Larviculture newsletter < Year 2005 < Issue 219

ELECTRONICAL LARVICULTURE NEWSLETTER ISSUE 219
May 1, 2005

1. EFFECT OF TEMPERATURE ON INCUBATION PERIOD AND HATCHING SUCCESS OF OBSCURE PUFFER TAKIFUGU OBSCURUS (ABE) EGGS
2. INCOMPLETENESS AND STATISTICAL UNCERTAINTY IN COMPETITION/STOCKING EXPERIMENTS
3. ARTIFICIAL SPAWNING IN CULTURED STERLET STURGEON, ACIPENSER RUTHENUS L., WITH SPECIAL EMPHASIS ON HERMAPHRODITES
4. EFFECTS OF DIFFERENT DIETARY PROTEIN CONTENT ON GROWTH AND PROTEASE ACTIVITY OF ERIOCHEIR SINENSIS LARVAE
5. DIETARY PROTEIN/LIPID RATIO AFFECTS GROWTH AND AMINO ACID AND FATTY ACID ABSORPTION AND METABOLISM IN SENEGALESE SOLE (SOLEA SENEGALENSIS KAUP 1858) LARVAE
6. QUANTITATIVE AND QUALITATIVE ANALYSIS OF RETINOIDS IN ARTEMIA AND COPEPODS BY HPLC AND DIODE ARRAY DETECTION
7. EFFECTS OF Α-TOCOPHEROL SUPPLEMENTATION OF ROTIFERS ON THE GROWTH OF STRIPED TRUMPETER LATRIS LINEATA LARVAE
8. PHOTOPERIOD AND LIGHT INTENSITY EFFECTS ON GROWTH AND UTILIZATION OF NUTRIENTS BY THE AQUACULTURE FEED MICROALGA, TETRASELMIS CHUI (PLY429)
9. GROWTH AND BIOCHEMICAL COMPOSITION OF THE DIATOM CHAETOCEROS CF. WIGHAMII BRIGHTWELL UNDER DIFFERENT TEMPERATURE, SALINITY AND CARBON DIOXIDE LEVELS. I. PROTEIN, CARBOHYDRATES AND LIPIDS
10. THE EFFECTS OF STRESS ON ANDROGEN PRODUCTION, SPERMIATION RESPONSE AND SPERM QUALITY IN HIGH AND LOW CORTISOL RESPONSIVE DOMESTICATED MALE STRIPED BASS
11. THE SHAPE OF THE LIPID VESICLE IS A POTENTIAL MARKER FOR EGG QUALITY DETERMINATION IN THE GILTHEAD SEABREAM, SPARUS AURATA, AND IN THE SHARPSNOUT SEABREAM, DIPLODUS PUNTAZZO
12. CHEMICAL AND PHYSICAL EFFECTS OF CROWDING ON GROWTH AND SURVIVAL OF PENAEUS MONODON FABRICIUS POST-LARVAE
13. SHORT COMMUNICATION: RELATIONSHIP BETWEEN EGG SPECIFIC GRAVITY AND EGG QUALITY IN THE JAPANESE EEL, ANGUILLA JAPONICA
14. OPTIMAL FIRST FEED ORGANISM FOR SOUTH AFRICAN MUD CRAB SCYLLA SERRATA (FORSKÅL) LARVAE
15. OPTIMUM TIME FOR WEANING SOUTH AFRICAN SCYLLA SERRATA (FORSKÅL) LARVAE FROM ROTIFERS TO ARTEMIA
16. GROWOUT OF HATCHERY-REARED JUVENILE SPOTTED BABYLON (BABYLONIA AREOLATE LINK 1807) TO MARKETABLE SIZE AT FOUR STOCKING DENSITIES IN FLOW-THROUGH AND RECIRCULATING SEAWATER SYSTEMS
17. EVIDENCE THAT THE ROTIFER BRACHIONUS PLICATILIS IS NOT AN OSMOCONFORMER
18. DEVELOPMENT AND CHARACTERIZATION OF COMPLEX PARTICLES FOR DELIVERY OF AMINO ACIDS TO EARLY MARINE FISH LARVAE
19. SINGLE-STEP NESTED MULTIPLEX PCR TO DIFFERENTIATE BETWEEN VARIOUS BIVALVE LARVAE
20. EFFICACY OF HYDROGEN PEROXIDE VERSUS FORMALIN TREATMENTS TO CONTROL MORTALITY ASSOCIATED WITH SAPROLEGNIASIS ON LAKE TROUT EGGS
21. EFFECT OF BACTERIAL LOAD IN FEEDS ON INTESTINAL MICROFLORA OF SEABREAM (SPARUS AURATA) LARVAE AND JUVENILES
22. EFFECTS OF PRE-WEANING FEEDING FREQUENCY ON GROWTH, SURVIVAL, AND DEFORMATION OF SENEGALESE SOLE, SOLEA SENEGALENSIS (KAUP, 1858)
23. GROWTH, BEHAVIOR, AND MATING OF PHARAOH CUTTLEFISH (SEPIA PHARAONIS EHRENBERG) IN CAPTIVITY
24. EFFECT OF STIMULANTS ON FEEDING RESPONSE, FEEDING BEHAVIOR, AND GROWTH OF FRY OF SEA BASS, LATES CALCARIFER (BLOCH, 1790)

