Now showing items 1-12 of 12

    • Article

      Biomass yield of Isochrysis galbana (Parke; clone T-ISO) and growth of Brachionus rotundiformis (Tschugunoff) using continuous cultivation method 

      MR de la Peña - Philippine Agricultural Scientist, 2014 - College of Agriculture, University of the Philippines Los Baños
      Batch culture of Isochrysis galbana clone T-ISO is difficult due to its unstable biomass production; hence, the effect of continuous cultivation at different dilution rates was investigated to compare its productivity with that of batch culture. Significantly higher total algal cell yield was attained in continuous cultures (1.70 × 108 and 1.03 × 108 cells L-1 at 0.60 d-1 and 0.30 d-1 dilution rates, respectively) compared with batch culture (0.16 × 108 cells L-1); the batch culture did not receive any inflow of nutrients. The amount of protein per cell was similar in both batch and continuous cultures at 0.60 d-1 dilution rate after 24 h and 5 d in both culture systems. Chlorophyll a yield was not affected by dilution rate but decreased as the culture aged. The dry weight yield was also similar in both batch and continuous cultures. The higher nitrate concentration supplemented in the batch culture resulted in higher cell density and elevated protein content of the alga. Rotifer (Brahionus rotundiformis) cultures that received inflow of nutrients from the algal tanks had significantly higher (P<0.05) peak population count (28 and 33 individuals mL-1 at 0.30 and 0.60 d-1 dilution rates, respectively) compared with rotifer cultures that did not receive an inflow of food (18.22 individuals mL-1). The higher biomass yield of T-ISO using continuous cultivation method can increase the population growth of rotifer under tropical conditions.
    • Article

      Characterization of a virus obtained from snakeheads Ophicephalus striatus with epizootic ulcerative syndrome (EUS) in the Philippines 

      GD Lio-Po, GS Traxler, LJ Albright & EM Leaño - Diseases of Aquatic Organisms, 2000 - Inter Research
      This is the first report of the isolation and characterization of a fish virus from the Philippines. The virus was isolated using snakehead spleen cells (SHS) from severely lesioned epizootic ulcerative syndrome (EUS)-affected snakehead Ophicephalus striatus from Laguna de Bay, in January 1991. The virus induced cytopathic effects (CPE) in SHS cells yielding a titer of 3.02 x 106 TCID50 ml-1 at 25°C within 2 to 3 d. Other susceptible cell lines included bluegill fry (BF-2), catfish spleen (CFS) and channel catfish ovary (CCO) cells. Replication in chinook salmon embryo cells (CHSE-214) was minimal while Epithelioma papulosum cyprini cells (EPC) and rainbow trout gonad cells (RTG 2) were refractory. Temperatures of 15 to 25°C were optimum for virus replication but the virus did not replicate at 37°C. The virus can be stored at -10 and 8°C for 30 and 10 d, respectively, without significant loss of infectivity. Viral replication was logarithmic with a 2 h lag phase; viral assembly in the host cells occurred in 4 h and release of virus occurred 8 h after viral infection. A 1-log difference in TCID50 titer between the cell-free virus and the total virus was noted. Freezing and thawing the virus caused a half-log drop in titer. Viral exposure to chloroform or heating to 56°C for 30 min inactivated the virus. Exposure to pH 3 medium for 30 min resulted in a more than 100 fold loss of viral infectivity. The 5-iododeoxyuridine (IUdR) did not affect virus replication, indicating a RNA genome. Neutralization tests using the Philippine virus, the ulcerative disease rhabdovirus (UDRV) and the infectious hematopoietic necrosis virus (IHNV) polyvalent antisera showed slight cross-reaction between the Philippine virus antiserum and UDRV but established no serological relationship with SHRV and IHN virus. Transmission electron microscopy (TEM) of SHS cells infected with the virus showed virus particles with typical bullet morphology and an estimated size of 65 x 175 nm. The Philippine virus was therefore a rhabdovirus, but the present study did not establish its role in the epizootiology of EUS.
    • Article

