Seminal plasma composition and its relationship with physical spermatological parameters of Grass carp (Ctenopharyngodon idella) semen: with emphasis on sperm motility

In this research, the mineral and organic composition of the seminal plasma, physical spermatological parameters and their physiological relationships were investigated in grass carp (Ctenopharyngodon idella). The seminal plasma contained 98.14±5.23 mM L^?1 (Na⁺), 380.85±25.95 mM L^?1 (K⁺), 30.25±4.96 mg dL^?1 (Ca²⁺), 19.16±1.70 mEq L^?1 (Mg²⁺), 1.36±0.11 mg dL^?1 glucose, 0.37±0.08 g dL^?1 total protein, 12.02±1.18 mg dL^?1 cholesterol, 14.85±1.50 mg dL^?1 triglyceride and 43.5±9.56 mg dL^?1 urea. The following spermatological parameters were found: sperm volume 14.44±1.16 mL, sperm motility 80.60±1.55%, movement duration 67.68±4.32 s, density 15.43±0.72 × 10⁹ mL^?1, total density 337.43+45.86 × 10⁹ and pH 7.24±0.17. The Na⁺ and Ca²⁺ ions correlated negatively with spermatozoa motility (r=?0.453, P>0.05 and r=?0.192, P>0.05) respectively. The K⁺ ion correlated positively with spermatozoa motility (r=0.545, P>0.05). But a statistically significant correlation was not observed between sperm motility and seminal plasma parameters. The following correlations were observed between mineral and organic components. The Mg²⁺ was positively correlated with glucose and cholesterol (r=0.692, P<0.05 and r=0.680, P<0.05) respectively. A highly significant positive relationship was also found between Mg²⁺ and total protein (r=0.837, P<0.01). On the other hand, a significantly negative relationship was found between Ca²⁺ and triglyceride (r=?0.639, P<0.05). These parameters should be considered when developing procedures for either artificial fertilization or for cryopreservation of grass carp sperm.     

Changes in Sperm Production,Sperm Motility,and Composition of Seminal Fluid in Caspian Brown Trout,Salmo trutta caspius,Over the Course of a Spawning Season

This study was carried out to evaluate milt quality in male Caspian brown trout (Salmo trutta caspius) over the course of the winter spawning season. Milt samples were collected biweekly during December and January. Chemical composition of seminal fluid, sperm production (milt volume, sperm density, spermatocrit,) and sperm motility characteristics (percentage and duration of motility) were measured. Milt volume, sperm density, osmolality, seminal minerals (Ca²⁺, Mg²⁺, K⁺, Na⁺, Cl^?), and total protein gradually decreased over the spawning season. Glucose and triglyceride content of milt did not show significant changes over the spawning season. Milt pH and the percentage and duration of motility were comparatively stable, declining only at the end of the season. Significant positive correlations were found between sperm density and seminal minerals, total protein and spermatocrit; percentage of motile spermatozoa and seminal minerals, total protein; and duration of motility and K⁺, Cl^?, total protein, and pH. Results show that season has a significant influence on milt quality in male Caspian brown trout, with the best milt being available at the beginning of spawning season.     

Sperm motility and seminal plasma characteristics in Barbus sharpeyi (Günther, 1874)

Spermatozoa concentration, ionic composition, osmolality, glucose and total protein contents of seminal plasma and sperm motility were determined in Barbus sharpeyi (Cyprinidae, Teleosotei). Spermatozoa concentration ranged from 9.77 to 20.20 × 10⁹ spermatozoa mL^?1. Osmolality (mOsmol kg^?1) and ionic contents (mM L^?1) of the seminal plasma were 274.5±9.0, 70.0±3.4 Na⁺, 28.8±0.9 K⁺, 101.7±3.1 Cl^?, 0.9±0.1 Mg²⁺ and 2.1±0.1 Ca²⁺ respectively. Total protein and glucose were 5.3±0.2 g L^?1 and 76.7±4.3 mM L^?1 respectively. Sperm motility was initiated in a hypo‐osmotic condition, composed of either an ionic (KCl or NaCl) or a non‐ionic (sucrose) activation medium. Duration of sperm motility was very short: <2 min after activation in distilled water. Percentage of motile spermatozoa was significantly higher in an activation medium containing NaCl compared with that of distilled water. An activating medium containing NaCl or KCl higher than 150 mM or sucrose higher than 275 mM totally inhibited the activation of sperm motility. Immediately after sperm activation, wave(s) propagated along the flagellum, but waves were restricted to the proximal part of the flagellum (close to the head) at 1 min post activation. Studied characteristics in the present study were compared with those of other cyprinids for understanding inter‐species differences.     