EFFECT OF TEMPERATURE ON INCUBATION PERIOD AND HATCHING SUCCESS OF OBSCURE PUFFER TAKIFUGU OBSCURUS (ABE) EGGS
Zhou Yang, Yafen Chen-2005
Aquaculture, 246 (1-4): 173-179
Abstract:
Artificially fertilized eggs of obscure puffer Takifugu obscurus were obtained by induced spawning of cultured broodstock and incubated at temperatures of 15, 19, 23, and 27 °C. The results showed that the optimal temperature for obscure puffer embryonic development ranged from 19 to 23 °C, based on total hatch rate, viability of newly hatched larvae 24 h post-hatch, and total mortality rate of eggs. At the given temperature range, the times taken for 50% embryos to hatch were 11.3, 6.6, 5.0, and 4.2 days, respectively. There was significant difference in time to 50% hatch among the temperatures used in this experiment. The power law model, quadratic equation, exponential equation, and effective degree-day model all provided good fits for the relationship between incubation temperature and time to 50% hatch, with r2 values greater than 0.90. The formulae for these were y=1031.7T−1.6885, y=44.721−3.1574T+0.0615T2, y=34.663e−0.0813T and y=78.905/(T−7.6033), respectively, where y is time to 50% hatch in days, and T is incubation temperature in degrees Celsius. The effective degree-day model was determined to be the best model because of efficient computation, good fit to the experimental data, and most importantly, the derived parameters, k (the sum of effective degree-days) and t0 (the temperature of biological zero), have important biological meaning. Based on the effective degree-day model, the t0 and k values were calculated as 7.6033 °C and 78.905 degree-days, respectively.
(Jiangsu Key Laboratory of Bioresource Technology, School of Biological Sciences, Nanjing Normal University, 122 Ninghai Road, Nanjing 210097, People's Republic of China; email of Zhou Yang: yangzhouff@vip.sina.com)

INCOMPLETENESS AND STATISTICAL UNCERTAINTY IN COMPETITION/STOCKING EXPERIMENTS
Marcel Fréchette, Marianne Alunno-Bruscia, Jean-François Dumais, Renée Sirois, Gaétan Daigle-2005
Aquaculture, 246 (1-4): 209-225
Abstract:
In competition experiments, decisions are made not only about experimental conditions such as initial population densities, of course, but also about population size structure, for instance. Here we use an individual-based simulation model to study the effect of size-grading of mussels. With low individual variability, predicted yield was lower and less variable, there was no density-dependent mortality, and optimal stocking density for aquaculture was lower than with high individual variability, whereby self-thinning occurred and yield was quite variable. Thus, individual variability was a critical factor for estimating survival effects of overstocking, at the expense of precision of growth estimates. Therefore, competition experiments are inherently incomplete. We argue that in practice, incompleteness cannot be overcome by using genetic information as a covariate because evidence from the literature shows that the effect of genetic makeup in competition situations is frequency-dependent. Apparently, the only approach presently available to obtain unbiased estimates is to use a size structure similar to that of the population under study. This contrasts with a literature review of bivalve stocking experiments published in Aquaculture through the last 30 years which clearly shows that the issue of size structure of test populations has been largely overlooked. The same principles hold for competition studies in natural settings.
(Institut Maurice-Lamontagne, Ministère des Pêches et des Océans, C.P. 1000, Mont-Joli, QC, Canada G5H 3Z4; email of Marcel Fréchette: frechettem@dfo-mpo.gc.ca)

ARTIFICIAL SPAWNING IN CULTURED STERLET STURGEON, ACIPENSER RUTHENUS L., WITH SPECIAL EMPHASIS ON HERMAPHRODITES
P. Williot, R. Brun, T. Rouault, M. Pelard, D. Mercier, A. Ludwig-2005
Aquaculture, 246 (1-4): 263-273
Abstract:
Hormonal stimulation of sterlet sturgeon, Acipenser ruthenus, was carried out with carp pituitary extract at 2 and 5 mg kg−1 body weight for males on the one hand, females and hermaphrodites on the other hand. Within our experimental stock, reproductive performances defined by relative number of ovulated females, fertilisation rate, and relative number of good quality semen samples had begun to decline in fish older than 14–16 years. Ovarian cycle have proved to be mostly annual recurring cycles with a 1-year interval (40% to 50%) or 2-year interval (27% to 34%). Spawnable females ranged from 39% to 86% in our experimental period 1994 to 2000. Selection of spawnable females was mainly based on a minimum size of oocytes of 2.5–2.6 mm.
For the first time, hermaphrodites have been reported in farmed sterlet sturgeon. Few sequential and simultaneous hermaphrodites have been observed. Most of the time both gametes proved to be functional in either mating. Embryonic survival of self-fertilised eggs ranged from 0% to 70%. Progeny was obtained twice. Out of 102 (1994) to 76 (2000) individuals representing an equilibrated sex ratio, 2 to 4 individuals, respectively, were hermaphrodites. The number of hermaphrodites increased with the age of the fish. Anatomical and physiological aspects are discussed. The modelling of our data demonstrates that fertilisation depends on gamete interaction, of which practical consequences are discussed. Artificial reproduction of hermaphrodite fish was confirmed by genetic analysis. Microsatellite analysis produced a homozygous excess of two alleles, both polymorphic loci.
(Cemagref, Ressources Aquatiques Continentales, 50, Avenue de Verdun, 33612 Cestas Cedex, France; email of Patrick Williot: patrick.williot@cemagref.fr )

