Laboratory of Aquaculture & Artemia Reference Center

Larviculture newsletter < Year 2005 < Issue 214

ELECTRONICAL LARVICULTURE NEWSLETTER ISSUE 214
February 15, 2005

Successful sex ratio of 1M:4F in the astacid crayfish Pacifastacus leniusculus Dana under captive breeding conditions
Toxicity of ozone generated from different combinations of ozone concentration (C) and exposure time (T): a comparison of the relative effect of C and T on hatch rates of Penaeus (Marsupenaeus) japonicus embryos
Improved survival and growth in Octopus vulgaris paralarvae by feeding large type Artemia and Pacific sandeel, Ammodytes personatus
Dietary L-ascorbic acid affects growth, nonspecific immune responses and disease resistance in juvenile grouper, Epinephelus malabaricus
Effect of prepared and macroalgal diets and seed stock source on somatic growth of juvenile green sea urchins (Strongylocentrotus droebachiensis)
Macronutrient composition of formulated diets for Atlantic halibut (Hippoglossus hippoglossus, L.) juveniles, II: protein/lipid levels at low carbohydrate
Ontogeny of tolerance to hypoxia and oxygen consumption of larval and juvenile red sea bream, Pagrus major
Spawning impact on lysosomal stability of the Pacific Oyster, Crassostrea gigas
Spirulina as a nutrient source in diets for growing sturgeon (Acipenser baeri)
Journal of Shellfish Research, 23 (2): August 2004
Journal of Shellfish Research , 23 (3): December 2004
Maternal and seasonal differences in egg sizes and spawning activity of northwest Atlantic haddock (Melanogrammus aeglefinus) in relation to body size and condition
Larval Development of the Grooved Shrimp (Penaeus kerathurus Forskal, 1775) Under Laboratory Conditions
Improving gonad colour and somatic index in the European sea urchin Paracentrotus lividus
Tolerance of Penaeus (Marsupenaeus) japonicus embryos to ozone disinfectION
The use of inert artificial commercial food sources as replacements of traditional live food items in the culture of larval shrimp, Farfantepenaeus aztecus
Effects of lactic acid bacteria cultures on pathogenic microbiota from fish
Effects of culture density on growth and broodstock management of the cuttlefish, Sepia officinalis (Linnaeus, 1758)
Growth, development, and survival of larval Mithraculus sculptus (Lamark) and Mithraculus forceps (A. Milne Edwards) (Decapoda: Brachyura: Majidae): economically important marine ornamental crabs
Arachidonic acid enriched live prey induces albinism in Senegal sole (Solea senegalensis) larvae
Effects of temperature, density, and diet on development, survival, settlement synchronism, and fatty acid profile of the ornamental shrimp Lysmata seticaudata
Activities of selected digestive enzymes during larval development of large yellow croaker (Pseudosciaena crocea)
Effects of n-3 HUFA content in broodstock diet on spawning performance and fatty acid composition of eggs and larvae in Plectorhynchus cinctus
The influence of oocyte maturational stage on hatching and triploidy rates in hybrid (bester) sturgeon, Huso huso×Acipneser ruthenus
Hemolymph vitellogenin levels during final maturation and post-spawning in the female kuruma prawn, Marsupenaeus japonicus
Cultivation of the brown alga Hizikia fusiformis (Harvey) Okamura: enhanced seedling production in tumbled culture
Growth and biomass production of Tetraselmis suecica and Dunaliella tertiolecta in a standard medium added with three products of zeolitic nature
A novel computer simulation model for design and management of re-circulating aquaculture systems
Estimation of flow in a rearing tank of marine fish larvae by simplified numerical computation—a case of two-dimensional flow
Air bubbling results in carbon loss during microalgal cultivation in bicarbonate-enriched media: experimental data and process modeling

SUCCESSFUL SEX RATIO OF 1M:4F IN THE ASTACID CRAYFISH PACIFASTACUS LENIUSCULUS DANA UNDER CAPTIVE BREEDING CONDITIONS
J.D. Celada, J.I. Antolín, J.M. Carral, M. Sáez-Royuela, R. Rodríguez-2005
Aquaculture, 244 (1-4): 89-95
Abstract:
In astacid crayfish breeding, a sex ratio of one male to two females (1M:2F) is usually recommended. In light of the fact that an increase in the proportion of females in the broodstock would be desirable, two experiments were carried out with Pacifastacus leniusculus Dana to test a proportion of females with a ratio as high as 1M:4F under different conditions of animal density and group size, with mating and spawning rates being evaluated in addition to the production and further viability of the eggs. In both experiments, no breeder mortality was recorded and all the females mated. No significant differences were noticed between groups of 5 and 125 animals nor between densities of 5 and 25 animals per square metre. Likewise, no differences were detected between the sex ratios 1M:2F and 1M:4F. With regard to overall results, some 10 days after spawning 98% of egg-bearing females was achieved, with a mean of 323 pleopodal eggs. When the eggs reached phases VII–IX (embryo with blastopore in closing process-embryo with naupliar appendages), the percentage of berried females was 93.6% with 245 eggs per female. At that point, eggs were stripped, pooled and artificially incubated by methods developed by this team. Finally, 165 stage 2 juveniles were obtained per female. This allows, at least in this species, a considerable increase in the proportion of females in the broodstock, and better use of farming facilities.
(Dpto. Producción Animal II, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain; email of J.D.Celada: dp2jcv@unileon.es)

TOXICITY OF OZONE GENERATED FROM DIFFERENT COMBINATIONS OF OZONE CONCENTRATION (C) AND EXPOSURE TIME (T): A COMPARISON OF THE RELATIVE EFFECT OF C AND T ON HATCH RATES OF PENAEUS (MARSUPENAEUS) JAPONICUS EMBRYOS
Greg J. Coman, Melony J. Sellars, David T. Morehead-2005
Aquaculture, 244 (1-4): 141-145
Abstract:
The toxicities of several CT values generated from different combinations of ozone concentration (C) and exposure time (T) were evaluated using hatch rates of Penaeus (Marsupenaeus) japonicus embryos as a measure of ozone toxicity. Embryo hatch rates were investigated at five different CT values (0.5, 1, 2, 4 and 8), produced from different combinations of C (0.5, 1 and 2 ppm) and T (0.5, 1, 2, 4 and 8 min). The experiment was conducted at 16, 120 and 480 min post-spawning for two P. japonicus families. The effect of C on embryo hatch rate when treated at different CT values varied between post-spawning treatment times and families. Where differences in hatch rates were found between C treatments at a single CT value, hatch rates decreased with increasing C. These results indicate that CT values generated by higher C and shorter T values are more toxic to P. japonicus embryos than CT values generated by lower C and longer T values. Our findings indicate that ozone dose cannot be prescribed solely by the CT value, but must also be qualified by describing the C and T values used to generate the CT value. These results have significant implications for designing treatment protocols that aim to use ozonation as a disinfection agent for cultured organisms.
(CSIRO Marine Research, 233 Middle Street, 4163 Cleveland, Qld, Australia; email of Greg Coman: Greg.Coman@csiro.au)