Estimation of sperm concentration of wild and reconditioned brown trout, Salmo trutta L.

Sperm concentrations were assessed for milt samples taken from three stocks of brown trout, Salmo trutta L., (wild resident trout, and reconditioned and seareared sea trout) using direct counts, spermatocrit and an optical density of 1:1000 dilutions. There were significant linear relationships between spermatocrit and absorbance, and both spermatocrit and absorbance with sperm concentration. The results gave sperm concentrations from 2.2 × 10⁹ mL^?1 to 26 × 10⁹ mL^?1. Mean concentrations differed significantly between stocks; the reconditioned males had a mean concentration of 9.1 × 10⁹ mL^?1, sea-reared males 18.0 × 10⁹ mL^?1 and 8.0 × 10⁹ mL^?1 in 1994 and 1995, respectively, and wild resident males 13.3 × 10⁹ mL^?1. Sperm concentrations from all three stocks of trout were negatively correlated with length, and therefore, age. It was indicated that sufficient milt was being produced to achieve good rates of fertilization, although some of the larger trout did have low sperm counts, suggesting that fertilizing ability may decrease with male size or age within any one stock.     

Biochemical Composition of Seminal Plasma and Annual Variations in Semen Characteristics of Jundiá <Emphasis Type="Italic">Rhamdia quelen</Emphasis> (Quoy and Gaimard,Pimelodidae)

This study investigated the composition of milt of the South American silver catfish (Rhamdia quelen) or jundiá. The semen was taken from jundiá in different periods during the four seasons. The biochemical composition of seminal fluid and the characteristics of sperm were analyzed. The semen quantity which can be extracted per fish in one day was 0.95 ± 0.08 ml during spring (maximum) and 0.24 ± 0.03 ml during winter (minimum). Sperm density (spermatocrit) showed higher values in the spring (75.1 ± 1.3%) decreasing slightly afterwards and reaching 63.0 ± 2.4% to 65.0 ± 2.2% in the fall and winter. Immediately after water dilution, 90–100% of the spermatozoa presented vigorous straightforward motility that remained for at least 20 s. The total duration of the motility was 47.9 ± 1.3 s in the spring and 38.6 ± 0.6 s in the other seasons (P < 0.05). This pattern of motility is maintained for more than 2 h after storage of the milt at room temperature. The pH from 5 to 10 of the water dilution does not influence the sperm motility. The mean seminal pH and osmolality values were 8.7 ± 0.07 and 274.8 ± 11.2 (mOsm/kg), respectively. The ion concentration was: Na 153.7 ± 2.4, K 10.7 ± 2.4, Cl 139.4 ± 2.1, Ca 4.2 ± 0.2, Mg 0.9 ± 0.05, P 0.9 ± 0.08 (mEq/l). The total protein was 0.6 ± 0.05 mg/dl and cholesterol concentration was 13.9 ± 0.9 mg/dl.     

Milt quality and spermatozoa morphology of captive Brycon siebenthalae (Eigenmann) broodstock

In order to develop artificial reproduction in freshwater fish for potential species to be developed in South American aquaculture, milt quality and sperm morphology were studied in yamú (Brycon siebenthalae) under captive conditions during the natural middle spermiation period. The volume of milt collected for each male was 1.8±1.2 mL and the sperm concentration was 13.9±4.0 × 10⁹ spermatozoa mL^?1. Spermatocrit (41.5±10.8%) was positively associated (r²=0.30) with sperm density calculated using a corpuscle counting chamber. Sperm motility was 88±9% and the average duration of forward motility was 41±7 s. Fertilization rate was 84±8% and there was no association between this trait and sperm motility (r²=0.009) or with sperm density (r²=0.073). These results suggest that captive B. siebenthalae broodstock can be reproduced successfully.     