EFFECTS OF DIFFERENT DIETARY PROTEIN CONTENT ON GROWTH AND PROTEASE ACTIVITY OF ERIOCHEIR SINENSIS LARVAE
Lu-Qing Pan, Guo-Qiang Xiao, Hong-Xia Zhang, Zhi-Hua Luan-2005
Aquaculture, 246 (1-4): 313-319
Abstract:
This paper studied the effects of dietary protein content on growth and protease activity of Eriocheir sinensis larvae. The results suggest that if E. sinensis larvae were fed diets of different protein content, their survival, metamorphic rate and weight gain all changed significantly (P<0.05), but the amount of change differed. Larvae survival was highest from Z3 to Z4, and the variation in weight gain of each treatment group declined gradually as the larvae developed. During the 20 h post-metamorphosis of every larval stage, the protease activity increased at Z1, Z2, Z3 and M, and declined at Z4 and Z5, meanwhile the protease activity of larvae was influenced significantly by the protein content of the diets (P<0.05). In addition, 4 h after the larvae were fed, the protease activity at each larval stage changed corresponding to dietary protein content, while 12 h later the changes tended to be stable. Considering the growth of larvae and the flexibility of protease, it can be concluded that the appropriate protein requirements at Z1, Z2, Z3, Z4, Z5 and M were, respectively, 45%, 45%, 50%, 45%, 45% and 40%.
(The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China Qingdao 266003 China; email of Lu-Qing Pan: panlq@ouc.edu.cn)

DIETARY PROTEIN/LIPID RATIO AFFECTS GROWTH AND AMINO ACID AND FATTY ACID ABSORPTION AND METABOLISM IN SENEGALESE SOLE (SOLEA SENEGALENSIS KAUP 1858) LARVAE
Sofia Morais, William Koven, Ivar Rønnestad, Maria Teresa Dinis, Luís E.C. Conceição-2005 Aquaculture, 246 (1-4): 347-357
Abstract:
Studies with fish larvae have reported poor performance associated with quantitative lipid imbalances in the diet and a lower dietary protein/neutral lipid ratio has been shown to result in an increased accumulation of lipid droplets in the enterocytes and in reduced fatty acid (FA) absorption efficiency in larval Senegalese sole. The present study examined the effect of dietary protein/neutral lipid ratios on amino acid (AA) absorption efficiency and metabolism, gut histology and growth in Senegalese sole larvae. Larvae were fed either non-enriched Artemia (NEA) or Artemia enriched on a soybean oil emulsion (EA) following larval settlement (at 16 days after hatching—DAH). AA absorption efficiency and metabolism were determined at 27 and 33 DAH by feeding the larvae on 14C-AA-labeled Artemia. The effect on FA absorption was also verified at 28 DAH by tube feeding a lipid mixture containing the 14C-labeled triacylglycerol triolein (TRI). A significantly lower growth was obtained with the EA diet, which also lead to an increased lipid accumulation in the gut epithelium. Feeding larvae with EA resulted in lower 14C-FA absorption (significantly lower gut and body retention and higher label evacuation) at 28 DAH but no effect was noted in 14C-AA absorption 24 h after feeding, at 27 and 33 DAH. However, larvae fed NEA evacuated a significantly higher amount of 14C-AA at 3 h after feeding and presented a significantly higher AA catabolism. This indicates a faster AA absorption in NEA-fed larvae, which may allow more time for its metabolic use. On the other hand, a higher net AA absorption may be achieved in larvae fed NEA through a more rapid clearance of the lumen and sustained ingestion of the diet. The significantly higher growth of larvae fed NEA may thus be explained by a higher FA absorption efficiency and/or by an increased ingestion rate of a diet containing a lower lipid level.
(CCMAR, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; email of Sofia Morais: smorais@ualg.pt)

QUANTITATIVE AND QUALITATIVE ANALYSIS OF RETINOIDS IN ARTEMIA AND COPEPODS BY HPLC AND DIODE ARRAY DETECTION
Mari Moren, Thomas E. Gundersen, Kristin Hamre-2005
Aquaculture 246 (1-4): 359-365
Abstract:
Different concentrations of retinoids have been reported in Artemia. The levels vary from 0–362 μg g−1 Artemia (dry wt.). The aim of this study was to investigate the actual retinoid concentration in Artemia and compare it with levels in copepods. Samples of both DC-DHA Selco (INVE, Ghent, Belgium) from the bottle and after 12 h in the enrichment tank in addition to enriched and unenriched Artemia and copepods from a pond system were collected and analysed for vitamin A components. The analyses were conducted using two different HPLC (high pressure liquid chromatography) methods to ensure the justness of the results. The DC-DHA Selco contained 132.7 μg vitamin A g−1. After 12 h in the enrichment tank we could not detect any vitamin A. None of the following retinoids were observed in Artemia or copepods with any of the methods: all-trans-retinol (at-ROH), 9-cis-ROH or at-3,4-didehydro-ROH (at-3,4-dd-ROH). Method 2 detects several other retinoids when present, but none of the following were found in the two live prey organisms: cis or trans 3,4-dd-RA, cis or trans 3,4-dd-ROH, cis or trans 3,4-dd-RAL, cis or trans ROH or cis or trans RA. This implies that larvae feeding on either copepods or Artemia must meet their retinoid requirement from other sources than retinoids.
(National Institute of Nutrition and Seafood Research, P.O. Box 2029 Nordnes, N-5817 Bergen, Norway; email of Mari Moren: mari.moren@nifes.no)