IMPROVED SURVIVAL AND GROWTH IN OCTOPUS VULGARIS PARALARVAE BY FEEDING LARGE TYPE ARTEMIA AND PACIFIC SANDEEL, AMMODYTES PERSONATUS
Shigenobu Okumura, Ayako Kurihara, Akio Iwamoto, Toshio Takeuchi-2005
Aquaculture, 244 (1-4): 147-157
Abstract:
Rearing experiments of common octopus, Octopus vulgaris, paralarvae were carried out during the first month of life by feeding with large type Artemia or small type Artemia supplemented with defrozen flakes of Pacific sandeel, Ammodytes personatus. Two experiments, based on different scale tanks of four 500 l circular tanks and two 4000 l rectangular tanks, were carried out in June to July 2003 to investigate the survival, growth and HUFA composition of the paralarvae and food organisms. The survival rate of paralarvae was significantly higher in the large type Artemia supplied groups (47.4% and 45.9%) than the small type Artemia supplied groups (8.8% and 2.7%). Similarly, the mean wet weight was 26.2 and 37.3 mg for the 25 and 32 day old paralarvae in the large type Artemia groups while 20.3 and 18.2 mg in the small type Artemia groups. The survival rate and growth of the large type Artemia groups were higher than the small type Artemia groups and the values given in the previous studies. Feeding large type Artemia and sandeel flakes was concluded as effective for improving survival and growth of the common octopus paralarvae. The DHA/EPA ratio in the 32 day old paralarvae of both Artemia supplied groups was equal 1.5, similar to that of hatchlings and wild subadults. Supplementing sandeel flakes improved the DHA/EPA ratio of the paralarvae, since both types of Artemia contained only minimal DHA. However, the reason(s) for the improved survival rate and growth between the large type Artemia supplied group and small type Artemia supplied group still remain to be solved.
(Yashima Station, National Center for Stock Enhancement, Fisheries Research Agency, Takamatsu, Kagawa, 761-0111, Japan; email of S. Okumura: sokumura@fra.affrc.go.jp)

DIETARY L-ASCORBIC ACID AFFECTS GROWTH, NONSPECIFIC IMMUNE RESPONSES AND DISEASE RESISTANCE IN JUVENILE GROUPER, EPINEPHELUS MALABARICUS
Mei-Fang Lin, Shi-Yen Shiau-2005
Aquaculture, 244 (1-4): 215-221
Abstract:
An 8-week feeding trial was conducted to estimate the adequate dietary L-ascorbic acid (AA) requirements of juvenile grouper and its effect on nonspecific immune responses and disease resistance when challenged with Vibrio carchariae. AA supplemented at 0, 20, 50, 80, 150, 250, 400 and 800 mg/kg diet in the basal diet providing of 0, 3, 14, 27, 46, 76, 135 and 288 AA mg/kg diet, respectively. Each diet was fed to triplicate groups of grouper with initial body weight of 7.58±0.05 g. Fish fed diets supplemented with ≥46 mg AA/kg had significantly (P<0.05) greater weight gain (WG) and feed efficiency (FE) than fish fed diets with 14 mg AA/kg. After the final weighing, 10 fish were randomly taken from each aquarium and injected with V. carchariae. Mortality was recorded daily for 7 days and nonspecific immune parameters were monitored in the remaining fish. Higher cumulative mortality was in fish fed the unsupplemented diet or the 3-mg AA/kg diet than other dietary groups. Fish fed the 288-mg AA/kg diet had higher respiratory burst activity (superoxide O2−) of head kidney leukocytes and alternative complement activity than fish fed the unsupplemented diet and diets with 76 mg AA /kg, respectively. Lysozyme activity was higher in fish fed diets with ≥76 mg AA than fish fed diets with 27 mg AA/kg. These data indicated that the adequate dietary AA concentration for optimum growth of juvenile grouper is 45.3 mg AA/kg diet, and six times the optimum dietary AA level was needed to enhance the nonspecific immune responses and maintain survival of the fish infected with bacteria.
(Department of Food Science, National Taiwan Ocean University, Keelung 202, Taiwan; emai of Shi-Yen Shiau: syshiau@mail.ntou.edu.tw)

EFFECT OF PREPARED AND MACROALGAL DIETS AND SEED STOCK SOURCE ON SOMATIC GROWTH OF JUVENILE GREEN SEA URCHINS (STRONGYLOCENTROTUS DROEBACHIENSIS)
T.L. Daggett, C.M. Pearce, M. Tingley, S.M.C. Robinson, T. Chopin-2005
Aquaculture, 244 (1-4): 263-281
Abstract:
Populations of sea urchins, harvested for their gonads, are in decline worldwide and so scientific research is now focusing on full life cycle grow-out. The objective of this study was to compare the growth rates of juvenile (initial test diameter: 4.5–13.7 mm) green sea urchins that were held in laboratory tanks and fed a variety of diets. Two separate experiments were conducted. The first compared juvenile growth on seven different diets: 1) prepared diet, 2) Porphyra purpurea, 3) Palmaria palmata, 4) Ulva linza, 5) a mixture of Ulvaria obscura and Ulva lactuca, 6) Laminaria saccharina collected from an Atlantic salmon aquaculture site, and 7) L. saccharina collected from a site relatively distant from salmon aquaculture operations. The latter two treatments were chosen in order to determine if the nutrient regime in which an alga was grown could affect juvenile growth rate. A second experiment compared the growth rates of wild-caught and hatchery-reared juvenile green sea urchins fed either a prepared diet or fresh kelp (L. saccharina) collected from a site relatively distant from salmon aquaculture. Test diameter and whole wet weight measurements were taken monthly for a period of 16 months. In the first experiment, feed type significantly affected somatic growth rate, the overall best growth being supported by Porphyra purpurea (mean growth rate ±SE: 0.059±0.001 mm d−1) and the prepared diet (0.056±0.001 mm d−1). L. saccharina collected from the site distant from salmon aquaculture operations (0.019±0.001 mm d−1) produced significantly slower growth than any other feeding treatment including L. saccharina collected from a salmon aquaculture site (0.047±0.001 mm d−1). In the second experiment, feed type also significantly affected growth with the prepared diet (0.058±0.001 mm d−1) supporting better growth than L. saccharina (0.027±0.001 mm d−1). Seed stock source also affected overall growth with the hatchery-reared individuals displaying significantly greater growth (0.045±0.002 mm d−1) than wild-caught individuals (0.040±0.002 mm d−1). Identifying which diets and sources of juvenile sea urchins optimize growth may help aquaculture operations produce market-size sea urchins in a minimum amount of time, thus maximizing profitability.
(Ross Island Salmon Ltd., P.O. Box 1304, Grand Manan, New Brunswick, Canada E5G 4M9; email of T. Daggett: tdaggett@simcorp.ca)

MACRONUTRIENT COMPOSITION OF FORMULATED DIETS FOR ATLANTIC HALIBUT (HIPPOGLOSSUS HIPPOGLOSSUS, L.) JUVENILES, II: PROTEIN/LIPID LEVELS AT LOW CARBOHYDRATE
Kristin Hamre, Grete Baeverfjord, Torstein Harboe-2005
Aquaculture, 244 (1-4): 283-291
Abstract:
The aim of the present study was to show that Atlantic halibut on the weaning stage, fed low carbohydrate levels, tolerates a wide variation in lipid as long as protein requirement is fulfilled. The fish (0.4 g) were fed diets with lipid levels increasing from 50 to 300 g kg-1 concomitant with protein decreasing from 860 to 620 g kg−1 with 50 g kg−1 intervals. No carbohydrate was added and the diets contained less than 12 g kg−1 digestible starch. The experiment lasted for 95 days. An increase in growth rate with increasing dietary lipid was registered for the whole population, but for the largest half of the population, growth was not affected by the dietary treatments. No specific pathology was observed in liver or intestine on histological examination, but a consistent increase in hepatocellular vacuolization was observed with increasing dietary lipid levels. Increasing dietary lipid led to decrease in survival and the small fish were affected most severely by mortality. We suspect that high levels of soy lecithin supplemented as 25% of the lipid in the present experiment may have caused the dietary effect on mortality. Based on this assumption and combined with previous studies, our results indicate that weaning diets for Atlantic halibut should contain no more than 50 g kg−1 carbohydrate, a minimum of 580 g kg−1 protein and 50–300 g kg−1 lipid.
(National Institute of Nutrition and Seafood Research (NIFES). P.O. Box 2029, Nordnes, N-5817 Bergen, Norway; email of K. Hamre: kristin.hamre@nifes.no)

