筛选方法的研究

卤虫是一种广温耐高盐的水生生物,由于对毒物敏感、个体微小、容易获得和培养等特点,用于污染物的检毒研究。通过测定常用杀虫剂对卤虫初孵无节幼体的毒力,探讨卤虫作为杀虫活性筛选模型生物的可行性,并研究应用卤虫进行杀虫生物测定的影响因子。     

Prey switching in red-necked phalaropes Phalaropus lobatus: Feeding limitations, the functional response and water management at Mono Lake, California, USA

The ability of red-necked phalaropes Phalaropus lobatus to switch prey under conditions of changing prey abundance at Mono Lake, California, was tested in order to predict the potential effects of continued water diversions there on migratory waterbird populations. Red-necked phaloropes cannot switch prey because they are incapable of surviving on a diet of just the hardier of two invertebrates threatened by salinity increases at Mono Lake. Individuals experimentally limited to brine shrimp Artemia monica as a primary prey source lost mass rapidly until death ensued, or until they were offered other prey. These data show that a marked preference for one prey may indicate important physiological limitations in a predator. Such limitations may partly explain Murdoch's empirically supported prediction (Ecol. Mongr. (196), 39, 335-54) that prey switching will not occur where strong prey preferences exist. These results also indicate that strong prey preferences of migratory birds can, and probably should, help determine water management policy at wetlands of importance to shorebirds, especially in cases where initial prey diversity is low.