EFFECTS OF Α-TOCOPHEROL SUPPLEMENTATION OF ROTIFERS ON THE GROWTH OF STRIPED TRUMPETER LATRIS LINEATA LARVAE
Malcolm R. Brown, Graeme A. Dunstan, Peter D. Nichols, Stephen C. Battaglene, David T. Morehead, Anna L. Overweter-2005
Aquaculture, 246 (1-4): 367-378
Abstract:
The effect of dietary α-tocopherol (α-T; vitamin E) on the performance of striped trumpeter larvae was assessed using a dose–response design. Five tuna oil/lecithin/water emulsions containing between 0% and 4% (40 mg g−1) dry weight (DW) of α-T were fed to rotifers, resulting in rotifer α-T concentrations between 114 and 1040 μg g−1 DW. These rotifers or a reference diet of rotifers enriched with AlgaMac 2000 (AM) were fed to larvae from first feeding at 5 days post-hatch (dph) until 23 dph.
In larvae fed the emulsion-enriched rotifers, tissue concentrations of α-T were correlated to dietary concentrations. Larvae at 5 dph contained 276 μg α-T g−1; concentrations in most larvae had reduced at 23 dph (to between 121 and 225 μg α-T g−1) except for those fed highest α-T, which contained 356 μg g−1. Larval weight at 20 dph, and length at 14 and 23 dph were positively correlated with dietary α-T concentration. Interpolation of data from the regression curves showed that higher dietary α-T (i.e. ≥437 μg α-T g−1) gave a maximum 7% increase in larval length and a maximum of 10% increase in weight. Larval survival was extremely variable (average 37.0±30.1%). Though not statistically significant, average survival was apparently higher (48.4±28.2%) in larvae fed diets containing ≥437 μg α-T g−1 than those fed diet with lower α-T, i.e. ≤144 μg α-T g−1 (25.6±30.3%), with larvae fed 221 μg α-T g−1 having intermediate survival (37.2±32.3).
(CSIRO Marine Research and the Aquafin Cooperative Research Centre, GPO Box 1538, Hobart, Tasmania 7001, Australia; email of Malcolm Brown: Malcolm.Brown@csiro.au)

PHOTOPERIOD AND LIGHT INTENSITY EFFECTS ON GROWTH AND UTILIZATION OF NUTRIENTS BY THE AQUACULTURE FEED MICROALGA, TETRASELMIS CHUI (PLY429)
Shannon L. Meseck, Jennifer H. Alix, Gary H. Wikfors-2005
Aquaculture, 246 (1-4): 393-404
Abstract:
Light intensity, day length, and nutrient concentrations are important factors regulating the growth of phytoplankton. To reduce culturing costs, natural sunlight and greenhouses can be used to minimize the amount of artificial light needed for algal growth. However, with natural sunlight there is much more variation in the light intensity and the day length than what would be found in a controlled laboratory environment. This study investigated how different light intensities and day lengths affect the growth and nutrient uptake of Tetraselmis chui (strain PLY429)—an algal strain used widely as an aquaculture feed. PLY429 was grown aseptically for 28 days under three different light intensities (220, 110, and 73 μEinst. m−2 s−1) and four different light:dark cycles (24:0, 16:8; 12:12; 8:16). Growth and net nutrient-uptake rates for PLY429 were calculated for each treatment. Longer day length and higher light intensities resulted in higher biomass production and complete utilization of nitrate and phosphate in less time, as compared with shorter days and lower intensities. PLY429 cultures that were exposed to only 8 h of light had the slowest growth and utilization of nutrients. These findings suggest that day length is important in determining growth and nutrient uptake in PLY429; at a latitude of 41°N, artificial light will need to be added to algal cultures in a greenhouse to increase both day length and total daily light input.
(NOAA Fisheries Service, 212 Rogers Ave., Milford, CT 06460, United States; email of Shannon Meseck: Shannon.Meseck@noaa.gov)