ONTOGENY OF TOLERANCE TO HYPOXIA AND OXYGEN CONSUMPTION OF LARVAL AND JUVENILE RED SEA BREAM, PAGRUS MAJOR
Yasunori Ishibashi, Kosuke Inoue, Hiromu Nakatsukasa, Yutaka Ishitani, Shigeru Miyashita, Osamu Murata-2005
Aquaculture, 244 (1-4): 331-340
Abstract:
Changes in tolerance to hypoxic stress and oxygen consumption were studied in the red sea bream, Pagrus major, from its early life stage until 42 days post-hatch. In the experiments, metamorphosis was observed mainly from days 15 to 30, and the morphological shift from larva to juvenile was completed at around 9.5 mm total length (TL). During the larval stage, lethally low dissolved oxygen (DO) levels and mass-specific metabolic rates increased with growth from 2.6 to 5 mm TL (P<0.01). Subsequently, the levels remained high and decreased until about 9.5 mm TL around the flexion stage and post flexion stage. Finally, beginning in the juvenile stage, lethal DO levels and mass-specific metabolic rates decreased as TL increased up to about 30 mm (P<0.01). The relationship between lethal DO levels and mass-specific metabolic rates was significantly linear (r=0.59, p<0.001, n=207) in fish larvae and juveniles. These results indicated that, around the stage of flexion and post flexion larvae in red sea bream, metabolic rates were highest during metamorphosis, and consequently hypoxia tolerance was lowest. It was presumed that the increasing metabolic rate during metamorphosis induced a decrease in the metabolic scope of activity and thereby induced the decrease of the tolerance to some environmental stressors in the background.
(Department of Fisheries, School of Agriculture, Kinki University, Nakamachi, Nara 631-8505, Japan; email of Y. Ishibashi: isibasi@nara.kindai.ac.jp)

SPAWNING IMPACT ON LYSOSOMAL STABILITY OF THE PACIFIC OYSTER, CRASSOSTREA GIGAS
Sang-Man Cho, Woo-Geon Jeong-2005
Aquaculture, 244 (1-4): 383-387
Short communication
Abstract:
The impact of spawning on the circulating hemocyte density and neutral red retention (NRR) time of lysosome in hemocytes of the Pacific Oyster, Crassostrea gigas, were assessed. Significant decreases were observed in both hemocyte density and NRR time in spawned oysters, which could aggravate the health of the oysters. These conditions may, therefore, facilitate summer mortality through increased infection with parasites and pathogens and decreased tolerance to environmental conditions.
(Division of Marine Bioscience, College of Marine Science, Gyeongsang National University, 445, Tongyeong, 650-160, Republic of Korea; email of Sang-Man Cho: s_gigas@gaechuk.gsnu.ac.kr)

SPIRULINA AS A NUTRIENT SOURCE IN DIETS FOR GROWING STURGEON (ACIPENSER BAERI) Giovanni B Palmegiano, Elisabetta Agradi, Gilberto Forneris, Francesco Gai, Laura Gasco, Elisabetta Rigamonti, Benedetto Sicuro, Ivo Zoccarato-2005
Aquaculture Research, 36 (2): 188 –
Abstract: The efficiency of diets with the inclusion of Spirulina for Siberian sturgeon weaning has been tested. Three isoproteic and isoenergetic diets were formulated with an increasing level of Indian strain Spirulina (SP 40%, SP 50% and SP 60%); the diets were tested against a control diet without microalgae. The results show that Spirulina inclusion improves growth and that an inclusion level of 50% gave the greatest growth rate, a better favourable feed conversion rate and the highest protein efficiency. The fatty acid composition of fillets showed differences between the experimental and control diets: an increase in the Spirulina level induces increases in palmitic and linoleic acids and a decrease in the myristic acid. The control diet was characterized by high levels of eicosapentaenoic and docosahexaenoic acids. At the end of the experiment, statistical differences appeared in the fatty acid profile of the sturgeon fillet, mainly concerning high content of monounsaturated fatty acid and polyunsaturated fatty acid in the sturgeon fillets. If the problems related to the high production costs are solved, Spirulina could prove a good partial substitute fish meal. (CNR Institute of Science of Food Production, Torino Division, Via L. da Vinci 44, Grugliasco (TO), Italy; email of G. Palmegiano: giovanni.palmegiano@ispa.cnr.it)

Journal of Shellfish Research, 23 (2): August 2004
• Effects of salinity on growth and survival of silver-lip pearl oyster, Pinctada maxima, spat. Joseph J. Taylor, Paul C. Southgate, Robert A. Rose
• Gametogenic processes in the pearl oyster, Pteria penguin (Röding, 1798) (Bivalvia, Mollusca). U. Arjarasirikoon, M. Kruatrachue, P. Sretarugsa, Y. Chitramvong, S. Jantataeme, E. S. Upatham
• Microscopic observations of larval Ostrea circumpicta (Bivalve: Ostreidae) in brood chambers. Do-Hyung Kang, Se-Jae Kim, Kwang-Sik Choi
• In situ aquaculture protocol for two tropical pectinids, Bractechlamys vexillum (Reeve 1853) and Mimachlamys gloriosa (Reeve 1853): spat collection, rearing, growth and mortality. Laurent Wantiez, Pierre Thollot
• Effect of depth and stocking density on growth and retrieval of the postlarval lion’s paw scallop, Nodipecten nodosus (Linnaeus, 1758). Guilherme S. Rupp, G. Jay Parsons, Raymond J. Thompson, Micheline M. de Bem
• Comparison of biochemical composition and muscle hypertrophy associated with the reproductive cycle of diploid and triploid Argopecten ventricosus. E. Palacios, I. S. Racotta, A. M. Ibarra, J. L. Ramı´rez, A. Milla´n, S. Avila
• Lipid classes and fatty acid composition in female gonads of great scallops—a selective field study. Arne Duinker, Bente E. Torstensen, Øyvind Lie
• Reproductive cycle of coexisting mussels, Mytilus californianus and Mytilus galloprovincialis, in Baja California, New Mexico. Sergio Curiel-Ramirez, Jorge Cáceres-Martinez
• Size specific fecundity of red abalone (Haliotis rufescens): evidence for reproductive senescence? Laura Rogers-Bennett, Richard F. Dondanville, Jerry Kashiwada
• The settlement of abalone (Haliotis discus hannai Ino) larvae on culture layers of different diatoms. Nurit Gordon, Muki Shpigel, Sheenan Harpaz, John J. Lee, Amir Neori