Production and storage of sperm from the black sea bass Centropristis striata L

Black sea bass Centropristis striata L. are protogynous hermaphrodites that develop and spawn as females before changing sex to male. Since all fish eventually become males, determining the relationship between sperm production, sperm quality and seasonal changes in plasma levels of testosterone (T) and 11‐ketotestosterone (11‐KT) could be useful for identifying appropriate males to maintain as broodstock. Milt and blood samples were collected three times during an 8‐week spawning season. Milt volume (3.5±0.76 mL kg^?1), sperm density (3.2 × 10⁸± 0.31 cells mL^?1), sperm production [11 × 10⁸±3.4 cells kg^?1 body weight (BW)] and sperm motility (80±0.6%) were at their highest during the first sampling interval and coincided with the highest 11‐KT levels (1.0± 0.11 ng mL^?1). All of the sperm indices decreased to their lowest levels during the final 3 weeks of the study. Sperm viability was highly correlated (adjusted R²=0.84) with sperm motility. Sperm cryopreserved in modified Mounib's extender (MME) had the highest post‐thaw motility compared with two other extenders. Post‐thaw motility of sperm cryopreserved in MME was not different from fresh after 90 days of storage. There was no difference in fertilization rates between fresh (69±2.4%) and post‐thaw (67±4.1%) sperm samples taken from the same male or among males. These results demonstrate that the quality of black sea bass spermatozoa is higher earlier in the spawning season and that acceptable post‐thaw fertilization rates can be obtained from cryopreserved sperm.     

Factors influencing the spawning success of Oreochromis karongae (Trewavas) in ponds

Fry and fingerlings production of a pelagic tilapia from Lake Malawi, Oreochromis karongae subgenus Nyasalapia (Trewavas), was lower (4.07 ± 5.09, 10–21 fry female⁻¹ month⁻¹) than reported for other tilapias (about 135 fry female⁻¹ month⁻¹). Although seasonality was very pronounced in all experimental systems, the use of net bags (hapas) improved fry yield to 24.7 ± 27.90, 0–354 fry female⁻¹ month⁻¹. Multiple regression analysis demonstrated that the depth of ponds, solar radiation, rainfall and maximum temperature significantly influenced fry and fingerling production (adjusted R²= 0.75; P= 0.0024). Injection of exogenous hormones intramuscularly (pimozide, LH-RHa) induced spawning and significantly (P < 0.05) improved spawning success to a maximum of 998 fry female⁻¹ month⁻¹. As in other cultured tilapias, when placed in fine-meshed net bags, broodstock density was critical to fry production. A density of 1.0 fish m⁻² for broodfish of 120–200 g produced significantly larger numbers of progeny in the hatchery system employed. Spawning was seasonal and restricted to November–February. Broodfish ponds given inputs of chicken layers' mash produced significantly (P < 0.05) higher numbers of fry and fingerlings than maize bran (4.17 vs. 1.22 fry m⁻² female⁻¹ month⁻¹).     

Sperm quality of Brazilian flounder Paralichthys orbignyanus throughout the reproductive season

The aim of this study was to evaluate the sperm quality of Brazilian flounder Paralichthys orbignyanus throughout its reproductive season. Sperm was collected at the beginning, middle and end of the breeding period. Spermatozoa density was maximum at the beginning (12.7 ± 0.92 × 10⁹ cells mL^?1) and at the end (11.8 ± 0.39 × 10⁹ cells mL^?1) of the breeding season (P<0.05). Sperm production and the percentage of spermatozoa moving fast forward increased significantly towards the end of the breeding season (P<0.05). The mean duration of progressive motility of spermatozoa was around 10 min. No difference was observed during the reproductive season in the percentage of motile cells, pH, osmolality and K⁺, Cl^? and Mg²⁺ concentrations in seminal plasma. The concentration of Na⁺ increased throughout the breeding season, reaching 174.62 ± 12.68 mmol L^?1 at the end (P<0.05). There was a decline in the concentration of Ca²⁺ (12.31 ± 3.08 mmol L^?1) in the middle of the breeding season, which coincided with the shortest motility duration of spermatozoa. The information reported in this study should help to improve management and optimize the development of protocols for short‐term storage and cryopreservation of Brazilian flounder semen.     