      Effect of different sizes of saline red tilapia hybrid Oreochromis niloticus Linnaeus x O. mossambicus Peters on the growth of luminous bacteria Vibrio harveyi 

      EA Tendencia & MR de la Peña - The Philippine Agricultural Scientist, 2010 - College of Agriculture, University of the Philippines Los Baños
      Luminous bacterial disease caused by Vibrio harveyi has devasted the shrimp industry. The use of different strains of tilapia and other fish species polycultured with shrimp cultured at a salinity of 24 ppt to control luminous bacteria has been reported. These species, however, could not tolerate salinities higher than 24 ppt. Alternative species/strains that could be used to control luminous bacteria at high salinities need to be investigated.

      Likewise, the effect of fish size on the growth of luminous bacteria is worth studying. Shrimp (Penaeus monodon Fabricius) were stocked in concrete tanks filled with 34 ppt cartridge filtered seawater. Tanks were stocked with two sizes (16 pcs, average body weight (ABW) = 55 g and 6 pcs ABW=250 g) of the red tilapia hybrid Oreochromis mossambicus Peters x O. niloticus Linnaeus, except for the tanks that served as the control. Luminous bacteria (V. harveyi) were inoculated into the tank water to a density of 104 Cfu mL-1. Significantly lower luminous bacterial count was observed in tanks with either of the two sizes of red tilapia hybrid compared with the control, after 5-7 d. Bacteria isolated from the fish feces, mucus and rearing water; and the fish feces and mucus themselves demonstrated anti-V. harveyi activity. Results showed that the red tilapia hybrid could be used to control luminous bacteria at salinities as high as 34 ppt and that the size of the fish did not affect its efficiency. The ability of the red tilapia hybrid to control the growth of the luminous bacteria V. harveyi is attributed to different factors such as the mucus, the feces and the bacteria associated with tilapia culture. Bacteria associated with the fish mucus and feces also contributed to the anti-V. harveyi activity of these biological substances.
    • Article

      Effect of streamer tags on survival and growth of juvenile tiger prawns, Penaeus monodon, under laboratory conditions 

      JH Primavera & RM Caballero - Marine and Freshwater Research, 1992 - CSIRO Publishing
      The effects of streamer tags and initial prawn size on survival and growth in 2-month- and 7-month-old pond-reared juveniles of Penaeus monodon Fabricius (11-30 mm carapace length, CL) were assessed under laboratory conditions. Tagging did not cause immediate mortality in juveniles of 11-21 mm CL within a one-week period but led to a significantly lower survival rate after 6 to 8 weeks in 1-m3 tanks. However, tagged prawns of 21-30 mm CL showed high long-term survival rates up to 90% in a 12-m3 tank. The 2-month-old juveniles had lower survival rates than 7-month-old prawns. Specific growth rate was not affected by tagging but was significantly higher in smaller prawns. In general, there was no interaction between the effects of tagging and prawn size in terms of growth and survival rates.

      The lower long-term survival rate associated with tags may be due to the attractiveness of tags to predators, or to trauma or stress caused by the weight of the tags. These factors are discussed in relation to findings for other penaeid species.
    • Article

      Induction of immunity and resistance to white spot syndrome virus (WSSV) in shrimp Penaeus monodon (Fabricius) by synthetic oligodeoxynucleotide and bacterial DNA 