Journal of Shellfish Research, 23 (3): December 2004
• Reproduction of the lion’s paw scallop Nodipecten subnodosus Sowerby, 1835 (Bivalvia: Pectinidae) from Laguna Ojo de Liebre, B.C.S., Mexico. Marcial Arellano-Martínez, Bertha Patricia Ceballos-Vázquez, Marcial Villalejo-Fuerte, Federico García-Domínguez, Juan Felix Elorduy-Garay, Aarón Esliman-Salgado, Ilie S. Racotta
• Reproduction and pathology of blue mussels, Mytilus edulis (L.) in an experimental longline in Long Island Sound, Connecticut. Inke Sunila, Lawrence Williams, Steve Russo, Tessa Getchis
• Reproductive cycle and mortality of the Japanese oyster Crassostrea gigas cultured in Bahía Falsa, Baja California, Mexico. Jorge Cáceres-Martínez, Sergio Curiel Ramírez Gutiérrez, Rebeca Vásquez-Yeomans, Patricia Macías Montes de Oca
• A survey of genetic changes and search for sex-specific markers by AFLP and SAMPL in a breeding program of Chinese shrimp (Penaeus chinensis. Liusuo Zhang, Xiaoyu Kong, Ziniu Yu, Jie Kong, Limei Chen

MATERNAL AND SEASONAL DIFFERENCES IN EGG SIZES AND SPAWNING ACTIVITY OF NORTHWEST ATLANTIC HADDOCK (MELANOGRAMMUS AEGLEFINUS) IN RELATION TO BODY SIZE AND CONDITION
Edward A. Trippel, Steven R.E. Neil-2004
Can. J. Fish. Aquat. Sci., 61(11): 2097-2110
Abstract:
Egg and larval production of 22 captive spawning pairs of northwest Atlantic haddock (Melanogrammus aeglefinus) were monitored. Females spawned an average of nine egg batches (range 3–16) with a mean batch fecundity of 60 000 eggs and mean total fecundity of 535 000 eggs. Mean spawning duration was 37 days with a mean batch interval of 5.4 days. In multiple linear regression, male Fulton's condition factor (range 1.10–1.55) and mean batch interval explained 56% of variation in fertilization rate (33% and 23%, respectively). Seasonal composite egg diameter spanned 1.37–1.53 mm among females. Mean egg diameter within females declined seasonally by an average of 10.4% (37% by volume). Females produced 46 larvae per gram body weight. Body weight was the single best predictor of fecundity (r2=0.57), with Fulton's condition factor (range 1.04–1.76) explaining no significant additional variation over length or weight. Length and condition explained 39% of variation in seasonal composite egg diameter (22% and 17%, respectively) and body weight independently explained 32%. Sex-specific parental condition and body size acted through large egg size and elevated fertility to enhance reproductive output. Male spawning success was more sensitive than egg production to changes in condition.

LARVAL DEVELOPMENT OF THE GROOVED SHRIMP (PENAEUS KERATHURUS FORSKAL, 1775) UNDER LABORATORY CONDITIONS
Gürel Türkmen-2004
Turkish Journal of Fisheries and Aquatic Sciences, 12: 97-103 Abstract: The larval stages of the grooved shrimp Penaeus kerathurus (Forskal, 1775) were described and photos were taken based on the materials hatched and reared in the laboratory. The larval development of P. kerathurus consists of 6 naupliar, 3 protozoeal, and 3 mysis stages before the first postlarva. Differences in the number of setae on 2nd antenna exopod and spine formation on caudal furca were described for naupliar (N1-N6) stages of P. kerathurus and the chronological pattern was compared with previous and relevant studies on other Penaeus species.
(Ege University, Faculty of Fisheries, Department of Aquaculture, Bornova 35100, Izmir, Turkey; E-mail: turkmen@sufak.ege.edu.tr)

IMPROVING GONAD COLOUR AND SOMATIC INDEX IN THE EUROPEAN SEA URCHIN PARACENTROTUS LIVIDUS
Muki Shpigel, Susan C. McBride, Sharon Marciano, Shiri Ron, Ami Ben-Amotz-2005
Aquaculture, 245 (1-4): 101-109
Abstract:
One of the major factors influencing marketability of sea urchins is their gonad colour. The effects of a prepared diet, algal diets, and rotational feeding of these diet treatments on the European sea urchin Paracentrotus lividus were studied to determine a diet that would provide optimal gonad colour and gonadal somatic index (GSI). P. lividus underwent six diet treatments: Ulva lactuca and Gracilaria conferta for 12 weeks (UG-12); prepared diet for 10 weeks followed by administration of Ulva and Gracilaria for 2 weeks (P-10); prepared diet for 8 weeks followed by Ulva and Gracilaria for 4 weeks (P-8); prepared diet for 6 weeks followed by Ulva and Gracilaria for 6 weeks (P-6); prepared diet for 12 weeks (P-12); and Ulva, Gracilaria and prepared diet for 12 weeks (UGP-12).
The algae diet produced a dark orange colour but a low GSI. The pellet diet produced a good GSI but pale gonad colour. P. lividus fed the prepared diet for 8 weeks followed by 4 weeks of algal diet produced the optimal combination of desired gonad colour and GSI.
The dominant carotenoid in the gonads was echinenone, which the sea urchin synthesises from β-carotene. The higher the echinenone level in the gonads, the more intense their colouration. The lack of echinenone found in the gut and its high accumulation in the gonad, in inverse proportion to the β-carotene profile, indicates bioconversion within the gonad or upon transfer from the gut to the gonad.
(National Center for Mariculture, Israel Oceanographic and Limnological Research, PO Box 1212, Eilat 88112, Israel; email of M. Shpigel: shpigelm@agri.huji.ac.il)

TOLERANCE OF PENAEUS (MARSUPENAEUS) JAPONICUS EMBRYOS TO OZONE DISINFECTION
Melony J. Sellars, Greg J. Coman, David T. Morehead-2005
Aquaculture, 245 (1-4): 111-119
Abstract:
This study investigated the tolerance of Penaeus (Marsupenaeus) japonicus embryos to ozone disinfection to establish a suitable treatment level that has no detrimental effect on embryo hatch rate. In a factorially design experiment, three families were exposed to four different ozone concentrations (C) (0, 0.5, 1 and 2 ppm), for five different exposure times (T) (0.5, 1, 2, 4 and 8 min), to give a total of eight ozone concentration×exposure time (CT) combinations, with an exception for family 1 which had no 8 min exposure time. This was conducted at 16, 120 and 480 min post-spawning for all three families. Embryos were least tolerant to ozonation 16 min post-spawning, with a CT value as low as 0.5 for family 1, and a CT value of 1 for families 2 and 3, significantly (P<0.05) affecting hatch rates relative to controls. For the 120 and 480 min post-spawning treatment times, CT values lower than 2 had no significant effect (P>0.05) on hatch rate relative to controls in any of the three families. Families 1 and 2 mean hatch rate was not significantly (P<0.05) affected when treated at a CT of 4 at 480 min post-spawning, whilst a CT of 8 had no significant effect on mean hatch rate for family 2 when applied 120 min post-spawning. Based on our results, future studies towards developing disinfection protocols for P. japonicus embryos should utilise an ozone concentration of 2 ppm and exposure time of 1 min (CT of 2) applied 120 or 480 min post-spawning.
(CSIRO Marine Research, 233 Middle Street, Cleveland, Qld, 4163 Australia; email of M. Sellars: Melony.Sellars@csiro.au)