Effects of light intensity,stocking density and temperature on the air-bubble disease,survivorship and growth of early juvenile seahorse Hippocampus erectus Perry, 1810

This investigation examined the effects of light intensity, stocking density and temperature on the air-bubble disease, survivorship and growth of early juveniles (2–30 days old) of seahorse Hippocampus erectus Perry. The juveniles in the 100 lx treatment had the highest air-bubble disease rate of 20.8 ± 6.2% and the juveniles in the 500 lx treatment had the highest survival rate of 84.4 ± 5.5%. The juvenile seahorses cultured in the 1500 lx treatment had the highest final wet weight of 0.13 ± 0.02 g and the highest final standard length of 4.54 ± 0.37 cm (F_{7, 144}=57.406, F_{7, 144}=12.315, P<0.05). There was no significant effect of stocking density on the air-bubble disease rate (F_{6, 21}=1.893, P=0.126). The juveniles cultured in the 1 ind L⁻¹ had the highest wet weight increment of 0.134 ± 0.031 g, but juveniles in the 2 ind L⁻¹ had the highest standard length increment of 3.17 ± 0.30 cm (F_{6, 126}=34.902, F_{6, 126}=11.726, P<0.05), and juveniles cultured in the 1.5 ind L⁻¹ had the highest survival rate of 86.1 ± 4.6%. The result of interaction of light intensity and temperature showed that the juveniles cultured in the 1500 lx and 26 °C had the highest weight gain and specific growth rate of 3791.17 ± 323.97% and 13.07 ± 0.18, respectively, and the lowest air-bubble disease rate of 9.3 ± 4.5% occurred in the 1000 lx and 26 °C (F_{8, 36}=12.355, P<0.05).     

Effects of stocking density on growth, yield and profitability of farming Nile tilapia, Oreochromis niloticus L., fed Azolla diet, in earthen ponds

Two consecutive experiments were conducted to study the effects of stocking density on growth, food utilization, production and farming profitability of Nile tilapia (Oreochromis niloticus) fingerlings (initial mean weight: 16.2 ± 0.2 g) fed Azolla, as a main component in diet. In experiment 1, fish were hand‐fed twice daily with three isonitrogenous (28.5% crude protein) and isocaloric (14.5 kJ g⁻¹) diets A30, A35 and A40 containing 30%, 35% and 40%Azolla, respectively, for 90 days. Diets were formulated by mixing Azolla with locally available by‐products. No significant differences were found in growth parameters and production (P>0.05). Total investment cost was significantly higher with A30 (P<0.05), but same profitability values were obtained with all diets (P>0.05). In experiment 2, three stocking densities, 1, 3 and 5 m⁻², were assigned to three treatments T₁, T₂ and T₃ respectively. Fish were hand‐fed twice daily with diet A40. The final mean weight (89.53–115.12 g), the mean weight gain (0.81–1.10 g day⁻¹), the specific growth rate (1.90–2.20% day⁻¹) and the apparent food conversion ratio (1.29–1.58) were affected by stocking density, with significant difference (P<0.05) at 5 m⁻², compared with the other densities. Stocking density did not affect survival rate (P>0.05). Yield and annual production increased with increasing stocking density, ranging from 7.10 ± 0.90 to 25.01 ± 1.84 kg are⁻¹ and 28.79 ± 3.66 to 101.42 ± 7.48 kg are⁻¹ year⁻¹, respectively, with significant differences between all densities (P<0.05). Higher stocking density resulted in higher gross return and lower cost of fish production, with significant variations (P<0.05). The net return increased with increasing stocking density (P<0.05). However, both densities of 3 and 5 m⁻² produced the same profitability values. On the basis of growth values and economic return, it was concluded that Nile tilapia could be raised at a density of 3 fish m⁻² with A40 to improve production and generate profit for nutritional security and poverty alleviation in rural areas.     

Cryopreservation of Persian sturgeon (Acipenser persicus) sperm: effects of cryoprotectants,antioxidant, membrane stabilizer,equilibration time and dilution ratio on sperm motility and fertility