GROWTH AND BIOCHEMICAL COMPOSITION OF THE DIATOM CHAETOCEROS CF. WIGHAMII BRIGHTWELL UNDER DIFFERENT TEMPERATURE, SALINITY AND CARBON DIOXIDE LEVELS. I. PROTEIN, CARBOHYDRATES AND LIPIDS
Sirlei de Castro Araújo, Virgínia Maria Tavano Garcia-2005
Aquaculture, 246 (1-4): 405-412
Abstract:
The marine diatom Chaetoceros cf. wighamii has been investigated for its potential use as food in mariculture. In this work, we investigated temperature (20, 25, and 30 °C), salinity (25 and 35) and carbon dioxide addition (air and air + CO2) effects on growth and biochemical composition of C. cf. wighamii, under laboratory conditions. C. cf. wighamii growth and biomass was primarily affected by carbon dioxide addition and to a lesser extent by temperature and salinity. In general, lipid and carbohydrate content were higher at lower temperatures (20 and 25 °C) while protein was unaffected. Carbon dioxide addition increased protein and lowered carbohydrates, but had no effect on lipid content. Carbohydrates were enhanced while lipids and protein decreased at the highest salinity (35). These results should be taken into consideration when evaluating the nutritional value of this microalga for marine invertebrate larvae.
(Laboratory of Ecology of Phytoplankton and Marine Microorganisms, Dept. of Oceanography, Federal University of Rio Grande, Avenida Itália, Km 8, Rio Grande-RS, Brazil, 96201-900; email of Sirlei de Castro: sirleicastro@yahoo.com.br)

THE EFFECTS OF STRESS ON ANDROGEN PRODUCTION, SPERMIATION RESPONSE AND SPERM QUALITY IN HIGH AND LOW CORTISOL RESPONSIVE DOMESTICATED MALE STRIPED BASS
Daniel A. Castranova, William King V, L. Curry Woods III-2005
Aquaculture, 246 (1-4): 413-422
Abstract:
Domesticated male striped bass were selected as high cortisol stress responders (HCR) or low cortisol stress responders (LCR) by ranking mean 1-h post-stress plasma cortisol levels following a 2-min standardized net challenge once per month for four consecutive months. During the selection period, HCR and LCR fish maintained a significant divergence in post-stress cortisol levels, but these differences were abolished coincident with the onset of sexual maturation. LCR fish stressed monthly during gonadal maturation and weekly during the spawning season had plasma testosterone (T) and 11-ketotestosterone (11-KT) levels 3–5 times lower than stressed HCR fish. During the simulated spawning season, plasma cortisol and glucose levels were moderately elevated but similar in HCR and LCR fish. There were no differences in sperm quality between HCR and LCR males; however, more HCR fish began spermiating earlier and maintained a spermiation response longer than LCR fish. There were no significant differences in weight, length or coefficient of condition, but HCR fish had a significantly greater specific growth rate on two sample intervals when compared to LCR fish. These results show that male striped bass selected for low cortisol stress responsiveness and exposed to repeated stress have diminished circulating levels of T and 11-KT associated with a shorter duration spermiation response when compared to males selected for high cortisol stress responsiveness. The data suggest that LCR male striped bass subjected to significant stress during maturation and spawning may have impaired reproductive performance.
(Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742, United States; email of Curry Woods: curry@umd.edu)

THE SHAPE OF THE LIPID VESICLE IS A POTENTIAL MARKER FOR EGG QUALITY DETERMINATION IN THE GILTHEAD SEABREAM, SPARUS AURATA, AND IN THE SHARPSNOUT SEABREAM, DIPLODUS PUNTAZZO
Franz Lahnsteiner, Pierpaolo Patarnello-2005
Aquaculture, 246 (1-4): 423-435
Abstract:
This study investigated whether morphological parameters measured in eggs during early embryonic stages (first cleavage to morula) were useful for prediction of egg quality (% hatching embryos out of floating eggs) in Sparus aurata and Diplodus puntazzo. Eggs obtained from natural spawning were collected from commercial broodstocks. In the viable, floating eggs, the minimal and maximal diameter of the egg, yolk, and lipid vesicle were measured. Based on these measurements several parameters were calculated describing the shape of the egg, yolk, and lipid vesicle, and the size relationship between these compartments. These parameters were investigated for correlation with egg viability.
From all investigated morphometric parameters only the ratio of the maximal to the minimal diameter of the lipid vesicle (RDLV) and the lipid vesicle shape coefficient (LVSC) were correlated with larval survival (%) from viable eggs. As the shape of a lipid droplet depends on the type and composition of lipid, the lipid to water ratio, and the interactions with the surrounding water molecules this parameter may be an index for the biochemical lipid composition.
(Institute for Zoology, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria; email of Franz.Lahnsteiner: Franz.Lahnsteiner@sbg.ac.at)

CHEMICAL AND PHYSICAL EFFECTS OF CROWDING ON GROWTH AND SURVIVAL OF PENAEUS MONODON FABRICIUS POST-LARVAE
B.T. Nga, M. Lürling, E.T.H.M. Peeters, R. Roijackers, M. Scheffer, T.T. Nghia-2005
Aquaculture, 246 (1-4): 455-465
Abstract:
The hypothesis that crowding effects through physical and/or chemical interference may be an important factor in lowering the chance of survival and reducing growth of Penaeus monodon post-larvae under high stocking densities was tested. To separate physical interference from chemically-exerted effects, two-stage systems were used in which shrimps were cultured at different densities (stage 1) and water from these being supplied to individually kept P. monodon (stage 2). Stocking density significantly affected P. monodon survival, body-size and dry-weights over a 4-week experimental period. At high densities of 50 and 100 shrimps/l, strong negative effects traveled into stage 2. Hence, physical interference stress and cannibalism could be excluded as causal factors meaning that the negative impact of crowding (at 50 and 100 shrimps/l) on shrimp growth and survival was due to some chemical compounds or other water quality variable. Among these pH, temperature, salinity, dissolved oxygen, chlorine, nitrite and nitrate appeared of minor influence. In contrast, ammonium toxicity could not be excluded as the causal factor for the observed mortality and reduced growth of P. monodon post-larvae in our experiments.
(Department of Environmental and Natural Resources Management, College of Agriculture, Cantho University, Vietnam; email of Miquel Lürling: miquel.lurling@wur.nl)

