Now showing items 1-20 of 41

    • Conference paper

      Aeromonas hydrophila in the epizootic ulcerative syndrome (EUS) of snakehead, Ophicephalus striatus, and catfish, Clarias batrachus: quantitative estimation in natural infection and experimental induction of dermo-muscular necrotic lesion 

      Snakehead (Ophicephalus striatus) and catfish (Clarias batraclus) with the Epizootic Ulcerative Syndrome (EUS) were sampled for bacteria. Total bacterial counts of skin and muscle/dermal lesions revealed mean colony forming units (CFU) per gram tissue of 1.22 x 103, 1.40 x 105, 5.31 x 195 and 1.14 x 107 in apparently normal, slightly lesioned, moderately lesioned and severely lesioned snakehead samples, respectively. In catfish, mean CFU per gram tissue were 4.30 x 104 and 2.00 x 105 in apparently normal and slightly lesioned specimens, respectively. Kidney samples likewise revealed the presence of bacteria. Bacteria isolated on trypticase soy agar and Rimler-Shotts medium were predominantly Aeromonas hydrophila occurring in 90% of snakeheads and in 33% of catfish specimens. Infection experiments of A. hydrophila injected intramuscularly into healthy snakehead and catfish induced dermo-muscular necrotic lesions. A dose of at least 106 cells of A. hydrophila was required to induce EUS-like lesions in snakehead and catfish at 21-25 degree C in 24-96 h.
    • Article

      Antibacterial activity of tilapia Tilapia hornorum against Vibrio harveyi 

      EA Tendencia, MR dela Peña, AC Fermin, G Lio-Po, CH Choresca Jr. & Y Inui - Aquaculture, 2004 - Elsevier
      Disease due to luminous Vibrio has been a major problem of the shrimp industry. Different technologies have been introduced to control the disease. One of the techniques reported to work against luminous bacteria in the Philippines is the green water culture system (or finfish–shrimp integrated culture system). A green water culture system is an innovative technique wherein shrimp are cultured in water collected from a pond where tilapia or other fish species are grown. In some cases, the fish are cultured in an isolated net pen inside the shrimp culture pond. This study clarifies the effect of one component of the green water culture system, the presence of all male tilapia (Tilapia hornorum) on luminous bacteria Vibrio harveyi. Results showed that stocking tilapia at a biomass not lower than 300 g/m3 efficiently inhibited the growth of luminous bacteria in shrimp (biomass=80 g/m3) rearing water without the growth of microalgae.
    • Article

      Antibiotic resistance of bacteria from shrimp ponds 

      EA Tendencia & LD de la Peña - Aquaculture, 2001 - Elsevier
      The incidence of antibiotic resistance was compared in bacteria isolated from pond water, pond sediment, water and sediment from the receiving environment (area where water from pond drains, which is 0 and 50 m away from the exit gate, in this study) and cultured shrimp from ponds that have not used any antimicrobials, ponds that have previously used antimicrobials and ponds that are currently using oxolinic acid. Most of the bacteria isolated from all sample and pond type were Vibrios. Among the Vibrios, V. harveyi were most commonly isolated. Multiple antibiotic resistance (MAR) to at least two antimicrobials was highest in ponds currently using oxolinic acid (24% of bacteria isolated from such ponds), followed by those that have previously used antimicrobials (19%) and the least was those from ponds that have not used any antimicrobials (17%). The lowest incidence of antibiotic resistance was observed in ponds that have not used any antimicrobials (41% of the isolates from such ponds). Among the individual antibiotics, incidence of resistance to oxytetracycline was highest (4.3% of the total number of isolates) followed by furazolidone (1.6%), oxolinic acid (1%) and chloramphenicol (0.66%).