THE USE OF INERT ARTIFICIAL COMMERCIAL FOOD SOURCES AS REPLACEMENTS OF TRADITIONAL LIVE FOOD ITEMS IN THE CULTURE OF LARVAL SHRIMP, FARFANTEPENAEUS AZTECUS
C.B. Robinson, T.M. Samocha, J.M. Fox, R.L. Gandy, D.A. McKee-2005
Aquaculture, 245 (1-4): 135-147
Abstract:
Replacement of live feeds with alternate food sources is of major importance in commercial shrimp hatcheries. In this study, partial and complete replacement of live microalgae and Artemia nauplii with microalgae pastes and inert feeds is reported in the larval rearing of the brown shrimp Farfantepenaeus aztecus. Five different experimental feeds were used for each live food replacement study. Partial replacement of live microalgae using Chaetoceros 1000 “Premium Fresh” Instant Algae™ paste and Liqualife™ liquid larval feed showed survival rates similar to a control feed, however, postlarvae mean dry weight and length were significantly less than the control. Use of other replacement feeds, Epifeed™ liquid larval feed, Zeigler™ E-Z Larvae liquid feed, and Zeigler™ Z-Plus feed, yielded inferior results compared to the control feed. Statistical analysis of results from the live Artemia nauplii replacement study indicated that larval shrimp fed a control feed had significantly greater survival, mean PL length, and mean PL dry weight. The only exception was the partial replacement of Artemia nauplii using Liqualife™ in which there was no significant difference in survival between the control and this treatment. Results indicated that although Liqualife™, Epifeed™, Zeigler™ E-Z Larvae, Zeigler™ Z-Plus and Zeigler™ E-Z Artemia feeds could serve as partial replacement of newly hatched Artemia nauplii in production of F. aztecus postlarvae. Significantly improved results can be expected when larvae are fed newly hatched Artemia nauplii (control diet) with no supplement
(Texas Agricultural Experiment Station–Shrimp Mariculture Research Facility, Texas A&M University System, 4301 Waldron Rd., Corpus Christi, TX 78418, USA)

EFFECTS OF LACTIC ACID BACTERIA CULTURES ON PATHOGENIC MICROBIOTA FROM FISH
J.A. Vázquez, M.P. González, M.A. Murado-2005
Aquaculture, 245 (1-4): 149-161
Abstract:
The concrete nature of the probiotic effects which the presence of micro-organisms (especially lactic acid bacteria: LAB) exercise on larval cultures of fish is not well defined, being attributable to different factors or action mechanisms. In fact, the production of diverse antibacterial metabolites (bacteriocins in particular) by many LAB forms may constitute the basis of these probiotic effects, as is repeatedly described in literature. Accordingly, the inhibition of pathogenic species in fish by extracts of LAB constitutes a rapid method for detecting potential probiotics. By studying the response of four common pathogens of turbot (Scophthalmus maximus) to nine potential probiotics, the diversity and mechanisms of effectors in the probiotics were shown to present complex dose–response and non-treatable profiles with conventional models. Proposed modifications allow satisfactory fits and the calculation of useful parameters in the comparison of activities. The results showed that lactic and acetic acids, and not the bacteriocins, are responsible for the effects (inhibitory or stimulatory depending on the concentrations considered) in all the cases studied.
(Instituto de Investigacións Mariñas (CSIC), r/ Eduardo Cabello, 6. Vigo 36208. Galicia, Spain; email of J. Vázquez: jvazquez@iim.csic.es)

EFFECTS OF CULTURE DENSITY ON GROWTH AND BROODSTOCK MANAGEMENT OF THE CUTTLEFISH, SEPIA OFFICINALIS (LINNAEUS, 1758)
Miguel Correia, Pedro M. Domingues, António Sykes, José P. Andrade-2005
Aquaculture, 245 (1-4): 163-173
Abstract:
The effects of culture density on growth and broodstock management of the cuttlefish S. officinalis were studied. Cuttlefish used were one month old at the start of the experiment, on average; two densities were used (16 and 76 cuttlefish m−2). During the first experiment (until day 43), dead cuttlefish were replaced by individuals of similar weight. From that day onwards, no cuttlefish were replaced. No significant differences in growth and feeding rates, or food conversions were found between densities, during the first experiment. Results indicate that densities up to 76 cuttlefish m−2 are suitable for cuttlefish weighing approximately 10 g. After day 43 until first female layed eggs (second experiment), no statistical differences were found between densities for all the parameters studied with the exception of growth. In this case, cuttlefish cultured at the lower density grew more than those ones cultured at the higher density, with average weights at the start of egg laying of 137.3±21.6 and 91.8±12.3 g, respectively. This difference in growth could be explained mainly by the different culture densities and biomass associated.
Fecundity obtained for cuttlefish cultured at the lower density (834 eggs female−1) was higher than for those ones cultured at the higher density (290 eggs female−1), however fertility was higher for the higher density. These results were expected, since fecundity is directly related to the size of females. Significant differences were found in fertility (hatching percentage) between densities. Mean hatching percentage was of 35.8±9.4% and 62.0±16.9% for low and high density, respectively. This difference was unexpected since we expected eggs from females cultured at lower densities to have higher quality. Mean hatchling weight was of 0.079±0.011 and 0.072±0.012 g for low and high density respectively, and significantly different.
Results indicate that lower culture density promoted higher growth, larger eggs and hatchlings, but had no influence on juvenile and adult survival. On the contrary, eggs from females cultured at higher densities resulted in higher hatching rates.
(CCMar, Universidade do Algarve. F.C.M.A., Campus de Gambelas, 8000-810 Faro, Portugal; email of M. Correia: mtcorreia@ualg.pt)

GROWTH, DEVELOPMENT, AND SURVIVAL OF LARVAL MITHRACULUS SCULPTUS (LAMARK) AND MITHRACULUS FORCEPS (A. MILNE EDWARDS) (DECAPODA: BRACHYURA: MAJIDAE): ECONOMICALLY IMPORTANT MARINE ORNAMENTAL CRABS
Andrew L. Rhyne, Gil Penha-Lopes, Junda Lin-2005
Aquaculture, 245 (1-4): 183-191
Abstract:
Brachyuran crabs Mithraculus sculptus and Mithraculus forceps are heavily traded in the marine aquarium industry. To evaluate the aquaculture potential of these two species and to determine the most suitable species for further investigation, the growth, development, and survival of the larvae fed with two diets—newly hatched Artemia nauplii (NHA) and enriched Artemia nauplii (EA) with Algamac 3050—and those that were not fed (controls) were compared. In both species, starved larvae failed to develop past zoea 1 stage; however, survival, developmental rates, and growth rates were not different between crabs fed the two diets. Mean larval duration was significantly shorter for M. forceps fed either diet (8.3±0.5 for both treatments) than for M. sculptus (9.5±0.5 and 9.2±0.4 days for NHA and EA, respectively). Survivorship to juveniles was significantly higher in M. forceps (79.8±7.0% and 74.3±7.3% for NHA and EA diets, respectively) than in M. sculptus (19.3±15.3% and 25.7±9.9% for NHA and EA diets, respectively). Larval size and weight were not significantly different between diets or species; however, the crab 1 stage of M. forceps reared with either diet (220±19 and 226±25 μg for NHA and EA, respectively) was significantly larger than that of M. sculptus (189±11 and 200±23 μg for NHA and EA, respectively). The rarity and higher market price, combined with the higher survivorship to juveniles, make M. forceps the better candidate for aquaculture.
(Department of Biological Sciences, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901, USA; email of A. Rhyne: arhyne@fit.edu)