SHORT COMMUNICATION:
RELATIONSHIP BETWEEN EGG SPECIFIC GRAVITY AND EGG QUALITY IN THE JAPANESE EEL, ANGUILLA JAPONICA
Tatsuya Unuma, Shigenori Kondo, Hideki Tanaka, Hirohiko Kagawa, Kazuharu Nomura, Hiromi Ohta-2005
Aquaculture, 246 (1-4): 493-500
Abstract:
Eggs from maturation-induced Japanese eels, Anguilla japonica, often sink in seawater immediately after artificial insemination and do not hatch. In the present study, the specific gravity of unfertilized eggs from individual females was measured in isotonic (about 310 mOsm/kg) and hypertonic (about 875 mOsm/kg) saline solutions and the relation of specific gravity to egg quality was examined. Egg specific gravity under isotonic conditions showed a significant negative correlation with egg fertility, hatchability and water content, suggesting that inadequate hydration of oocytes during final maturation, which leads to insufficient egg buoyancy, is one of the causes of poor egg quality. Some of the eggs that showed lower specific gravity than seawater under isotonic conditions exhibited higher specific gravity than seawater under hypertonic conditions, indicating that the buoyancy acquired by the eggs is sometimes lost after their transfer to seawater. Only eggs that retained low specific gravity under hypertonic as well as isotonic conditions exhibited high fertility and hatchability. Taken together with data from other studies, these results suggest that the poor quality of eggs that sink immediately after artificial insemination is attributable to at least two causes: the failure of oocytes to acquire sufficient buoyancy during maturation and the loss of buoyancy in seawater because of the inability of egg osmoregulation.
(National Research Institute of Aquaculture, Fisheries Research Agency, Nansei, Mie 516-0193, Japan; email of T. Unuma: unuma@fra.affrc.go.jp)

GROWOUT OF HATCHERY-REARED JUVENILE SPOTTED BABYLON (BABYLONIA AREOLATE LINK 1807) TO MARKETABLE SIZE AT FOUR STOCKING DENSITIES IN FLOW-THROUGH AND RECIRCULATING SEAWATER SYSTEMS
N. Chaitanawisuti, S. Kritsanapuntu, S. Y. Natsukari-2005
Aquaculture International, 13 (3): 233 - 239
Abstract:
Hatchery reared juvenile spotted babylon, Babylonia areolata, were raised in canvas rearing tanks at four stocking densities (100, 200, 300 and 400 ind. m–2) in flow-through and recirculating seawater systems until they reached the marketable sizes of 100–140 snails/kg. At all stocking densities, final increments in mean length and weight of snails held in flow-through systems were higher than those in recirculating systems, there was a significant effect (p < 0.05) of culture system on final length and weight. Mean (±SE) survival of snails held at 100 ind. m–2 in the flow-through system was 100.0 ± 0.1% but was not significantly higher than survival in any other treatment (p > 0.05). Mean survival of snails held in the recirculating system was not significantly lower than at any stocking density in the flow-through system (p > 0.05).
(Aquatic Resources Research Institute, Chulalongkorn University, Phya Thai Road, 10330 Pathumwan, Bangkok, Thailand; email of N. Chaitanawisuti: nilnajc1@hotmail.com)

EVIDENCE THAT THE ROTIFER BRACHIONUS PLICATILIS IS NOT AN OSMOCONFORMER
C. D. Lowe, S. J. Kemp, A. D. Bates, D. J. S. Montagnes-2005
Marine Biology, 146 (5): 923 - 929
Abstract:
The rotifer Brachionus plicatilis is euryhaline (growing between 2 and 97 ppt) and has previously been considered an osmoconformer. We suggest that B. plicatilis is an osmoregulator, exhibiting a pattern of Na+/K+ ATPase activity in response to salinity consistent with that of other osmoregulating euryhaline invertebrates. To examine salinity tolerance, growth rates between 5 and 60 ppt were determined. The activity of Na+/K+ ATPase was examined, over the same range of salinities, by measuring ATPase activity in rotifer homogenates in the presence and absence of a Na+/K+ ATPase inhibitor. Maximum specific growth rate (0.95 day-1) occurred at 16 ppt, highest mean amictic eggs per female (1.41) occurred at 20 ppt, and both parameters decreased rapidly as salinity increased. Egg development time was constant with salinity at 0.92 days. The activity of Na+/K+ ATPase per milligram protein increased from 3.9 µmol h-1 at 5 ppt to 6.8 µmol h-1 at 50 ppt and accounted for 15 and 30% of total ATPase activity, respectively. We suggest that these observations are consistent with increasing stress at high salinities and the occurrence of a hypo-osmoregulatory response. Given the high ATP consumption of Na+/K+ ATPase at high salinities, it is possible that a proportion of the corresponding decreases in growth rate and egg production are a direct cost of regulation.
(School of Biological Sciences University of Liverpool Biosciences Building, Crown Street Liverpool L69 7ZB UK)