      Resistance to individual chemotherapeutants did not reflect the pattern of antimicrobial use with ponds that have previously used antimicrobials showing the highest incidence of resistance to one antimicrobial (12% of total isolates from such ponds). Resistance to both oxolinic acid and furazolidone (15% of total number of isolates) was highest compared to other antimicrobial resistance profiles (1–12%). Multiple antimicrobial resistance and intermediate reaction to at least one antimicrobial are associated with antimicrobial use.
    • Book chapter

      Bacterial diseases 

      EA Tendencia & CR Lavilla-Pitogo - In K Nagasawa & ER Cruz-Lacierda (Eds.), Diseases of cultured groupers, 2004 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Bacteria are very common in the aquatic environment. Most bacterial disease agents are part of the normal flora of the water. They cause disease only when the fish are stressed due to poor environmental conditions, inadequate diet and poor husbandry techniques.

      This chapter focuses on the most common bacterial diseases of groupers.
    • Article

      Bacterial flora of milkfish, Chanos chanos, eggs and larvae 

      RD Fernandez, EA Tendencia, EM Leaño & MN Duray - Fish Pathology, 1996 - Japanese Society of Fish Pathology
      Aerobic bacterial flora of eggs and larvae of milkfish, Chanos chanos, was investigated. Microflora in the incubating water of egg, rearing water of larvae, water source, and larval food was also analyzed.

      Aerobic bacterial flora of milkfish eggs was largely influenced by the bacterial flora in the incubating water. Both in eggs and in the incubating water Pseudomonas species were the dominant bacteria. During milkfish larval rearing, intestinal aerobic bacterial flora was examined at days 1, 3, 7, 10, 15, 18, and 21. Bacterial number in the larvae and rearing water significantly increased during the culture period up to day 18 but dropped significant at day 21. Pseudomonas species were detected from yolk-sac larvae (day 1) as the dominant bacteria, similarly to the normal flora in the rearing water. However, intestinal bacteria were predominated with Vibrio species when the yolk-sac was absorbed on day 3. Larval rearing water, water source, and larval food contained predominantly Pseudomonas species.
    • Book chapter

      Bacterial isolation, identification and storage 

      L Ruangpan & EA Tendencia - In Laboratory manual of standardized methods for antimicrobial sensitivity tests for bacteria isolated from aquatic animals and environment, 2004 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Bacterial isolation, purification and identification are the first steps to bacteriological studies. Isolation is done to obtain pure bacterial cultures. Bacteria are usually isolated from fish kidney and spleen; and from the hepatopancreas, lymphoid organ and muscles of shrimp. These tissues are monitor organs that usually harbor the disease-causing bacteria during infection.
    • Article

      Bacterial microbiota of eggs from cage-reared and tank-reared grouper, Epinephelus coioides 

      EA Tendencia - Bulletin of the European Association of Fish Pathologists, 2004 - European Association of Fish Pathologists
      At SEAFDEC AQD, opaque spawned grouper eggs are observed during collection in cage-reared brood stock; while opaque and multi-colored eggs are often observed in tank-reared fishes. This study aimed to investigate the occurrence of these opaque and multicolored eggs and at the same time to compare the bacterial microbiota of eggs from brood stock reared in cages, to those from fish reared in concrete tanks. Grouper eggs from brood stocks reared in cages and tanks were processed for bacterial count and identification. Results showed that total bacterial count (on MA) and presumptive Vibrio count (on TCBS) of eggs from brood stock reared in concrete tanks were lower than those from cage-reared fishes. Aeromonads (for tank-reared) and Pseudomonads (for cage-reared) were the dominant bacteria in the good eggs; while Vibrios were dominant in the bad eggs for both egg sources. Total bacterial count of the egg-incubating medium from the brood stock tanks (104 cfu/ml) was lower than the total bacterial count of water from the cages (107 cfu/ml). Presumptive Vibrio counts of water from the tanks (102 cfu/ml) were lower than those from the cages (106 cfu/ml). The Aeromonads dominated the water from the tanks; while Vibrios dominated those from the cages. Good eggs that did not hatch, turned yellow after 3 days, and pink after 5 days.
    • Article

