Toxic effects of ammonia on the embryonic development of the cuttlefish Sepia pharaonis

The objective of this study was to investigate the effects of ammonia nitrogen on the embryonic development of the cuttlefish Sepia pharaonis . Embryos were exposed to different concentrations (0, 1, 3, and 5 mg/L) of total ammonia–nitrogen (TAN) during incubation. The developmental rate, malformations, mortality, hatching rate, incubation period, yolk utilization efficiency ratio, and weight of the newly hatched cuttlefish were determined. The results showed that ammonia nitrogen significantly inhibited the development of S. pharaonis embryos and induced malformations and even death. Hatching was delayed, the hatching rate was reduced, mortality and the incubation period increased, and the yolk utilization efficiency ratio and weight of the newly hatched cuttlefish significantly decreased in a dose‐dependent manner after the embryos were exposed to more than 1 mg/L TAN for prolonged period. These variables could be used as an integrative biomarker or indicator of aquatic environmental ammonia contamination. In summary, our results indicated that ammonia caused toxicity in the embryos. When the concentration of TAN is greater than 1 mg/L, ammonia levels should be reduced to prevent toxic effects on embryonic development.     

Cu~(2+)、Pb~(2+)、Cd~(2+)、Cr~(6+)对鳙胚胎和仔鱼的急性致毒效应

研究了Cu2+、Pb2+、Cd2+、Cr6+ 4种重金属对鳙胚胎发育及仔鱼存活的影响.试验结果表明,在试验浓度范围内,除0.5、1.0 mg/L的Cd2+可促进胚胎发育速率外,其余3种重金属均不同程度地减慢胚胎孵化速率;受精卵孵化率明显低于对照组;初孵仔鱼出现不同程度的畸形;Cu2+、Pb2+、Cd2+、Cr6+对鳙仔鱼的毒性强度为Cu2+>Cd2+>Pb2+>Cr6+.根据试验数据求得4种重金属对鳙仔鱼的24、48、72、96 h的LC50值及安全质量浓度.     

Effects of photoperiod on egg production and hatching success, naupliar and copepodite development, adult sex ratio and life expectancy of the tropical calanoid copepod Acartia sinjiensis

The tropical calanoid copepod Acartia sinjiensis has good potential for mass culture as live feed for reef fish larvae. The present study was conducted to evaluate the effects of photoperiod on various parameters related to A. sinjiensis productivity in culture.Five photoperiods of Light:Dark = 0:24; 6:18; 12:12; 18:6 and 24:0h were setup. Daily egg production of individual females under each photoperiod was monitored for 8 consecutive days. The females were randomly selected daily from stock cultures kept under respective photoperiods and discarded after experiment. The results showed a clear trend of increasing egg production with longer illumination period. Under constant darkness, acclimatization was evident as egg output increased steadily over the 8 day period. Statistics showed that photoperiod significantly (p < 0.005) affected mean daily egg production, with the highest egg output recorded at 18L:6D and 24L:0D (17.6 ± 1.7 and 17.6 ± 1.8 eggs/female/day respectively), which were significantly higher than all other treatments. Photoperiod also significantly affected 48 h egg hatching success (p < 0.005), a trend of increased hatching success with longer light phase was demonstrated. The highest hatching rate (87.2 ± 1.4%) was recorded at 24L:0D, which was significantly higher than the 0L:24D and 6L:18D treatments but not significantly different from the second highest (85.3 ± 2.6%) hatching rate of 18L:6D treatment.Photoperiod was further confirmed to significantly (p < 0.005) affected naupliar and copepodite development with accelerated development observed with increased illumination period of photoperiods. Mean development time from egg to adult was the shortest at 6.00 ± 0.33 days under constant light (24L:0D), followed by 6.24 ± 0.24 days at 18L:6D, both were significantly shorter than that of 0L:24D and 6L:18D treatments although no significantly difference was detected between themselves. Adult life expectancy was also found significantly (p < 0.005) affected by photoperiod with the shortest adult life span recorded under constant light (24L:0D) (9.4 ± 0.4 days), which was significantly shorter than all other photoperiods tested. Adult sex ratio was the only parameter tested that was not significantly affected by photoperiod, a skewed sex ratio in favor of female was found across all photoperiod treatments.Based on results of current study, it is recommended that a photoperiod of 18L:6D being adopted for A. sinjiensis culture to maximize its productivity for aquaculture hatcheries.     

Hatching time effect on the intra‐spawning larval morphology and growth in Northern pike (Esox luciusL.)