DEVELOPMENT AND CHARACTERIZATION OF COMPLEX PARTICLES FOR DELIVERY OF AMINO ACIDS TO EARLY MARINE FISH LARVAE
Umur Önal, Chris Langdon-2005
Marine Biology, 146 (5): 1031 - 1038
Abstract:
Complex particles (CP), zein microbound particles and lipid-spray beads (LSB) were prepared and their performances were compared for delivering glycine and a mixture of free amino acids (FAA; alanine, glycine, leucine, serine and tyrosine) to early fish larvae. Measures of performances of microparticles included inclusion, encapsulation, retention and delivery efficiencies in addition to T50 (time to 50% retention) values. CP were prepared containing LSB and a defined dietary mixture that were bound together with zein. CP had significantly higher retention and delivery efficiencies for FAA compared to those of zein microbound particles. Free LSB had higher retention efficiencies for particulate glycine compared with CP, possibly due to differences in suspension characteristics. Free LSB clumped and floated when suspended in water, negatively affecting their acceptability by fish larvae; therefore, LSB should be incorporated into CP for more effective delivery of amino acids. There was a significant inverse correlation between retention efficiencies and solubilities of FAA encapsulated in CP. After 1 h of aqueous suspension, highest retention (44%) and delivery efficiencies (20.3 mg tyrosine g-1 particle) were achieved with tyrosine. T50 values indicated 50% of the initial tyrosine in CP was still available after 36.7 min of suspension in water. Furthermore, CP can deliver FAA to marine fish larvae based on the results of feeding studies in which CP were digested by 3-day-old clownfish larvae; therefore, this particle type could be a valuable tool in studies of larval fish nutrition.
(Department of Aquaculture, Fisheries Faculty Çanakkale Onsekiz Mart University 17100 Çanakkale Turkey)

SINGLE-STEP NESTED MULTIPLEX PCR TO DIFFERENTIATE BETWEEN VARIOUS BIVALVE LARVAE
J. B. Larsen, M. E. Frischer, L. J. Rasmussen, B. W. Hansen-2005
Marine Biology, 146 (6): 1119 - 1129
Abstract:
A nested multiplex polymerase chain reaction (PCR) assay has been developed that allows the discrimination between six bivalve larvae common to Danish coastal waters (Cerastoderma edule, Macoma balthica, Mytilus edulis, Spisula subtruncata, Ensis americanus and members of the order Myoida). This assay involves the simultaneous use of a pair of general universally targeted 18S rRNA gene primers, five specific 18S rRNA gene targeted oligonucleotide primers internal (nested) to the universal primer pair and one species-specific primer that is not nested (Mya). The specificity of each primer was evaluated in silico, empirically, and verified further by sequencing of amplification products from single larvae collected from plankton samples. Identification of individually isolated bivalve larvae from plankton samples was based on the size of the PCR product produced by the specific primers after visualisation by agarose gel electrophoresis. Preliminary studies indicated that this method was suitable for use with freshly collected and preserved larvae, and is therefore suitable for field application.
(Department of Life Sciences and Chemistry, Roskilde University, 4000 Roskilde, Denmark; email of B.W. Hansen: bhansen@ruc.dk)

EFFICACY OF HYDROGEN PEROXIDE VERSUS FORMALIN TREATMENTS TO CONTROL MORTALITY ASSOCIATED WITH SAPROLEGNIASIS ON LAKE TROUT EGGS
Jeff J. Rach, Steven Redman, Dale Bast, Mark P. Gaikowski-2005
North American Journal of Aquaculture, 67 (2): 148–154
Abstract:
We compared the efficacy of hydrogen peroxide versus formalin treatments to control fungal infections on eggs of lake trout Salvelinus namaycush incubated at a hatchery in Wisconsin. Four strains of lake trout eggs were incubated in six vertical-flow Heath incubators; three replicate incubators for each chemical. Each incubator had 13 trays containing approximately 25,000–30,000 eggs/tray. Formalin (1,667 mg/L) or hydrogen peroxide (1,000 mg/L) treatments were administered once daily for 15 min up to the development of visible eye spots in the eggs (eyed egg stage). Eyed and dead eggs were separated using a photoelectric egg sorter, and the number of live and dead eggs was determined volumetrically. In the hydrogen peroxide test group, the bottom trays of each incubator had fungus present on the eggs, whereas no fungus was observed on eggs treated with formalin. The mean percentage of eyed eggs for an incubator treated with formalin (75%) was significantly greater than an incubator treated with hydrogen peroxide (70%). Formalin was the most efficacious therapeutant; however, both therapeutants were effective in increasing lake trout egg survival up to the eyed egg stage.
(U.S. Geological Survey, Upper Midwest Environmental Sciences Center, 2630 Fanta Reed Road, La Crosse, Wisconsin 54603, USA)