      Bamboo back disease in tiger shrimp, Penaeus monodon 

      EA Tendencia - Bulletin of the European Association of Fish Pathologists, 2002 - European Association of Fish Pathologists
      This report describes bamboo back disease affecting Penaeus monodon in the Philippines. Affected and normal shrimps were processed for bacterial isolation and histopathology. Morphological changes in the external anatomy were also noted. The cuticle of the abdominal segments of shrimp with bamboo back disease do not overlap properly which gives them a bamboo-like appearance. The appendages are shorter compared with normal shrimps. No bacteria were recovered from the hepatopancreas, lymphoid organ, and hemolymph thus ruling out bacterial infection. Histopathology shows normal hepatopancreas, but the muscle fibers of the abdominal segments are fragmented and necrotic.
    • Article

      Comparing profits from shrimp aquaculture with and without green-water technology in the Philippines 

      RH Bosma & EA Tendencia - Journal of Applied Aquaculture, 2014 - Taylor & Francis
      To reduce disease impact, Philippine farmers developed the green-water (GW) system, which has been spreading rapidly since 2008. In the most applied GW-system, the shrimp pond receives water from a reservoir stocked with tilapia. We collected financial data on GW and non-GW systems from farms having similar management and environmental context. All farms had more than one pond; the average pond area was < 1 ha, and total pond areas per farm ranged from 1.4 to 139 ha. The total variable and fixed costs per ha of shrimp pond were not different for GW and non-GW farms, but on GW farms the cost per kg of shrimp produced was lower. The latter was higher than the 2009 market price of 30 g shrimp for non-GW farms mainly. In GW farms the cost of seed was lower, and survival rates and individual shrimp weights at harvest were higher for an equally long culture period.
    • Conference paper

      Diseases affecting wild and farmed mud crab in the Philippines 

      EA Tendencia & MVC Cabilitasan - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Mortalities due to cannibalism and diseases have been reported as major problems in the grow-out phase of mud crab production. This study aimed to identify and describe diseases affecting farmed and wild mud crab (mangrove crab) including predisposing, risk and protective factors, and possible prevention and control measures. A total of 767 wild and farmed mud crab samples were collected. External examination showed abnormalities such as short abdominal flap, discoloration of the abdominal region, darker carapace, lesions on carapace, claws and legs, and presence of epibionts like algae and the barnacles Balanus sp. on the carapace. Internally, necrotic, black and brown gills, and discolored gonads were observed. Stalked barnacles, Octolasmis spp., were observed in the gills. White spot syndrome virus (WSSV) was detected in 14 samples sourced from farms and Infectious hypodermal and haematopoietic necrosis virus (IHHNV) in 2 wild samples. WSSV was implicated in mortality cases. Low temperature and presence of WSSV positive shrimp were identified as risk factors for WSSV infection or outbreak. Pathogenicity tests for some isolated bacteria suggested that these may cause mortality in mud crab under stressful conditions. To prevent mortality due to WSSV infection, it is recommended to avoid polyculture of mud crab with shrimp and/or other crustaceans.
    • Book

      Diseases of juvenile and adult mud crab Scylla spp. in the Philippines 

      EA Tendencia, MVC Cabilitasan & E Tobias-Quinitio - 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 64
      This manual aims to provide updated information on the diseases of mud crabs initially authored by Lavilla-Pitogo and dela Peña (2004). It includes the name of the disease, causative agent, stages affected, effects on mud crab and methods of prevention and control. Except for the infectious diseases caused by viruses, which can be detected through molecular methods, most of the diseases can be visually diagnosed. Photographs of the external and internal anatomy of a normal mud crab, including the different sexes and species are included to help readers differentiate a normal from a diseased mud crab.
    • Book