Three experiments were performed to develop protocols for cryopreservation of Persian sturgeon Acipenser persicus, sperm. In the first experiment, sperm from six males was individually split in three subsamples and cryopreserved using Modified Tsvetkova's extender (mT) supplemented with dimethyl sulfoxide (DMSO), methanol (MeOH), glycerol (Gly) and ethylene glycol (EG) at concentration of 5%, 10%, 15% and 20%. In the second set of experiments, the effects of six equilibration times (0, 5, 10, 20, 40 and 60 min) and dilution ratios (volume sperm: volume extender 1:0.5, 1:1, 1:2, 1:3, 1:5 and 1:10) and the additive advantage of bovine serum albumin (BSA; 0, 2.5, 5 and 10 mg mL^?1) and ascorbic acid (0, 2.5, 5 and 10 U mL^?1), on the post‐thaw survival of sperm (triplicate set of six fish) were evaluated. Then, sperm was diluted in 1:1 mT extender with 10 mg mL^?1 BSA with selected cryoprotectants (15% MeOH and 10% DMSO) for 5 min. After a month of storage in liquid nitrogen, post‐thawed sperm motility; fertilization and hatching rate and viability of derived larvae were measured (Exp.3). Evaluation of cryoprotectants efficiency showed that MeOH 15% and DMSO 10% were suitable for cryopreservation of Persian sturgeon sperm. Gly and EG resulted in very low post‐thaw motility rates even at lowest concentration. No significant difference was observed among the four different equilibration times (0, 5, 10, 20 min) (P > 0.05) although higher equilibration times than 20 min resulted low post‐thaw motility (P < 0.05). The motility of frozen–thawed sperm did not significantly change when dilution ratio was increased from 1:0.5 to 1:3 (P > 0.05). However, higher dilution ratios (1:5 and 1:10) reduced the percentage of motile sperm. Supplementation of the cryoprotectant solution with 10 mg mL^?1 BSA significantly improved post‐thaw motility (P < 0.05), but ascorbic acid did not improve post‐thaw motility (P > 0.05). The results of experiment 3 showed that the highest fertilization (30.2 ± 5.75) and hatching rates (28.2 ± 5.25) were observed when samples were frozen with 15% MeOH (P > 0.05). Our study indicates that the use of mT extender consisting of 10 mg mL^?1 BSA in 15% MeOH diluted with sperm at 1:1 ratio for 5 min can be recommended cryopreservation method for Persian sturgeon sperm.     

Dynamics of glucose in the haemolymph of female giant freshwater prawn,Macrobrachium rosenbergii,influences reproductive and non‐reproductive moulting cycles

Glucose, when measured in haemolymph, has been found to reflect a useful predictor of energetic investment. This study evaluated the pattern of glucose in the haemolymph, with an attempt to gain a better insight into the role of glucose as nutritional source of ovarian development and energy reserves during reproductive and non‐reproductive moulting cycles. The haemolymph of female giant freshwater prawn, Macrobrachium rosenbergii, was obtained at eight different moulting stages, and levels of glucose were determined using an enzymatic colorimetric glucose‐oxidase method in parallel with a histological examination of ovarian development. Glucose levels were relatively low (0.15 ± 0.02 mg mL^?1) at D₀ stage, an abrupt increase (0.52 ± 0.13 mg mL^?1) during premoult D₁ stage and declined (0.32 ± 0.10 and 0.31 ± 0.09 mg mL^?1) during premoult D₂ and D₃ stages, respectively; thereafter, a slight increase (0.43 ± 0.09 mg mL^?1) occurred at post‐moult A stage. The progression of ovarian growth, marked by an increasing gonadosomatic index (GSI) pattern during the reproductive moulting cycle (C₀–D₃ stages), was directly proportionate to fluctuations in glucose levels. GSI was significantly positively correlated with glucose (R = 0.40; P < 0.05). In contrast, glucose was notably higher at post‐moult A and premoult D₂ stages during non‐reproductive moulting cycle, the period during which glucose is crucial for exoskeletal chitin synthesis. At this particular stage, a negative correlation between body weight and glucose (R = ?0.36; P < 0.05) was observed. The dynamics of glucose in the haemolymph of female M. rosenbergii correlated with ovarian growth, which signify that glucose as nutritional source for vitellogenesis, and affects the body weight of this species.     

Mass culture of fairy shrimp Streptocephalus proboscideus (Crustacea – Anostraca) and its use in larviculture of the Persian sturgeon, Acipenser persicus

This study was conducted with cysts of Streptocephalus proboscideus obtained from the University of Gent‐Belgium. The cysts were hatched in Environmental Protection Agency (EPA) medium. The nauplii were reared at the Sturgeon Research Institute using a pure culture of Scenedesmus obliquus alga supplied at a density of 5 × 10³ cell mL⁻¹ that gradually increased to 1 × 10⁴, 5 × 10⁴ and 1 × 10⁵ cell mL⁻¹ with the growth of the nauplii. The nauplii attained sexual maturity and started producing cysts in 8 days and yielded a mean cyst number of 220±40 female⁻¹ brood⁻¹ cysts. These cysts were used in the larviculture of Persian sturgeon, Acipenser persicus (Borodin). Forty‐three larvae of Persian sturgeon (mean weight: 15.4±1.1 mg; mean length: 27.1±2.7 mm) with roughly absorbed yolk sacs were stocked in three aquaria and fed S. proboscideus nauplii at 8‐h intervals. By the end of the experiment (day 5), the mean weight and length of Persian sturgeon larvae were 51.4±13.3 mg and 20.7±1.4 mm respectively.     