Based on the analysis of 11 morphometric variables of body (total length, body area and perimeter, myotome height and eye diameter) and yolk sac (length, height, area, perimeter and volume) of pike larvae, the aim of this study was to evaluate how larval size at hatching and growth of larvae hatched from single egg batches vary according to three hatching times: early, mid and late. Hatching time structures strongly pike larval morphometrics. Early hatched larvae have smaller body sizes at hatch, faster growth and higher yolk use efficiency than late hatched ones. Early hatched larvae seem to be premature and hatch at precocious developmental stage whereas late hatched individuals continue their growth within the egg shell and hatch at larger size but with lower reserves (yolk). A compensatory growth phase was observed for the early hatching pike larvae particularly during the first 5 days post hatch. Consequently, no significant difference in body parameters was recorded from day 10 post hatching whatever the hatching time. The higher growth accomplished by early hatched larvae may be related to a particular metabolic activity that converts more efficiently yolk into body tissues.     

Heavy metals removal from influents to prevent mortality in salmon fry

The concentration of heavy metals in water, above certain values, threaten industrial salmon production and have occurred in two of the most important salmon producers, Norway and Chile. Aluminum and iron are two of the main heavy metals found in fresh water of the salmon industry, although manganese, zinc and copper have also been detected. In Chile, an experimental study found a solution to remove aluminum, iron and manganese. The present works studies copper and zinc removal by ionic exchange using AMBERLITE IRC747. The resin's removal capacity is 0.025 meq/g and does not depend on the solution's pH. An ionic exchange column was designed and continuously operated to remove copper and zinc from concentrations equal to 1000 μg/L of each metal. Then, the column was modularly operated with an aluminum, iron and manganese abatement system removing them by precipitation, oxidation (for iron and manganese) and granular filtration. When operating the modular system, the final aluminum, copper, iron, manganese, and zinc concentrations were 0.1, 0.4, 0.6, 0.8 and 0.3 μg/L, respectively. As a result, the system implemented obtained values below the maximum limits allowed for aluminum, iron, manganese, copper and zinc.     

4种常用消毒药物对棕点石斑鱼(♀)×鞍带石斑鱼(♂)受精卵孵化的影响

人工育苗中对受精卵进行消毒,可以很大程度上预防各种病原对受精卵的危害,防止病原体的垂直传播。但是,用化学药物消毒,总会对鱼的受精卵产生一定程度的毒害作用。因此,人工育苗中进行受精卵消毒处理时必须控制药物种类、药物浓度及消毒时间。本研究在(27.0±0.5)℃条件下,使用药物浸泡的方法,研究了4种常用水产消毒药物对珍珠龙胆石斑鱼受精卵[棕点石斑鱼(♀)×鞍带石斑鱼(♂)]孵化效果的影响。聚维酮碘、甲醛和二氧化氯的处理时间均为10 min,臭氧处理分1 min、2 min和3 min共3个梯度。使用SPSS 17.0软件对试验数据进行方差分析,结果表明,其受精卵的孵化率和畸形率与药物的浓度、处理时间呈负相关。甲醛和二氧化氯处理组与对照组的孵化率、畸形率差异显著;聚维酮碘处理组中25 mg/L、50 mg/L与75 mg/L各处理与对照组无差异,100 mg/L处理出现显著差异;臭氧处理组,0.3 mg/L处理中的各时间梯度间的孵化率和畸形率与对照组差异性不显著,0.5 mg/L、0.7 mg/L及1.0 mg/L处理中各时间梯度间差异极显著,0.5 mg/L处理2 min时,孵化率已极低,仅为4.14%,畸形率为50.00%。试验结果证明,在珍珠龙胆石斑鱼苗种生产中,其受精卵的适宜消毒药物、浓度范围及处理时间分别为:聚维酮碘20–70 mg/L处理10 min,臭氧0.3–0.5 mg/L处理1 min;二氧化氯、甲醛对受精卵刺激显著,而且对环境及人体有毒副作用,建议在生产中尽量不要使用。     