      Diseases of penaeid shrimps in the Philippines 

      CR Lavilla-Pitogo, GD Lio-Po, ER Cruz-Lacierda, EV Alapide-Tendencia & LD de la Peña - 2000 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual / SEAFDEC. Aquaculture Department; No. 16
      The manual provides information on the diseases that affect the 3 major species of shrimps cultured in the Philippines: Penaeus monodon, P. merguiensis and P. indicus. It includes the common name of the disease, causative agent, species affected, stages affected, gross signs, effects on the host and methods of prevention and treatment. This revised edition includes newly discovered diseases. It is hoped that the manual will be of considerable help to shrimp farmers in identifying the disease and lead to prevention or early disease diagnosis and control.
    • Book chapter

      Disk diffusion method 

      EA Tendencia - In Laboratory manual of standardized methods for antimicrobial sensitivity tests for bacteria isolated from aquatic animals and environment, 2004 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Disk diffusion method is based on the principle that antibiotic-impregnated disk, placed on agar previously inoculated with the test bacterium, pick-up moisture and the antibiotic diffuse radially outward through the agar medium producing an antibiotic concentration gradient. The concentration of the antibiotic at the edge of the disk is high and gradually diminishes as the distance from the disk increases to a point where it is no longer inhibitory for the organism, which then grows freely. A clear zone or ring is formed around an antibiotic disk after incubation if the agent inhibits bacterial growth.
    • Article

      Effect of different mangrove-to-pond area ratios on influent water quality and WSSV occurrence in Penaeus monodon semi-intensive farms using the greenwater culture technique 

      EA Tendencia, RH Bosma, JH Primavera & JAJ Verreth - Aquaculture, 2012 - Elsevier
      White spot syndrome virus (WSSV) has been affecting the shrimp industry worldwide for two decades now. It continues to bring economic losses to affected farms. Despite the many studies on its epidemiology, there is no proven treatment or control measure. Diseases, like the WSSV, results from the interaction of three factors: host, pathogen and environment. The environment plays an important role in disease development and determines the health or the immune capacity of the shrimp. High mangrove-to-pond area ratio (MPR) is reported as a protective factor against WSSV. This study investigates if mangroves affect the physicochemical properties of the water and soil as well as the prevalence of infectious agents like the WSSV by monitoring farms with different MPR (0:1, 1:1, 4:1).

      Results showed that quality of influent water was not significantly better in farms with high MPR. Significantly higher available sulfur was observed in MPR-4; significantly higher percentage green vibrios in the soil in MPR-0. WSSV was detected in farms with MPR-1 and MPR-4 but did not result in an outbreak, suggesting that the presence of mangroves could prevent WSSV outbreak.
    • 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 Epinephelus coioides, Chanos chanos, and GIFT tilapia in polyculture with Penaeus monodon on the growth of the luminous bacteria Vibrio harveyi 

      EA Tendencia, AC Fermin, MR dela Peña & CH Choresca Jr. - Aquaculture, 2006 - Elsevier
      Studies have shown that the presence of Tilapia hornorum hybrid has antibacterial effect against luminous bacteria. The present study aims to determine the effect of different fish species such as grouper, milkfish and tilapia in polyculture with shrimp on the growth of luminous bacteria. Results showed that stocking of tilapia Oreochromis niloticus hybrid and grouper Epinephelus coioides at a biomass of 500 g/m3 efficiently inhibited the growth of luminous bacteria in shrimp (biomass = 80 g/m3) rearing water and positively affected shrimp survival. Results also showed that the presence of milkfish Chanos chanos at a biomass of 500 g/m3 did not inhibit the growth of luminous bacteria in shrimp (biomass = 80 g/m3) rearing water.
    • Article

      Effect of iodine disinfection on the bacterial flora and hatching rate of grouper, Epinephelus coioides eggs at the cleavage and eyed stages 