Spermiation time affect the milt quality indices of the Russian sturgeon,Acipenser gueldenstaedtii,Brandt & Ratzeburg, 1833

In this study, the effects of spermiation time are investigated on milt quality of Russian sturgeon over the course of the spawning season. The milt samples were collected from three broodstock batches at three time points including: the beginning, middle and at the end of the spawning season. According to the results, the milt quality parameters including pH, sperm density, spermatocrit, duration of sperm motility and percentage of sperm motility were significantly low in the beginning and end of season than middle of season. The values of milt quality parameters in the middle of season were as follows: (motility percentage: 69.6 ± 3.5, motility duration: 460.3 ± 37.2 s, sperm density: 8.7 ± 0.4 × 10⁹, milt volume: 86.3 ± 8.1 and milt pH: 8.3 ± 0.15). Significant positive correlations were also found between milt pH and sperm motility as well as between sperm density and spermatocrit. In conclusion, our study showed that the middle of season is the best time for collection of milt with appropriate quality in Russian sturgeon. Selection of milt with good quality is necessary aim to cryopreservation of spermatozoa in endangered fish species including Russian sturgeon.     

Seminal plasma proteins of Atlantic halibut (Hippoglossus hippoglossus L.)

Protein content and properties in the seminal plasma of Atlantic halibut (Hippoglossus hippoglossus) were assayed using spectrophotometric and electrophoretic methods. The protein concentration ranged from 6.4 ± 3.1 to 19.4 ± 3.4 mg ml⁻¹ and anti-proteolytic activity from 585.2 ± 104.6 to 2912.4 ± 367.4 U l^−l. A high correlation between anti-proteolytic activity and protein concentration (r = 0.95), and between sperm concentration and osmolality was found (r = 0.92). There was a significant decrease in anti-proteolytic activity from the first to the second sampling, but not in protein concentration. Anti-proteolytic activity and protein concentration were significantly affected by variations in individual males. Electrophoresis revealed four anti-proteolytic bands and individual differences in bands of proteolytic activity, which were subsequently characterized as metalloproteases and serine proteases.     

Some characteristics and short-term preservation of spermatozoa of Deccan mahseer, Tor khudree (Sykes)

Over the years, the natural stocks of Tor khudree (Cyprinidae) have depleted due to anthropogenic activities and hence it is considered a threatened species in India. Several in situ and ex situ conservation strategies have been suggested for the revival of T. khudree stocks. The total volume of milt obtained from hormone‐injected (gonadotropin‐releasing hormone analogue+domperidone) T. khudree were significantly higher (six to seven times) than that of uninjected fish. The total number of spermatozoa per fish was also higher in injected fish (6.5 × 10⁸–7.6 × 10⁸) than that obtained from uninjected counterparts (1.3 × 10⁸–1.8 × 10⁸). On the contrary, the spermatozoa density and spermatocrit were found to be lower in injected fish than that of the controls. Spermatozoa density and spermatocrit ranged between 4.1 × 10⁸–4.4 × 10⁸ spermatozoa mL^?1 and 38.1–39.4%, respectively, in injected fish, whereas the figures fluctuated between 6.0 × 10⁸–7.8 × 10⁸ spermatozoa mL^?1 and 61.5–63.1%, respectively, in uninjected fish. However, there was no significant difference in the spermatozoa motility rates between experimental and control fish. Different spermatozoa‐activating media revealed no significant difference in spermatozoa motility between hormone‐injected and uninjected mahseers. But motility duration was the longest with NaCl+urea (190–193 s) and the shortest with tap water (50–55 s) in the experimental and control groups. Short‐term preservation of the spermatozoa of T. khudree indicated that spermatozoa stored at 4°C had higher motility rates than those preserved at room temperature either in the presence or absence of oxygen.     

Bioencapsulation of five forms of erythromycin by adult Artemia salina (L.)