      EC Amar & JP Faisan Jr. - Philippine Agricultural Scientist, 2012 - University of the Philippines Los Baños
      Shrimps like all invertebrates are believed to lack true adaptive immunity but recent evidence indicate that they can be protected against pathogenic organisms by priming their immune system with immunostimulatory substances. Here, we describe results of investigation aimed to strengthen shrimp immunity as a preventive strategy against white spot syndrome virus (WSSV) infection. Oligodeoxynucleotides (ODNs) with and without Cytosine-Guanine (CpG) motifs, and Vibrio harveyi genomic DNA (VHD) were administered by intramuscular injection and shrimp responses were assessed by ex vivo assays and experimental infection trials. Results showed that CpG ODN significantly increased ex-vivo immunity indices such as total hemocyte count (THC), plasma agglutination titer (PAT) and hemocyte lysate agglutination titer (HLAT). VHD significantly increased immune indices such as THC, plasma total protein (PTP) and HLAT. Reverse (GpC) motifs increased THC only. At a lower viral challenge dose, both CpG and GpC motifs, and VHD, were able to reduce shrimp mortality significantly but only CpG and VHD did so at a higher challenge dose. Strengthening shrimp immunity by the use of immunostimulatory nucleotides and bacterial genomic DNA could be a feasible preventive approach in the management of WSSV infections in shrimp.
    • Conference paper

      Life history of Acrothrix pacifica and Sphaerotrichia divaricata in laboratory cultures 

      I Umezaki - In IJ Dogma Jr., GC Trono Jr. & RA Tabbada (Eds.), Culture and use of algae in Southeast Asia. Proceedings of the Symposium on Culture and Utilization of Algae in Southeast Asia, 8-11 December 1981, Tigbauan, Iloilo, Philippines, 1990 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The life histories of Acrothrix pacifica and Sphaerotrichia divaricata in the Chordariales, Phaeophyceae were studied in the laboratory. Both species showed an alternation of macroscopic sporophyte (2n) and microscopic gametophyte (n). In A. pacific , unfused gametes developed into haploid sporophytes under cooler conditions or into gametophytes under warmer conditions. In S. pacifica , unfused gametes developed into gametophytes under warmer conditions.
    • magazineArticle

      Live food: A lesser known essential 

      MB Surtida - SEAFDEC Asian Aquaculture, 2003 - Aquaculture Department, Southeast Asian Fisheries Development Center
      This article is a short discussion of the requirements for live food production in aquaculture and a brief presentation of the processes involved.
    • magazineArticle

      Managing a fish hatchery with oxygen injection 

      Southeast Asian Fisheries Development Center, Aquaculture Department - Aqua Farm News, 1994 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      Notes on the induced spawning, embryonic and larval development of the window-pane shell, Placuna placenta (Linnaeus, 1758), in the laboratory 

      JA Madrones-Ladja - Aquaculture, 1997 - Elsevier
      Intragonadal injection of 0.5 ml of a 2-mM serotonin solution or seawater irradiated by ultraviolet (UV) light (925–1395 mW h/l) induced spawning in male and female window-pane shell, Placuna placenta (Linnaeus, 1758). Generally, mature shells spawned 15–30 min after serotonin injection or 30–60 min after exposure to UV light-irradiated seawater. The average number of eggs released per female were 1.57 × 106 and 1.24 × 106, for serotonin and UV light-irradiated seawater, respectively. The method using UV light-irradiated seawater is simpler to perform than serotonin injection into the gonads and can be applied to both individual- and mass-spawning experiments. Spawned eggs averaged 56 ± 5 μm in diameter and fertilization was 100% successful. After fertilization, the polar body formed after 15 min and trochophores were observed actively moving in 325 min. Embryonic development was completed in less than 6 h. Straight-hinged veligers with mean shell length (SL) of 84 ± 18 μm appeared in the cultures 18–20 h after fertilization. Fed daily with microalgae Isoschrysis galbana (Parke), the larvae developed to early umbo on the second day of culture when SL was 103 ± 17 μm, while late-umbonal veligers of SL 145 ± 21 μm appeared on the seventh day. Crawling pediveligers were observed on day 9 when SL reached 205 ± 15 μm. Newly metamorphosed larvae appeared on the 14th day when SL of 238 ± 9 μm was reached. The survival rate at metamorphosis was 13%. The duration of the planktonic larval stages of P. placenta was about 14 d.
    • Potentials of Kappaphycus striatum (Schnitz) and Gracilaria heteroclada Zhang (Ad Xia) to control the growth of luminous bacteria Vibrio harveyi 