      EA Tendencia - Bulletin of the European Association of Fish Pathologists, 2001 - European Association of Fish Pathologists
      In this study, the effect of iodine disinfection on the bacterial flora and hatching rate of grouper egg at two different stages of development were investigated. The eggs (at cleavage and eyed stages) were soaked for 10 min in sterile seawater (control) and at different free iodine concentrations- 2.5, 5, 10, 15 and 20 ppm. Total bacterial and presumptive Vibrio count, as well as the hatching rate of the treated eggs were determined. Results showed that Vibrios are eliminated by iodine disinfection (2.5-20 ppm) but not by rinsing with sterile seawater. The total bacterial load and hatching rate of eggs decreased as the iodine concentration increased. Iodine concentrations of 15 and 20 ppm were effective in significantly reducing the total bacterial load of grouper egg at both the cleavage and eyed stages. However, at these concentrations the hatching rates were also significantly lower. Results also showed that grouper, Epinephelus coioides, eggs tolerate stress better at the eyed stage than at the cleavage stage.
    • Article

      Effect of shrimp biomass and feeding on the anti-Vibrio harveyi activity of Tilapia sp. in a simulated shrimp–tilapia polyculture system 

      EA Tendencia, MR dela Peña & CH Choresca Jr. - Aquaculture, 2006 - Elsevier
      The efficiency of Tilapia hornorum to control luminous bacteria in a simulated shrimp farm environment has been reported. However, the effects of different factors such as feed input and the shrimp biomass were not taken into consideration. This study investigated the effect of feeding and increased shrimp biomass on the efficiency of tilapia to inhibit the growth of luminous bacteria. Results showed that feeding enhances the antibacterial activity or improves the efficiency of tilapia to inhibit the growth of luminous bacteria. However, the efficiency of tilapia at a biomass of 500 g/m3 is reduced if the shrimp biomass is greater than 80 g/m3. This explains the discrepancies in the results obtained in the use of tilapia to control luminous bacterial disease in shrimp ponds.

      The effect of starvation on the bacterial load of tilapia, grouper and milkfish feces and the amount of feces in the intestine was also investigated. Results showed that total bacterial and presumptive Vibrio count of fish feces decreased after 1 week of starvation except for the presumptive Vibrio count of grouper. The amount of feces in the intestine also decreased as starvation progressed. Moreover, bacteria isolated from the three species have antibacterial activity against the luminous bacteria Vibrio harveyi.
    • Article

      Effect of three innovative culture systems on water quality and whitespot syndrome virus (WSSV) viral load in WSSV-fed Penaeus monodon cultured in indoor tanks 

      EA Tendencia, RH Bosma & LR Sorio - Aquaculture, 2012 - Elsevier
      White spot syndrome virus is the most important among the shrimp diseases. It has been devastating the shrimp industry for more than 3 decades. Previous studies reported that greater percentage of yellow colonies on thiosulfate citrate bile salt sucrose agar (yellow vibrios) in the rearing water, abundant supply of natural food such as Chlorella, and the use of the greenwater technology (GW) are some ecological ways of preventing WSSV outbreak. The aim of this study was to investigate the efficiency of the 3 systems against WSSV.

      Shrimp, experimentally infected with WSSV by feeding with WSSV positive shrimp carcass, was cultured in tanks using three treatments: with tilapia to simulate the GW, seeded with Chlorella, and with molasses added to enhance growth of yellow vibrios. Shrimp cultured in seawater served as the control. Survival was recorded and shrimp were analyzed for WSSV quantification using qPCR upon termination.

      Analysis showed no significant differences in shrimp survival at 120 h post infection in all treatments and the control. However, from the original viral load of 1.40 × 101 WSSV/mg sample, WSSV decreased and was significantly lowest in shrimp cultured using GW (7.0 × 100), compared to the control (4.82 × 105) and the other treatments (3.66 × 105 for molasses added and 4.64 × 105 for Chlorella seeded) in which viral load increased 4–5 times. Shrimp survival was highest in Chlorella seeded treatment and lowest in GW. Nitrogenous waste concentrations were lowest in molasses added water and highest in GW.

      Results suggest that the GW culture technology provides protection against WSSV while addition of molasses lowers nitrogenous waste concentration. The use of GW in combination with the addition of molasses for shrimp culture is suggested.