Cu2+、Zn2 、Pb2 对七带石斑鱼(Epinephelus septemfasciatus)胚胎和初孵仔鱼的毒性效应

在(21.0±0.5)℃条件下,研究了Cu2+、Zn2+、Pb2+3种金属离子对七带石斑鱼胚胎和初孵仔鱼的毒性效应。结果表明:1)随着3种金属离子浓度的升高,受精卵的孵化速率和孵化率逐渐降低,畸形率逐渐增加。重金属引发胚胎发育发生各种畸形,如胚体增生异常而死亡、尾芽弯曲,仔鱼不能正常出膜而死亡,初孵仔鱼脊椎弯曲多呈L、S、V型或尾部未展开呈逗号状畸形。综合孵化速率、孵化率和畸形率等指标,可以看出,3种金属离子对胚胎发育的毒性大小依次为Cu2+Zn2+Pb2+;2)初孵仔鱼的毒性试验周期为96 h,随着时间加长,仔鱼的存活率逐渐降低,且金属离子浓度越大,其下降幅度越大。此外,仔鱼出现脊椎S、V型弯曲等畸形也越来越多。通过计算各时间段的半致死浓度(LC50)和安全浓度得出,3种金属离子对初孵仔鱼的毒性大小依次为Cu2+Pb2+Zn2+。本研究的一系列数据可以为新渔业水质标准的制定和水环境的监测提供理论参数,为七带石斑鱼等鱼类繁育养殖中的重金属监测与治理提供重要科学依据。     

重金属离子除去装置在中国对虾育苗生产中的应用

自行研制的高分子吸附剂装置，在两处中等规模的中国对虾育苗场进行了应用实验。结果表明，在其他条件一致的情况下，应用装置与使用自然海水育苗对比，卵子的孵化率平均提高１１．８％，无节幼体到蚤状幼体变态率平均提高１０．２％；应用装置与使用ＥＤＴＡ（２．０ｍｇ／Ｌ）比较，卵子的孵化率平均提高７．５％，无节幼体到蚤状幼体的变态率平均提高３．６％。     

Embryonic development and morphology of eggs and newly hatched larvae of Pacific herring <Emphasis Type="Italic">Clupea pallasii</Emphasis>

The embryonic development and morphology of eggs and newly hatched larvae of the Pacific herring Clupea pallasii were described using laboratory-reared specimens originating from the Miyako Bay stock. The eggs were almost spherical in shape, 1.33–1.46 mm (mean: 1.38 mm) in diameter, and had a thick adherent chorion. They had a segmented pale yellow yolk, no oil globule, and a relatively wide perivitelline space. A subgerminal cavity was observed during the gastrula period, whereas the blastocoel did not appear. Mass hatching occurred by 271 h 45 min after fertilization, and the newly hatched larvae were 7.1–7.7 mm (mean: 7.5 mm) in total length with 53–56 myomeres at 9.6°C. The embryonic development of Pacific herring was substantially similar to that of zebrafish Danio rerio, American shad Alosa sapidissima, as well as Atlantic herring Clupea harengus, and generally followed the basic developmental pattern of teleosts. However, Pacific herring larvae hatched at a more developed stage than some other clupeoids, such as Japanese sardine Sardinops melanostictus, and the progressed developmental stage at hatching could be interpreted as an advanced adaptation.     

铬对鲤、草鱼胚胎发育及鱼苗的毒性影响

以水体不同浓度铬（CrCl3.6H2O)处理草鲤鱼卵和鱼苗,观察铬对鱼卵的发育和鱼苗的毒性作用,结果表明：铬处理组浓度高于（2mg/L)对鱼苗,鱼胚发育有毒性作用;染毒7天内,10mgCr/L组鱼苗致死率30％,草,鲤鱼卵孵化率分别下降46％和88．9％,15mgCr/L组草鱼苗致死率达100％,鱼卵孵化率为零,两种鱼对铬的耐受量无明显差异。     

The effects of heavy metals on embryonic development of fish (a review)

Early developmental stages of fish are particularly sensitive to water pollution. Heavy metals may affect various developmental processes during the embryonic period, which results in a reduction of offspring quantity and quality. Waterborne metals may accumulate in the gonads of spawners and adversely affect gamete production and viability, or exert direct toxic influence upon developing embryos. The egg shell does not fully protect the embryo against metal penetration, particularly during the swelling phase; thus, metals may accumulate in the egg. The results depend on metal concentration and range from developmental disturbances to death of the embryo. Metals disturb various processes of fish embryonic development and affect the development rate. Early stages just after fertilization are particularly sensitive to metal intoxication, when most disturbances and the highest embryonic mortality occur. Waterborne metals also promote developmental anomalies during organogenesis, including body malformations. Heavy metals often induce a delay in the hatching process, premature hatching, deformations and death of newly hatched larvae. All these disturbances result in reduced numbers and poor quality of the larvae, which show small body size, high frequency of malformations and reduced viability.     