      EA Tendencia & MR de la Peña - The Philippine Agricultural Scientist, 2010 - University of the Philippines Los Baños
      Different aquaculture species such as finfishes and bivalves have been reported to control the luminous bacterial disease of shrimp, usually caused by Vibrio harveyi. The use of seaweeds in shrimp culture system has reportedly improved water quality and reduced the bacterial count. This study evaluated the potentials of two species of seaweeds, Gracilaria heteroclada (Ad Xia) and Kappaphycus striatum (Schnitz), to control the growth of V. harveyi.

      V. harveyi was inoculated into control tanks containing shrimps only and into treated tanks containing both shrimp and macroalgae. Luminous bacterial counts were monitored daily. From day 2 to day 6, luminous bacterial count in tanks with G. heteroclada was significantly lower than those in tanks with K. striatum. Bacteria isolated from the rearing water containing K. striatum and G. heteroclada and from the seaweed homogenized in sterile seawater showed anti-Vibrio harveyi activity. The seaweed homogenate per se also showed anti-luminous bacterial property. Presence of both G. heteroclada and K. striatum in shrimp culture system has the potential to control the growth of luminous bacteria. G. heteroclada was more efficient and sustainable, as shown by the lower luminous bacterial count and the higher percentage recovery of this macroalga after 11 d in experimental tanks.
    • Article

      Semi-mass culture of the dinoflagellate Gymnodinium splendens as a live food source for the initial feeding of marine finfish larvae 

      EM Rodriguez & K Hirayama - Hydrobiologia, 1997 - Springer Verlag
      A technique was developed for the semi-mass culture of the unarmored dinoflagellate, Gymnodinium splendens under laboratory conditions. A maximum cell density of 4600 to 6800 cells ml−1 was observed within 8 to 11 days of culture. An initial feeding test for 8 days with three important marine finfish larvae showed that red spotted grouper, Epinephelus akaara preferred G. splendens fed 200 cells ml−1 with 44% survival. The Japanese stripe knife jaw, Oplegnathus fasciatus, attained 22% survival fed a combination of G. splendens and rotifers (200 cells ml−1 and 5 ind. ml−1, respectively). Red sea bream, Pagrus major larvae did not respond well to the initial feeding of G. splendens alone. Red sea bream were observed to be solely dependent on rotifers (5 ind. ml−1) as initial food. Gymnodinium splendens may be used as a live food in the initial feeding of red spotted grouper larvae (E. akaara) to reduce mortality and to further enhance growth during the critical first few days of rearing.
    • Article

      Spawning behavior and early life history of the rabbitfish, Siganus guttatus, in the laboratory 

      S Hara, H Kohno & Y Taki - Aquaculture, 1986 - Elsevier
      The spawning behavior and embryonic and larval development of Siganus guttatus are described from laboratory observations. Characteristic prespawning behavior began 4 h before actual spawning: the female touched the anal region of the abdomen on the bottom of the tank; the male displayed short, jerky, rushing movements towards the female, often with rapid circling around her. The male and the female separately released small amounts of milt and eggs several times during the pre-spawning ritual. The color of both sexes changed, the male becoming lighter and the female darker in ground color. Spawning took place at 02.30 h on the third day after the first quarter of the moon. During actual spawning, the pair swam side by side, with the female slightly ahead of the male. Fertilized eggs were small (0.56±0.008 mm), demersal and adhesive, with many oil globules. Larvae measured 1.74±0.043 mm total length at hatching, and possessed eight pairs of free neuromasts with long cupulae (60–180 μm) from 6 h to 39 h after hatching. The adult complement of fin ray counts was attained on day 16 when larvae (=juveniles) measured 8.34 mm total length on the average.