Uptake of five chemical forms of erythromycin by adult Artemia salina (L.) (erythromycin phosphate – EP, erythromycin stearate – ES, erythromycin estolate – EE, erythromycin hydrate – EH and crystalline erythromycin – CE) was investigated in two trials. In each trial, final erythromycin concentration in Artemia tissue and survival after a 12‐h bioencapsulation period were determined. In the first trial, Artemia tissue concentration after a 12‐h bioencapsulation period was significantly (P < 0.05) affected by erythromycin form with ES (68.5 ± 3.3 μg mL^?1, mean ± SEM) ≈ EH (61.2 ± 3.4 μg mL^?1) > CE (37.1 ± 10.7 μg mL^?1) > EP (16.4 ± 7.7 μg mL^?1) > control. In trial 2, Artemia tissue concentration was also significantly (P < 0.05) affected by erythromycin form with EE (111.4 ± 9.6 μg mL^?1) > CE (89.1 ± 1.7 μg mL^?1) > ES (78.9 ± 1.6 μg mL^?1) > EP (33.4 ± 5.2 μg mL^?1) > control. Survival was significantly affected by erythromycin form in trial 1 with EP=control (100 ± 0.0%) > ES (74.4 ± 2.0%) > CE (32.2 ± 0.3%) > EH (8.8 ± 4.4%). In trial 2, survival was also significantly affected by erythromycin form with EP=control (100 ± 0.0%) > ES (67.1 ±3.7%) > CE (52.5 ± 7.7%) > EE (5.0 ± 2.5%). Based on both uptake and survival, EP and ES appear to be appropriate compounds for bioencapsulation of erythromycin using live adult Artemia.     

Effects of stocking density and algal concentration on the survival,growth and metamorphosis of Bobu Ivory shell,Babylonia formosae habei (Neogastropoda: Buccinidae) larvae

Independent and combined effects of stocking density and algal concentration on the survival, growth and metamorphosis of the Bobu Ivory shell Babylonia formosae habei larvae were assessed using a 5 × 5 factorial design with densities of 0.25, 0.5, 0.75, 1.00 and 1.50 larvae mL⁻¹ and algal concentrations of 5, 10, 15, 20 and 25 × 10⁴ cells mL⁻¹ in the laboratory. Larval growth, survival and metamorphosis were significantly affected by both the independent effects of stocking density and algal concentration and by their interaction. The highest per cent survival (72.5%) and metamorphosis (49.5%), fastest growth (41.57 μm day⁻¹) and shortest time to initial metamorphosis (10 days) all occurred at the lowest stocking density and the highest algal concentration. Both crowding and food limitation had independently negative impacts on the survival, growth and metamorphosis of larvae, and these negative impacts were further strengthened by the interaction of a higher stocking density and a lower algal concentration. Moreover, the results suggest that stocking density and algal concentration obviously played different roles in determining larval survival and growth. To maximize survival and growth, B. formosae habei larvae should be reared at a lower stoking density of 0.25 larvae mL⁻¹ and fed a higher algal concentration of 25 × 10⁴ cells mL⁻¹ in large-scale hatchery seed culture.     

Growth and survival of juvenile lined seahorse,Hippocampus erectus (Perry), at different stocking densities

The lined seahorse, Hippocampus erectus (Perry), is an important species in both medicinal and aquarium trades. The aim of this study was to evaluate the effects of stocking density (1, 3 and 5 individuals L⁻¹) on the growth performance and survival of the early-stage juvenile H. erectus. The height (HT), wet weight, weight gain (WG) and specific growth rate (SGR) were affected significantly by the stocking density during the 40-day study. The HT, WG and SGR of the seahorse at 1 and 3 juveniles L⁻¹ were significantly higher than that at 5 juveniles L⁻¹. The survival of juveniles at the three stocking densities was not significantly different at day 25 (90.3 ± 4.5%, 86.7 ± 4.2% and 86.2 ± 3.8% for 1, 3 and 5 juveniles L⁻¹ respectively), but was significantly different at day 40 (87.8 ± 3.9%, 69.6 ± 4.2% and 52.9 ± 2.8% for 1, 3 and 5 juveniles L⁻¹ respectively). For the early-stage juvenile H. erectus, we recommend a stocking density of 3 juveniles L⁻¹, but the density should be reduced to 1–2 juveniles L⁻¹ to avoid reduced and variable growth and high mortality after 25 days.