Quality assessment of newly hatched mud crab,Scylla serrata,larvae

Starvation and exposure to formalin were investigated as possible stress tests for evaluating the quality of mud crab, Scylla serrata, larvae. For the starvation stress test, newly hatched zoeae stocked in 150‐ml containers were either starved or fed rotifers. Similarly, newly hatched zoeae were stocked in containers with seawater of 0 (control), 20, 30 and 40 mg/L formalin for the formalin stress test. The zoeae from the same batches were used for seed production to monitor their performance and validate the results of stress tests. Starvation was found to be unsuitable for larval quality evaluation. However, the impact of initial food deprivation on the newly hatched larvae indicates that feeding immediately after hatching is necessary for mud crab larvae. Exposure of larvae to 40 mg/L formalin for 3 hr appeared to be a reliable and practical method for larval quality assessment as the survival of larvae in the mass production tanks validated the classification of good and poor quality batches in the stress tests. On this basis, a hatchery operator can decide which batch should be cultured further. Finally, there appears to be a link between the quality of larvae and the performance at the megalopa and early juvenile crabs.     

Incubation experimentale et developpement embryonnaire de la daurade royale, Sparus aurata (L.), a differentes temperaturesIncubation and embryonic development of gilthead bream, Sparus aurata (L.), at a range of temperatures

Eggs of raised gilthead bream, Sparus aurata (L.), were incubated to hatching at various temperatures ranging from 7.7°C to 26.3°C. For four stages of development, the relationship between temperature and incubation time is given. Time from fertilization to hatching varies from 135 h at 11°C to 40 h at 21.3°C. In our experiments no egg hatched below 11°C or above 22°C. The highest hatching rate and the lowest rate of larval abnormalities were both observed at 14.5°C which is also the spawning temperature.     

Effects of Heavy Metals on the Hatching Rates of Brine Shrimp Artemia salina Cysts

The effects of heavy metals (Hg²⁺, Cd²⁺, Co²⁺, Cr³+, Pb²⁺, Cu²⁺, Fe²⁺. Ni²⁺, Zn²⁺, Mn⁷⁺, Mn⁴⁺ and Mn²⁺) on the relative hatching percentage of brine shrimp, Artemia salina were assessed. Artemia salina cysts (San Francisco Bay Brand) hatched in seawater containing various heavy metal concentrations. After 48 hours, the number of hatched nauplii were counted. A negative linear relationship between hatching rate of Ariemia salina cysts and heavy metal concentration occurred, except copper which conformed to a cubic model. The relative toxicities of heavy metals on Artemia salina cysts were as follows (Cu²⁺, most toxic; Mn²⁺, least toxic): Cu²⁺ > Zn²⁺ > Ni²⁺ > Co²⁺ > Mn⁷⁺ > Cr³⁺ > Cd²⁺ > Fe²⁺ > Hg²⁺ > Mn⁴⁺ > Pb²⁺ > Mn²⁺.     

镧对草鱼卵子孵化的影响

本文研究了La~(3+)对草鱼受精卵孵化的影响,结果表明:La~(3+)的最佳浓度范围为0.6～4.8mg/L,可提高孵化率9.7～19.4％     

Cathepsin L in eggs and larvae of perch Perca fluviatilis: variations with developmental stage and spawning period

This study describes changes in cathepsin L activity during early development in Eurasian perch (Perca fluviatilis) and determines to which extend a precocious proteolysis of the yolk reserves by activated cathepsin L could be involved in the seasonal decline of egg and larval quality. During embryogenesis and early larval stages, samples were collected for determination of fertilization and hatching rates, assays of cathepsin L activity, and evaluation of larval resistance to stress (osmotic shock and fasting). Cathepsin L activity increased significantly during the embryonic development, reaching a maximum of 177.1±12.3 nmol min^–1mg fresh weight^–1 on day 1 post-hatching and significantly decreasing on day 3. Activity increased significantly during the spawning season and individual variations between egg strands became very high during the second half of the spawning period. An inverse relationship was established between the cathepsin L activity in 7-day old eggs and the decrease of hatching rate. A negative exponential regression was calculated between the cathepsin L activity of eggs and the resistance of corresponding newly-hatched larvae to osmotic shock. Resistance to fasting was significantly reduced in larvae from eggs with cathepsin L activity higher or lower than 20 nmol min^–1 mg^–1 (lethal time₅₀=4.7±0.7 and 3.5±0.4 days, respectively). The involvement of cathepsin L in the degradation of yolk reserves and its potential consequences on the quality of perch eggs and larvae are discussed in relation to results reported in salmonid fishes.     