EFFECT OF BACTERIAL LOAD IN FEEDS ON INTESTINAL MICROFLORA OF SEABREAM (SPARUS AURATA) LARVAE AND JUVENILES
Sevgi Savas, Aysegul Kubilay, Nevin Basmaz-2005
The Israeli Journal of Aquaculture – Bamidgeh 57(1): 3-9
Abstract:
Aerobic bacterial flora in the intestines of seabream (Sparus aurata) larvae and juveniles, in diets they were fed (rotifers, brine shrimp, artificial diet), and in their rearing water were analyzed. Fish fed live feeds had a higher bacterial count than the fish fed the artificial diet. In rotifers, the total bacteria count was 8.7 x 106 and Pseudomonas dominated the flora (60.2%). In larvae fed rotifers, the bacteria count was 9.8 x 102, with Pseudomonas (48.4%) and Vibrio (28.3%) dominating. In brine shrimp, the bacterial count was 1.7-3.5 x 107 cfu/g and Vibrio (73.7-81.3%) was more prevalent than Pseudomonas (10.2-15.5%). In larvae fed brine shrimp, the bacterial count was 5.3 x 104-1.8 x 105 and Vibrio (61.2-70.1%) dominated. The count for the artificial feed was 1.2 x 104 with Pseudomonas slightly dominating while for juveniles fed artificial feed the count was 2.3 x 104, with Vibrio slightly dominating. Bacterial microflora in the rearing water ranged from 1.3 x 102 to 3.2 x 103 cfu/ml. The study showed that the microflora of fish feeds quantitatively and qualitatively affect the intestinal microflora of seabream larvae and juveniles.
(Suleyman Demirel Universty, Faculty of Fisheries, Egirdir, Isparta, Turkey; email of Sevgi Sagas: segi68@yahoo.com)

EFFECTS OF PRE-WEANING FEEDING FREQUENCY ON GROWTH, SURVIVAL, AND DEFORMATION OF SENEGALESE SOLE, SOLEA SENEGALENSIS (KAUP, 1858)
Sofia Engrola, Luis E.C. Conceicao, Paulo J. Gavaia, M. Leonor Cancela, Maria T. Dinis-2005
The Israeli Journal of Aquaculture – Bamidgeh 57(1): 10-18
Abstract:
Despite much interest in the production of Senegalese sole (Solea senegalensis) in southern Europe, weaning of this species onto artificial diets is problematic and varying results are obtained. The aim of this study was to test two feeding frequencies during a 13-day pre-weaning period and assess their impact on the growth and survival of Senegalese sole. Postlarvae were fed Artemia metanauplii with a peristaltic pump every hour for 12 hours per day or twice daily (morning and late afternoon). Both groups were suddenly weaned onto a commercial diet for an additional 30 days. At the end of the experiment, the relative growth rate and final dry weight were significantly higher and the survival significantly lower in the 12-hour treatment than in the twice-daily treatment. The feeding frequency had no effect on condition factor. The incidence of deformities was about 80% in both treatments.
(CCMAR, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; email of S. Engrola: sengrola@ualg.pt)

GROWTH, BEHAVIOR, AND MATING OF PHARAOH CUTTLEFISH (SEPIA PHARAONIS EHRENBERG) IN CAPTIVITY
M.K. Anil, Joseph Andrews, C. Unnikrishnan-2005
The Israeli Journal of Aquaculture – Bamidgeh 57(1): 25-31
Abstract:
The pharaoh cuttlefish (Sepia pharaonis) was successfully reared from egg to an average size of 168 mm mantle length and 521 g in 210 days, using simple biological filtration systems. The period of egg incubation was 15 days at a temperature of 27-31°C. Hatchlings were reared at a stocking density of one animal per liter during the first month; density was reduced as growth proceeded. Food items consisted of live mysids, Artemia salina, juvenile fishes, and prawns. Juveniles were gradually acquainted with dead food items such as caridian prawns and small fishes. The present study shows that the pharaoh cuttlefish can be reared in captivity with a survival rate of 41%, using live feeds during the first 50 days. Future commercial scale culture of this species depends on development of artificial feeds and high density culture systems. (Vizhinjam Research Center, Central Marine Fisheries Research Institute, Vizhinjam 695 521, Kerala, India; email of M.K. Anil: mkanil19@rediffmail.com)

EFFECT OF STIMULANTS ON FEEDING RESPONSE, FEEDING BEHAVIOR, AND GROWTH OF FRY OF SEA BASS, LATES CALCARIFER (BLOCH, 1790)
Ravendra Kumar Singh, Vivek Vartak, Amjad Balange-2005
The Israeli Journal of Aquaculture – Bamidgeh 57(1): 32-38
Abstract:
The influence of four stimulants (glycine, proline, L-lysine, and Bombay duck fishmeal) on the feeding behavior of sea bass fry was studied. The substances were added at a level of 1% of the weight of moist pellets made from purified diets. Feeding responses were observed in glass tanks containing one or two fish.The fishmeal had significantly greater stimulating effect on the feeding behavior than the chemical substances. Feeding responses were significantly different when there were two fish in the tank. Inclusion of fishmeal at a 10% level (compared to 1%, 5%, 7.5%) produced the greatest ingestion response (50%). Compared to 7.5%, inclusion at 10% produced a significantly higher weight gain (0.54±0.03 g), FCR (1.79), and PER (1.20). The present investigation revealed that Bombay duck meal is a better natural fish feed stimulant than the tested chemicals.
(Taraporevala Marine Biological Research Station, New Administrative Building, Third Floor, Bandra (E), Mumbai, 400051, India; email of Ravendra Kumar Singh: tmbrs@rediffmail.com)

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