ARACHIDONIC ACID ENRICHED LIVE PREY INDUCES ALBINISM IN SENEGAL SOLE (SOLEA SENEGALENSIS) LARVAE
Mireia Villalta, Alicia Estévez, Matthew P. Bransden-2005
Aquaculture, 245 (1-4): 193-209
Abstract:
We examined the effect of dietary arachidonic acid (20:4n-6, ARA) on growth, survival, pigmentation and fatty acid composition of Senegal sole larvae using a dose–response design. From 3 to 37 days post-hatch (dph), larvae were fed live food (rotifers from 3 to 9 dph, Artemia nauplii from −37 dph) that had been enriched using one of three experimental emulsions containing 3 graduated concentrations (1.3, 68 and 120.1 mg ARA g−1 dry weight) of ARA and constant docosahexaenoic acid (22:6n-3, DHA). A commercial enrichment product (DHA-Protein Selco, ARA content 7.8 mg g−1 dry weight) was used as a reference diet. Final concentration of ARA in Artemia nauplii ranged from 0.2 to 17.5 mg g−1 lipids. Growth and survival were independent of dietary levels of ARA tested. However, there was a correlation between dietary ARA and a significant reduction in pigmentation leading to increased albinism. Tissue fatty acid concentrations reflected the corresponding dietary composition. Eicosapentaenoic acid (20:5n-3, EPA) levels in all the tissues examined were inversely related to dietary ARA. There was almost a 100-fold increase in the proportion of docosapentaenoic acid (22:5n-3, DPA) in the tissues relative to the diet, which might indicate chain elongation from EPA as a result of inadequate dietary DHA. A negative, linear correlation was found between the pigmentation rate and the ARA content in the head, as well as with dietary ARA/EPA ratio.
(Centro de Acuicultura-IRTA and Centro de Referencia en Acuicultura, Generalitat de Cataluña, Ctra. Poble Nou Km 6, 43540 San Carlos de la Rápita, Tarragona, Spain; email of A. Estevez: alicia.estevez@irta.es)

EFFECTS OF TEMPERATURE, DENSITY, AND DIET ON DEVELOPMENT, SURVIVAL, SETTLEMENT SYNCHRONISM, AND FATTY ACID PROFILE OF THE ORNAMENTAL SHRIMP LYSMATA SETICAUDATA
R. Calado, J. Figueiredo, R. Rosa, M.L. Nunes, L. Narciso-2005
Aquaculture, 245 (1-4): 221-237
Abstract:
The effects of different rearing temperatures, densities, and diets on the larval development, survival to metamorphosis, settlement synchronism, and fatty acid profile of the ornamental shrimp Lysmata seticaudata were evaluated. Survival of larvae raised at 20 °C was not significantly different (average±standard deviation) (94.8±4.5%) from that of those raised at 26 °C (85.3±9.5%), and presented significantly longer larval durations (31.8±1.0 days) than the ones raised at 26 °C (19.5±1.3 days). Larvae starved in zoea I displayed significantly lower survival (64.7±10.0%), and higher numbers of larvae remained in the last zoeal stage and died before metamorphosing. Larvae fed newly hatched Artemia nauplii, Artemia metanauplii or enriched Artemia metanauplii displayed similar survival (85.3±9.5%, 81.3±5.9%, and 75.5±2.1%, respectively) and similar larval stage durations. Larvae cultured at rearing densities of 10, 20, and 40 larvae l−1 showed similar survival rates (85.3±9.5%, 88.0±1.8%, and 86.8±5.4%, respectively). When cultured at 40 larvae l−1, a significantly higher proportion of larvae remained in the last zoeal stage (13.5±5.9%) 15 days after the settlement of the first postlarva. The survival of larvae fed newly hatched Artemia nauplii, or fed newly hatched Artemia nauplii until zoea V and switched to enriched Artemia metanauplii until settlement did not differ significantly (86.8±5.4% and 87.0±6.0%, respectively). Both treatments showed similar proportions of late stage larvae that did not metamorphose by the 15th day following the first settled postlarva. With the exception of larvae starved in zoea I, and those cultured at 40 larvae l−1, that did not display any “mass settlement period,” settlement mainly occurred during the 3rd and the 7th day following the settlement of the first postlarva. The fatty acid content of postlarvae cultured under different temperatures (20 and 26 °C) and fed the same larval diet (newly hatched Artemia) were similar. With the exception of docosahexaenoic acid (DHA) content, postlarvae fed enriched Artemia metanauplii displayed similar fatty acid content to those displayed by postlarvae fed on newly hatched Artemia and Artemia metanauplii. Wild postlarvae displayed a significantly lower fatty acid content (46.95±2.85 μg/mg dry weight), when compared to cultured organisms. These differences in fatty acid composition were more pronounced on saturated and monounsaturated fatty acids. Wild postlarvae always displayed a significantly higher DHA/EPA ratio (1.01±0.13), even when compared with that of postlarvae fed on enriched Artemia.
(Laboratório Marítimo da Guia, Departamento de Biologia Animal, Faculdade de Ciências da Universidade de Lisboa, Estrada do Guincho, Forte N. S. da Guia, 2750-642 Cascais, Portugal; email of R. Calado: rjcalado@hotmail.com)

ACTIVITIES OF SELECTED DIGESTIVE ENZYMES DURING LARVAL DEVELOPMENT OF LARGE YELLOW CROAKER (PSEUDOSCIAENA CROCEA)
Hongming Ma, Chantal Cahu, José Zambonino, Hairui Yu, Qingyuan Duan, Marie-Madeleine Le Gall, Kangsen Mai-2005
Aquaculture, 245 (1-4): 239-248
Abstract:
Large yellow croaker is an important marine fish species for aquaculture in China. Larval rearing of this species is still based on live prey feeding. The aim of this study was to describe the onset and development of the main digestive enzymes during larval development of this species, in order to obtain essential data for the formulation of a compound diet adapted to larvae. Enzymatic assays were conducted from day 1 post hatching to day 40 in larvae fed the following live prey sequence: rotifers, Artemia nauplii, copepods, and then frozen copepods. Assays were done on whole larvae until day 19, then on dissected larvae and on purified brush border membranes of intestine. Pancreatic enzymes, amylase, and trypsin, showed high activities from early stages, even before mouth opening. Mechanisms of pancreatic secretion were achieved from day 19. Enzymes of brush border membranes, alkaline phosphatase, and aminopeptidase N, increased abruptly between day 23 and 25, showing maturation of the intestinal digestive process. These data, together with data describing mouth enlargement during development, suggest that large yellow croaker larvae could be fed successfully with a compound diet from early stages, at least from day 23.
(The Key laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao 266003, PR China; email of Kangsen Mai: kmai@ouc.edu.cn)