Effects of light and short-term temperature elevation on the 48-h hatching success of cold-stored Acartia tonsa Dana eggs

The effects of light and short-term temperature elevation on the 48-h egg hatching success (HS) of cold-stored (2 °C) Acartia tonsa Dana (Copepoda: Calanoida) eggs were examined in the present study. The eggs can be stored for up to 7.5 months and maintain their high hatching rate under optimal conditions. Intensively produced eggs from the copepod A. tonsa may be hatched and used as an inoculum for producing copepod nauplii as live feed for fish larvae. The HS for eggs that were directly exposed to LED light declined rapidly after 1 month of storage (from 91 to 25 %), and these eggs did not hatch at all after 3 months of storage. The highest HS found was for eggs stored in complete darkness. The HS for eggs stored in normoxic (≥7 mg DO L^?1) and anoxic (≤0.03 mg DO L^?1) seawater was not affected by short-term temperature transitions from 2 °C up to 9 or 17 °C for a period of 12 or 24 h, when hatched 1 week post-exposure. The global mean HS for eggs stored in normoxic seawater was 85.9 % and significantly lower compared to eggs stored under anoxic conditions after 3 weeks of storage (91.8 %) (P = 0.001; SNK).     

Is batch variability in hatching time related to size heterogeneity and cannibalism in pikeperch (Sander lucioperca)?

Larval size heterogeneity is known to induce cannibalism, and procedures to avoid larval size differences are consequently implemented already during egg incubation and hatching. We investigated the relation between larval development variability, size heterogeneity and cannibalism in pikeperch. Larvae were sorted into five groups according to the time of hatching during a 65‐h period. The larvae with different times of hatch were then reared separately or together during an 18‐day period. Late hatched larvae were longer (P=0.003) and had less yolk remaining (P<0.001) than early hatched individuals at the time of hatching. However, on 11 days post fertilization, the late‐hatching larvae tended to have larger yolk reserves than earlier hatched individuals (P=0.07). Furthermore, the next day, a lower proportion in the late fraction had switched to exogenous feeding (P=0.024). That larvae with a late hatching time developed slower suggests a positive relationship between the hatching time and the embryonic developmental rate. However, differences in the length and available yolk reserves at hatching between larval fractions with different hatching times suggest that hatching is not strictly associated with a specific developmental stage, and that factors other than the development rate of the embryo are involved in the timing of hatching.     

氟离子对西伯利亚鲟胚胎发育的影响

本试验在水温17±1℃的条件下,采用半静态式生物毒性试验方法,探讨了氟离子(F-)对西伯利亚鲟胚胎发育的影响。结果表明,100~600 mg/L氟暴露会导致胚胎孵化延迟,氟暴露组半数孵化时间(MHT)比对照组推迟9~22 h。氟暴露同时导致胚胎死亡率显著增加(P<0.05),出膜仔鱼活力减弱、存活时间缩短、畸形率显著升高(P<0.05),出现卵黄囊畸形、脊椎畸形、眼部充血等畸形症状。试验得出F-致西伯利亚鲟胚胎144 h半致死浓度(LC50)为447.61 mg/L,孵化安全浓度(SC)为4.48 mg/L,导致仔鱼畸形的半数效应浓度(EC50)为536 mg/L。氟对西伯利亚鲟胚胎的安全质量浓度低于我国部分高氟地区地下水、地表水及人为氟污染水域中氟含量,提示天然水体中氟可能会对鱼类胚胎产生负面影响,应引起重视。     

Dietary effects on egg production,egg‐hatching rate and female life span of the tropical calanoid copepod Acartia bilobata

Copepods are crucial source of live feeds in the aquaculture industry. In particular, several species of the genus Acartia are considered optimal prey for fish larvae. The species Acartia bilobata has excellent potential for marine larvae culture, as it is easy for mass culture. This study investigated the effects of various algal diets on the egg production and egg‐hatching rate of A. bilobata. The results indicated that the single‐species diet Isochrysis galbana was the most supportive diet for A. bilobata egg production and female life span in all treatments (egg production: 23.85 ± 0.70 eggs female^?1 day^?1 and female life span: 18.00 ± 1.45 days). Nannochloropsis oculata and Tetraselmis chui treatments gave markedly lower egg production and female life span as both single‐species and multiple‐species diets. For the egg hatching‐rate experiment, except for the T. chui treatment, which yielded a considerably lower hatching rate than the other diets, the hatching rate was only slightly affected by the algal diets. These results confirm that A. bilobata, a tropical brackish‐water copepod species, develops rapidly at 28°C and can produce a large number of eggs; therefore, it has considerable potential for larvae culture.