EFFECTS OF N-3 HUFA CONTENT IN BROODSTOCK DIET ON SPAWNING PERFORMANCE AND FATTY ACID COMPOSITION OF EGGS AND LARVAE IN PLECTORHYNCHUS CINCTUS
Yuan-you Li, Wei-zhou Chen, Ze-wei Sun, Jie-hui Chen, Ke-gang Wu-2005
Aquaculture, 245 (1-4): 263-272
Abstract:
The effects of n-3 highly unsaturated fatty acid (n-3 HUFA) content in broodstock diets on the quality and fatty acid composition of eggs and larvae were investigated in Plectorhynchus cinctus. Broodstocks were fed a natural diet (trash fish) and four formulated diets with similar proximate compositions but different levels of n-3 HUFA (1.12, 2.40, 3.70 or 5.85%) through their reproductive cycle. Compared with the natural diet-fed group, the egg production per kg of females, percentage of buoyant eggs, survival and length of larvae at 3 days post hatching were similar in fish fed 2.40% and 3.70% n-3 HUFA diets, but markedly decreased in the groups fed 1.12 and 5.85% n-3 HUFA diets. The content of most fatty acids and fatty acid class in eggs and larvae was directly influenced by dietary n-3 HUFA levels and exhibited parallel change pattern with the respective dietary levels. The results showed that either deficient or excess level of dietary n-3 HUFA had a negative effect on egg and larval quality, good spawning performance was obtained when the dietary n-3 HUFA content was 2.40 and 3.70%, or the n-3 HUFA level took 12.17 and 18.63% of the total fatty acids. Dietary n-3 HUFA content may affect egg and larval quality by influencing their fatty acid composition.
(Marine Biology Institute of Shantou University, Shantou, Guangdong, 515063, China; email of Yuan-you Li: yyli@stu.edu.cn)

THE INFLUENCE OF OOCYTE MATURATIONAL STAGE ON HATCHING AND TRIPLOIDY RATES IN HYBRID (BESTER) STURGEON, HUSO HUSO×ACIPNESER RUTHENUS
Naotaka Omoto, Mamoru Maebayashi, Shinji Adachi, Katsutoshi Arai, Kohei Yamauchi-2005
Aquaculture, 245 (1-4): 287-294
Abstract:
We have investigated the relationship between maturational competence and hatching rate of eggs ovulated following injection of lutenizing hormone releasing hormone ethylamide (LH-RHa) in the cultured hybrid (bester) sturgeon (Huso huso female×Acipenser ruthenus male). Among 10 steroids tested (including progesterone) in a previous study, 17α-hydroxyprogesterone (17αOHP) was the most potent inducer of final maturation in the bester, with results similar to 17α,20β,21-trihydroxy-4-pregnen-3-one and 17α,20β-dihydroxy-4-pregnen-3-one. We therefore used 17αOHP to estimate maturational competence in the present study. In vitro oocyte maturation response to 17αOHP at a concentration of 0.1 μg/ml was correlated with ovulatory response to hormone treatment and quality of ovulated eggs. Two females exhibited higher in vitro oocyte maturation rate (100% germinal vesicle breakdown), ovulated sooner after hormone injection, and also had a higher hatching rate (77, 92%). In the F2 bester broodstock with a lower hatching rate (10–21%), a higher incidence (15–64%) of spontaneous triploidy was found. These results indicate that maturational competence can be estimated by in vitro oocyte maturation response to 17αOHP at 0.1 μg/ml and that this is a useful technique for selecting the proper female for breeding. Ovulatory success, hatching rate and occurrence of triploidy are thus all predictable in the cultured bester.
(Department of Research and Development, The Hokkaido Electric Power Co., Inc, Tsuishikari Ebetsu Hokkaido 067-0033, Japan; email of N. Omoto: omoto@epmail.hepco.co.jp)

HEMOLYMPH VITELLOGENIN LEVELS DURING FINAL MATURATION AND POST-SPAWNING IN THE FEMALE KURUMA PRAWN, MARSUPENAEUS JAPONICUS
Daisuke Tahara, Katsuyoshi Suitoh, Hisatake Hattori-2005
Aquaculture, 245 (1-4): 311-319
Abstract:
A vitellogenin (VTG) ELISA was developed to clarify the relationship between hemolymph VTG levels and spawning conditions in female kuruma prawns. Hemolymph VTG was measured at the final maturation and spent stages. Collected hemolymph and oocytes were assessed for the 5 consecutive days of the spawning test. Of gravid females, 22.7% were broodstock, ready-to-spawn with cortical rods in oocytes. A negative correlation (r2=0.71) was found between the release rate of eggs and the hemolymph VTG concentration 1 day before spawning. Hemolymph VTG levels did not fluctuate significantly through the late granule, pre-maturation, and maturation stages. Late perinucleolus oocytes, which have already accumulated vitellin (Vn) in the cytoplasm, were found at the maturation stage. Positive immunoreactions against the anti-Vn serum were observed in the ovarian sections at the spent stage just after spawning. These results indicate that female prawns are preparing for the next spawning just before and after spawning, resulting in a high levels of hemolymph VTG throughout the late maturation and spent stages.
(Department of Marine Bioscience, Fukui Prefectural University, 1-1 Gakuen, Obama, Fukui 917-0003, Japan; email of D. Tahara: tahara@fpu.ac.jp)

CULTIVATION OF THE BROWN ALGA HIZIKIA FUSIFORMIS (HARVEY) OKAMURA: ENHANCED SEEDLING PRODUCTION IN TUMBLED CULTURE
Shao Jun Pang, Lan Tao Chen, Ding Gen Zhuang, Xiu Geng Fei, Jian Zhang Sun-2005
Aquaculture, 245 (1-4): 321-329
Abstract:
The reuse of holdfasts for regeneration of young seedlings or using wild juvenile plants as the seedling source has played the major role in commercial cultivation of the brown alga Hizikia fusiformis in East Asia over the past 20 years. The possibility of employing zygote-derived germlings for producing seedlings has been discussed in the literature, but has not yet become a reality. Three main obstacles have limited the use of zygotes as a main source of seedlings, (1) the dioecious nature of the algal life cycle which may lead to asynchronous male and female receptacle development and thus different timing of egg and spermatozoa expulsion, (2) the low attachment rate when using zygote-derived germlings with developed rhizoids from wild parental plants for seeding production, and (3) the problem of culturing young germlings in regions where water temperature is high in summer. In this investigation, shifting the timing of receptacle formation earlier than in nature was performed by tumbling the algae in a long-day tank (16-h light per day). Synchronization of egg and spermatozoa expulsion and thereafter fertilization were conducted in indoor tanks. Receptacle formation in constant long days could be shifted by 20 days earlier than in plants cultured on long lines in the open sea, or 1 month earlier than in plants growing on intertidal rocks. Synchronized expulsion of eggs and spermatozoon led to a high rate of fertilization. This was achieved by tumbling the male and female receptacle-bearing branchlets in the same tank at low density in high irradiance. In two independent trials, a total of 1,400,000 zygote-derived germlings were obtained from 620 g (fresh weight) female sporophytes. The germlings shed from the receptacles were at an identical developmental stage indicating high synchronization of expulsion of eggs and spermatozoon followed by fertilization. Approximately 63% (±9.6%) of the germlings were shed from the receptacle between 16 and 24 h after fertilization and 20% (±11.9%) remained on the receptacle for 3 days after fertilization. Germlings were seeded on string collectors before rhizoids started to elongate and the attachment efficiency was enhanced. Young seedlings reached 800 (±50) μm in length in 25 days at 25 °C before they were transferred to open sea cultivation. These results provide the basis of a practical way of seedling production by use of zygote-derived germlings in the commercial cultivation of H. fusiformis.
(Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Rd., Qingdao 266071, China; email of Shao Jun Pang: sjpang@ms.qdio.ac.cn)

GROWTH AND BIOMASS PRODUCTION OF TETRASELMIS SUECICA AND DUNALIELLA TERTIOLECTA IN A STANDARD MEDIUM ADDED WITH THREE PRODUCTS OF ZEOLITIC NATURE
Mario Nieves, Domenico Voltolina, Pablo Piña-2005
Aquacultural Engineering, 32 (3-4): 403-410
Abstract:
At the end of the exponential growth phase, the cell concentrations of batch cultures of Tetraselmis suecica and Dunaliella tertiolecta grown in f medium added with 5, 10 and 20 mg l−1 of the zeolitic products Zestec 56, Zesep 56 and Zeben 06 (ZT56, ZS56 and ZB06) were similar to those obtained with the same medium without zeolites. At the end of the following period of slow growth, all the experimental media gave significantly higher concentrations of T. suecica than the control cultures, but only the addition of 20 mg l−1 of ZT56 and ZB06 gave significantly better results with D. tertiolecta. However, in all cases the final harvests of total and ash-free biomass were similar to those of the controls, indicating the presence of smaller or lighter cell in the experimental cultures. The effect of these products is to enhance cell division rates in the phase of slow growth, with no advantage in terms of biomass production.
(Facultad de Ciencias del Mar, Universidad Autónoma de Sinaloa, Paseo Claussen s/n, P.O. Box 1132, Mazatlán, Sinaloa, Mexico; email of M. Nieves: maniso@mzt.megared.net.mx)

A NOVEL COMPUTER SIMULATION MODEL FOR DESIGN AND MANAGEMENT OF RE-CIRCULATING AQUACULTURE SYSTEMS
Ilan Halachmi, Yitzchak Simon, Rami Guetta, Eric M. Hallerman-2005
Aquacultural Engineering, 32 (3-4): 443-464
Abstract:
The aim of this study was to develop a simulation model for finding the optimal layout and management regime for a re-circulating aquaculture system (RAS). The work plan involved: (1) quantifying the effects of fish growth and management practices on production; (2) developing a mathematical simulation model for the RAS, taking into account all factors that directly influence system profitability; and (3) estimating the production costs and, hence, the profitability of an RAS. The resulting model is process-oriented, following the flow of fish through the RAS facility, and generates an animated graphic representation of the processes through which the fish passes as it progress through the system. The simulation assesses the performance in terms of yearly turnover, stocking density, tank utilization and biomass in process, and uses statistics to track the state of the RAS and record changes that affect efficiency. The economic impact of system design and operation was modeled to enable a user to anticipate how changes in design or operating practices, costs of inputs, or price of products affect system profitability. The proposed approach overcomes difficulties in characterizing RAS design and operation. The simulation approach allows all of the RAS's components such as equipment, biological processes (e.g., fish growth), and management practices to be evaluated jointly, so that an initial design can be fine-tuned to produce an optimized system and management regime suited to a specific fish farm within a reasonable time. The methodology was executed step-by-step to design an optimal RAS that meets both economic and stocking-density limits. Optimal design specifications were presented for several case studies based on data from Kibbutz Sde Eliahu's RAS, in which Nile tilapia (Oreochromis niloticus) are raised in 20 concrete raceways. Further research should include more extensive testing and validation of the integrated model, which then should be disseminated to the aquaculture community.
Keywords: Re-circulating aquaculture systems
(Institute of Agricultural Engineering, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel; email of I. Halachmi: halachmi@volcani.agri.gov.il)

ESTIMATION OF FLOW IN A REARING TANK OF MARINE FISH LARVAE BY SIMPLIFIED NUMERICAL COMPUTATION—A CASE OF TWO-DIMENSIONAL FLOW
Shigeaki Shiotani, Atsushi Hagiwara, Yoshitaka Sakakura, Hisashi Chuda-2005
Aquacultural Engineering, 32 (3-4): 465-481
Abstract:
Marine fish larvae are fragile against physical stress. However, few studies have been conducted to evaluate the flow field in a rearing tank, which is assumed to provide a high degree of physical stress to marine fish larvae. The flow field in a rearing tank (volume of 1 m3) is generated by aerators, which are commonly used to provide oxygen.
This paper is a report on the estimation of stationary flow in the rearing tank of marine fish larvae. The larvae are seven band grouper larvae of Epinephelus septemfasciatus, which have a very low survival rate immediately after the hatching of eggs. The experiments of rearing of seven band grouper larvae were carried out using rearing tanks with four aeration rates (1000, 200, 50 ml/min, and no aeration). The effects of aeration on the survival and floating death of seven band grouper larvae were examined. The experiments confirmed that the mass mortality of seven band grouper larvae depends on the flow rate in the rearing tank. Aeration at 200 ml/min resulted in the highest survival and growth rates of grouper larvae.
Larvae-rearing experiments provided evidence that the flow rates of the rearing tanks are very important design aspects of rearing tanks. The estimation of flow in a rearing tank for an aerating rate of 200 ml/min was carried out by numerical calculation. The computation was simplified by a two-dimensional flow based on experimental results. The calculated flow in the rearing tank was compared with the experimental one. The calculation of the stationary flow in the rearing tank showed good qualitative and quantitative agreement with the experimental results. The numerical estimation of the flow in a rearing tank of marine fish larvae was confirmed to be effective and satisfactory for the design of a tank that would provide optimum performance.
(Faculty of Maritime Sciences, Kobe University, 5-1-1 Fukae-Minami, Higashinada, Kobe 658-0022, Japan; email of S. Shiotani: shiotani@maritime.kobe-u.ac.jp)

AIR BUBBLING RESULTS IN CARBON LOSS DURING MICROALGAL CULTIVATION IN BICARBONATE-ENRICHED MEDIA: EXPERIMENTAL DATA AND PROCESS MODELING
J.M. Rodríguez-Maroto, Carlos Jiménez, José Aguilera, F.X. Niell-2005
Aquacultural Engineering, 32 (3-4): 493-508
Abstract:
Turbulence is a major variable controlling growth of microalgae. When turbulence is provided by means of air bubbling, mass transfer phenomena take place between the culture medium and the air bubbles. A mathematical model has been developed to evaluate the effects of air bubbling in bicarbonate-enriched media for microalgae cultivation, and in cultures of the halotolerant alga Dunaliella viridis. Simulations have been made using a four order Runger–Kutta method combined with Marquardt's algorithm to establish the parameters of the system. The model permits: (i) simulation of the experimental behavior of organic (cellular) and inorganic (CO2 + H2CO3 + HCO3− + CO32−) carbon in the cultures; (ii) performance of a sensitive analysis of the effects of varied operative conditions and (iii) development of strategies for optimizing the use of culture media and subsidiary energy. Simulation of the model demonstrated that in air-bubbled HCO3− enriched media there is a loss of CO2 from the medium to the air bubbles, which escapes from the culture vessel, and no transference of CO2 from the air bubbles to the water occurred. Validation of the model has been carried out by comparison of experimental and predicted values under different conditions.
(Department of Chemical Engineering, Faculty of Sciences, University of Malaga, 29071 Malaga, Spain; email of C. Jiménez: carlosj@uma.es)

ELECTRONICAL LARVICULTURE NEWSLETTER ISSUE 214 February 15, 2005

ELECTRONICAL LARVICULTURE NEWSLETTER ISSUE 214
February 15, 2005